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  • A new European report on climate extremes is out « RealClimate
    reading a bit disappointed Basically the only certain thing is we will have more heat waves and less cold days Precipitation floods storms no data reliable enough to identify a trend only some models Thank you for sharing anyway 15 Steve Fish says 28 Oct 2013 at 9 12 PM Re Comment by markogts 28 Oct 2013 5 07 PM Only some models Steve 16 Kevin McKinney says 29 Oct 2013 at 8 30 AM I m surprised by the kerfuffle over wildfire attribution the question has been studied quite a bit Google Scholar offers up a whole bunch if you search wildfire and climate change Here s a selection Wildfire in Yosemite Park 1992 study Univariate and multivariate analytical techniques reveal that a summer temperatures in the Park are increasing b January June precipitation levels are decreasing and c variations in burn area within the Park are significantly related to the observed variations in climate http link springer com article 10 1007 BF00143342 Wildfire in NE coastal Spain 1998 study A climatic series 1941 to 1994 from a Mediterranean locality of NE Spain was used to calculate two wildfire hazard indices based on daily meteorological data Both fire hazard indices increased over this period as a consequence of increasing mean daily maximum temperature and decreasing minimum daily relative humidity These trends were observed in both mean values of the indices and in the number of very high risk days Annual data on the number of wildfires and burned area also show an increase from 1968 to 1994 and are significantly correlated with both fire hazard indices http link springer com article 10 1023 A 1005316632105 Wildfire in boreal North American and Eurasia 2009 we found heterogeneous patterns of drought severity changes that were inherent to the nonuniformly distributed impacts of climate change on dryness Notably significant trends toward increasing summer moisture in southeastern and southwestern boreal Canada were detected The diminishing wildfire risk in these regions is coherent with widely reported decreases in area burned since about 1850 as reconstructed by dendrochronological dating of forest stands Conversely we found evidence for increasing percentage area affected by extreme droughts in Eurasia 0 57 per decade P 0 05 and occurrence rates of extreme drought years in Eurasian taiga centered principally on the Okhotsk Manchurian taiga P 0 07 Although not statistically significant temporal changes in occurrence rates are sufficiently important spatially to be paid further attention Long link Global projections of wildfire risk 2010 The increased fire potential is mainly caused by warming in the U S South America and Australia and by the combination of warming and drying in the other regions Sensitivity analysis shows that future fire potential depends on many factors such as climate model and emission scenario used for climate change projection The results suggest dramatic increases in wildfire potential that will require increased future resources and management efforts for disaster prevention and recovery http www sciencedirect com science article pii S0378112709006148 The first two studies show the association of wildfire and climate change and show also that that association has been known now for more than 20 years though apparently not by Tony Abbott The second shows that climate change can cut both ways under projections for precipitation most of the Canada boreal is expected to become moister therefore wildfire risk should drop The converse is true of course for most of the Eurasian boreal forest Sure enough observations are coherent with this expectation And for poster child on that score we have the 2010 Russian wildfires And wasn t this summer pretty bad for that too FWIW Finally we have a global level analysis that quantifies the expected response as measured by a straight forward metric of fire risk Amazingly Australia was expected to see more wildfire guess Mr Abbott didn t know that either He really should try to keep up he has responsibilities after all Anyway there is lots and lots more the search terms here show nearly 10 000 hits Here s the link for a quick in those interested can play with the search terms to find items of interest to them Wildfire risk where you live The Greek fire outbreaks the Eastern Med has long been expected to dry as the present European report certainly highlights and Greece had a very nasty fire outbreak in IIRC 2005 Strict attributional studies of wildfire 17 Kevin McKinney says 29 Oct 2013 at 8 32 AM The second shows that climate change can cut both ways Strike that and make it third shows 18 Kevin McKinney says 29 Oct 2013 at 11 47 AM Reposted from Tamino s blog a nice bit of snark on the Australian wildfire question https pbs twimg com media BXjq 4SCIAAi8UC jpg 19 Ed Barbar says 29 Oct 2013 at 5 10 PM The insurance industry could have a vested interest in the outcome of Global Warming causes extreme weather events First they could argue that certain events even if they are normal catastrophic events would not have occurred without global warming they may seek government reimbursement I could also imagine an argument that governments ought to subsidize insurance thereby increasing the marketplace because the responsibility for increasing risks is shared even in non risk areas Studies with insurance industry sponsorship or contribution should be viewed with a healthy dose of skepticism 20 John Shelton says 29 Oct 2013 at 7 28 PM 16 K McKinney You had my hopes up about a study on Fire in Yosemite it s actually in Yellowstone Your point is well made though 21 Sean says 29 Oct 2013 at 8 02 PM 5 John L re On page 25 this leads to multiple conceptual confusion But it gives a very sloppy impression in my opinion The RISK is that you lose confidence sic in the assessments even if it is not deserved John I totally agree with you here Not only does this make it incredibly difficult for the public to read the summaries and the documents like this the Journalists ideologically pro or con always conflate things as a result with their articles going global the CC Denialism activists then pick this mis information confusion only to spread it as DIS Information in a billion anti science blog pages world wide which further acerbates the pre existing confusion levels then Lord Monckton gets 100 calls for a paid appearance at the next Heartland Institute Corporate dinner Political fund raiser or Tea Party public forum Or some well meaning Climate communicator educator eg an pro CC advocate such as Prof Tim Flannery in Australia stumbles on the words and speaks a technical untruth and is pilloriaed for it further undermining the public s and politicians true knowledge of what the IPCC etc really meant to say imho this is a key reason behind the success of the denialist industry and it s success over the last 5 years It needs ot be nipped in the bud from the get go and everyone in Climate Science presenting public information has to be on the same page with the same words and the exact same meaning consistently or forget it The science itself is complicated enough for Politicians Policy makers to get their heads around already Too much focus and attention cannot be placed on this one issue about the complexity in the words being used in my view best to all 22 Hank Roberts says 30 Oct 2013 at 10 08 AM Ed Barbar insurance industry healthy skepticism Dr Punnett 23 Ray Ladbury says 30 Oct 2013 at 11 44 AM Ed Barbar Healthy skepticism does not mean ignoring the information It means considering it validating it against other sources and examining its implications What you are suggesting is effectively an appeal to ad hominem fallacy 24 SecularAnimist says 30 Oct 2013 at 12 06 PM Ed Barbar wrote they may seek government reimbursement I could also