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  • Recul mondial des glaciers « RealClimate
    resorts were hurting for business This is going to skew a comparison because the snow on Baker should have made the glaciers advance like wild yet it did not The weather patterns over the Pacific showed a striking regularity that showed up as a similar weather roughly 120 degrees longitude over in Switzerland on the same year While measuring the relative advancing and retreating of lower latitude glaciers is interesting I assert that the weather patterns that control the precititation or lack of it show a striking pattern at time and therefore are more interesting This fits well with the arctic heating up roughly twice as fast as the lower latitudes and the current anomalous heat that has wiped out the snow festival in Greenland 14 Henry Molvar says 21 Mar 2005 at 12 37 AM Re 8 A book review By Richard Dyer of The Boston Globe see opens with Michael Crichton s new novel comes equipped with appendices an author s message a 21 page bibliography graphs and charts in the text and even footnotes A disclaimer at the front indicates that this is a work of fiction but footnotes are real My position is that the novel footnotes bibliography author s message and even the disclaimer are parts of the work of fiction It is all part of his literary licence to entertain if it helps to sell more books or even leads to a movie deal so much the better Any controversy Crichton scares up by whatever means is to HIS advantage 15 Dan Hughes says 21 Mar 2005 at 11 19 AM I think that the graph shown in the note provides a basis for the following comments The snow and ice in glaciers might melt when the energy addition into the glacier material is sufficient to supply the energy necessary to raise the temperature to the melting point plus the latent heat of melting The physical processes by which energy might be added into the glacier material include A convection between the glacier surfaces and local surrounding atmosphere and water B direct radiation onto the exposed surfaces of the material C addition of material that is at a temperature higher than the melting temperature onto the top of the glacier rain say D Sublimation of the ice directly into the atmosphere and E conduction into the material from the contact areas between the glacier and surrounding solid material All these processes are local to the glacier of interest An increase in the rate of change of the decrease in the mass of glaciers might occur when the rate of energy addition into the glacier material increases The rate of energy addition by the above physical processes might increase because of the following physical phenomena 1 the heat transfer coefficient between the glacier surface and surrounding gaseous or liquid material increases 2 the local temperature of the surrounding gas or liquid increases 3 the radiative energy exchange properties of the surface of the glacier change in the direction of increasing the absorption of radiative energy 4 conduction energy exchange into the glacier increases due to say the temperature of the surrounding material increasing 5 an increase in the amount of warmer material rain falling onto the glacier and 6 the surface area to volume ratio of the glacier surfaces exposed to its surroundings increases as the shape of the glacier changes Each of these is local to and characteristic of a single glacier of interest A glacier responds to changes in the local processes A D and local phenomena 1 6 In order correctly argue that an increase in the global average temperature is the only dominant phenomena requires the following First a physical phenomena or process based causal relationship between the global average temperature and the local temperature 2 above must be proven Second all the other phenomena must be demonstrated to be insignificant for each individual glacier of interest Demonstration of a physically based causal relationship is necessary because relationships determined only by correlation and stats do not prove anything Correlations are interpolation methods and are useful only after all possible physical process connections have been considered and the proven dominant ones selected for correlating parameters Additionally even under these conditions interpolating within the range of experimental measured parameters is about the only safe use of correlations And I would argue that the only valid physical parameters are those local to and characteristic of each individual glacier Extrapolation should almost always be avoided Thus even if it is rigorously demonstrated that for a given glacier a causal connection between the global average temperature and the decrease in the mass of a glacier exists extrapolation to other glaciers is not recommended To demonstrate this point note that in the graph some of the glaciers have recently increased in length If one accepts that the global average temperature is the one and only important correlating parameter it seems that one would have to conclude that an increase in the global average temperature results in an increase in the mass of glaciers 16 eric says 21 Mar 2005 at 3 06 PM Response Thanks everyone for your comments on this post I was too busy to respond to each one as I was at a meeting on the decline of British Columbia glaciers shortly after I posted the commentary I will try to respond in a bit more detail to some of these as time permits A couple of quick comments though The discussion of Crichton is rather off topic but I will note that we ve addressed Crichton at length on earlier RealClimate posts See Michael Crichton s State of Confusion and State of Confusion II The questions about Kilimanjaro are good ones and I will defer to R Pierrhumbert who has kindly offered a piece on this for RealClimate see 8 above for the details I ll just note here that mass loss on high altitude tropical tropical glaciers is largely by sublimation not by melting and that the relationship with temperature is quite different than the mid latitude glaciers that dominate the Oerlemans work Oerlemans did not include Kilimanjaro or other such glaciers presumably for this reason Finally I agree very much with 13 On a year to year basis it is certaintly not average temperature but local seasonal weather that dominantes glacier mass balance The extreme snowfall year at Baker certaintly would have led to advance of the glaciers given a few more years like that But subsequent years cancelled that influence This year is a case in point when we now have record low snowfall about 10 of average or less and this time it is because the storms are being directed very much away from Mt Baker the opposite to what happened in 98 99 Over time these things tend to average out and for most but not all glaciers the temperature change generally winds up being the dominant signal 17 Lynn Vincentnathan says 22 Mar 2005 at 2 00 PM Re 16 my limited understanding of GW is that it entails not only increased average warming but also greater swings between temperature extremes including colder warmer temperatures beyond the mean I E the standard deviation from the mean also gets larger In that case along with greater precipitation and the precipitation belt moving to higher latitudes there could be more snow in the winter greater melting in the summer in higher latitudes while I d think the lower latitudes with less precip and the local mean temp being higher would melt the glaciers faster without adequate snowfall low winter temps to slow this glacial decrease However average warming is greater at higher latitudes which would reduce the difference between glaciers at higher lower latitudes Please tell me where I m wrong I m struggling to understand and am not only writing a screenplay which scientists might like to dismiss as not science but am also working on an anthropological paper about GW representation as fact fiction Response You are very right It is not the mean annual temperature but rather the seasonal energy budgets and snowfall amounts that determine what glaciers do Whether seasonal extremes become greater with overall increased warmth will vary from place to place We expect there to be a more detailed tutorial on all this at some time in the future Note however that your intuition about latitudes is probalby not right Most of the low latitudes glaciers are necessarily at very high altitudes and many have both high accumulation rate and very cold temperatures In contrast mid latitude glaciers such as the South Cascade Glacier shown in the photos is very warm ice temperature is about zero celcius all year round and snowfall rates are also high At the highest latitudes low precip and cold temperatures are both found eric 18 Francis MASSEN says 22 Mar 2005 at 6 25 PM Please read this sober paper on glaciers and climate by french professor and glaciologist Robert Vivian sorry it is in french http virtedit online fr article html In a follow up article he starts saying No glaciers do not risk disappearing Response My French is good enough for me to question whether this is a sober assessment of the situation It appears all to be personal opinion with a few examples There is no attempt at any kind of quantitative analysis and in any case the article is just a web site You ll need a stronger argument to convince the skier in me not to worry about the future of glaciers in the Alps eric Response I did read this article which was not in any case peer reviewed and I confirm Eric s comment This article is not really sober jumping from glaciers length to the french society s confidence in science from the snowball earth to Svensmark and so on As pointed out by Eric there s no quantitative analysis simply because the author does not like the stats statistically averages do not mean anything and the author prefers to do some peremptory affirmations I would recommend two alternative readings for the francophones on recent results obtained on alpine glaciers ici et la articles published in PIGB thibault 19 Hans Erren says 23 Mar 2005 at 5 08 AM Here is a 2000 year study for the alpine Aletsch glacier http www klimanotizen de html newsletter 4 html http www klimanotizen de assets images 2003 10 25 aletschgletscher 2000 1 gif see also http www zamg ac at ALP IMP downloads session haeberli pdf 20 John Finn says 23 Mar 2005 at 7 23 AM Having looked at the graphic depicting the reduction in various glaciers I have a problem accepting the consenus view represented by most of the comments that anthropogenic warming is the cause of the glacier retreat This is related to a similar issue over which I ve had a previous argument i e the famous lake study elsewhere on this site Basically the reduction in glaciers begins before well before in most cases greenhouse gas concentrations could have had any warming effect Where data is available it s apparent that glacier retreat begins around the mid 19th century Before we cite human influence in the form of increased CO2 emissions as the cause it is perhaps reasonable to ask what the levels of atmospheric CO2 were at the time It s generally accepted that pre industrial CO2 levels were around 280 ppm and that levels in 1900 were around 295 ppm Since industrial CO2 emissions were massively higher between 1850 and 1900 than any period up to 1850 it s hard to believe that 1850 CO2 levels in the atmosphere were any more than 285 ppm There s no way this small increase could be responsible for a climate forcing which produced the dramatic results shown in the diagram This of course leaves another question If mid 19th century glacier retreat is not due to human causes then why can t 20th century glacier retreat simply be an extension of that same natural process Response As I noted in the post Oerlemans s work doesn t address whether or not the worldwide glacier retreat is part of a natural phenomenon You can t simply take one curve look at it by eye and start to make claims about the validity of the idea that human influence on climate is significant Investigating the cause of 20th Century warming is properly done in detection and attribution studies which analyze the various forcings e g solar variations greenhouse gases or volcanic activity and the observed time and space patterns of climate change in detail Work like that of Oerlemans or the so called hockey stick curve provide some of the observations used in such studies but don t replace such studies Detection and attribution analyses with a range of different techniques have invariably concluded that the dominant cause of 20th Century warming is man made greenhouse gases See the earlier post by stefan here eric 21 Lynn Vincentnathan says 23 Mar 2005 at 1 02 PM Dan Kellog an engineer not climate scientist on another blog has raised the issue of once a glacier has melted away the local temps could rise dramatically and perhaps averaged altogether around the world as glaciers melt away increase the rate of global warming Could you comment on this Here is what he wrote http www marklynas org The process of melting large quantities of ice takes time only because of the tremendous heat required to do that Since melting ice absorbs so much more energy than heating land or even water then once the ice melts the local area should expect a faster rise in temperature due to decreased albedo and no more ice to absorb further heat For the lay person know that a glass of ice water maintains its cold temperature as long as there is ice Once the ice melts the glass of water warms fairly quickly This fact is based on the physics of changing the phase of water from solid to a liquid It is called the latent heat of fusion For water it is 143 3 Btu per pound And since water s specific heat is 0 998 Btu per pound degree Fahrenheit then it would take 143 times the heat energy to melt water at its freezing point than to raise the same quantity of water 1 degree Fahrenheit once it became a liquid For the metric people that converts to 257 times the heat energy needed it melt water at its freezing point than to raise the same quantity of liquid water to 1 degree Celsius Is this a factor of any significance related to local and perhaps global warming is it being considered Response I couldn t find the specific post you refer to but in any case the answer is that alpine glaciers cover a very small fraction of the globe and their disappearance will have very little impact on local temperature Locally their loss could matter but only very very locally i e in the same valley the glacier is in and only in late summer in winter it is the snowpack which covers a far greater part of the landscape which strongly influences temperature If the glaciers are gone but snowpack continues which of course it may not then the effects will be minimal Finally it is not the latent heat of melting but the reflectivity albedo that is the more important factor eric 22 Dano says 23 Mar 2005 at 2 30 PM RE eric s response to 20 We would do well to remember the reason for RealClimate which is to better address and disseminate the latest climate science findings Eric points at the flaw in the poster s argument looking at one graph and declaring a HA I suggest that this is a very common argument perfected by Daly and acolytes and we should think about this as a sub category of argumentation and address it as such Best D 23 Michael Jankowski says 23 Mar 2005 at 4 44 PM Re 17 Re 16 my limited understanding of GW is that it entails not only increased average warming but also greater swings between temperature extremes including colder warmer temperatures beyond the mean I think you ve confused a few theories together Some GW theorists do think weather patterns could change and cause some of today s warm mild climates to become cold so maybe that s what you re thinking of Many theorize that a warmer world would have more frequent and stronger extreme weather events but they are not referring to temperature instead preciptation tornado hurricane etc So maybe that s another theory you re thinking of However I would be surprised to find that someone has claimed that GH warming will produce colder temperatures relative to the mean except for localized regions due to the changing weather patterns theory above In fact cold dry air masses such as you typically have on extremely cold days would warm the first most in a GW scenario Hence they should be even closer to the mean in a GW world I would think that max temps would also tend to be closer to the new warmer average temps in a greenhouse GW world too In other words the average temperature minimum temperature and high temperature in a GW world would tend to be higher than it currently is but the difference between avg min and avg max would be smaller than it currently is This may differ from region to region if weather patterns ocean currents etc change due to GW but it should hold true in general in a GW world I m just going on my own limted GW knowledge and some basic physics and greenhouse theory Someone step in if I erred 24 Stephen Berg says 23 Mar 2005 at 5 49 PM This post may not belong on this thread but the Climate Change Disinformation thread comments have been ended An interesting study done by the MIT has found that the general public in the US is quite unaware of the phenomenon and the hazards of climate change The summary is linked below http www eurekalert org pub releases 2005 03 miot ccp032305 php 25 Jo Calder says 24 Mar 2005 at 3 37 AM Re Eric s comment in 20 You mean the dominant cause of late 20th Century warming don t you Cheers Jo Response Sure though in fact the late 20th century rise dominates the total for the entire century 26 John Finn says 24 Mar 2005 at 6 01 AM You can t simply take one curve look at it by eye and start to make claims about the validity of