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  • October « 2007 « RealClimate
    warming trend of the deglaciation in Europe particularly was interrupted for a period of about 1300 years before it got going again There were clear glacier advances during this time and the moraines can be seen very clearly all around Europe and Scandinavia The clues to what caused this remarkable if temporary turnaround have always lain in assessing its spatial extent the exact timing and correspondence with other events Two recent papers have shed some welcome and potentially controversial light on the subject More Comments pop up 70 Sweatin the Mediterranean Heat Filed under Climate Science Instrumental Record group 22 October 2007 Guest Commentary from Figen Mekik This quote from Drew Shindell NASA Goddard Institute for Space Studies New York hit me very close to home Much of the Mediterranean area North Africa and the Middle East rapidly are becoming drier If the trend continues as expected the consequences may be severe in only a couple of decades These changes could pose significant water resource challenges to large segments of the population February 2007 NASA Science Daily I live in Michigan but Turkey is my home where I go for vacation on the Med This year s drought was especially noteworthy so I would like to share some of my observations with you and then explore the links between the North Atlantic Oscillation NAO Mediterranean drought and anthropogenic global warming AGW The 10 hour flight from Chicago to Istanbul often inspires passengers to romanticize about Istanbul both tourists and natives alike Istanbul is the city of legends forests and the Bosphorus It is an open museum of millennia of history with archeological and cultural remnants surrounded by green lush gardens It is the place where east meets west where blue meets green where the great Mevlâna s inviting words whisper in the wind Come come again whoever you are come So you can imagine our collective horror as the plane started circling Istanbul and we saw a dry desolate dusty city without even a hint of green anywhere More Comments pop up 124 Global Warming Delusions at the Wall Street Journal Filed under Climate Science david 18 October 2007 Daniel Botkin emeritus professor of ecology at UC Santa Barbara argues in the Wall Street Journal Oct 17 page A19 that global warming will not have much impact on life on Earth We ll summarize some of his points and then take our turn More Comments pop up 453 Older Entries Site Google Custom Search Recent Comments 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 What is the best description

    Original URL path: http://www.realclimate.org/index.php/archives/2007/10/ (2016-02-13)
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  • September « 2007 « RealClimate
    majority of Shanghai s motorbikes and scooters were electric rather than gasoline powered These efforts clearly help but they are just as clearly not sufficient on their own Finally the limited access to the Internet that one gets in China through a combination of having better things to do with one s time and the sometimes capricious nature of what gets through the Great Firewall allowed me to take a bit of break from the constant back and forth on the climate blogs In getting back into it one appreciates just how much time is wasted dealing with the most ridiculous of issues Hansen s imagined endorsement of a paper he didn t write thirty six years ago the debunking of papers that even E E won t publish and the non impact of the current fad for amateur photography at the expense of anything substantive In effect if possibly not in intention this wastes a huge amount of people s time and diverts attention from more significant issues at least in the various sections of the blogosphere Serious climate bloggers might all benefit from not getting too caught up in it and keeping an closer eye on the bigger picture We will continue to try and do so here Comments pop up 183 Worth a Look Filed under Climate Science mike 20 September 2007 We re pleased to report that after a rough start Nature s blog Climate Feedback seems to have gotten back on track We re happy to endorse it as a useful resource for those interested in relatively informal discussions of issues at the leading edge of current climate research A good place to start are two excellent recent entries by Kevin Trenberth of NCAR The first of these provides an update on where the scientific debate over the influence of global warming on hurricanes currently stands The second responds to the latest attempt by the Wall Street Journal editorial page to foist fallacies about climate change upon its readers Comments pop up 99 Climate Insensitivity Filed under Climate Science group 16 September 2007 Guest post by Tamino In a paper Heat Capacity Time Constant and Sensitivity of Earth s Climate System soon to be published in the Journal of Geophysical Research and discussed briefly at RealClimate a few weeks back Stephen Schwartz of Brookhaven National Laboratory estimates climate sensitivity using observed 20th century data on ocean heat content and global surface temperature He arrives at the estimate 1 1 0 5 deg C for a doubling of CO2 concentration 0 3 deg C for every 1 W m 2 of climate forcing a figure far lower than most estimates which fall generally in the range 2 to 4 5 deg C for doubling CO2 This paper has been heralded by global warming denialists as the death knell for global warming theory as most such papers are More Comments pop up 370 Friday roundup Filed under Climate Science group 6 September 2007 Schwartz in the news