imagine an argument that governments ought to subsidize insurance So basically you are arguing that because the economic losses and other destructive consequences of global warming may result in demands for government action to deal with them we should reject the scientific evidence that such consequences are already occurring and are likely to get worse Where have I heard that before Oh that s right from pretty much every denier who ever commented on a blog 25 Kevin McKinney says 31 Oct 2013 at 5 13 AM 20 D oh Sorry bout that 26 Philip Machanick says 31 Oct 2013 at 10 11 AM Thanks for all the comments on Australia fires I had seen some of that but having all this in one place will help those searching for attribution evidence Not that evidence ranks very high in the concerns of the current Australian government 27 Doug Bostrom says 31 Oct 2013 at 3 26 PM Ed I could also imagine an argument that governments ought to subsidize insurance thereby increasing the marketplace because the responsibility for increasing risks is shared even in non risk areas Your imagination is is in congruence with facts It s deemed economically beneficial for government to intervene in the insurance market Ed concludes Studies with insurance industry sponsorship or contribution should be viewed with a healthy dose of skepticism More generally The insurance industry is in the business of spreading claims costs among a larger population than loss victims something a skeptic must acknowledge in a productive critique of the industry Suggesting that the insurance industry is somehow wrong in spreading claims costs isn t useful Useful skepticism should also include the notion that insurance companies seek to entirely avoid paying claims The easiest and most efficient way to do that is to ensure that claims are to the very greatest extent possible completely avoided Public information campaigns directing potential claims beneficiaries toward behaviors minimizing claims are not dishonest and are quite in keeping with the nature of the insurance business More the insurance industry indeed pushes government to better regulate activities prone to generating expensive claims An insurance claim is a formal acknowledgement of a poor outcome a disaster of one kind or another Fewer claims record success in reducing the frequency of disasters In the past the insurance industry has promoted such things as mandatory automobile safety belt installation and use Was this a bad thing Most of us would agree it wasn t Insurance companies are uniquely positioned to record the ebb and flow of disaster by the proxy of claims payouts Despite their best efforts to shape their markets we ll learn a lot about climate impacts from insurance companies as statistical margins are eaten away by forthcoming changes 28 tokodave says 1 Nov 2013 at 9 18 AM 27 Doug Bostrom s comments For a detailed look at insurance companies and climate change visit sites like Munich Re http www munichre com en group focus climate change default aspx or Lloyd s of London http www lloyds com news and insight lloyds blog our experts trevor maynard 2013 10 climate change the future is in our hands These guys have skin in the game If they don t come close to getting it right they lose big money Doug is exactly right in observing their unique position 29 BillS says 1 Nov 2013 at 6 32 PM Re Doug 27 tokodave 28 At my place many spend their time talking to lawyers insurance companies and municipal engineers These people the executives engineers are no longer sitting quietly on the sidelines They have bottom lines and communities to protect and most seem willing to do what is necessary to protect both We can bemoan the fact that they weren t driven earlier to act but better late than never 30 Hank Roberts says 1 Nov 2013 at 7 44 PM Actuaries are statisticians The trends are emerging from the background variation Attribution done by professionals on their own data convinces them 31 Jack Maloney says 2 Nov 2013 at 7 19 AM tokodave says For a detailed look at insurance companies and climate change visit sites like Munich Re or Lloyd s of London These guys have skin in the game If they don t come close to getting it right they lose big money Actually the insurance game makes its money by peddling fear The difference between feared costs and real costs is where they make their profits more fear more money paid in to Munich Re and Lloyd s If no one feared the future there would be no insurance industry 32 Steve Fish says 2 Nov 2013 at 9 59 AM Re Comment by Jack Maloney 2 Nov 2013 7 19 AM It sound like you are saying that if no one feared the effects of increasing CO2 there would be no problem Steve 33 Ray Ladbury says 2 Nov 2013 at 11 05 AM Jack Maloney Any insurance company that adopted the business model you posit would fail in a matter of a few years Insurance companies rely on investments to make up the difference between premiums and pay outs I would suggest talking out of your mouth rather than the orifice you currently employ 34 Timothy Chase says 2 Nov 2013 at 4 06 PM tokodave wrote in 28 For a detailed look at insurance companies and climate change visit sites like Munich Re or Lloyd s of London These guys have skin in the game If they don t come close to getting it right they lose big money Jack Maloney responded in 31 Actually the insurance game makes its money by peddling fear The difference between feared costs and real costs is where they make their profits more fear more money paid in to Munich Re and Lloyd s If no one feared the future there would be no insurance industry The people you should really pay attention to are the re insur ers Munich Re is one of them but there are others re insur ers are the insurance companies that the insurance companies go to insurance companies hedge their risk against big payouts by taking out their own insurance which they get from the reinsurers If reinsurers were playing the game that you claim the insurance companies are playing namely inflating the perceived risks in order to increase their profits then any insurance company that saw through this game would stand to benefit by not paying the inflated prices Furthermore a re insur er that did not inflate the perceived risks would stand to benefit by undercutting the competition What they lost in lower rates they would make up for in volume To be continued 35 Timothy Chase says 2 Nov 2013 at 4 11 PM So where do the reinsurers stand Let me quote from the executive summary of a document recently published by the Geneva Association In the non stationary environment caused by ocean warming traditional approaches which are solely based on analysing historical data increasingly fail to estimate today s hazard probabilities A paradigm shift from historic to predictive ri sk assessment methods is necessary pg 3 Warming of the Oceans And Implications for the Re insurance Industry The Geneva Association June 2013 https www genevaassociation org media 616661 ga2013 warming of the oceans pdf The members of the board of the Geneva Association consist of representatives from over a dozen major prestigious companies from throughout the world I don t trust any one insurance company or any one reinsurer But if the perceived risks of climate change were being inflated by reinsurers someone would stand to make a great deal of money by bursting the bubble and the reputations of those inflating the perceived risks would be greatly damaged But nobody is bursting any bubble here In point of fact re insur ers have released a document that stresses the risks posed by climate change to their way of doing business and a shift in paradigms is required if their industry is to survive 36 Jack Maloney says 2 Nov 2013 at 11 40 PM Steve 32 No I am only saying that the insurance industry depends on fear of the future More fear more demand for insurance I worked in corporate management at a major life