the idea that human influence on climate is significant I haven t taken one curve I ve looked at them all And the majority of them or those for which data is available start to nose dive before or around the mid 19th century Investigating the cause of 20th Century warming is properly done in detection and attribution studies which analyze the various forcings e g solar variations greenhouse gases or volcanic activity Good However as far as the mid 19th century is concerned forcings due to GHG concentrations are insignificant so we are only left with natural forcings or causes as an explanation for glacier retreat and the observed time and space patterns of climate change in detail I think the argument is much simpler than this If the cause hasn t yet happened but the effect has then there is a problem with the suggested cause effect relationship The level of detail in the analysis is irrelevant But if you have some data which shows AGW was a factor before 1900 say then let s see it Response GHGs starts to be a factor around 1850 as is clear from the forcing diagrams we have discussed multiple times But other factors were of equal or greater magnitude Only after 1950 or so do anthropogenic effects become dominant Thus the argument is it AGW or not prior to 1950 is a false dichotomy Of the forcings leading to a warming in the early part of the records solar decreasing volcanism and GHGs all play a part and with a role for cooling due to land use change and aerosol increases The specific attribution in a nice percentage figure is more difficult becuase of the uncertainty in the solar and aerosol effects in particular The statement that warming from 1850 onwards is partially due to increased GHG forcing is perfectly valid Hopefully we can now move on to a more interesting discussion gavin 27 Jemima says 25 Mar 2005 at 2 32 AM Further to Eric s response to John Finn at 20 presumably the simplest answer of all is that almost everyone agrees that there was a Little Ice Age of sorts which affected at least Europe and from which rewarming had begun by the 18th century Consequently almost everyone would expect to see glacial records indicate some retreat of the ice dating to the earliest stages of that period of that warming just as John sees in the graph above So really no surprises here situation quite uncontroversial 28 dave says 25 Mar 2005 at 3 47 AM I was just thinking that the now inaptly named Glacier National Park could be described as Glacial Moraine National Park Glacial Moraine or even as Glacial Till National Park Glacial Till in the next few decades I think these newly transformed natural parks will have something to offer for interested scientists For example the young geologist student can study the recent effects on the landscape of rapidly retreating glacial ice Given most people s inability to understand irony of any kind if my level of sarcasm in this comment is not understood I will spell it out the glaciers there will almost entirely gone 29 eric says 25 Mar 2005 at 4 19 PM With respect to 27 it is worth noting that in fact there is a serious question as to whether the Little Ice Age was a global event or was largely restricted to Europe It has by no means been proven that the Little Ice Age had the same degree of spatial coherence of advance as does the current retreat As an example of what I mean by this consider two of the long European records shown in the figure d Argentiere evidently advanced from about 1820 to 1850 while Grindelwald was retreating But both retreated together from about 1940 Unfortunately there really isn t enough data from enough locations going back far enough in time to examine this question rigorously That s one of the reasons why the glacier data aren t a particularly strong data set for assessing the relative influences of natural vs anthropogenic change They are however useful for assessing the amount of change that has occurred That s the point of Oerelmans s paper and this post 30 Joseph O Sullivan says 25 Mar 2005 at 6 12 PM Thanks Gavin for the short and simple response to the mid 19th century anthropogenic warming question Is anything known about how mountain ecosystems are reacting to glacial retreat I would like to see a post from Realclimate about current ecological effects of anthropogenic climate change Something detailing any ongoing changes in communities of living things in the natural world like coral reefs lakes and alpine regions caused by anthropogenic climate change would be great if its not too off topic for RC Response In general ecology is not our area of expertise but I would venture that ecosystems around glaciers are generally used to significant changes I suspect a larger effect is not the glaciers themselves but the rising treeline see e g this article from Science eric 31 Eero Priha says 27 Mar 2005 at 1 14 PM Why satellite measurements show much lower warming than earth stations especially in western Europe Has urban heat island effect corrected adequately because American and Siberian stations not so ueban show less warming or no warming at all Also in Helsinki measurement point in the middle of city shows much more warming than Sodankylà in Lappland no clear warming Response There is information on the urban heat island effect and the satellite data already posted on RealClimate See here Response The satellite stuff is probably better covered at http en wikipedia org wiki Satellite temperature record William 32 Stephen Berg says 28 Mar 2005 at 6 01 PM Did anyone catch CNN Presents last night It was on climate change and was more balanced than I was thinking it would be They had James Speth Ross Gelbspan and Russ Schnell as guests but also had Richard Lindzen and Pat Michaels However the time they allotted to Lindzen and Michaels was maybe 1 8 of the show They talked about sea level rise due to melting glaciers and the disintegration of Antarctica s vast ice sheets and the effects of this rise on the planet especially coastal regions which are heavily populated and the Island states specifically Tuvalu They also discussed the situation in the North where polar bears are much less healthy than 30 years ago due to a three week earlier break up period and the loss of the culture of the Inuit and northern Aboriginal tribes One guest that really peeved me was Jim Conatin You can see for yourself what rubbish he was saying Here is an unofficial transcript of the show http edition cnn com TRANSCRIPTS 0503 27 cp 01 html 33 Michael Jankowski says 28 Mar 2005 at 6 44 PM Response The satellite stuff is probably better covered at http en wikipedia org wiki Satellite temperature record William Covers the basics but a rather poor coverage IMHO especially with regard to the poster s questions It even includes a reference to Fu s 2004 Nature article which Spencer Christy and others have ripped to shreds Fu himself adjusted his methodology in response rebuttal and showed results much closer to those of Christy and Spencer in a subsequent publication although Christy and Spencer still think there are errors in the methodology and still lower than surface warming rates For some time the UAH satellite data s chief significance is that they appeared to contradict the United Nations IPCC predictions about global warming In April 2002 for example their satellite temperature trend was only 0 04  C decade compared with 0 17 0 06  C decade from surface measurements however in the years since the UAH trend has roughly doubled to come more in line with other trends Roughly doubled certainly has it more in line with other trends but I d say still showing only 50 of surface warming is a huge gap to fill when it is supposed to be at least as large as the surface warming A report by the National Research Council that reviewed upper air temperature trends stated Data collected by satellites and balloon borne instruments since 1979 indicate little if any warming of the low to mid troposphere the atmospheric layer extending up to about 5 miles from the Earth s surface Climate models generally predict that temperatures should increase in the upper air as well as at the surface if increased concentrations of greenhouse gases are causing the warming 12 The huge disparity the AGH skeptics always point to On the other side However the same panel then concluded that the warming trend in global mean surface temperature observations during the past 20 years is undoubtedly real and is substantially greater than the average rate of warming during the twentieth century The disparity between surface and upper air trends in no way invalidates the conclusion that surface temperature has been rising 13 Whether the surface temperature had been rising since 1979 was not in doubt The magnitude it actually had actually risen how different these temperatures were from the 1940s the conflict between model prediction theory and observation etc were the issues the satellite data raised And then there s the next statement An important critique of the satellite record is its shortness adding a few years on to the record or picking a particular time frame can change the trends considerably We see this issue when it comes to other temperature records too We ve all seen bookends used to identify surface temperature trends that if expanded or contracted by a few years reveal drastically different results Regardless 25 years of side by side comparison with surface based readings and corroboration with weather balloon data seems like plenty of time to determine that something is amiss It will be interesting to see how everything sorts out concerning the interpretation of the satellite data However I think the big picture effect that the satellite interpretests are going for by coming up with average global trends may be the incorrect approach A better approach may be to compare the data of individual stations vs satellite data for corresponding areas This will reveal flaws in the data either surface or satellite far more quickly It would seem to me that the global average approach would serve to dampen errors 34 stephan harrison says 29 Mar 2005 at 6 43 AM A few comments following No 15 it is indeed true that some mountain and valley glaciers display asynchronous responses to climate change The most obvious example of this is the case of calving glaciers where their gross behaviour may relate more to water depth at the calving front than small scale climate variations However even in these cases such topographic factors are only second order controls on fluctuations and climate will eventually dominate the behaviour Following No 29 I would argue that the glacier signal shows that the Little Ice Age may well have been global For instance in Patagonia we have evidence to show that most of the outlet glaciers of the Northern Icefield receded from their late Neoglacial limit around 1880 or so This ties in with many of the glacier climate records from the Northern Hemisphere although we don t yet have much evidence for glacier advances in Patagonia around the 16th century Response There s no question that many most glaciers were at their most advanced in the last few thousand years some time in the mid to late 19th century To what extent those advances really represent a globally synchronous event requiring external forcing i e the sun is less clear to me at least I think an interesting question is whether the LIA was a globally coherent as today s recession is eric 35 Tim says 29 Mar 2005 at 9 38 AM In reply to 30 you might find it interesting to have a look at http 192 171 163 165 which is the home page for the Continuous Plankton Recorder Survey I know that they have analysed this survey and found trends due to climate change in plankton populations they have some links to publications from the above page I don t know any details unfortunately 36 Pat Neuman Hydrologist says 29 Mar 2005 at 11 22 PM As global warming continues the amount of water vapor in the atmosphere increases The significance of latent heat for snowmelt has been described by Dunne and Leopold 1978 If water from moist air condenses on a snowpack 590 calories of heat are released by each gram of condensate This is enough energy to melt approximately 7 5 gm of ice which when added to the condensate yields a total of 8 5 gm of potential runoff Quote shown in my Sep 2003 article Earlier in the Year Snowmelt Runoff and Increasing Dewpoints for Rivers in Minnesota Wisconsin and North Dakota at http www mnforsustain org climate change htm The rate of snowmelt will increase as water vapor increases even with assumed no change in temperature during a given period of above freezing temperatures due to latent heat as moist air condenses on snow and ice Response Increased humidity may indeed be responsible for the Kiliminajaro glacier retreat discussed above eric 37 Lynn Vincentnathan says 30 Mar 2005 at 2 01 PM I think 33 is arguing against global warming or is claiming the warming might be just an urban heat effect So forgive me for being off glacier topic but haven t there been recent findings of deep ocean warming from Scripps Inst of Ocean Do these ocean findings finally lay to rest any arguments against anthropogenic global warming according to news coverage claims Do the findings definitively prove anthropogenic GW against any contradictory satellite data or non retreating glacier arguments Response See our post on this Why looking for global warming in the oceans is a good idea 38 John Dodds says 30 Mar 2005 at 8 19 PM Yes glaciers ARE melting But in the last ice age global warming 123 000 years ago ALL the ice in central Greenland melted the proof being that the ice cores stop hit bedrock at that time So WHY shouldn t we expect the glaciers to melt during this warming cycle Especially since 1 the sun is pouring out energy at a higher rate than it has for the the previous 800 1000 years 2 by Milankovitch orbital mechanics we are closer to the sun in our eliptical orbit the tilt is tending towards warmer winters cooler summers less ice accumulation a few hundred years ago the precession passed aphelion so that we are now receiving more solar energy due to precession that we did for the previous few thousand years AND 3 there is more CO2 to enhance multiply the increased solar radiation heat effects Response You are mixing apples with fish Yes there have been warmer times in earth history So what My still unanswered question is why does the hockey stick shape of Earth temperatures show up in a chart of the Solar magnetic flux How did some CO2 molecule on earth spread THAT news back to the sun Response Recent solar variations do not look just like the recent temperature history as this comment implies See our post on climate forcings Response A further comment All Greenland ice did not melt during the last intergalcial The ice cores hit bedrock because there is a continual divergence of ice near the base that feeds ice streams going to the ocean Greenland has probably had large amounts of ice for the last 3 million years although some significant portion may have melted during the last interglacial Similarly the best cores in Antarctica are likely to go back only a million years and yet Antarctica has been glaciated for at least 30 million years The answer to your question is that of course we expect glaciers to melt in a warming phase and that they are doing is a strong indication that we are in fact in a warming phase gavin 39 Joseph O Sullivan says 30 Mar 2005 at 10 50 PM Thanks Eric for recommending that article in Science comment 30 It s a great piece and refers to a lot of other sources that address climate change and ecosystems It s on a non subscription site at http meteora ucsd edu cap all downhill sci12mar04 pdf I have wanted to learn more about the effect of human caused climate change on the natural world I do have a bachelors in marine biology and some profession experience in ecology but that was a while ago I don t have the same connection to scientific areas I used to I decided to ask the working scientists at RealClimate to point me in the right direction Ecology is a separate area of science but climate and climate change are important parts of it I know

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  • Worldwide glacier retreat « RealClimate