    Original URL path: http://www.realclimate.org/index.php/archives/2007/09/ (2016-02-13)
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  • August « 2007 « RealClimate
    observation time and the examples that he thinks have the potential to be large scale tipping elements are Arctic sea ice a reorganisation of the Atlantic thermohaline circulation melt of the Greenland or West Antarctic Ice Sheets dieback of the Amazon rainforest a greening of the Sahara Indian summer monsoon collapse boreal forest dieback and ocean methane hydrates To that list we d probably add any number of ecosystems where small changes can have cascading effects such as fisheries It s interesting to note that most of these elements include physics that modellers are least confident about hydrology ice sheets and vegetation dynamics Prediction vs Projections As we discussed recently in connection with climate forecasting the kinds of simulations used in AR4 are all projections i e runs that attempt to estimate the forced response of the climate to emission changes but that don t attempt to estimate the trajectory of the unforced weather As we mentioned briefly that leads to a sweet spot for forecasting of a couple of decades into the future where the initial condition uncertainty dies away but the uncertainty in the emission scenario is not yet so large as to be dominating Last week there was a paper by Smith and colleagues in Science that tried to fill in those early years using a model that initialises the heat content from the upper ocean with the idea that the structure of those anomalies control the weather progression over the next few years They find that their initialisation makes a difference for a about a decade but that at longer timescales the results look like the standard projections i e 0 2 to 0 3ºC per decade warming One big caveat is that they aren t able to predict El Niño events and since they account for a great deal of the interannual global temperature anomaly that is a limitation Nonetheless this is a good step forward and people should be looking out for whether their predictions for a plateau until 2009 and then a big ramp up materialise over the next few years Model ensembles as probabilities A rather esoteric point of discussion concerning Bayesian priors got a mainstream outing this week in the Economist The very narrow point in question is to what extent model ensembles are probability distributions i e if only 10 of models show a particular behaviour does this mean that the likelihood of this happening is 10 The answer is no The other 90 could all be missing some key piece of physics However there has been a bit of confusion generated though through the work of climateprediction net the multi thousand member perturbed parameter ensembles that notoriously suggested that climate sensitivity could be as high as 11 ºC in a paper a couple of years back The very specific issue is whether the histograms generated through that process could be considered a probability distribution function or not Not is the correct answer The point in the Economist article is that one can demonstrate that very clearly by changing the variables you are perturbing in the example they use an inverse If you evenly sample X or evenly sample 1 X or any other function of X you will get a different distribution of results Then instead of in one case getting 10 of models runs to show behaviour X now maybe 30 of models will And all this is completely independent of any change to the physics My only complaint about the Economist piece is the conclusion that because of this inherent ambiguity dealing with it becomes a logistical nightmare that s is incorrect What should happen is that people should stop trying to think that counting finite samples of model ensembles can give a probability Nothing else changes Comments pop up 167 1934 and all that Filed under Climate Science Instrumental Record gavin 10 August 2007 Another week another ado over nothing Last Saturday Steve McIntyre wrote an email to NASA GISS pointing out that for some North American stations in the GISTEMP analysis there was an odd jump in going from 1999 to 2000 On Monday the people who work on the temperature analysis not me looked into it and found that this coincided with the switch between two sources of US temperature data There had been a faulty assumption that these two sources matched but that turned out not to be the case There were in fact a number of small offsets of both sign between the same stations in the two different data sets The obvious fix was to make an adjustment based on a period of overlap so that these offsets disappear This was duly done by Tuesday an email thanking McIntyre was sent and the data analysis