insurance company Insiders called one of the classic sales techniques backing up the hearse It was certainly not in their interest to minimize their prospects consciousness of risk A paradigm shift from historic to predictive risk assessment methods is necessary Translation rather than calculate our premiums on known risk we ll just guess 37 Hank Roberts says 3 Nov 2013 at 10 20 AM rather than calculate our premiums on known risk It d be foolish to continue to base expectation on the past history after changing the facts Until the middle of the 20th century the discipline of climatology was a stagnant field preoccupied with regional statistics representing a static normal climate The study of climate change what to many climatologists seemed a contradiction in terms was only an occasional interest of individuals people saw catastrophes as just part of the normal situation transient excursions within an overall state that looked permanent on the timescale of human society The job of the climatologist was to remove uncertainties with statistics fixing the probable size of a hundred year flood and so forth http www aip org history climate climogy htm 38 Hank Roberts says 3 Nov 2013 at 10 28 AM And seriously read that AIP page One further quote just to point out how outdated Jack Maloney s position on change is References are at the original page Painful experience drove the point home One notorious case was the experience of firms that contracted to build dams in central Africa in the 1950s and consulted with climatologists about the largest floods that could be expected according to past statistics The firms then began construction only to suffer fifty year floods in each

    Original URL path: http://www.realclimate.org/index.php/archives/2013/10/a-new-european-report-on-climate-extremes-is-out/ (2016-02-13)
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  • Extras « RealClimate
    rise around 10 of the total at the moment All of these observations match the response predicted in the late 1970s by glaciologist John Mercer of the Antarctic to anthropogenic global warming As such they are frequently taken as harbingers of greater future sea level rise to come Are they Two papers published this week in Nature Geoscience provide new information that helps to address this question One of the studies led by me says probably while another Abram et al gives a more definitive yes More Comments pop up 49 Language Intelligence Lessons on persuasion from Jesus Shakespeare Lincoln and Lady Gaga A Review Filed under Communicating Climate Reviews mike 20 August 2012 Any book that manages to link together the lessons of the Bible Shakespeare Abraham Lincoln and Lady Gaga not to mention Martin Luther King Winston Churchill Bob Dylan and Jerry Seinfeld can t be all bad With Joe Romm s new book Language Intelligence it is in fact ALL good There are lessons galore for the scientists among us who value public outreach and communication The book is a de facto field guide for recognizing and assimilating many of the key tools of persuasive language and speech something that is ever more important to science communicators who face the daunting challenge of having to communicate technical and nuanced material to an audience largely unfamiliar with the lexicon of science sometimes agnostic or even unreceptive to its message and in the case of contentious areas like climate change and evolution already subject to a concerted campaign to misinform and confuse them More Comments pop up 171 The IPCC SREX the report is finally out Filed under Climate Science RC Forum Reporting on climate Reviews statistics rasmus 29 March 2012 Some of us have been waiting quite a while now especially since the road tour meant to present the Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation starting in Oslo on January 24th this year The summary for policymakers SPM was released already in 18 November 2011 Kampala and now the report is finally available link More Comments pop up 39 Older Entries Newer 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

    Original URL path: http://www.realclimate.org/index.php/archives/category/extras/page/2/ (2016-02-13)
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  • Extras « RealClimate
    known by the cryptic name CMIP5 It turned out that the results were ok but we had made an error when reading and processing the model output The particular climate model that initially gave the strange results had used a different calendar set up to the previous models we had examined More Comments pop up 12 A new European report on climate extremes is out Filed under Climate impacts Climate Science Communicating Climate Reporting on climate Reviews rasmus 26 October 2013 A new report on extreme climate events in Europe is just published Extreme Weather Events in Europe preparing for climate change adaptation It was launched in Oslo on October 24th by the Norwegian Academy of Science and Letters and the report is now available online Front cover of Extreme Weather Events in Europe preparing for climate change adaptation What s new The new report provides information that is more specific to Europe than the SREX report from the Intergovernmental Panel on Climate Change IPCC and incorporate phenomena that have not been widely covered It provides some compelling information drawn from the insurance industry and indeed a representative from Munich Re participated in writing this report There is also material on convective storms hail lightening and cold snaps and the report provides a background on extreme value statistics risk analysis impacts and adaptation More Comments pop up 90 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 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 El Nino Geoengineering Greenhouse gases Hurricanes Instrumental Record IPCC Oceans Paleoclimate Sun earth connections Communicating Climate Reporting on climate skeptics Extras Attic Comment Policy Contributor Bio s FAQ Glossary In the News Reviews Supplemental data Tutorials hydrological cycle Open thread RC Forum Scientific practice statistics The Bore Hole Books Contributors Highlights Dummies

    Original URL path: http://www.realclimate.org/index.php/archives/category/extras/%5C (2016-02-13)
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  • How do we know that recent CO2 increases are due to human activities? « RealClimate
    American Institute of Physics http www aip org history climate A Hyperlinked History of Climate Change Science Weart s history is quite a remarquable work It is also well written and easily accessible for many I believe that for many people the historical description of how one has come to a particular insight for example the question How do we know Co2 increases are due to human activities might be enlightening Especially in view of the current debate where many viewpoints and conclusions are presented by the press as if they came out of a hat 4 Andrew Lonigro says 3 Jan 2005 at 2 59 PM Is there any evidence that carbon dioxide concentrations in the atmosphere prior to the industrial revolution ever approached the concentrations that we are seeing now Response CO2 levels are currently higher than for any time when we have direct measurements directly from 1950 before that from air trapped in ice cores which amounts to the last 780 000 years see e g a picture here for the last 400 kyr Various considerations suggest that in the far past CO2 levels were considerably higher From memory the last time CO2 levels exceeded present was about 40 million years ago William 5 m de gosson says 5 Jan 2005 at 2 55 AM This is Science of course Bravo 6 Dan Hughes says 7 Jan 2005 at 10 27 AM Can you point me to the details of the calculation mentioned in this statement The roughly 500 billion metric tons of carbon we have produced is enough to have raised the atmospheric concentration