    Crichton s new novel comes equipped with appendices an author s message a 21 page bibliography graphs and charts in the text and even footnotes A disclaimer at the front indicates that this is a work of fiction but footnotes are real My position is that the novel footnotes bibliography author s message and even the disclaimer are parts of the work of fiction It is all part of his literary licence to entertain if it helps to sell more books or even leads to a movie deal so much the better Any controversy Crichton scares up by whatever means is to HIS advantage 15 Dan Hughes says 21 Mar 2005 at 11 19 AM I think that the graph shown in the note provides a basis for the following comments The snow and ice in glaciers might melt when the energy addition into the glacier material is sufficient to supply the energy necessary to raise the temperature to the melting point plus the latent heat of melting The physical processes by which energy might be added into the glacier material include A convection between the glacier surfaces and local surrounding atmosphere and water B direct radiation onto the exposed surfaces of the material C addition of material that is at a temperature higher than the melting temperature onto the top of the glacier rain say D Sublimation of the ice directly into the atmosphere and E conduction into the material from the contact areas between the glacier and surrounding solid material All these processes are local to the glacier of interest An increase in the rate of change of the decrease in the mass of glaciers might occur when the rate of energy addition into the glacier material increases The rate of energy addition by the above physical processes might increase because of the following physical phenomena 1 the heat transfer coefficient between the glacier surface and surrounding gaseous or liquid material increases 2 the local temperature of the surrounding gas or liquid increases 3 the radiative energy exchange properties of the surface of the glacier change in the direction of increasing the absorption of radiative energy 4 conduction energy exchange into the glacier increases due to say the temperature of the surrounding material increasing 5 an increase in the amount of warmer material rain falling onto the glacier and 6 the surface area to volume ratio of the glacier surfaces exposed to its surroundings increases as the shape of the glacier changes Each of these is local to and characteristic of a single glacier of interest A glacier responds to changes in the local processes A D and local phenomena 1 6 In order correctly argue that an increase in the global average temperature is the only dominant phenomena requires the following First a physical phenomena or process based causal relationship between the global average temperature and the local temperature 2 above must be proven Second all the other phenomena must be demonstrated to be insignificant for each individual glacier of interest Demonstration of a physically based causal relationship is necessary because relationships determined only by correlation and stats do not prove anything Correlations are interpolation methods and are useful only after all possible physical process connections have been considered and the proven dominant ones selected for correlating parameters Additionally even under these conditions interpolating within the range of experimental measured parameters is about the only safe use of correlations And I would argue that the only valid physical parameters are those local to and characteristic of each individual glacier Extrapolation should almost always be avoided Thus even if it is rigorously demonstrated that for a given glacier a causal connection between the global average temperature and the decrease in the mass of a glacier exists extrapolation to other glaciers is not recommended To demonstrate this point note that in the graph some of the glaciers have recently increased in length If one accepts that the global average temperature is the one and only important correlating parameter it seems that one would have to conclude that an increase in the global average temperature results in an increase in the mass of glaciers 16 eric says 21 Mar 2005 at 3 06 PM Response Thanks everyone for your comments on this post I was too busy to respond to each one as I was at a meeting on the decline of British Columbia glaciers shortly after I posted the commentary I will try to respond in a bit more detail to some of these as time permits A couple of quick comments though The discussion of Crichton is rather off topic but I will note that we ve addressed Crichton at length on earlier RealClimate posts See Michael Crichton s State of Confusion and State of Confusion II The questions about Kilimanjaro are good ones and I will defer to R Pierrhumbert who has kindly offered a piece on this for RealClimate see 8 above for the details I ll just note here that mass loss on high altitude tropical tropical glaciers is largely by sublimation not by melting and that the relationship with temperature is quite different than the mid latitude glaciers that dominate the Oerlemans work Oerlemans did not include Kilimanjaro or other such glaciers presumably for this reason Finally I agree very much with 13 On a year to year basis it is certaintly not average temperature but local seasonal weather that dominantes glacier mass balance The extreme snowfall year at Baker certaintly would have led to advance of the glaciers given a few more years like that But subsequent years cancelled that influence This year is a case in point when we now have record low snowfall about 10 of average or less and this time it is because the storms are being directed very much away from Mt Baker the opposite to what happened in 98 99 Over time these things tend to average out and for most but not all glaciers the temperature change generally winds up being the dominant signal 17 Lynn Vincentnathan says 22 Mar 2005 at 2 00 PM Re 16 my limited understanding of GW is that it entails not only increased average warming but also greater swings between temperature extremes including colder warmer temperatures beyond the mean I E the standard deviation from the mean also gets larger In that case along with greater precipitation and the precipitation belt moving to higher latitudes there could be more snow in the winter greater melting in the summer in higher latitudes while I d think the lower latitudes with less precip and the local mean temp being higher would melt the glaciers faster without adequate snowfall low winter temps to slow this glacial decrease However average warming is greater at higher latitudes which would reduce the difference between glaciers at higher lower latitudes Please tell me where I m wrong I m struggling to understand and am not only writing a screenplay which scientists might like to dismiss as not science but am also working on an anthropological paper about GW representation as fact fiction Response You are very right It is not the mean annual temperature but rather the seasonal energy budgets and snowfall amounts that determine what glaciers do Whether seasonal extremes become greater with overall increased warmth will vary from place to place We expect there to be a more detailed tutorial on all this at some time in the future Note however that your intuition about latitudes is probalby not right Most of the low latitudes glaciers are necessarily at very high altitudes and many have both high accumulation rate and very cold temperatures In contrast mid latitude glaciers such as the South Cascade Glacier shown in the photos is very warm ice temperature is about zero celcius all year round and snowfall rates are also high At the highest latitudes low precip and cold temperatures are both found eric 18 Francis MASSEN says 22 Mar 2005 at 6 25 PM Please read this sober paper on glaciers and climate by french professor and glaciologist Robert Vivian sorry it is in french http virtedit online fr article html In a follow up article he starts saying No glaciers do not risk disappearing Response My French is good enough for me to question whether this is a sober assessment of the situation It appears all to be personal opinion with a few examples There is no attempt at any kind of quantitative analysis and in any case the article is just a web site You ll need a stronger argument to convince the skier in me not to worry about the future of glaciers in the Alps eric Response I did read this article which was not in any case peer reviewed and I confirm Eric s comment This article is not really sober jumping from glaciers length to the french society s confidence in science from the snowball earth to Svensmark and so on As pointed out by Eric there s no quantitative analysis simply because the author does not like the stats statistically averages do not mean anything and the author prefers to do some peremptory affirmations I would recommend two alternative readings for the francophones on recent results obtained on alpine glaciers ici et la articles published in PIGB thibault 19 Hans Erren says 23 Mar 2005 at 5 08 AM Here is a 2000 year study for the alpine Aletsch glacier http www klimanotizen de html newsletter 4 html http www klimanotizen de assets images 2003 10 25 aletschgletscher 2000 1 gif see also http www zamg ac at ALP IMP downloads session haeberli pdf 20 John Finn says 23 Mar 2005 at 7 23 AM Having looked at the graphic depicting the reduction in various glaciers I have a problem accepting the consenus view represented by most of the comments that anthropogenic warming is the cause of the glacier retreat This is related to a similar issue over which I ve had a previous argument i e the famous lake study elsewhere on this site Basically the reduction in glaciers begins before well before in most cases greenhouse gas concentrations could have had any warming effect Where data is available it s apparent that glacier retreat begins around the mid 19th century Before we cite human influence in the form of increased CO2 emissions as the cause it is perhaps reasonable to ask what the levels of atmospheric CO2 were at the time It s generally accepted that pre industrial CO2 levels were around 280 ppm and that levels in 1900 were around 295 ppm Since industrial CO2 emissions were massively higher between 1850 and 1900 than any period up to 1850 it s hard to believe that 1850 CO2 levels in the atmosphere were any more than 285 ppm There s no way this small increase could be responsible for a climate forcing which produced the dramatic results shown in the diagram This of course leaves another question If mid 19th century glacier retreat is not due to human causes then why can t 20th century glacier retreat simply be an extension of that same natural process Response As I noted in the post Oerlemans s work doesn t address whether or not the worldwide glacier retreat is part of a natural phenomenon You can t simply take one curve look at it by eye and start to make claims about the validity of the idea that human influence on climate is significant Investigating the cause of 20th Century warming is properly done in detection and attribution studies which analyze the various forcings e g solar variations greenhouse gases or volcanic activity and the observed time and space patterns of climate change in detail Work like that of Oerlemans or the so called hockey stick curve provide some of the observations used in such studies but don t replace such studies Detection and attribution analyses with a range of different techniques have invariably concluded that the dominant cause of 20th Century warming is man made greenhouse gases See the earlier post by stefan here eric 21 Lynn Vincentnathan says 23 Mar 2005 at 1 02 PM Dan Kellog an engineer not climate scientist on another blog has raised the issue of once a glacier has melted away the local temps could rise dramatically and perhaps averaged altogether around the world as glaciers melt away increase the rate of global warming Could you comment on this Here is what he wrote http www marklynas org The process of melting large quantities of ice takes time only because of the tremendous heat required to do that Since melting ice absorbs so much more energy than heating land or even water then once the ice melts the local area should expect a faster rise in temperature due to decreased albedo and no more ice to absorb further heat For the lay person know that a glass of ice water maintains its cold temperature as long as there is ice Once the ice melts the glass of water warms fairly quickly This fact is based on the physics of changing the phase of water from solid to a liquid It is called the latent heat of fusion For water it is 143 3 Btu per pound And since water s specific heat is 0 998 Btu per pound degree Fahrenheit then it would take 143 times the heat energy to melt water at its freezing point than to raise the same quantity of water 1 degree Fahrenheit once it became a liquid For the metric people that converts to 257 times the heat energy needed it melt water at its freezing point than to raise the same quantity of liquid water to 1 degree Celsius Is this a factor of any significance related to local and perhaps global warming is it being considered Response I couldn t find the specific post you refer to but in any case the answer is that alpine glaciers cover a very small fraction of the globe and their disappearance will have very little impact on local temperature Locally their loss could matter but only very very locally i e in the same valley the glacier is in and only in late summer in winter it is the snowpack which covers a far greater part of the landscape which strongly influences temperature If the glaciers are gone but snowpack continues which of course it may not then the effects will be minimal Finally it is not the latent heat of melting but the reflectivity albedo that is the more important factor eric 22 Dano says 23 Mar 2005 at 2 30 PM RE eric s response to 20 We would do well to remember the reason for RealClimate which is to better address and disseminate the latest climate science findings Eric points at the flaw in the poster s argument looking at one graph and declaring a HA I suggest that this is a very common argument perfected by Daly and acolytes and we should think about this as a sub category of argumentation and address it as such Best D 23 Michael Jankowski says 23 Mar 2005 at 4 44 PM Re 17 Re 16 my limited understanding of GW is that it entails not only increased average warming but also greater swings between temperature extremes including colder warmer temperatures beyond the mean I think you ve confused a few theories together Some GW theorists do think weather patterns could change and cause some of today s warm mild climates to become cold so maybe that s what you re thinking of Many theorize that a warmer world would have more frequent and stronger extreme weather events but they are not referring to temperature instead preciptation tornado hurricane etc So maybe that s another theory you re thinking of However I would be surprised to find that someone has claimed that GH warming will produce colder temperatures relative to the mean except for localized regions due to the changing weather patterns theory above In fact cold dry air masses such as you typically have on extremely cold days would warm the first most in a GW scenario Hence they should be even closer to the mean in a GW world I would think that max temps would also tend to be closer to the new warmer average temps in a greenhouse GW world too In other words the average temperature minimum temperature and high temperature in a GW world would tend to be higher than it currently is but the difference between avg min and avg max would be smaller than it currently is This may differ from region to region if weather patterns ocean currents etc change due to GW but it should hold true in general in a GW world I m just going on my own limted GW knowledge and some basic physics and greenhouse theory Someone step in if I erred 24 Stephen Berg says 23 Mar 2005 at 5 49 PM This post may not belong on this thread but the Climate Change Disinformation thread comments have been ended An interesting study done by the MIT has found that the general public in the US is quite unaware of the phenomenon and the hazards of climate change The summary is linked below http www eurekalert org pub releases 2005 03 miot ccp032305 php 25 Jo Calder says 24 Mar 2005 at 3 37 AM Re Eric s comment in 20 You mean the dominant cause of late 20th Century warming don t you Cheers Jo Response Sure though in fact the late 20th century rise dominates the total for the entire century 26 John Finn says 24 Mar 2005 at 6 01 AM You can t simply take one curve look at it by eye and start to make claims about the validity of the idea that human influence on climate is significant I haven t taken one curve I ve looked at them all And the majority of them or those for which data is available start to nose dive before or around the mid 19th century Investigating the cause of 20th Century warming is properly done in detection and attribution studies which analyze the various forcings e g solar variations greenhouse gases or volcanic activity Good However as far as the mid 19th century is concerned forcings due to GHG concentrations are insignificant so we are only left with natural forcings or causes as an explanation for glacier retreat and the observed time and space patterns of climate change in detail I think the argument is much simpler than this If the cause hasn t yet happened but the effect has then there is a problem with the suggested cause effect relationship The level of detail in the analysis is irrelevant But if you have some data which shows AGW was a factor before 1900 say then let s see it Response GHGs starts to be a factor around 1850 as is clear from the forcing diagrams we have discussed multiple times But other factors were of equal or greater magnitude Only after 1950 or so do anthropogenic effects become dominant Thus the argument is it AGW or not prior to 1950 is a false dichotomy Of the forcings leading to a warming in the early part of the records solar decreasing volcanism and GHGs all play a part and with a role for cooling due to land use change and aerosol increases The specific attribution in a nice percentage figure is more difficult becuase of the uncertainty in the solar and aerosol effects in particular The statement that warming from 1850 onwards is partially due to increased GHG forcing is perfectly valid Hopefully we can now move on to a more interesting discussion gavin 27 Jemima says 25 Mar 2005 at 2 32 AM Further to Eric s response to John Finn at 20 presumably the simplest answer of all is that almost everyone agrees that there was a Little Ice Age of sorts which affected at least Europe and from which rewarming had begun by the 18th century Consequently almost everyone would expect to see glacial records indicate some retreat of the ice dating to the earliest stages of that period of that warming just as John sees in the graph above So really no surprises here situation quite uncontroversial 28 dave says 25 Mar 2005 at 3 47 AM I was just thinking that the now inaptly named Glacier National Park could be described as Glacial Moraine National