which had been due in any case for the processing of the July numbers was updated accordingly along with an acknowledgment to McIntyre and update of the methodology The net effect of the change was to reduce mean US anomalies by about 0 15 ºC for the years 2000 2006 There were some very minor knock on effects in earlier years due to the GISTEMP adjustments for rural vs urban trends In the global or hemispheric mean the differences were imperceptible since the US is only a small fraction of the global area There were however some very minor re arrangements in the various rankings see data As it existed in Sep 2007 Specifically where 1998 1 24 ºC anomaly compared to 1951 1980 had previously just beaten out 1934 1 23 ºC for the top US year it now just misses 1934 1 25ºC vs 1998 1 23ºC None of these differences are statistically significant Indeed in the 2001 paper describing the GISTEMP methodology which was prior to this particularly error being introduced it says The U S annual January December mean temperature is slightly warmer in 1934 than in 1998 in the GISS analysis Plate 6 This contrasts with the USHCN data which has

    Original URL path: http://www.realclimate.org/index.php/archives/2007/08/ (2016-02-13)
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  • July « 2007 « RealClimate
    was used the first time around and edited out the misleading segment with Carl Wunsch There is some amusing feedback in the post show discussion panel and interview via DeSmogBlog RC Wiki As an aside this is as good a time as any to point people to a new resource we are putting together RC Wiki which is an index to the various debunkings of the contrarian articles TV programs and internet pseudo science that is out there The idea is to have a one stop shop so that anyone who comes across a piece and wants to know what the real story just has to start there For instance the page on TGGWS has a listing of many of the substantive criticisms from the time of the first showing Editing the wiki is by invitation only but let us know if you want to help out or if you have any suggestions or comments The sweet spot for climate predictability Between the difficulty of long term weather forecasts and the impossibility of accurate predictions for economic conditions a century hence there is a sweet spot for climate forecasts This spot maybe between 20 and 50 years out is where the emissions scenarios don t matter too much given the inertia of the system and where the trends start to be discernible over the noise of year to year weather Cox and Stephenson have a good discussion of the point in this week s Science and a great conceptual graphic of the issues One could quibble with the details we d put the sweet spot a little earlier but the underlying idea is sound and in judging climate forecasts it will be projections in that range that should be judged i e the early Hansen projections Comments pop up 350 Making sense of Greenland s ice Filed under Arctic and Antarctic Climate Science Paleoclimate gavin 9 July 2007 A widely publicised paper in Science last week discussed the recovery ancient DNA from the base of the Dye 3 ice core in southern Greenland This was an impressive technical feat and the DNA recovered may well be the oldest pure DNA ever dating back maybe half a million years However much of the press coverage of this paper dwelt not on the positive aspects of the study but on its supposed implications for the stability of the Greenland ice sheet and future sea level rise something that was not greatly discussed in the paper at all So why was this More Comments pop up 235 No man is an Urban Heat Island Filed under Climate Science Instrumental Record gavin 2 July 2007 Observant readers will have noticed a renewed assault upon the meteorological station data that underpin some conclusions about recent warming trends Curiously enough it comes just as the IPCC AR4 report declared that the recent warming trends are unequivocal and when even Richard Lindzen has accepted that globe has in fact warmed over the last century The new focus

    Original URL path: http://www.realclimate.org/index.php/archives/2007/07/ (2016-02-13)
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  • June « 2007 « RealClimate
    about which there is a serious scientific discussion whether they are paced by a 1500 year cycle see my paper in GRL Beck s curve shows a warm phase 400 BC and the next one 1200 AD that s 1600 years difference so it just about fits I m not endorsing his curve by the way I have no idea where it comes from I m just playing along with it for the sake of the argument So the next warm phase should be in the year oooops 2700 or 2800 Hang on how come it looks like the current warmth fits so nicely into the cycle Shouldn t we be right in the coldest phase Now I see it two little lines across the x axis indicate that the axis has been broken there tick marks after the break are in 200 year intervals and before the break in 400 year intervals and there s also a gap of 200 missing years there So that s how we make the current global warming fit past climate cycles it s so easy p s Beck appeared on German TV last Monday after the