of CO2 to nearly 500 ppm I m especially interested in finding out 1 the extent volume and mass of the atmosphere into which the carbon mass was added and 2 the ranges of uncertainty associated with both the extent of the atmosphere and the mass of carbon produced Response the CO2 produced is spread throughout essentially the entire atmosphere by mass at least Atmospheric pressure is approx 100 000 Pa m2 and from that you can work out the mass about 5 10 18 kg 500 billion tons CO2 5 10 14 kg 1 5 10 15 kg CO2 so by mass that much CO2 increases the atmos by a b ie 3 10 4 which is about right These done off the top of my head so please check JBS The extent of the atmos and of the bit which CO2 is spread through is very well known as are fossil fuel emissions William To me the opening sentences of the second paragraph One way that we know that human activities are responsible for the increased CO2 is simply by looking at historical records of human activities Since the industrial revolution we have been burning fossil fuels and clearing and burning forested land at an unprecedented rate and these processes convert organic carbon into CO2 are not very clear as follows The addition of carbon into the atmosphere by human activities does not automatically imply that the atmospheric concentration must necessarily increase Might the natural sinks of carbon at some times be able to absorb the human additions and result in no net increase Response If we see CO2 increasing in the atmosphere and humans emitting enough CO2 to account for that rise then you have to go through some odd contortions to avoid a connection You would have to postulate a suddenly increased natural sink to remove the human CO2 and then a suddenly increased natural source to increase the atmospheric CO2 William Thanks for your assistance 7 Tony Weddle says 7 Jan 2005 at 8 13 PM I don t think there is any question that 6 billion living people and rising will have some effect on CO2 levels not to mention CH4 levels What seems clear however is that we don t know exactly what that effect is From the article above the expected rise to 500 ppm hasn t occurred Nowhere near But the precise reasons for the apparent shortfall are not known So we really can t say how much of an effect humans are having and whether they might be responsible for all or part of the current rise The concensus that humans are responsible for all of the rise seems to be intuitive rather than scientific I d agree with the intuitive conclusion that humans are responsible for most of it but that isn t the story going out Response How can I word my response strongly enough NO NO NO Intuition has nothing to do with this This is one of the best understood aspects in the entire science of climate change and it really is not that complicated We understand very very well why the level hasn t yet reached 500 ppm If you add CO2 to the atmosphere some of it will have to go into the ocean This is very basic chemistry Imagine taking a bottle filled half with water and half with pure air that has no CO2 in it Add CO2 to the air in the bottle Some of the CO2 will dissolve in the water resulting in less CO2 in the air that you have originally put in We expect this to happen and the isotope measurements demonstrate it IS happening and at what rate In response to the question whether the natural sinks of carbon might compensate for the CO2 we are putting into the atmosphere the answer is yes but not very quickly In the short term the ocean cannot simply magically absorb all the excess CO2 If you try to pack all this excess CO2 in the surface ocean it will come right back out Again that is what chemical equilibrium demands there is no way around this In the long term the deep ocean will probably absorb much more of the CO2 we have put into the atmosphere but this is the long term If humans stopped producing CO2 today it would

    Original URL path: http://www.realclimate.org/index.php?p=87 (2016-02-13)
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  • Isotopes « RealClimate
    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 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 El Nino Geoengineering Greenhouse gases Hurricanes Instrumental Record IPCC Oceans Paleoclimate Sun earth connections Communicating Climate Reporting on climate skeptics Extras Attic Comment Policy Contributor Bio s FAQ Glossary In the News Reviews Supplemental data Tutorials hydrological cycle Open thread RC Forum Scientific practice statistics The Bore Hole Books Contributors Highlights Dummies Guide to the latest Hockey Stick controversy El Nino Global Warming and Anomalous U S Winter Warmth Hurricanes and Global Warming Myth vs Fact Regarding the Hockey Stick On attribution On mismatches between models and observations On Sensitivity Part I Tropical Glacier Retreat Water Vapour feedback or forcing Welcome to RealClimate Other Opinions A Few Things Ill Considered Accuweather Climate Blog And Then

    Original URL path: http://www.realclimate.org/index.php?p=83 (2016-02-13)
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  • Why does the stratosphere cool when the troposphere warms? « RealClimate
    will all be absorbed by and warm the layer If the emissivity of the layer is low most of the additional upward radiation can pass right through the layer without warming it The net effect is increased emissivity can cause a cooling effect even if the layer is already cooler than the layers below 6 Eli Rabett says 23 Dec 2004 at 9 43 PM James Shearer s comment about If the emissivity of the layer is low most of the additional upward radiation can pass right through the layer without warming it is one of those it depends things Mosly what it depends on is that the two layers have different composition If we are talking about clear atmosphere then no because the radiation will be ONLY at exactly those frequencies where the greenhouse gases above and below absorb emit If you are talking about clouds and aerosols then maybe but maybe not if the layer above is also cloud aerosol Trapping of radiation in clouds can be significant 7 James B Shearer says 26 Dec 2004 at 10 05 PM Eli Rabett I don t understand your point If we consider a thin enough layer most radiation will pass right through the layer even at the most absorbant frequencies 8 Eli Rabett says 28 Dec 2004 at 12 19 AM You have to integrate my answer As you say in the limit everything is thin but irrelevant 9 James B Shearer says 28 Dec 2004 at 10 10 PM Let me present a model illustrating my point Consider a slab atmosphere modeled as a gray body at long wavelengths with emissivity e Suppose further that a fraction a of the incoming shortwave radiation is absorbed in the atmosphere with the remainder being absorbed by the ground Let T1 be the temperature of the atmosphere T2 be the temperature of the ground and TB be the black body temperature of the ground with no atmosphere Then I believe we have T1 4 TB 4 a e a e e 2 e T2 4 TB 4 2 a 2 e Then for certain values of a and e the atmosphere will be cooler than the ground but increasing e will cool the atmosphere further For example a 05 e 1 I think this shows gavin s argument that this cannot occur is incorrect 10 Nobuki Matsui says 30 Dec 2004 at 6 32 PM I found those web site below Are they really non sense If so how Could anybody explain to us http people freenet de klima indexe htm http www geocities com atmosco2 backrad htm http www geocities com atmosco2 Influence htm Response Yes These arguments are nonsense If I have time I ll try and see what the major error is and report back gavin 11 James B Shearer says 15 Jan 2005 at 6 46 PM Unfortunately I believe the updated post is still incorrect First as the temperature gradient in the atmosphere increases at a certain point the atmosphere becomes unstable because rising falling packets of air do not cool warm fast enough