Park Glacial Moraine or even as Glacial Till National Park Glacial Till in the next few decades I think these newly transformed natural parks will have something to offer for interested scientists For example the young geologist student can study the recent effects on the landscape of rapidly retreating glacial ice Given most people s inability to understand irony of any kind if my level of sarcasm in this comment is not understood I will spell it out the glaciers there will almost entirely gone 29 eric says 25 Mar 2005 at 4 19 PM With respect to 27 it is worth noting that in fact there is a serious question as to whether the Little Ice Age was a global event or was largely restricted to Europe It has by no means been proven that the Little Ice Age had the same degree of spatial coherence of advance as does the current retreat As an example of what I mean by this consider two of the long European records shown in the figure d Argentiere evidently advanced from about 1820 to 1850 while Grindelwald was retreating But both retreated together from about 1940 Unfortunately there really isn t enough data from enough locations going back far enough in time to examine this question rigorously That s one of the reasons why the glacier data aren t a particularly strong data set for assessing the relative influences of natural vs anthropogenic change They are however useful for assessing the amount of change that has occurred That s the point of Oerelmans s paper and this post 30 Joseph O Sullivan says 25 Mar 2005 at 6 12 PM Thanks Gavin for the short and simple response to the mid 19th century anthropogenic warming question Is anything known about how mountain ecosystems are reacting to glacial retreat I would like to see a post from Realclimate about current ecological effects of anthropogenic climate change Something detailing any ongoing changes in communities of living things in the natural world like coral reefs lakes and alpine regions caused by anthropogenic climate change would be great if its not too off topic for RC Response In general ecology is not our area of expertise but I would venture that ecosystems around glaciers are generally used to significant changes I suspect a larger effect is not the glaciers themselves but the rising treeline see e g this article from Science eric 31 Eero Priha says 27 Mar 2005 at 1 14 PM Why satellite measurements show much lower warming than earth stations especially in western Europe Has urban heat island effect corrected adequately because American and Siberian stations not so ueban show less warming or no warming at all Also in Helsinki measurement point in the middle of city shows much more warming than Sodankylà in Lappland no clear warming Response There is information on the urban heat island effect and the satellite data already posted on RealClimate See here Response The satellite stuff is probably better covered at http en wikipedia org wiki Satellite temperature record William 32 Stephen Berg says 28 Mar 2005 at 6 01 PM Did anyone catch CNN Presents last night It was on climate change and was more balanced than I was thinking it would be They had James Speth Ross Gelbspan and Russ Schnell as guests but also had Richard Lindzen and Pat Michaels However the time they allotted to Lindzen and Michaels was maybe 1 8 of the show They talked about sea level rise due to melting glaciers and the disintegration of Antarctica s vast ice sheets and the effects of this rise on the planet especially coastal regions which are heavily populated and the Island states specifically Tuvalu They also discussed the situation in the North where polar bears are much less healthy than 30 years ago due to a three week earlier break up period and the loss of the culture of the Inuit and northern Aboriginal tribes One guest that really peeved me was Jim Conatin You can see for yourself what rubbish he was saying Here is an unofficial transcript of the show http edition cnn com TRANSCRIPTS 0503 27 cp 01 html 33 Michael Jankowski says 28 Mar 2005 at 6 44 PM Response The satellite stuff is probably better covered at http en wikipedia org wiki Satellite temperature record William Covers the basics but a rather poor coverage IMHO especially with regard to the poster s questions It even includes a reference to Fu s 2004 Nature article which Spencer Christy and others have ripped to shreds Fu himself adjusted his methodology in response rebuttal and showed results much closer to those of Christy and Spencer in a subsequent publication although Christy and Spencer still think there are errors in the methodology and still lower than surface warming rates For some time the UAH satellite data s chief significance is that they appeared to contradict the United Nations IPCC predictions about global warming In April 2002 for example their satellite temperature trend was only 0 04  C decade compared with 0 17 0 06  C decade from surface measurements however in the years since the UAH trend has roughly doubled to come more in line with other trends Roughly doubled certainly has it more in line with other trends but I d say still showing only 50 of surface warming is a huge gap to fill when it is supposed to be at least as large as the surface warming A report by the National Research Council that reviewed upper air temperature trends stated Data collected by satellites and balloon borne instruments since 1979 indicate little if any warming of the low to mid troposphere the atmospheric layer extending up to about 5 miles from the Earth s surface Climate models generally predict that temperatures should increase in the upper air as well as at the surface if increased concentrations of greenhouse gases are causing the warming 12 The huge disparity the AGH skeptics always point to On the other side However the same panel then concluded that the warming trend in global mean surface temperature observations during the past 20 years is undoubtedly real and is substantially greater than the average rate of warming during the twentieth century The disparity between surface and upper air trends in no way invalidates the conclusion that surface temperature has been rising 13 Whether the surface temperature had been rising since 1979 was not in doubt The magnitude it actually had actually risen how different these temperatures were from the 1940s the conflict between model prediction theory and observation etc were the issues the satellite data raised And then there s the next statement An important critique of the satellite record is its shortness adding a few years on to the record or picking a particular time frame can change the trends considerably We see this issue when it comes to other temperature records too We ve all seen bookends used to identify surface temperature trends that if expanded or contracted by a few years reveal drastically different results Regardless 25 years of side by side comparison with surface based readings and corroboration with weather balloon data seems like plenty of time to determine that something is amiss It will be interesting to see how everything sorts out concerning the interpretation of the satellite data However I think the big picture effect that the satellite interpretests are going for by coming up with average global trends may be the incorrect approach A better approach may be to compare the data of individual stations vs satellite data for corresponding areas This will reveal flaws in the data either surface or satellite far more quickly It would seem to me that the global average approach would serve to dampen errors 34 stephan harrison says 29 Mar 2005 at 6 43 AM A few comments following No 15 it is indeed true that some mountain and valley glaciers display asynchronous responses to climate change The most obvious example of this is the case of calving glaciers where their gross behaviour may relate more to water depth at the calving front than small scale climate variations However even in these cases such topographic factors are only second order controls on fluctuations and climate will eventually dominate the behaviour Following No 29 I would argue that the glacier signal shows that the Little Ice Age may well have been global For instance in Patagonia we have evidence to show that most of the outlet glaciers of the Northern Icefield receded from their late Neoglacial limit around 1880 or so This ties in with many of the glacier climate records from the Northern Hemisphere although we don t yet have much evidence for glacier advances in Patagonia around the 16th century Response There s no question that many most glaciers were at their most advanced in the last few thousand years some time in the mid to late 19th century To what extent those advances really represent a globally synchronous event requiring external forcing i e the sun is less clear to me at least I think an interesting question is whether the LIA was a globally coherent as today s recession is eric 35 Tim says 29 Mar 2005 at 9 38 AM In reply to 30 you might find it interesting to have a look at http 192 171 163 165 which is the home page for the Continuous Plankton Recorder Survey I know that they have analysed this survey and found trends due to climate change in plankton populations they have some links to publications from the above page I don t know any details unfortunately 36 Pat Neuman Hydrologist says 29 Mar 2005 at 11 22 PM As global warming continues the amount of water vapor in the atmosphere increases The significance of latent heat for snowmelt has been described by Dunne and Leopold 1978 If water from moist air condenses on a snowpack 590 calories of heat are released by each gram of condensate This is enough energy to melt approximately 7 5 gm of ice which when added to the condensate yields a total of 8 5 gm of potential runoff Quote shown in my Sep 2003 article Earlier in the Year Snowmelt Runoff and Increasing Dewpoints for Rivers in Minnesota Wisconsin and North Dakota at http www mnforsustain org climate change htm The rate of snowmelt will increase as water vapor increases even with assumed no change in temperature during a given period of above freezing temperatures due to latent heat as moist air condenses on snow and ice Response Increased humidity may indeed be responsible for the Kiliminajaro glacier retreat discussed above eric 37 Lynn Vincentnathan says 30 Mar 2005 at 2 01 PM I think 33 is arguing against global warming or is claiming the warming might be just an urban heat effect So forgive me for being off glacier topic but haven t there been recent findings of deep ocean warming from Scripps Inst of Ocean Do these ocean findings finally lay to rest any arguments against anthropogenic global warming according to news coverage claims Do the findings definitively prove anthropogenic GW against any contradictory satellite data or non retreating glacier arguments Response See our post on this Why looking for global warming in the oceans is a good idea 38 John Dodds says 30 Mar 2005 at 8 19 PM Yes glaciers ARE melting But in the last ice age global warming 123 000 years ago ALL the ice in central Greenland melted the proof being that the ice cores stop hit bedrock at that time So WHY shouldn t we expect the glaciers to melt during this warming cycle Especially since 1 the sun is pouring out energy at a higher rate than it has for the the previous 800 1000 years 2 by Milankovitch orbital mechanics we are closer to the sun in our eliptical orbit the tilt is tending towards warmer winters cooler summers less ice accumulation a few hundred years ago the precession passed aphelion so that we are now receiving more solar energy due to precession that we did for the previous few thousand years AND 3 there is more CO2 to enhance multiply the increased solar radiation heat effects Response You are mixing apples with fish Yes there have been warmer times in earth history So what My still unanswered question is why does the hockey stick shape of Earth temperatures show up in a chart of the Solar magnetic flux How did some CO2 molecule on earth spread THAT news back to the sun Response Recent solar variations do not look just like the recent temperature history as this comment implies See our post on climate forcings Response A further comment All Greenland ice did not melt during the last intergalcial The ice cores hit bedrock because there is a continual divergence of ice near the base that feeds ice streams going to the ocean Greenland has probably had large amounts of ice for the last 3 million years although some significant portion may have melted during the last interglacial Similarly the best cores in Antarctica are likely to go back only a million years and yet Antarctica has been glaciated for at least 30 million years The answer to your question is that of course we expect glaciers to melt in a warming phase and that they are doing is a strong indication that we are in fact in a warming phase gavin 39 Joseph O Sullivan says 30 Mar 2005 at 10 50 PM Thanks Eric for recommending that article in Science comment 30 It s a great piece and refers to a lot of other sources that address climate change and ecosystems It s on a non subscription site at http meteora ucsd edu cap all downhill sci12mar04 pdf I have wanted to learn more about the effect of human caused climate change on the natural world I do have a bachelors in marine biology and some profession experience in ecology but that was a while ago I don t have the same connection to scientific areas I used to I decided to ask the working scientists at RealClimate to point me in the right direction Ecology is a separate area of science but climate and climate change are important parts of it I know ecologists are examining past climate change to see what the current anthropogenic climate change could do Thanks Tim for that link comment 35 It also has some great info I read a journal article about 10 years ago that looked at past temperature changes and how these changes effected fish populations It basically said that populations of larger fish would just move but the big problem could be changes in the plankton which is the basis of the food chain The articles on the SAHFOS site http 192 171 163 165 bring up the same concerns namely that anthropogenic climate change could affect plankton and these changes in the plankton communities could cascade through the entire ocean ecosystem and show that these changes in the plankton communities have already started Response You may also be interested in the article by Richard Feely and colleagues Impact of Anthropogenic CO2 on the CaCO3 System

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    the long term trend that we are forcing it to have I think the money is on 2011 2020 being warmer than 1990 2000 But if it isn t it won t make me think we missed something or have some fundamental lack of knowledge Of course various pundits will claim the scientists had it wrong but I guess we will cross that bridge if and when we come to it Accepting that climate is the statistics of weather over some reasonable time period I want to ask about something that climate modelling does not seem to address thresholds Since there has been noticeably increased warming over the last 20 years or so and less so before that is it possible that the forcing from GHGs in the atmosphere surpassed some threshold around then and that there is some feedback outside the normal physics affecting water vapor that has kicked in to create the observed warming See this data for example GHG levels were also quite high in 1984 344 5 ppm CO2 as measured at Mauna Loa but the warming has risen dramatically since then We are at about 379 ppm CO2 now awaiting the official measurement due soon Naively it looks like something happened Response I very much doubt it See my response to 11 below eric 11 Peter J Wetzel says 16 Feb 2005 at 10 47 PM Dave 10 Let s suppose just suppose that we have just recently encountered the onset of a Dansgaard Oeschger event These events produce rapid climate warming which is followed by a gradual steady cooling over many years centuries in fact Superimposed on this event might be a true anthropogenic signal However the D O event itself is a phenomenon that is clearly within the bounds of natural variability Although there is little solid confirmation of the cause of these sudden D O warmings one of the most plausible explanations is based on a parallel phenomenon which well known in the atmosphere The oceanic boundary layer is driven by the identical thermodynamic processes that drive the atmospheric boundary layer In the ocean there are dual buoyancy mechanisms salinity and temperature which drive boundary layer instability In the atmosphere there is fundamentally only one dominant driving mechanism temperature although modulated by water vapor and the latent heat released by condensation into clouds The equivalent to a D O event in the atmospheric boundary layer occurs when large amounts of potential instability accumulate and the instability is then released in the form of violent thunderstorms The phenomenon which delays the release of instability while it continues to accumulate is known as a cap a stable layer which contains the instability until a threshold is reached at just one most unstable location Then the vast reservoir of instability is released explosively This is a process with large hysteresis Instability accumulates far beyond an equilbrium state before its release is triggered The system then restores itself to a relaxed stable state as the instability is released And once this stable state is established a new reservoir of pent up instability begins to accumulate In the atmosphere these processes operate on time scales of hours to days The oceanic boundary layer the thermocline with its much more vast reservoirs