Swindle film was shown and he is announced to appear on the program Report München in the first channel of public German TV next Monday 18 June to educate the viewers about another of his fantasy graphs namely his CO2 curve It promises to be a must see for friends of the unintentionally farcical Comments pop up 346 G8 summit declaration Filed under Climate Science stefan 8 June 2007 We assume that many of our readers will be interested in the declaration of the G8 summit in Heiligendamm Germany which was agreed yesterday by the leaders of the G8 countries We therefore document the key passages on climate change below As usual we refrain from a political analysis but as scientists we note that it is rewarding to see that the results of climate science are fully acknowledged by the heads of state The declaration states CLIMATE CHANGE 48 We take note of and are concerned about the recent UN Intergovernmental Panel on Climate Change IPCC reports The most recent report concluded both that global temperatures are rising that this is caused largely by human activities and in addition that for increases in global average temperature there are projected to be major changes in ecosystem structure and function with predominantly negative consequences for biodiversity and ecosystems e g water and food supply Fighting Climate Change 49 We are therefore committed to taking strong and early action to tackle climate change in order to stabilize greenhouse gas concentrations at a level that would prevent dangerous anthropogenic interference with the climate system Taking into account the scientific knowledge as represented in the recent IPCC reports global greenhouse gas emissions must stop rising followed by substantial global emission reductions In setting a global goal for emissions reductions in the process we have agreed today involving all major emitters we will

    Original URL path: http://www.realclimate.org/index.php/archives/2007/06/ (2016-02-13)
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  • May « 2007 « RealClimate
    on The Science of Climate Change added Sep 2010 The portal for climate and climate change of the ZAMG Zentralaanstalt für Meteorologie und Geodynamik Vienna Austria In German added Jan 2011 Those with some knowledge The IPCC AR4 Frequently Asked Questions here pdf are an excellent start These cover What Factors Determine Earth s Climate What is the Relationship between Climate Change and Weather What is the Greenhouse Effect How do Human Activities Contribute to Climate Change and How do They Compare with Natural Influences How are Temperatures on Earth Changing How is Precipitation Changing Has there been a Change in Extreme Events like Heat Waves Droughts Floods and Hurricanes Is the Amount of Snow and Ice on the Earth Decreasing Is Sea Level Rising What Caused the Ice Ages and Other Important Climate Changes Before the Industrial Era Is the Current Climate Change Unusual Compared to Earlier Changes in Earth s History Are the Increases in Atmospheric Carbon Dioxide and Other Greenhouse Gases During the Industrial Era Caused by Human Activities How Reliable Are the Models Used to Make Projections of Future Climate Change Can Individual Extreme Events be Explained by Greenhouse Warming Can the Warming of the 20th Century be Explained by Natural Variability Are Extreme Events Like Heat Waves Droughts or Floods Expected to Change as the Earth s Climate Changes How Likely are Major or Abrupt Climate Changes such as Loss of Ice Sheets or Changes in Global Ocean Circulation If Emissions of Greenhouse Gases are Reduced How Quickly do Their Concentrations in the Atmosphere Decrease Do Projected Changes in Climate Vary from Region to Region RealClimate Start with our index Informed but in need of more detail Science You can t do better than the IPCC reports themselves AR4 2007 TAR 2001 History Spencer Weart s Discovery of Global Warming AIP Art Robert Rohde s Global Warming Art Informed but seeking serious discussion of common contrarian talking points All of the below links have indexed debunks of most of the common points of confusion Coby Beck s How to talk to Global Warming Skeptic New Scientist Climate Change A guide for the perplexed RealClimate Response to common contrarian arguments NERC UK Climate change debate summary UK Met Office Climate Change FAQ Brian Angliss A Thorough Debunking John Cook Skeptical Science The Global Warming Debate slides Please feel free to suggest other suitable resources particularly in different languages and we ll try to keep this list up to date Comments pop up 293 A bit of philosophy Filed under Climate Science eric 16 May 2007 Eric Steig and Gavin Schmidt The two of us participated last week in an interesting meeting at the University of Washington on Ethics and Climate Change Other scientists in attendance included Dennis Hartmann who gave an overview of the current state of the science and sometime RealClimate contributor Cecilia Bitz Organized by Associate Professor of Philosophy Stephen Gardiner the conference was dedicated to the particular ethical and moral issues raised by

    Original URL path: http://www.realclimate.org/index.php/archives/2007/05/ (2016-02-13)