by expansion compression to stop rising falling When this point is reached convection starts and effectively prevents the temperature gradient from increasing further This point has already been reached in the lower atmosphere otherwise the surface would be much warmer than it actually is As far as I know there is no reason to expect greenhouse warming to increase the lapse rate near the surface Second even if we ignore convection and assume all warming of the atmosphere is from below ie no incoming solar radiation is absorbed in the atmosphere it is not the case that the atmosphere temperatures will pivot around some fixed level increasing below it and falling above it Instead it is reasonably easy to see that in this case the temperature of the top of the atmosphere will remain fixed at 84 TB where TB is the black body temperature of the earth and the rest of the atmosphere will warm with the greatest warming near the ground This means the effective radiating level will rise which makes sense as it is harder to see into the atmosphere Finally if I am not mistaken the temperature of the top layer of an atmosphere consisting of n blackbody shells should be Tg n 1 25 not Tg 2 n 4 as stated Response I concur with your correction of the n shell problem I should have worked it out for myself instead of trusting what someone told me and the post is amended accordingly While your other two points are valid they are not strictly corrections I specifically state that I m ignoring convection and other atmospheric mixing processes in order to simplify the discussion They are clearly important in the troposphere but it doesn t help understand the stratospheric part As part of the final response to a change in GHGs the effective radiating level will indeed move up but above that level the tendency will be to cool Possibly a more complete statement would have been that you can think of the temperature profile pivoting around the radiative level and having that pivot move up a bit There will still be cooling in the upper atmosphere gavin 12 John Davis says 18 Jan 2005 at 5 25 AM I see that Steve Milloy has posted some graphs on junkscience com which purport to show that the stratosphere has in fact NOT cooled over the past 10 years or so Can you debunk please Response There is too much junk on junkscience to take it seriously A better reference is http www ghcc msfc nasa gov MSU msusci html though the graph there is substantially the same as SM s Fitting a curve through 10 years of data isn t a very good idea if you use the full set you obviously get a very different answer Given that CFC concentrations in the atmos have largely stabalised I would suppose that ozone too should stabalise SM seems to reject that but for no very clear reason William Response This is bad even by Milloy s own standards While the basic physics is sometimes difficult to explain see above the basic issue is that stratospheric temperatures change in response to local effects they do not change because the troposphere does i e troposphere warming does NOT imply stratosphere cooling Thus the changes in the stratosphere are basically a function of the greenhouse gases ozone levels and volcanic aerosols there The changes seen in the MSU 4 data as even Roy Spencer has pointed out are mainly due to ozone depletion cooling and volcanic eruptions which warm the stratopshere because the extra aerosols absorb more heat locally As William points out ozone depletion is levelling out since the Montreal Protocol and so lower stratospheric cooling will start to attenuate but then Milloy doesn t appear to think that ozone depletion was a real phenomena either gavin 13 Eli Rabett says 26 Feb 2005 at 8 47 PM I don t know if this is still open but one point to keep in mind is that the temperature increases with altitude in the stratosphere James Shearer seems to be saying that it decreases with altitude 14 James B Shearer says 26 Feb 2005 at 9 12 PM I don t agree that temperatures will pivot around the effective radiating level Instead the entire atmosphere will get warmer assuming no atmospheric absorption of incoming solar radiation Consider the case of n black body shells Adding shells makes the ground hotter but the temperature of the top shell remains at TB the blackbody temperature of the earth More generally assume the top shell is a graybody shell with emissivity e Then its temperature will be 1 2 e 25 TB Note this is an increasing function of e so even for the top layer increasing e causes the layer to warm As we let this layer get thinner e will go to 0 and the temperature of the top layer will go to 84 TB So as I said in my previous comment the temperature at the top of the atmosphere is effectively fixed at 84 TB Still more generally consider n graybody shells emissivity e numbered from the top Then if I calculated correctly the temperature of the jth shell is TB 1 j 1 e 2 e 25 and the temperature of the ground is TB 2 n 1 e 2 e 25 All of these are increasing in e Also note the discontinuity at the ground If we let e 1 n and let n go to infinity the temperature of the bottom layer is TB but the temperature of the ground is 1 1 TB Response You can only understand the strat cooling by knowing the atmos is non grey In a grey atmos it all warms The stratosphere exists because it is non grey ozone abs of UV Adding CO2 increases its ability to cool but less its ability to warm since most comes from UV so it cools I think this means I m agreeing with JBS William Response Et tu William Take a step back here I am not saying the atmosphere is like the n blackbody shell atmosphere This example is given as an end member for the extreme GHG effect which is to be compared to the no GHG case It is the difference between them that tells you what increasing GHGs do not what happens when you increase the number of shells In the real world we are in between the two cases but increasing GHGs pushes us towards an n shell case Since that case has a much steeper temperature gradient the basic effect of increasing GHG is to increase that gradient Given that the effective blackbody emission must be constant and allowing for a small movement in the effective radiating level an increasing gradient must therefore lead to cooling far above this level UV absorbtion by O3 is irrelevant for this point as is convection in the troposphere although it is key in setting the actual temperature profile gavin 15 James B Shearer says 27 Feb 2005 at 6 51 PM Eli Gavin is arguing above that adding greenhouse gasses would cause the stratosphere to cool even if the stratosphere was not being warmed by the adsorption of UV and that this is the explanantion of stratosphere cooling I am arguing that this is incorrect if all warming was from below there would be no cooling Gavin the gradient increases but the fixed point is the top of the atmosphere not the effective radiating level As a result all layers warm with the amount of warming increasing as you move towards the surface This means the effective radiating level rises Consider the top of the atmosphere as an arbitrarily thin gray body Looking down from this layer we see the earth radiating at its black body temperature TB Looking up we see space at near absolute zero So this layer will have temperature TB 4 0 4 2 25 or 5 25 TB or 84 TB as claimed above If the top layer is not arbitrarily thin but instead has emissivity e then its temperature will be TB 2 e 25 In either case the temperature is independent of the details of the temperature structure below the key point is that the total outgoing radiation must balance the incoming solar radiation Response Obviously radiaitve balance must be maintained and I am not disputing that the effective radiative level will rise Possibly the solution to this is that in the real atmopshere the movement of this level is severely constrained mainly by adiabatic cooling and so cannot