of heat operates on much longer time scales I contend that a likely trigger of the D O events is the same sort of local break of an instability cap which initiates an intense episode of Deep Water formation either in the North Atlantic or in the Antarctic seas the latter is more likely the case in today s climate Over decades to centuries this instability is released cold water which previously lingered at the surface is sequestered in the deep ocean and the circulation gradually subsides just as the explosive development of initial thunderstorms following the first breach of the atmospheric cap is followed by a succession of weaker and weaker storms As I said let us suppose that such a D O event was triggered some time in the last two decades If so then the prognosis as defined by the course of natural variability would be for a short period of rapid warming followed by a gradual steady cooling Since D O events are a fairly common feature of past climates there certainly is precedent Since our observational record is far to short to have documented any D O event previously we could be blindsided by the onset of such a phenomenon And since we happen to be in an unprecedented period of increasing CO2 it would be exceedingly difficult to separate such an uncommon natural event a D O warming from the anthropogenic signal What we think we know as climate scientists pales miserably in comparison to all the phenomena we have never observed with modern technology Response I would agree with much of this comment though I m far less sanguine about our understanding of D O events and I m far less convinced of their relevance to modern climate It seems increasingly clear that D O events must involve major sea ice changes and there is not much sea ice left by comparison with what was present during the glacial period 20000 years ago when these events happened so D O events are increasingly unlikely in the future I would also add that the prediction made by 11 about what a D O event would look like is based on the Greenland ice core records and the picture of abrupt warming slow cooling picture comes from the data on millennial timescales It does not begin to describe what did actually happen globally during these events and is even less relevant to what might happen in the future In any case the key point is that there is no evidence to suggest we have crossed any sort of threshold Comment 10 implies there are aspects of the data which suggest this That is an eyeball approach to the data which is not backed up by any sort of analysis So to 10 I would say again that the answer is firmly no there is no evidence for any sort of threshold being crossed eric 12 John Finn says 17 Feb 2005 at 7 44 AM I think the money is on 2011 2020 being warmer than 1990 2000 But if it isn t it won t make me think we missed something or have some fundamental lack of knowledge Of course various pundits will claim the scientists had it wrong but I guess we will cross that bridge if and when we come to it Hang on a minute This site has consistently maintained that past climate variability had occurrred within a fairly narrow range It s argued against the MWP and LIA or their extent It supports the hockey stick representation of shallow fluctuations of climate over the past 1000 years and points to the sudden unprecedented increase in 20th century temperatures as evidence that increased CO2 levels are the main contributory factor Now apparently if the next 20 years fail to show the expected level of increase then it s all down to natural variability Never mind the continuing increase in atmospheric CO2 what happened to the 0 5 degree rise due to equilibrium response to recent levels of GHGs I d like to remind you we are now 15 years into the 1990 2100 period when everything is about to unfold In 2020 we will be 30 years along the journey This will be 32 years after James Hansen told the world that global warming was happening now If the evidence in 2020 is no stronger than it is to day then you ve got at least 2 things wrong Climate sensitivity which I believe is about 1 3 of your claims and past climate variability which is probably wrong anyway Apart from that you ll be spot on Response I would agree that the money is on 2011 2020 being warmer than 1990 2000 I would somewhat disagree that if it isn t there is no problem Assuming Co2 levels increase roughly as expected then it would I would guess plucking numbers somewhat out of the air be better than 95 certain that the latter period would be warmer What I think Eric was saying was that even given that there is a small chance that natural variability could cause a downturn That is the science point of view But from a political point of view if there was a decade long downturn in temperature and all the attribution analyses showed it to be a temporary downswing with more warming expected later no one would listen William Response Yes William has properly interpreted my point Another way to look at this is that while I won t be that suprised if 2011 2020 is not warmer than 1990 2000 I will be very surprised if 2000 2030 is cooler than 1970 2000 The data show that natural variabilty on decadal timescales is non trivial but that on multidecadal timescales it becomes much more trivial Having said all that this is a little off the cuff One could quibble with the detais My point is merely this natural variability exists and looking at individual decades in not really long enough eric 13 dave says 17 Feb 2005 at 1 44 PM Re 10 11 I merely raised the possibility of a threshold being crossed wondering whether there was any serious analysis that supported it Of course I ve seen the often used IPCC TAR result here showing that modelling results combining natural and anthropogenic forcings reproduce 20th century global mean surface temperature anomalies relative to the 1880 to 1920 mean This would seem to imply that no threshold has been crossed However Richard Alley writing for a general audience in Scientific American Nov 2004 in an article entitled Abrupt Climate Change spends a lot of time talking about thresholds changes of state using his canoe tipping analogy He states that many thresholds may still await discovery And we know how Wally Broeker feels about this So I was wondering what the thinking was about thresholds with respect to the current warming trend on this blog I also think that paleoclimate scientists tend to see more possibility of abrupt climate changes than climate modellers do Also re the current warming trend Hansen and Sato expect 2005 to surpass 1998 due to a weak El Nino superimposed on the general anthropogenic forcing in this GISS press release So we know which way they re betting If this indeed comes to pass and the warming grows in subsequent years there may come a point when the signal exceeds the known forcings and feedbacks as currently modelled At which point it might be decided that transient climate sensitivity is too weak or some unknown threshold has been crossed Of course this is all just pure speculation on my part And hey why not Finally when I raise the possibility of some undetected threshold in the current warming signal that doesn t mean I believe it Response Thresholds stuff is quite difficult On the one hand they may be there awaiting discovery OTOH there is no good sign of them at the moment One example is the THC shutdown which was predicted by simpler models but tends not to occur in the more sophisticated models coupled AOGCMs OTTH although these models are capable of showing some emergent behaviour ie stuff not built into them this may be limited HadCM3 vegetation for example shows a speed up of atmos CO2 in mid C21 when the Amazon forests start to decline due to climate change But if the thresholds were related to GHG levels we would have noticed because CO2 etc are continuously monitored The bottom line is probably that whilst we should take the idea of sudden changes seriously and investigate possibilities within the scientific arena it wouldn t work to take such stuff out into the wide world without a rather better basis Analogies are nice but they aren t evidence just guides to thinking William 14 Peter J Wetzel says 17 Feb 2005 at 7 43 PM The undetected threshold scenario that I posed in 11 could be more generally characterized as a shift in the thermo haline circulation THC caused by an emergent new source region for deep water formation The most obvious D O Dansgaard Oechsger events in the vicinity of the LGM Last Glacial Maximum 20 000 years ago represent extreme examples of this scenario The interactions feedbacks between THC shifts and sea ice and glacial calving as indicated by ice rafted debris in deep sea core records would tend to seriously magnify the climate changes compared to what would be expected from a similar THC shift today But I d like to move beyond the discussion of simple thresholds There is another class of slightly more subtle climate shifts that could be driven by long time scale ocean circulation processes which fall beyond the scope of observational recognition The most tangible example of how such a shift might appear is the apparent recent emergence last half of the 20th century of a much more intense oscillation in and particularly a much more intense positive phase of the Arctic Oscillation AO which is closely paralleled by the North Atlantic Oscillation NAO The class of hypothetical climate shifts to which I allude involve fundamental changes in the frequency and amplitude of known oscillatory behavio u r of the atmosphere ocean cryosphere system and the potential emergence of new oscillatory behaviors We should not limit ourselves to being vigilant for the crossing of thresholds The undiscovered effects that may emerge as we proceed with our uncontrolled experiment in anthropogenic forcing run the gamut from modulation of the frequency and duration of relatively short term well characterized cycles such as ENSO El Nino Southern Oscillation AO and the Pacific Decadal Oscillation through long term oscillations which have always been a part of the natural variability of the Earth system but which operate on such long time scales that they have not been properly recognized or understood e g D O type events to the emergence of completely new modes of oscillation as climate is influenced by anthropogenic processes The statement there is no evidence of such emergent changes about which I ve speculated only means that vigilant climate scientists have not yet identified the possible evidence perhaps because it does not exist and my speculation is wrong or because it has either been overlooked or is still in the early stages of emergence 15 dave says 17 Feb 2005 at 7 47 PM I hope you re receptive to a follow up on this interesting subject I couldn t agree more with your remarks I wasn t trying to be alarmist Alley s article really does emphasize non linear state changes I was puzzled by the related to GHG levels we would have noticed statement I take threshold to mean that GHG forcing could alter some natural variability like the Arctic Oscillation which spends more and more time in its positive mode increasing heat transport from mid latitudes or ENSO more frequent or stronger El Nino events There tends to be an emphasis here at realclimate org on the hockey team results Mike prefers this term for example this posted subject Moberg et al And while the hockey team shows the late 20th century and current warming to be unusual it is not as important in my view as the current warming trend itself Why Well because that s just how people work Humans work on human timescales which are short I know that s not the scientific view but that s reality So for example here s some bad luck from the GISS press release cited in 13 and given the U S refusal to participate in Kyoto or otherwise make meaningful GHG reductions Compared to the average temperatures from the 1951 to 1980 period the largest unusually warm areas over all of 2004 were in Alaska near the Caspian Sea and over the Antarctic Peninsula But compared to the previous five years the United States as a whole was quite cool particularly during the summer emphasis added So when Eric says Still this doesn t mean the period 2001 2010 or 2011 2020 will also be as warm We ll see citing some possible natural variablity which masks a longer term climate warming trend I want to say we re doomed doomed This point of view guides my posts I m being as honest as I can be Response I assume that by your we re doomed statement you are saying you worry that in the event it is not warmer in 2001 2010 than 1990 2000 that this will damage our ability to get the word out I think that is true but it doesn t change the fact that climate is highly variable and it might just work out that way The natural world doesn t always cooperate in a way that makes things easy to explain Now on the thresholds business you should be aware that I m probably more conservative on this than most in the paleoclimate research community especially those like Alley and me that have worked mostly on ice cores looking at longer timescales My take on this is that the case that big non linear responses can happen is strong but that the case that they will happen in the near or medium term is weak I would echo William s comment that this is an interesting and important area of scientific study but I do not think it is well enough understood that it makes sense to spend a lot of energy warning people about it The reality of global warming is to paraphrase IPCC very well understood and very very likely and that is a statement few would disagree with On

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  • Weren’t temperatures warmer than today during the “Medieval Warm Period”? « RealClimate
    Warming says 6 Jan 2008 at 9 08 PM and had relatively little impact on the global averages Dr Michael Mann addresses this here and for an example of a contrarian tactic that can make it appear otherwise or that the current 5 Hypography Science Forums Co2 Acquittal says 1 Feb 2008 at 1 35 AM by mitigating our impact And I know you like this place so yes I did look here RealClimate Here is an interesting article 6 Earth The Climate Wars Wildlife and Environment Forums says 20 Sep 2008 at 12 52 AM of the little ice age and medieval warm period and many other discussions of climate change RealClimate To summarise the ideas very simplistically I think this is what they say the little ice age and 7 Understanding the Basics of Global Holocene Climate Change Understanding Global Warming says 16 Mar 2009 at 8 57 PM magnitude of medieval warmth was weaker than that of today Dr Michael Mann also addresses this here and for an example of a contrarian tactic that makes it appear otherwise or that the current 8 Understanding Global Warming says 17 Mar 2009 at 1 46 PM magnitude of medieval warmth was weaker than that of today Dr Michael Mann also addresses this here and for an example of a contrarian tactic that makes it appear otherwise or that the current 9 Ben s Blog Blog Archive Head to head with a Cardinal says 24 May 2009 at 10 58 PM qualified in a way that I and the good Cardinal are not The medieval warm period wasn t warmer Warming didn t stop in 1998 But most appalling to me was this childish attempt to use his Site Google Custom Search Recent Comments Unforced Variations Feb 2016 Digby Scorgie Unforced Variations Feb 2016 T What is the best description of the greenhouse effect Jim Eager What is the best description of the greenhouse effect Patrick Eriksson What is the best description of the greenhouse effect Kevin McKinney Anti scientists Carbomontanus What is the best description of the greenhouse effect Spencer Marvel et al 2015 Part III Response to Nic Lewis SteveS What is the best description of the greenhouse effect Chris Colose Blizzard Jonas and the slowdown of the Gulf Stream System doiknow With Inline Responses Marvel et al 2015 Part III Response to Nic Lewis SteveS Marvel et al 2015 Part III Response to Nic Lewis steve s Marvel et al 2015 Part III Response to Nic Lewis Andrew Kerber Blizzard Jonas and the slowdown of the Gulf Stream System Hank Roberts Blizzard Jonas and the slowdown of the Gulf Stream System doiknow Marvel et al 2015 Part III Response to Nic Lewis MartinM Anti scientists Don McKenzie Marvel et al 2015 Part III Response to Nic Lewis Matt Skaggs Anti scientists mikeworst New On line Classes and Models Marcus Pages Acronym index Data Sources Categories Climate Science Aerosols Arctic and Antarctic Carbon cycle Climate impacts Climate modelling

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  • Worldwide glacier retreat « RealClimate