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  • April « 2007 « RealClimate
    the subject More Comments pop up 87 Hurricane Spin Filed under Climate Science Hurricanes group 24 April 2007 Michael Mann and Gavin Schmidt A recent paper by Vecchi and Soden preprint published in the journal Geophysical Research Letters has been widely touted in the news and some egregiously bad editorials and the blogosphere as suggesting that increased vertical wind shear associated with tropical circulation changes may offset any tendencies for increased hurricane activity in the tropical Atlantic due to warming oceans Some have even gone so far as to state that this study proves that recent trends in hurricane activity are part of a natural cycle Most of this is just spin pun intended but as usual the real story is a little more nuanced More Comments pop up 100 Ocean Cooling Not Filed under Climate Science Instrumental Record Oceans gavin 18 April 2007 A lot has been made of a paper Lyman et al 2006 that appeared last year that claimed that the oceans had contrary to expectation cooled over the period 2003 2005 At the time we correctly pointed out that this result was going to be hard to reconcile with continued increases in sea level rise driven in large part by thermal expansion effects and that there may still be issues with way that the new ARGO floats were being incorporated into the ocean measurement network Now it seems as if there is a problem in the data and in the latest analysis the cooling has disappeared More Comments pop up 282 Lindzen in Newsweek Filed under Climate Science Reporting on climate group 17 April 2007 Gavin Schmidt and Michael Mann As part of a much larger discussion on Learning to live with Global Warming in Newsweek recently the editors gave some space for Richard Lindzen to give his standard it s no big deal opinion While we disagree we have no beef with serious discussions of the costs and benefits of various courses of action and on the need for adaption to the climate change that is already locked in However Lindzen s piece is not a serious discussion More Comments pop up 174 Older Entries Site Google Custom Search Recent Comments 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 What is the best description of the greenhouse effect James Powell Unforced Variations Feb 2016 Jim Galasyn 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

    Original URL path: http://www.realclimate.org/index.php/archives/2007/04/ (2016-02-13)
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  • March « 2007 « RealClimate
    at the University of Washington over the state of the snowpack in United States Pacific Northwest region The Seattle city mayor Greg Nickels a well known advocate for city based CO 2 reduction initiatives wrote in an Op Ed piece in the Seattle Times that The average snowpack in the Cascades has declined 50 percent since 1950 and will be cut in half again in 30 years if we don t start addressing the problems of climate change now That snow not only provides our drinking water it powers the hydroelectric dams that keep our lights on More Comments pop up 173 A much more eloquent rebuttal of TGGWS Filed under Climate Science Reporting on climate gavin 17 March 2007 Promoted from the comments the download of the BBC Radio 4 Now Show Mar 16 is available here at least for now Key bit starts at about 18min in the rest of the show is pretty funny too Comments pop up 307 Adventures on the East Side Filed under Climate Science Reporting on climate gavin 15 March 2007 So that was interesting First off I d like to thank the commenters for all of the suggestions and ideas to the previous post They were certainly useful In particularly the connection with the difficulties faced by evolutionists in debates vs creationists proved to be very a propos Our side played it it pretty straight the basic IPCC line Richard Somerville commentary on the how scientized political debates abuse science me though without using the word scientized and the projections and potential solutions Brenda Ekwurzel Crichton went with the crowd pleasing condemnation of private jet flying liberals very popular even among the private jet flying Eastsiders present and the apparent hypocrisy of people who think that global warming is a problem using any energy at all Lindzen used his standard presentation CO2 will be trivial effect no one knows anything about aerosols sensitivity from the 20th Century is tiny and by the way global warming stopped in 1998 Stott is a bit of a force of nature and essentially accused anyone who thinks global warming is a problem of explicitly rooting for misery and poverty in the third world He also brought up the whole cosmic ray issue as the next big thing in climate science Update The transcript is now available though be aware that it has not yet been verified for accuracy Audio Podcast More Comments pop up 490 Older Entries Site Google Custom Search Recent Comments 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 What is the best

    Original URL path: http://www.realclimate.org/index.php/archives/2007/03/ (2016-02-13)
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