rise enough to produce your solution I ll think about this a little more gavin 16 James B Shearer says 28 Feb 2005 at 7 17 PM Suppose we add absorption of incoming solar radiation to our model of the top of the atmosphere Let the top layer be a gray body with emissivity e and suppose it also absorbs a fraction f of the incoming solar radiation Then if I have calculated correctly it will have temperature T e f ef e 2 e 25 TB where as before TB is the black body temperature of the earth Note for e f T TB so the temperature increases from the effective radiating level to the top of the atmosphere Now let f a e for some constant a and let e go to zero ie let the top layer become arbitrarily thin Then in the limit T 1 a 2 25 TB Now if adding greenhouse gasses increases e but not f then a will decrease as will the temperature at the top of the atmosphere We can check this by computing the dT de and comparing it to zero By my calculation the derivative will be negative for f e e 1 1 e 2 So if f a e for some fixed a 0 the derivative will become negative as e goes to zero as expected This is true even if a 1 and the temperature of the top of the atmosphere is less than the black body temperature of the earth So I agree with William the cooling effect at the top of the atmosphere requires that the atmosphere be absorbing some incoming radiation and that this absorption be mostly by non greenhouse gasses Response You have simply restated the problem as being the same as for a single atmospheric layer read Tg for your new TB This doesn t help ascertain why different layers react differently And it doesn t explain why the mesosphere with very few absorbers also cools gavin 17 Andy Lacis says 2 Mar 2005 at 12 56 PM The question of why the stratosphere cools when the troposphere warms addresses an important validation point for the CO2 greenhouse effect but the question as stated is ill posed in that the correct answer depends on the proverbial details Climate forcing perturbations such as increasing the solar constant increasing black carbon aerosols tropospheric and decreasing surface albedo low cloud cover sea salt aerosol will on global average warm the ground and troposphere and will also warm the stratosphere For these types of radiative climate forcings the atmospheric temperature profile will be shifted basically unchanged to its new equilibrium position On the other hand decreasing stratospheric ozone above 25 km increasing stratospheric water vapor and increasing atmospheric CO2 uniformly with height will produce global surface and tropospheric warming along with stratospheric cooling These results are described in considerable detail in Hansen Sato and Ruedy 1997 Radiative forcing and climate response in JGR 102 6831 6864 see their Plate 2 for 2xCO2 Plate 3 for 2 So Plate 5 for ozone The radiative effects of increased stratospheric water vapor act to cool the stratosphere and warm the troposphere and are described by Oinas et al 2001 Radiative cooling by stratospheric water vapor big differences in GCM results GRL 28 2791 2794 That holds for the global mean temperatures Oinas et al also show that stratospheric dynamics make their contribution in the polar vortex regions to produce local warming in the 1 mb region for the uniformly applied increase in stratospheric water vapor This just shows that while the stratosphere as a whole may be in radiative equilibrium i e energy transfer is primarily by radiative means there are some locations in the stratosphere where dynamic energy transport is also significant The oversimplified analytic expressions that have been used to make the case pro and con a given explanation for why the atmosphere responds as it does are of limited validity For example the formula given by JBS that T e f ef e 2 e 25 TB can t really be correct since setting the solar input fraction f to zero does not reproduce temperature of the earth TB unless the emissivity e is equal to unity The 2 layer equilibrium relationship Ta 0 84Tg which is valid for an isothermal gray absorbing layer above a Planck emitting ground when applied to multiple layers is valid only when the layers are either totally transparent or totally opaque Also the T 4 dependence refers only to spectrally integrated radiation Planck radiation is linear in T at microwave wavelengths and goes to an increasingly higher exponential dependence toward shorter wavelengths Simple formulas can be useful but they are a poor substitute for the physics involved Radiative transfer in the earth s atmosphere is not particularly amenable to simple formulas because the atmosphere is semi transparent to differing degree at different wavelengths which allows radiation emitted locally to interact with the entire atmosphere Even for a relatively simple example of a gray medium calculating the equilibrium temperature profile within a homogeneous slab involves a singular Fredholm integral equation of the second kind as described by M N Ozisik in Radiative Transfer 1973 The radiative transfer problem is best addressed numerically with a sufficient number of vertical layers to resolve the atmospheric temperature and absorber distributions and with a sufficient number of spectral intervals to resolve the spectral dependence of the contributing gases as is being done in most GCMs For radiative transfer the vertical geometric scale is not relevant only the optical depth distribution matters From a semi transparent atmosphere radiation to space can come from virtually all parts of the atmosphere But the bulk of it comes from the so called TAU 1 level looking down from space where the opacity is near unity This is because the fundamentals of thermal radiation from an isolated slab emissivity absorptivity transmissivity are related by emissivity absorptivity 1 transmissivity where transmissivity exp TAU neglecting directionality Thus radiation emitted from below the TAU 1 level gets mostly absorbed before it can get out to space And radiation emitted from the uppermost levels of the atmosphere

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  • Pourquoi la stratosphère refroidit alors que la troposphère se réchauffe ? « RealClimate
    two layers have different composition If we are talking about clear atmosphere then no because the radiation will be ONLY at exactly those frequencies where the greenhouse gases above and below absorb emit If you are talking about clouds and aerosols then maybe but maybe not if the layer above is also cloud aerosol Trapping of radiation in clouds can be significant 7 James B Shearer says 26 Dec 2004 at 10 05 PM Eli Rabett I don t understand your point If we consider a thin enough layer most radiation will pass right through the layer even at the most absorbant frequencies 8 Eli Rabett says 28 Dec 2004 at 12 19 AM You have to integrate my answer As you say in the limit everything is thin but irrelevant 9 James B Shearer says 28 Dec 2004 at 10 10 PM Let me present a model illustrating my point Consider a slab atmosphere modeled as a gray body at long wavelengths with emissivity e Suppose further that a fraction a of the incoming shortwave radiation is absorbed in the atmosphere with the remainder being absorbed by the ground Let T1 be the temperature of the atmosphere T2 be the temperature of the ground and TB be the black body temperature of the ground with no atmosphere Then I believe we have T1 4 TB 4 a e a e e 2 e T2 4 TB 4 2 a 2 e Then for certain values of a and e the atmosphere will be cooler than the ground but increasing e will cool the atmosphere further For example a 05 e 1 I think this shows gavin s argument that this cannot occur is incorrect 10 Nobuki Matsui says 30 Dec 2004 at 6 32 PM I found those web site below Are they really non sense If so how Could anybody explain to us http people freenet de klima indexe htm http www geocities com atmosco2 backrad htm http www geocities