    the web at http www igbp kva se uploads NL 57 5 Kullman pdf For the non scientist or non ecologist mountain regions are divided into ecological zones that are divided by climate From the highest altitude and coldest to the lowest altitude and warmest the general pattern is ice bare rock to mosses lichens to grasses brush to trees forests As the climate is warming the ecological zones are moving up the mountain and in some cases the colder ecological zone are disappearing Thanks Eric for recommending the article in Science All Downhill From Here Science Vol303 12March2004 It s on the web at http meteora ucsd edu cap all downhill sci12mar04 pdf It was a great starting point to do some independent research on how the receding glaciers were affecting the local ecosystem Thanks also for recommending the Freely et al 2004 article on the effect of CO2 on seawater chemistry and the ecosystem It s on the web on a non subscription site at http eco link net node view 32 pollresults 5B5 5D 1 A less technical summary in the popular press is at http www newportnewstimes com articles 2004 12 24 news news34 txt I have read some about the change of the chemistry of the oceans caused by anthropogenic CO2 and I wondered about how it could affect the marine ecosystem It was great to read something about this The short comment about scientists raising alarms was also very instructive Finally thanks to Lynn Vincentnathan for the cite for the paper in Nature The abstract is at http www newportnewstimes com articles 2004 12 24 news news34 txt Lynn Vincentnathan basically got it right if climate change disrupts the ocean current system that brings nutrients up from deep waters that the plankton in surface waters need the plankton productivity would drop The study s statement that this effect could last centuries was something that grabbed my attention 55 Joseph O Sullivan says 7 Apr 2005 at 12 04 PM A correction of my earlier comment the study in Nature Lynn Vincentnathan commented about Decline of the marine ecosystem caused by a reduction in the Atlantic overturning circulation abstract can be found on the web at http www nature com cgi taf DynaPage taf file nature journal v434 n7033 abs nature03476 fs html 56 John Dodds says 11 Apr 2005 at 12 33 PM Re 36 Isn t the latent heat of vaporization released when you go from steam to water at 100 C not from water vapor to water I thought that water vapor in air is already water so there is no big heat resevoir to melt all that ice as claimed 57 John Dodds says 11 Apr 2005 at 2 31 PM Re the UNATTRIBUTED responses to 38 My point was that in the past it has gotten warmer and glacier melt was due to all the listed causes be they apples or fish In the previous warming 130 000 years ago they melted without the added benefit of anthropogenic CO2 My comment on the shape of the hockey stick being represented in the Solar MAGNETIC FLUX but now that you identify it it is also evident in the solar energy vaiations was intended to point out that not all of the hockey stick is due to anthropogenic CO2 which seems to be a common perception It is quite evident to me that the Earth Temp and the Solar Mag flux and the Solar energy variations bottom 1820 rise to the mid 1800s fall back to retest the bottom in 1905 with the Solar fluxes staying higher the Earth temp retesting to the 1820 low probably indicating a time LAG on earth Rise to the 1940s top and fall back to the 1970s bottom Rise to the 1998 top with the Earth temp rising MUCH more than the solar presumably due to CO2 which apparently resulted in your recent comment and then begin to fall again in 1999 2000 etc To me this is a hockey stick starting in 1820 on the SUN and also on the earth It also says to me that MOST of the hockey stick is solar induced altho there is NO doubt in my mind that anthropogenic CO2 has added to the 1970 98 temp rise BUT if I go back to the last 15 000 years of Greenland ice core temperatures that the current temp is still well below the peaks induced by the sun without the use of anthropogenic CO2 about 8000 7000 and 3500 years ago It also raises questions with me as to how does the ever increasing CO2 forcing account for the temp drops in 1999 or 2000 etc if the CO2 forcing is so so so much more dominant that the solar forcings My bottom line Glaciers are melting the earth is warming there is more CO2 inducing some warming we are not yet warmer than we were several times in the past 15 000 years I do not yet believe that the computer simulation models are accurate enough to model the systems and I think that there is probably an under estimate of solar energy and especially the fluctuations AND maybe even solar mag flux induced warming and an overestimate of CO2 effects I also think that the modelling is deficient by not including the supposedly small Milankovitch effects AND their multiplying effects on solar forcings and the associated water vapor feedbacks If they are so small then WHY in the ice core histories have they been responsible for the sudden changes in temperature eg 2 4 degrees over 10s to 100s of years 58 John Dodds says 11 Apr 2005 at 3 29 PM Re 38 Gavin s comments on melting Glaciers in Greenland Yes I agree there is divergence of ice near the base of glaciers BUT why did the ice core happen to stop 123 000 years ago a few thousand years after the peak of the last warming and why did the ice start accumulating again a few thousand years after the Vostok temp Global Cooling since Greenland temp is not available dropped by 2 3 degrees just coincidence Did the second GISP core stop at a similar time Why would GISP not include more than one ice age cycle like Vostok other than the obvious that there is less ice in the north AND there are NOW trees in Alaska and Russia at latitudes higher than in the bottom part of Greenland still covered in ice but I would expect lower Greenland to be warmer due to the sea warmer ocean currents AND due to the Earth Precession the teardrop shape of the north ice sheet rotates around the north pole in about 20 000 years sequentially exposing some places with more ice at lower latitudes than others eg Chicago was covered to 40 degrees latitude but much of western Russia 60 degrees lat was not at the previous ice peak With the current orbital precession minimizing solar input over North America I would expect it to be colder there BUT in 5000 years or 1 4 of a precession cycle the teardrop will have moved exposing Greenland to less precession induced cold hence opening up the possibility of more faster warming and ice glacier melting in lower Greenland Added to this in 5000 10 000 years we will again be approaching the eccentricity of 130 000 years ago further reducing the overall size of the northern ice sheets and the tilt will have also reduced resulting in cooler summers warmer winters less ice not to mention the higher CO2 levels I do not think I would so cavalierly reject the idea that glaciers will melt to expose significant amounts of land in Southern Greenland but It will not happen in the next few hundred years Yes the northern ice sheet has existed for 3 million years but before that it was intermittent and we know that it moves around due to sea land weather and orbital influences Likewise the southern ice sheet has existed for 30 million years BUT it was intermittent for 12 15 million of those 30 ref Zachos 2001 You realy do have a tendency to exaggerate your arguments with the use of all just like I do Sincerely I really do thank you for taking the time to respond to all of us You are providing a useful service even if in my view a little biased I only hope we also expose you to other alternatives Response Don t underestimate the power of coincidence GRIP and GISP2 did hit bedrock at about the same depth but given their proximity that s maybe not surprising Note that no one knows exactly how old the base ice was because it had been deformed and mixed up NGRIP goes back further into Stage 5e Talking to ice core people they think that even older ice might be found further north still but that is a little speculative The trees found under the Greenland ice are Pliocene in age supporting the idea that Greenland has not been substantially de glaciated since then Greenland s ice is there partly because it s there That is if the glacier disappeared it s unclear whether it would reform Both the albedo and the altitude effects help Greenland stay relatively stable even though similar latitudes do not have glaciers Another help is that the topography helps keep the ice trapped Greenland is like a bowl with mountains around the side This was not true for the Laurentide or Fenno Scandanavian ice sheets which therefore come and go more easily gavin Those unattributed responses above were mine my apologies In any case if I may further clarify this Greenland MAY have been somewhat or even substantially smaller than today at the last interglacial warm period see Cuffey and Marshall 2000 Nature But the age of the ice at bedrock has very little bearing on this The oldest ice in Antarctica is probably not much more than 1 million years but the age of the ice sheet is at a minimum several million Ice sheets and glaciers are like slow rivers The age of the oldest water in the Mississippi river is of order decades yet the river has obviously been there for much much longer eric 59 Pat Neuman Hydrologist says 12 Apr 2005 at 5 02 AM Re 36 Isn t the latent heat of vaporization released when you go from steam to water at 100 C not from water vapor to water I thought that water vapor in air is already water so there is no big heat resevoir to melt all that ice as claimed Snowmelt with high humidity is more rapid than with low humidity other things held constant The same is true for thawing of ice on lakes and rivers 60 John Dodds says 13 Apr 2005 at 2 44 PM Eric Thanks for the apology Cuffey Marshall ref in 58 I think you are helping my Greenland melting case If the C M Abstract IS actually correct then of the 6 7m sea level rise that Greenland ice is now capable of if 4 5 5m came from Greenland during the last warming then 60 80 of the ice would have melted And as Gavin pointed out logically less ice would melt further north higher up I see this as further evidence that it was probable that the GISP ice core site in lower Greenland could have been uncovered or at least have had at least 60 80 less ice Which might explain along with the mashing melting at the base of glaciers why there is NOT 3 or 4 ice age cycles of ice there Now given that 60 80 of the current 3000m of ice is one hellofa lot AND that ice ages are apparently cyclical and caused by Milankovitch solar cycles and we are approaching similar to eemian time orbital conditions in 10 20K years then I again say do not be surprised if a hellofa lot of Greenland ice melts even without CO2 influences The point being that I believe that we have a tendency to think that our current recent conditions have always been there Apparently such major changes as some much bare land in central Greenland would not be so unexpected AND no amount of Kyoto CO2 intervention will stop it Now care to comment on my admittedly off topic observation about the hockey stick apparent cause of recent glacier melting is actually evident in solar and solar mag flux data going back to the mid 1800s One other observation CO2 Warming theory can NOT explain why ice ages occur hence leaving the admittedly not perfect Milankovitch theroy which to me includes Solar variations in place and Past ice age data shows multi degree temp rises drops within 100s of years If this is valid then WHY do you all keep insisting that orbital influences which currently would be a positive multiplier on solar and would also increase the water vapor feedback are so small I wish you would could revisit this assumption in your models or maybe make it a discussion topic Thanks keep up the effort Response A couple of quick comments I think you are confusing the timescales of things Sure in the long term climate change will happen with our without human intervention and if I were around 20 kyr from now I wouldn t be suprised to see Greenland melted away CO2 or no With respect to our own lifetimes though Milankovitch is simply not important orbital changes are swamped by other forcing You are also conflating Milankovitch orbital changes and solar irradiance changes Milankovich theory has nothing to do with irradience changes only the seasonally varying distance of Earth to the sun and orientation of the rotation axis with respect to the sun Now the argument against the sun drives the hockey stick has a least two basic underpinnings 1 the solar changes don t competing with the CO2 changes in magnitude of equivalent forcing 2 the solar changes don t go in the right direction that is they are not as highly correlated with the temperature changes as are the GHG changes We ve had some other posts and I ll track them down and put the links here We probably ought to do a longer post on this topic too and will when time permits eric 61 Thomas Mölg says 14 Apr 2005 at 6 57 AM Glacier recession on Kilimanjaro As one member of the group who is currently doing research on glacier climate interactions on Kilimanjaro joint project between Massachusetts and Innsbruck universities I would like to make some comments on Kilimanjaro glacier recession They may hopefully be useful for colleagues as well as for non scientists who are in contact with glaciology and climatology And maybe a contribution to the RealClimate tropical glaciers backgrounder proposed in comment no 8 Up to date we have published three studies that address the issue Unfortunately the third one has got little attention until now although it is the one which is most supported by in situ data STUDY 1 link Kaser G D R Hardy T Mölg R S Bradley and T M Hyera 2004 Modern glacier retreat on Kilimanjaro as evidence of climate change Observations and facts In International Journal of Climatology vol 24 no 3 pp 329 229 In this study we review a variety of papers ranging from the first observations of Kilimanjaro glaciers by Hans Meyer in the 1880s to 20th century satellite data of tropospheric temperature This happens with the intent to develop a working hypothesis for our research Based on all these studies a late 19th century moisture drop is by far the most likely event that has initiated the retreat of glaciers on Kilimanjaro A subsequent drier climate was the main driver for maintaining this retreat As correctly mentioned in comment no 8 it cannot be ruled out that this local climate change driving glacier retreat drying is connected to the large scale change of our atmosphere as we suggest on pages 336 and 337 of the paper We intend to explore during the next three years official duration of current project if such a connection does exist Hence we certainly don t deny general global warming at all Unfortunately climate skeptic groups have misused mainly this study but also the others below to argue against the global warming issue All we aim at is to explore glacier recession on Kilimanjaro in its full complexity STUDY 2 link Mölg T D R Hardy and G Kaser 2003 Solar radiation maintained glacier recession on Kilimanjaro drawn from combined ice radiation geometry modeling In Journal of Geophysical Research vol 108 no D23 4731 doi 10 1029 2003JD003546 Although submitted after the paper above it was published three months earlier due to the fast JGR review process This is the first study that builds on the concept from Kaser et al 2004 It shows with a simple ice cap model that the lateral retreat of the vertical ice walls that form the margin of the ice bodies on the summit plateau is controlled by the spatial distribution of energy from solar radiation Solar radiation receipt at the surface is much more tied to moisture related parameters especially cloudiness than to air temperature The existence of sharp features like the ice walls further excludes a significant impact of air temperature on the glacier This is nicely explained in the paper of Kraus 1972 cited in Kaser et al 2004 from a physical viewpoint On page 4 of our paper we note that we pursue an exploratory approach thus we are aware of the fact that this is not a classical scheme study Nonetheless it revealed the basic process forcing ice wall retreat and helped us to design the new measurements see below STUDY 3 link

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  • Michael Crichton’s State of Confusion II: Return of the Science « RealClimate