com atmosco2 Influence htm Response Yes These arguments are nonsense If I have time I ll try and see what the major error is and report back gavin 11 James B Shearer says 15 Jan 2005 at 6 46 PM Unfortunately I believe the updated post is still incorrect First as the temperature gradient in the atmosphere increases at a certain point the atmosphere becomes unstable because rising falling packets of air do not cool warm fast enough by expansion compression to stop rising falling When this point is reached convection starts and effectively prevents the temperature gradient from increasing further This point has already been reached in the lower atmosphere otherwise the surface would be much warmer than it actually is As far as I know there is no reason to expect greenhouse warming to increase the lapse rate near the surface Second even if we ignore convection and assume all warming of the atmosphere is from below ie no incoming solar radiation is absorbed in the atmosphere it is not the case that the atmosphere temperatures will pivot around some fixed level increasing below it and falling above it Instead it is reasonably easy to see that in this case the temperature of the top of the atmosphere will remain fixed at 84 TB where TB is the black body temperature of the earth and the rest of the atmosphere will warm with the greatest warming near the ground This means the effective radiating level will rise which makes sense as it is harder to see into the atmosphere Finally if I am not mistaken the temperature of the top layer of an atmosphere consisting of n blackbody shells should be Tg n 1 25 not Tg 2 n 4 as stated Response I concur with your correction of the n shell problem I should have worked it out for myself instead of trusting what someone told me and the post is amended accordingly While your other two points are valid they are not strictly corrections I specifically state that I m ignoring convection and other atmospheric mixing processes in order to simplify the discussion They are clearly important in the troposphere but it doesn t help understand the stratospheric part As part of the final response to a change in GHGs the effective radiating level will indeed move up but above that level the tendency will be to cool Possibly a more complete statement would have been that you can think of the temperature profile pivoting around the radiative level and having that pivot move up a bit There will still be cooling in the upper atmosphere gavin 12 John Davis says 18 Jan 2005 at 5 25 AM I see that Steve Milloy has posted some graphs on junkscience com which purport to show that the stratosphere has in fact NOT cooled over the past 10 years or so Can you debunk please Response There is too much junk on junkscience to take it seriously A better reference is http www ghcc msfc nasa gov MSU msusci html though the graph there is substantially the same as SM s Fitting a curve through 10 years of data isn t a very good idea if you use the full set you obviously get a very different answer Given that CFC concentrations in the atmos have largely stabalised I would suppose that ozone too should stabalise SM seems to reject that but for no very clear reason William Response This is bad even by Milloy s own standards While the basic physics is sometimes difficult to explain see above the basic issue is that stratospheric temperatures change in response to local effects they do not change because the troposphere does i e troposphere warming does NOT imply stratosphere cooling Thus the changes in the stratosphere are basically a function of the greenhouse gases ozone levels and volcanic aerosols there The changes seen in the MSU 4 data as even Roy Spencer has pointed out are mainly due to ozone depletion cooling and volcanic eruptions which warm the stratopshere because the extra aerosols absorb more heat locally As William points out ozone depletion is levelling out since the Montreal Protocol and so lower stratospheric cooling will start to attenuate but then Milloy doesn t appear to think that ozone depletion was a real phenomena either gavin 13 Eli Rabett says 26 Feb 2005 at 8 47 PM I don t know if this is still open but one point to keep in mind is that the temperature increases with altitude in the stratosphere James Shearer seems to be saying that it decreases with altitude 14 James B Shearer says 26 Feb 2005 at 9 12 PM I don t agree that temperatures will pivot around the effective radiating level Instead the entire atmosphere will get warmer assuming no atmospheric absorption of incoming solar radiation Consider the case of n black body shells Adding shells makes the ground hotter but the temperature of the top shell remains at TB the blackbody temperature of the earth More generally assume the top shell is a graybody shell with emissivity e Then its temperature will be 1 2 e 25 TB Note this is an increasing function of e so even for the top layer increasing e causes the layer to warm As we let this layer get thinner e will go to 0 and the temperature of the top layer will go to 84 TB So as I said in my previous comment the temperature at the top of the atmosphere is effectively fixed at 84 TB Still more generally consider n graybody shells emissivity e numbered from the top Then if I calculated correctly the temperature of the jth shell is TB 1 j 1 e 2 e 25 and the temperature of the ground is TB 2 n 1 e 2 e 25 All of these are increasing in e Also note the discontinuity at the ground If we let e 1 n and let n go to infinity the temperature of the bottom layer is TB but the temperature of the ground is 1 1 TB Response You can only understand the strat cooling by knowing the atmos is non grey In a grey atmos it all warms The stratosphere exists because it is non grey ozone abs of UV Adding CO2 increases its ability to cool but less its ability to warm since most comes from UV so it cools I think this means I m agreeing with JBS William Response Et tu William Take a step back here I am not saying the atmosphere is like the n blackbody shell atmosphere This example is given as an end member for the extreme GHG effect which is to be compared to the no GHG case It is the difference between them that tells you what increasing GHGs do not what happens when you increase the number of shells In the real world we are in between the two cases but increasing GHGs pushes us towards an n shell case Since that case has a much steeper temperature gradient the basic effect of increasing GHG is to increase that gradient Given that the effective blackbody emission must be constant and allowing for a small movement in the effective radiating level an increasing gradient must therefore lead to cooling far above this level UV absorbtion by O3 is irrelevant for this point as is convection in the troposphere although it is key in setting the actual temperature profile gavin 15 James B Shearer says 27 Feb 2005 at 6 51 PM Eli Gavin is arguing above that adding greenhouse gasses would cause the stratosphere to cool even if the stratosphere was not being warmed by the adsorption of UV and that this is the explanantion of stratosphere cooling I am arguing that this is incorrect if all warming was from below there would be no cooling Gavin the gradient increases but the fixed point is the top of the atmosphere not the effective radiating level As a result all layers warm with the amount of warming increasing as you move towards the surface This means the effective radiating level rises Consider the top of the atmosphere as an arbitrarily thin gray body Looking down from this layer we see the earth radiating at its black body temperature TB Looking up we see space at near absolute zero So this layer will have temperature TB 4 0 4 2 25 or 5 25 TB or 84 TB as claimed above If the top layer is not arbitrarily thin but instead has emissivity e then its temperature will be TB 2 e 25 In either case the temperature is independent of the details of the temperature structure below the key point is that the total outgoing radiation must balance the incoming solar radiation Response Obviously radiaitve balance must be maintained and I am not disputing that the effective radiative level will rise Possibly the solution to this is that in the real atmopshere the movement of this level is severely constrained mainly by adiabatic cooling and so cannot rise enough to produce your solution I ll think about this a little more gavin 16 James B Shearer says 28 Feb 2005 at 7 17 PM Suppose we add absorption of incoming solar radiation to our model of the top of the atmosphere Let the top layer be a gray body with emissivity e and suppose it also absorbs a fraction f of the incoming solar radiation Then if I have calculated correctly it will have temperature T e f ef e 2 e 25 TB where as before TB is the black body temperature of the earth Note for e f T TB so the temperature increases from the effective radiating level to the top of the atmosphere Now let f a e for some constant a and let e go to zero ie let the top layer become arbitrarily thin Then in the limit T 1 a 2 25 TB Now if adding greenhouse gasses increases e but not f then a will decrease as will the temperature at the top of the atmosphere We can check this by computing the dT de and comparing it to zero By my calculation the derivative will be negative for f e e 1 1 e 2 So if f a e for some fixed a 0 the derivative will become negative as e goes to zero as expected This is true even if a 1 and the temperature of the top of the atmosphere is less than the black body temperature of the earth So I agree with William the cooling effect at the top of the atmosphere requires that the atmosphere be absorbing some incoming radiation and that this absorption be mostly by non greenhouse gasses Response You have simply restated the problem as being the same as for a single atmospheric layer read Tg for your new TB This doesn t help ascertain why different layers react differently And it doesn t explain why the mesosphere with very few absorbers also cools gavin 17 Andy Lacis says 2 Mar 2005 at 12 56 PM The question of why the stratosphere cools when the troposphere warms addresses an important validation point for the CO2 greenhouse effect but the question as stated is ill posed in that the correct answer depends on the proverbial details Climate forcing perturbations such as increasing the solar constant increasing black carbon aerosols tropospheric and decreasing surface albedo low cloud cover sea salt aerosol will on global average warm the ground and troposphere and will also warm the stratosphere For these types of radiative climate forcings the atmospheric temperature profile will be shifted basically unchanged to its new equilibrium position On the other hand decreasing stratospheric ozone above 25 km increasing stratospheric water vapor and increasing atmospheric CO2 uniformly with height will produce global surface and tropospheric warming along with stratospheric cooling These results are described in considerable detail in Hansen Sato and Ruedy 1997 Radiative forcing and climate response in JGR 102 6831 6864 see their Plate 2 for 2xCO2 Plate 3 for 2 So Plate 5 for ozone The radiative effects of increased stratospheric water vapor act to cool the stratosphere and warm the troposphere and are described by Oinas et al 2001 Radiative cooling by stratospheric water vapor big differences in GCM results GRL 28 2791 2794 That holds for the global mean temperatures Oinas et al also show that stratospheric dynamics make their contribution in the polar vortex regions to produce local warming in the 1 mb region for the uniformly applied increase in stratospheric water vapor This just shows that while the stratosphere as a whole may be in radiative equilibrium i e energy transfer is primarily by radiative means there are some locations in the stratosphere where dynamic energy transport is also significant The oversimplified analytic expressions that have been used to make the case pro and con a given explanation for why the atmosphere responds as it does are of limited validity For example the formula given by JBS that T e f ef e 2 e 25 TB can t really be correct since setting the solar input fraction f to zero does not reproduce temperature of the earth TB unless the emissivity e is equal to unity The 2 layer equilibrium relationship Ta 0 84Tg which is valid for an isothermal gray absorbing layer above a Planck emitting ground when applied to multiple layers is valid only when the layers are either totally transparent or totally opaque Also the T 4 dependence refers only to spectrally integrated radiation Planck radiation is linear in T at microwave wavelengths and goes to an increasingly higher exponential dependence toward shorter wavelengths Simple formulas can be useful but they are a poor substitute for the physics involved Radiative transfer in the earth s atmosphere is not particularly amenable to simple formulas because the atmosphere is semi transparent to differing degree at different wavelengths which allows radiation emitted locally to interact with the entire atmosphere Even for a relatively simple example of a gray medium calculating the equilibrium temperature profile within a homogeneous slab involves a singular Fredholm integral equation of the second kind as described by M N Ozisik in Radiative Transfer 1973 The radiative transfer problem is best addressed numerically with a sufficient number of vertical layers to resolve the atmospheric temperature and absorber distributions and with a sufficient number of spectral intervals to resolve the spectral dependence of the contributing gases as is being done in most GCMs For radiative transfer the vertical geometric scale is not relevant only the optical depth distribution matters From a semi transparent atmosphere radiation to space can come from virtually all parts of the atmosphere But the bulk of it comes from the so called TAU 1 level looking down from space where the opacity is near unity This is because the fundamentals of thermal radiation from an isolated slab emissivity absorptivity transmissivity are related by emissivity absorptivity 1 transmissivity where transmissivity exp TAU neglecting directionality Thus radiation emitted from below the TAU 1 level gets mostly absorbed before it can get out to space And radiation emitted from the uppermost levels of the atmosphere is small because the opacity there hence the emissivity is small and little flux is emitted Spectrally the opacity of the atmospheric column ranges from a few tenths in the 10 micron window region to many thousands in the center of the 15 micron CO2 band As a result the thermal radiation that is emitted to space comes from a wide range of points in the atmosphere ranging all the way from the ground to the top of the stratosphere The spectrally averaged effective emission temperature of the earth is about 252 K which corresponds to the physical temperature near the 6 km level This is also then

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  • MSU Temperature Record « RealClimate
    Measurements of Atmospheric Temperature Trends Meanwhile you can find decent up to date discussions on Wikipedia and in the recent National Academy of Sciences report on Radiative Forcing of Climate Change Expanding the Concept and Addressing Uncertainties 2005 see specifically the discussion on page 62 and pages 101 102 of the report mike 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 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 El Nino Geoengineering Greenhouse gases Hurricanes Instrumental Record IPCC Oceans Paleoclimate Sun earth connections Communicating Climate Reporting on climate skeptics Extras Attic Comment Policy Contributor Bio s FAQ Glossary

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