    Age caused by our pollution Since that fearmongering theory did not pan out today the scientific community now declares mankind is going to perish because of Global Warming caused by our pollution Paging Dr Connolley Paging Dr Connolley Done see above William 18 Pensa says 16 Dec 2004 at 2 50 PM Ummm joma Mike is Dr Michael Mann He has a Ph D in Geology and Geophysics He is no advocate but an actual scientist with a proven track record What is Crichton An author A bit more informed than an ordinary person maybe but no scientist that s for sure Actually Crichton is Dr Michael Crichton graduate of Harvard Medical School Response which makes him Michael Crichton M D not Dr if you want to be pedantic I often do William His new junk science angle sucks nonetheless 19 Stephen Berg says 16 Dec 2004 at 3 08 PM OK Pensa However Crichton he is no climate scientist which is what Dr Mann is Crichton should stick to his area of expertise 20 John Fleck says 16 Dec 2004 at 4 34 PM Syn Your two examples of when the mainstream of scientific thinking believed something that turned out to be wrong is not terribly helpful There also of course are many more examples in which the mainstream of science believed something that turned out to be right and you ve given us no way to usefully distinguish between the two This in fact is a fundamental error Crichton himself made in his Caltech talk I could liken the belief in a 4 plus billion year old Earth to the time when scientific man believed that the world was flat and if we were to sail beyond the horizon we would fall off that planet and die but that wouldn t advance a discussion of the age of the Earth I m granting here for purpose of discussion your 1970s ice age example though it s clearly questionable 21 tom says 16 Dec 2004 at 5 18 PM It is not helpful to point out what man used to believe or did not believe It seems to me that most of us would believe that science has progressed and our ability to understand our environment has improved somewhat since the dawn of man and even since the 1970s The real issue is what scientists using generally accepted scientific methodology believe now I cannot refuse to make decisions today based upon the knowledge that information I had yesterday or a decade ago was incorrect or the knowledge that I have ever made a bad decision This mode of thought leads to paralysis and the inability to make any decisions about what is the appropriate human response to what we believe is happening or will happen The fact that we may be wrong proves nothing and shouldn t be a rationale for total inaction which is pretty much what we have under the current American administration 22 Steve Funk says 16 Dec 2004 at 6 46 PM I think I read the coming ice age theory in the Readers Digest around 1956 or 1957 I was about 12 I haven t been able to google it up Possibly Ponte wrote it since he was once an associate editor there There was probably nothing unique in that article but I d like to see it again if anyone has it 23 GeniusNZ says 16 Dec 2004 at 9 01 PM What I meant by this was a rhetorical reference to Americans everywhere in all states who are threatened by and reject science Fair enough david and you are right that some people are more in search of finding a market for their product than finding the truth and that those markets often just want the truth that makes them feel they were right all along or that allows them to not feel guilty about what they do 24 PB says 16 Dec 2004 at 10 46 PM It is my undestanding that no scientific community ever thought the Earth was flat the Earth as a globe has certainly been understood since early Greek culture In Europe anyway a flat Earth was a product of religion not science I realize this is a bit off topic but my point is that science eventually usually comes to an accurate conclusion The global warming hypothesis that exists today is supported by available data and is certainly our best guess as to what is actually happening 25 oliver says 17 Dec 2004 at 9 54 AM When people like Chrichton bring up the accuracy of predicting the weather I suggest we bring up the accuracy with which we can predict the seasons and where New Yorkers will retire in old age Response Well said These are indeed the sorts of examples I find helpful when explaining the distinction between weather and climate in a public lecture mike 26 praktike says 17 Dec 2004 at 3 12 PM To say nothing of his outrageous claims about gorilla civilizations in Africa giant pschotic squids and alien bacteria 27 David Holland says 17 Dec 2004 at 3 47 PM With all the hype you guys have given to State of Fear I and I suspect a lot more had to get a copy It s now been wrapped for Christmas but I managed a quick peek and can see why so many of you are exercised by it Someone pointed out elsewhere in this site that many ordinary people are casual sceptics Brits in particular are instinctively sceptical and lately have had good reasons to question anything that has the government s or EU s fingerprints on it Casual sceptics do not generally proselytise but informed ones and those that think they are informed most definitely do To get informed on this subject is an arduous project even for those well educated in maths and science It requires hours of surfing and is so boring relatively few bother to do it State of Fear on the other hand looks like a good read and if they turn it into a movie it will be even easier to absorb Never mind if is scientifically correct Expect it get to get tougher 28 Mark Paris says 17 Dec 2004 at 6 09 PM Crichton s example of Wegener and continental drift is actually an example I use to describe the way science is supposed to work A new and significantly different explanation for facts must not be accepted without lots of scrutiny Geologists were right to reject continental drift until the facts caught up with the proposed explanation I intentionally do not use theory for Wegener s continental drift ideas SETI is not a good example either SETI is not based on the belief that ETs exist it is an attempt to search for evidence of their existence 29 Dave says 17 Dec 2004 at 7 09 PM Nobody believes a weather prediction twelve hours ahead Now weâ re asked to believe a prediction that goes out 100 years into the future This kind of comment makes my teeth itch As a meteorologist I know only too well the shortcomings of weather prediction I also know just how good near term i e within the first 12 hours forecasts really are What Crichton is really saying is that because we can t provide him with a bullet proof forecast for the next 12 hours we should discount long term climate forecasts Aside from being non sequitur we re talking about forecasts not prophecies There s a huge difference between them 30 TangoMan says 17 Dec 2004 at 7 42 PM It seems that debate is shaping up nicely on your blog Congratulations I second Joma s comment to refrain from turning this blog into a platform for advocacy I m a great believer in letting the light shine on a poorly constructed hypothesis and letting the heat of intellectual battle forge the consensus that can be agreed upon I think the global warming deniers have a poor case for their position however I m leery when I see those who study the issue overplaying their hand It s far easier to hold the feet of the deniers to the fire for there is evidence that is incontrovertible but the totality of the scientific findings are not all rock solid There is room for skepticism A healthy practice of science requires skepticism and that s why I find Dr Mann s dispute with Dr McKittrick McIntyre to be healthy for the process Let each objection be answered in the full light of day This healthy process is a far better testiment to scientific process than the whole Lumborg Scientific American affair which smacked of censorship and advocacy and prompted me to end my subscription to that journal I don t know it to be the case but I suspect that Crichton didn t delve too deeply into the literature and his position is one centered on providing compelling drama and entertainment The way I read his essay is that he is concerned about process and overreach Regardless I don t think people should be turning to him as an authority on the subject he s a dramatist That said this site should painstakingly rebut with links and citations the claims of deniers and let people of good conscience see the process of science play out If you become advocates which I think is a far easier road to follow then you re granting the deniers a legitimacy that they haven t earned That said I don t think that Crichton is completely off his rocker He points to a few instances in his essay where he thinks that the science has turned into advocacy Specifically he writes The 1995 IPCC draft report said Any claims of positive detection of significant climate change are likely to remain controversial until uncertainties in the total natural variability of the climate system are reduced It also said No study to date has positively attributed all or part of observed climate changes to anthropogenic causes Those statements were removed and in their place appeared The balance of evidence suggests a discernable human influence on climate The two statements from the draft report were more accurate positions about the state of knowledge in 1995 They properly hedged and didn t go beyond what was known The final statement drastically changed the tone and underplays the rightful role of skepticism It seems that Crichton had a problem with the process that IPCC used back then and I agree with him on this issue I m also quite certain that matters have firmed up in the following years but it would be a logical fallacy to use recent findings in support of the political decision involved in the 1995 IPCC statement As to the questions I raised in the previous thread about model validation let me flesh out my concerns in a little more detail I m fully aware of the enormity of the task before climate researchers as they try to model worldwide climate but I don t think and I m quite open to being corrected on this issue that the models have the same degree of confidence that for instance nuclear explosion models have More here and here And while modeling nuclear explosions is a complex task the modelers have data from over a 1 000 previous explosions and have found that the models quite accurately reflect the dynamics involved in an explosion Even so some are recognizing that the aging of the stockpile is calling into question some of the variables incorporated into the models and validation would help to more accurately model those variables I applaud recent news like the world s fastest supercomputer being used for climate modeling for I think that trying to model the number of variables is a herculean task far greater than that encountered by the nuclear weapons designers That said though I m extremely bothered by articles such as the one published last January in Nature entitled Extinction risk from climate change by Thomas et al The article is chock full of conditionals and the authors reference a range of climate scenarios in their models Further the model that they use for this study is built upon a compositional fallacy They state The approach has been validated by successfully predicting distributions of invading species when they arrive in new continents and by predicting distributional changes in response to glacial climate changes emphasis added I think that the model falls apart logically when it is extended beyond what is known The model was validated so that we knew that parts of the whole X have characteristics A B C and then extended to the conclusion that therefore the whole X must have characteristics A B C How an article like this passes peer review is beyond me I don t consider that to be science It s simply a computer run with some data It s quite possible to have a Garbage In Garbage Out outcome to this kind of science Further climate modelers unlike the nuclear modelers mentioned above have to work with a lot of proxy data and how these proxies are modeled can introduce a lot of error into the models I look at this site which goes into extensive discussion of the model validation procedures and I conclude that climate scientists can t yet speak with the degree of certainty that we d all like There appears to be little replicability between the nine models shown in this graphic and against the pollen proxy model at the bottom Back to Crichton in his essay he also writes Just as we have established a tradition of double blinded research to determine drug efficacy we must institute double blinded research in other policy areas as well Certainly the increased use of computer models such as GCMs cries out for the separation of those who make the models from those who verify them The fact is that the present structure of science is entrepeneurial with individual investigative teams vying for funding from organizations which all too often have a clear stake in the outcome of the research or appear to which may be just as bad This is not healthy for science Too often I read in studies where the authors are running their own data or that of associates in their models These associations are too close for my comfort While Crichton may be way off base in his references to the state of knowledge in the field I do grant him points on raising some legitimate process concerns The science can only get better if there is a more adversarial approach and the findings can be debated At least that s my point of view 31 Webster Hubble Telescope says 18 Dec 2004 at 12 29 AM TangoMan back off on the analysis You bring in validation of nuclear explosion models Why You talk about double blind experiments Why What do you want an extra planet or two to do experiments on 32 Kalkin says 19 Dec 2004 at 2 52 AM TangoMan you mostly raise good points but about the 95 IPCC report the problem with leaving in qualifiers even if they re true is that they re so easily quote mined by people who take them out of context and present them as the conclusion of the report Certainly overstating the evidence is not justifiable but I don t think that s what the IPCC did One simply must be careful about negative language because it ll get picked up by one s ideological opponents and presented alone as representative of one s views To the bloggers you oughta link to the Panda s Thumb http www pandasthumb org Very similar project to yours only about evolutionary biology I suspect at least some of you know about it already of course 33 TangoMan says 19 Dec 2004 at 3 55 PM Kalkin One simply must be careful about negative language because itâ ll get picked up by oneâ s ideological opponents and presented alone as representative of oneâ s views It comes with the territory If scientists become advocates and massage the data and or message to fit the ideology then all hope of impartial science is lost The science should be impeccable If there is negative language that is exploited by the deniers then the job of advocates is a little harder but at least the reputation of the science is preserved and that only works to the benefit of the advocates BTW I am a bit peeved at having a comment censored There was nothing at all inflammatory in its content and if you re censoring me for raising process questions then frankly I m disappointed in how your blog is shaping up Response In order to keep the signal to noise ratio at a reasonable level we have a comment policy that moderates comments based on relevance to the post as well as avoiding inflammatory comments I m sorry if you feel your comment was wrongly deleted but you are free to repost gavin 34 Bill Canada says 22 Dec 2004 at 1 15 PM I having lived in the arctic can only state that it is a very fragile ecosystem Therefore research and remediation of GHG s is essential We here in Canada get the real world experience of even the most minor climate changes as part of our daily reality The Great Lakes are a micro laboratory of land mass water mass climatological interactions Observations do not require decades but merely hours I believe this reflects the macro model analysis examining the global patterns Environment Canada has network of RADAR stations that show preceipitation levels in almost real time I would suggest referring to the various stations animated displays as study reference http www weatheroffice ec gc ca radar

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  • Réchauffement global sur Terre ? « RealClimate
    t live in nature Anyway there is a big debate occurring now about framing this issue and how your phraseology is completely er natural here Re 9 if I can expand on gavin s reply Karl first quantified the effect of the UHI in 1989 Sixteen years ago We knew what it was then and it is corrected for now But it might be useful for all of us if David could actually back his claim that the data are bad and what constitutes bad Set some parameters ahead of time DW Best D 11 dan allan says 13 Oct 2005 at 11 24 PM I have a general question on the temperature anomalies As I understand it they refer to the anomaly versus the previous 100 years of global average temperatures But if this is so that suggests that 1998 anomaly is against a different 100 years than the 2005 anomaly which I have trouble believing because it would serve to downplay the rate of GW Anyone care to clarify Response When you see a graph of anomalies they are usually against a 30 year not 100 year reference period Usually 1960 90 nowadays But on any one graph the same ref period would be used for all the data it would indeed be very confusing is each year were anomaly from the 30y before that very year if thats what you re wondering William Thanks Dan BTW Dano your definition of natural is pretty silly since you have succeeded in encompassing everything that has ever happened and could ever happen into natural events So we no longer need the word do we Of course we are just another species and what we do arguably is therefore natural But we all know what is meant by the word it is a useful term and your version of it renders it useless Just my opinion 12 nanny govt sucks says 14 Oct 2005 at 1 52 AM Isn t a flat or slight cooling trend in the surface data over the last 3 years some good news to crow about Or has no one noticed this in all the alarmist hysteria 13 Andrew Dodds says 14 Oct 2005 at 3 34 AM Re 12 Just as a thought experiment if the last 3 years had each gotten progressively warmer would you accept it as definitive proof of global warming Since you consider 3 years long enough to establish a stastically valid trend in climate Or would that be different Actually this news is quite bad Previously is was claimed by skeptics that the 1998 anomoly made the temperature trend look far worse than it was The fact that we are now seeing global temperatures exceeding this without such strong el nino effects is a confirmation that AGW theories are correct 14 Janne Sinkkonen says 14 Oct 2005 at 4 00 AM Re 12 If you look at the same dataset at the NASA site you find out a yearly variation around the trend with standard deviation about 0 12 degrees The trend of last three years has been about 0 06 degrees in 2002 2003 and 0 04 degrees in 2003 2004 which as absolute yearly differences are actually below average During the last 30 years there have been four such three year downward trends IMO there is nothing to write home about By the way by all likelihood 2005 will be warmer than 1998 currently the hottest year on record 15 Timothy says 14 Oct 2005 at 7 37 AM Re 12 and more generally As pointed out in the body of the post above The important climate trends aren t based on individual years but on decades Three years isn t enough for a trend Since ENSO variability is a big driver of the global temperature variability around the trend you d want a decrease to be sustained over a couple of ENSO cycles 10 yrs rather than three years What is significant about this year is that it would be a new record warmest year without there being a strong El Nino as in 1998 This suggests that the next time there is a strong El Nino comparable to 1998 you d set a new record even higher than 1998 and 2005 As long as the trend in rising temperature continues as CO2 continues to rise then eventually even the coldest years that happen due to variability will be warmer than 1998 16 Dano says 14 Oct 2005 at 12 09 PM BTW Dano your definition of natural is pretty silly since you have succeeded in encompassing everything that has ever happened and could ever happen into natural events So we no longer need the word do we Thanks for the critique of my argument dan obviously this needs work We do need the word What prompted my reply was the statement that man made pollution was unnatural when that is not the case If the only conclusion drawn from my argumentation is that every event is natural that s OK but my linky and larger point was that there is a larger discussion over the environment as a thing a distinction which allows the environment to be devalued and allows the environmental movement to be seen as a special interest We see evidence of this in this very thread alarmist hysteria Highlighting the distinction is a semiotic and framing exercise intended to show that the environment isn t separate from man therefore when we pollute into the environment that pollution doesn t go somewhere that doesn t affect man it s not an externality but rather an accounting error Arguments made and entered into the public discourse about the effects of AGW and our response to them should be seen as affecting all of us not just as an argument by special interest or about thing Best D 17 Lynn Vincentnathan says 14 Oct 2005 at 12 47 PM RE 7 8 10 11 Let me

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  • Q & A: Global Warming « RealClimate
    compensate for the thicking at higher levels Response This is related to a new Science express paper Johannessen et al 2005 which gives some of the best data yet on the elevation trends for the last decade or so Interestingly much of the variability they see is related to the NAO index high index implies less accumulation but they are not able to give a full mass balance of the ice sheet as you correctly say There is a review paper on a similar topic by Alley and coauthors in this week s Science as well gavin 69 Blair Dowden says 21 Oct 2005 at 7 41 AM Re 66 The wording of the abstract quoted in 62 leaves the impression that 3 degrees of warming will melt the Greenland ice cap in 1000 years although read very carefully it does not quite say that The report says it will take 8 degrees to do that The reality is bad enough Why twist words to make it sound worse than it is Response It is unfair to accuse the authors of twisting words You are exploiting a highly semantic point i e what the authors meant by more than 3C The topic is in fact discussed in great detail in a review paper by Alley et al just out in this week s Science These authors note that a warming of 3 8C will lead to the eventual melting of the Greenland ice sheet This is consistent with other studies indicating that 3C is an approximate threshold for the eventual melting of the Greenland ice sheet There are no inconsistencies here Now lets move on to other topics mike Re 67 I see no increase in the number of storms from looking at the graph and I understand that warming ocean water is not linked to number of storms It is linked to the intensity of those storms However I note that the most intense storms this year have passed through the Gulf of Mexico which is a warm shallow body of water Unlike the Atlantic ocean I do not believe there is a long term warming trend there Response Your statement is not quite accurate Wilma achieved the greatest strength lowest central pressure 882 mb of any Atlantic Hurricane on record without entering the Gulf of Mexico For a discussion of what can and cannot be concluded about possible relationships between recent Hurricane activity and climate change please see our post on Hurricanes and Global Warming Is There a Connection mike 70 Keith Moulton says 21 Oct 2005 at 11 52 AM I was struck by John Wallace s assertion in the Seattle Times article that The warming is much more rapid than most of the natural variations we ve seen in the past Is that true I m having trouble reconciling that statement with this paper by Kendrick Taylor and to a lesser extent ice core data Looking by eye the Vostok graph seems to show temperature rebounds after an ice age to be around 8 degrees C in say 6000 years That by itself would seem to support Wallace s statement since it would work out to about 1 degree C per 750 years But that s an Antarctica average based on air samples that were each gradually trapped in the ice over thousands of years There must have been brief periods of very rapid temperature change mixed in there certainly on the regional level in addition to slower warming periods and I m under the impression other data such as Greenland ice cores and deep sea cores support that scenario as well 71 nanny govt sucks says 21 Oct 2005 at 2 31 PM 67 One can fairly easily visualise a best fit line from around the 1930s to the present and see an increase in the number of storms What I see is a flat trend until about 1995 or so 72 Scott Church says 21 Oct 2005 at 2 33 PM It s great to see this story getting attention here I hail from Seattle and the ST is my home paper As it turns out Sandi Doughton interviewed me for this story and I provided her with much of her information on global warming skeptics and the tropospheric satellite record It was great to be a part of it SC 73 nanny govt sucks says 21 Oct 2005 at 3 12 PM Just found this Greenland icecap thickens despite warming http abc net au science news stories s1485573 htm Greenland s icecap has thickened slightly in recent years despite concerns that it is thawing out due to global warming says an international team of scientists 74 Dan says 21 Oct 2005 at 3 20 PM re 73 Note that the article concludes by saying A separate study in today s issue of Science reports that sea levels are probably rising slightly because of a melt of ice sheets Ice sheets now appear to be contributing modestly to sea level rise because warming has increased mass loss from coastal areas more than warming has increased mass gain from enhanced snowfall in cold central regions the report by a team led by Professor Richard Alley of Pennsylvania State University in the US says Greenland presently makes the largest contribution to sea level rise 75 Stephen Berg says 21 Oct 2005 at 4 36 PM Re 71 What I see is a flat trend until about 1995 or so The rate of tropical storm and hurricane increase is certainly not great prior to 1995 However I fit a best fit line myself on the actual newspaper of which I am a subscriber and found a slight increase What is alarming is the post 1995 record which makes it look like the oceans have lagged in terms of temperature increase until the last decade It now looks like the plaent is in for something terrible in this part of the world and in other regions which are affected by tropical cyclones a massive increase in the numbers and intensities of such storms I know circulation patterns currents are primarily responsible for thermal transmission In my view however the ocean atmospheric couplet is becoming more and more of a factor in the warming or cooling of the oceans 76 Blair Dowden says 21 Oct 2005 at 7 59 PM Re 69 I was wrong about Wilma It strengthened in the Caribbean which shows a clear pattern of warming especially this year It is reasonable to conclude that global warming played a part in Wilma s intensity I note that the RealClimate article confirms there is no link between sea surface temperatures and hurricane frequency which is extreme this year but it is linked to intensity also high this year Re 60 I am still having a hard time understanding the statement Approximately 98 of the energy supplied annually to the Arctic system is advected from lower latitudes by the atmosphere from the EOS paper and confirmed by wayne davidson Does this mean only 2 of the energy comes from the sun Given that average arctic insolation is about 100 watts per square meter this makes no sense A better idea of the energy balance in the arctic might help me understand events there better Speaking of Greenland cooling and the ice sheet thickening I am struck by the image of northern surface air temperature change for 1980 1999 in the Nansen Environmental and Remote Sensing Center paper p 7 It shows Greenland as a small island of cooling in a large sea of warming I guess ice caps are resiliant but how long can this situation last 77 Steve Bloom says 21 Oct 2005 at 8 46 PM Re s 59 and 65 The albedo change when sea ice melts is by no means considered to be insignificant Quoting from http nsidc org news press 20050928 trendscontinue html the recent press release on this year s record low sea ice extent The trend in sea ice decline lack of winter recovery early onset of spring melting and warmer than average temperatures suggest a system that is trapped in a loop of positive feedbacks in which responses to inputs into the system cause it to shift even further away from normal One of these positive feedbacks centers on increasingly warm temperatures Serreze explained that as sea ice declines because of warmer temperatures the loss of ice is likely to lead to still further ice losses Sea ice reflects much of the sun s radiation back into space whereas dark ice free ocean absorbs more of the sun s energy As sea ice melts Earth s overall albedo the fraction of energy reflected away from the planet decreases The increased absorption of energy further warms the planet â Feedbacks in the system are starting to take hold â argues NSIDC Lead Scientist Ted Scambos Moreover these feedbacks could change our estimate of the rate of decline of sea ice â Right now our projections for the future use a steady linear decline but when feedbacks are involved the decline is not necessarily steadyâ it could pick up speed â 78 wayne davidson says 21 Oct 2005 at 11 37 PM 76 I am not sure also about that 98 figure but there is definitely some very strong advection activity on a continuous basis feeding heat to several distinct circumpolar geographical locations in the Arctic every day I would like to ask a Gulf coast Climate Historian a question you never know may be someone like Gulf Coast resident like Mr Wallace reads Real Climate After speaking to a native Floridian who was around in the 40 s I was surprised to learn that hurricanes then didn t seem to be as numerous as 2005 An account about those numerous hurricanes in the 40 s would be nice to hear about since they are mentionned so oftenly as reoccuring today 79 Steve Bloom says 22 Oct 2005 at 5 36 AM Judith Curry Kerry Emanuel and Kevin Trenberth have come out swinging and are now saying that there is a causal relationship between global warming increased SSTs and stronger hurricanes Curry is interviewed at http pubs acs org subscribe journals esthag w 2005 oct policy pt curry html What you can do is show an unambiguous link between the increase in hurricane intensity and the warming sea surface temperatures And if you look for why the sea surface temperatures are warming since the 1970s you donâ t have any explanation other than greenhouse warming Wow There s a more detailed joint statement at http www ametsoc org atmospolicy EnvironmentalScienceSeminarSeries html I am so happy that these prominent scientists have decided to come out swinging Among other things in the interview Curry goes after Bill Gray James O Brien Max Mayfield and Roger Pielke Jr for the various negative roles they ve been playing Chris Landsea is not named but he s there in spirit The timing with Wilma could not be better for this of course Yabba dabba doo 80 Keith Moulton says 22 Oct 2005 at 12 46 PM Yabba dabba doo I m sorry Steve the seminar where those three will appear is on October 25th Today s the 22nd Only the first link offers any kind of statement and it s from Curry only not the other two 81 Ferdinand Engelbeen says 22 Oct 2005 at 4 17 PM Re 76 Blair one again need to be carefull with the time frame of the graph presented The winter rate of change in the previous warming period was stronger between 1915 1935 and the overall warming 1930 1940 than for the current one as can be seen in the circumpolar stations which existed then see Fig 2 page 6 3268 of the Overland e a papers What is interesting in the Nansen Centre paper is that much of the recent summer and partly winter warming seems to be outside the Arctic in the mid latitudes Further have a look at Fig 1 of the Nansen paper The difference between measurements and models still is large The model underestimates the 1930 1940 warming as good for the Arctic as for lower latitudes and underestimates the lower latitude recent warming in my opinion as a result of overestimated influences of GHGs and aerosols at one side and underestimated solar influences at the other side But that is more for the Modeller vs modeller discussion 82 Steve Bloom says 22 Oct 2005 at 4 18 PM Re 80 KM Keith I do apologize well sort of for the Flintstones reference Wilma Fred yabba dabba doo but I couldn t resist I m not sure what the implied problem is with the seminar being on the 25th but in any case to see the 1000 word statement from the three of them just scroll down on the second linked page It s powerful stuff 83 Stephen Berg says 22 Oct 2005 at 4 54 PM Thank you Steve Bloom for your links in 79 Curry Emanuel and Trenberth are certainly beacons in the fog 84 wayne davidson says 22 Oct 2005 at 5 32 PM 79 thanks Steve for the links There is no debate as well with the few media savy scientists taking a stance against Global Warming it is after all their raison D etre as they themselves get funded by Groups opposing the theory But I recently read that 66 of Americans have already made the link between fierce Hurricanes and Global Warming the attention spotlight will eventually change to raison d avoir a better understanding there is nothing more strong then being right I am also ready to listen to the memories of Elders from the Gulf and Carribean about how similar 2005 is say to any year To counter the matter of fact smug cycle theorists there has to be a proper history recounted by climatologists capable of recounting that there was so called similar year s the it was just as bad as in the 1940 s ball is lobbed out now we have to say ho ya When then Name a year say the horror stories perhaps on a smaller scale Then peers of that time can confirm or deny the veracity of it Elders to the rescue In the older days there were no NOAA s TV s and internet hardly any warning compared to today frequent disatrous hurricanes like 05 would have been scarred in many memories If there is no resonance with a previous years somewhat similar to 2004 05 there is none in the media now nobody is saying its like 1949 all over again therefore this adds to the formidable pile of evidence in favor of AGW and also shows the weaker side of those negating AGW s influence 85 Gerald Machnee says 22 Oct 2005 at 7 05 PM Re 79 Following is a Q A from the Curry interview Q People can criticize the paper because you only went back to the 1970s Can you actually see a pattern with such limited data A We do not have global data prior to 1970 We have data from 1945 to 1970 from aircraft in the North Pacific and the North Atlantic Prior to 1945 we only have statistics on landfalling hurricanes Now events in the Atlantic comprise only 11 of global hurricanes and U S landfalling hurricanes only comprise 1 So trying to draw inferences about global hurricane activity from these statistics just doesnâ t work Using the sampling data from the Atlantic to understand whatâ s happening globally is like only sampling California voters to try and infer U S presidential preferences If you look at landfalling hurricanes the statistics are really just looking at California voters over 65 laughs Itâ s a sampling error Just to give you a counterexample during the same time period landfalling hurricanes in Australia have actually gone down So if we had only relied on landfalling hurricanes we would have a different story But clearly the Australian story doesnâ t tell you anything about what is going on globally Curry uses an example of looking at voters over 65 when talking about landfalling hurricanes However the work she refers to dating from 1970 to the present is like using voters under 35 She can write all the refereed papers in the world but the data is not complete whan you use half of a cycle 86 Gerald Machnee says 22 Oct 2005 at 7 25 PM Re 84 You do not need to look for deceased elders in the computer age The following site has the 10 deadliest 10 costliest and 10 most intense hurricanes http www cnn com SPECIALS 2005 hurricanes RE To counter the matter of fact smug cycle theorists there has to be a proper history recounted by climatologists capable of recounting that there was so called similar year s the it was just as bad as in the 1940 s ball is lobbed out now we have to say ho ya When then Name a year say the horror stories perhaps on a smaller scale Historical records exist beyond the elders With very little effort you can find records of typhoons into the 1700 s killing 10 s of thousands The years are there and are included in the previously named site RE There is no debate as well with the few media savy scientists taking a stance against Global Warming it is after all their raison D etre as they themselves get funded by Groups opposing the theory Do the forecasters in Miami Hurricane Centre get paid by special interests 87 Stephen Berg says 22 Oct 2005 at 8 07 PM Well hello Tropical Storm Alpha First time ever hitting the Greek alphabet 88 Steve Bloom says 22 Oct 2005 at 8 53 PM Re 85 GM By that very same logic your speculation about natural cycles is

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