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Comments 67901 to 67950:

  1. Arctic settles into new phase – warmer, greener, and less ice
    funglestrumpet; The paper you are referring to is: "Recent changes in shelf hydrography in the Siberian Arctic: Potential for subsea permafrost instability" JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 116, C10027, 10 PP., 2011 doi:10.1029/2011JC007218 The "Key Points" of the paper: •Our data provide evidence of drastic bottom layer heating over the coastal zone •We attribute this warming to changes in the Arctic atmosphere •Recent climate change cannot produce an immediate response in subsea permafrost The Abstract and additional information about this paper is available here.
  2. Arctic settles into new phase – warmer, greener, and less ice
    cRR Kampen: If you have not already done so, you may wish to peruse “As Permafrost Thaws, Scientists Study the Risks” published in the New York Times on This in-depth article portrays in words and in photos what's happening to the permafrost in the Arctic. It is part of the NY Times' Temperature Rising series. To access “As Permafrost Thaws, Scientists Study the Risks”, click here.
  3. Arctic settles into new phase – warmer, greener, and less ice
    #11, the methane thing in the Arctic becomes the single and by far most alarming change in existence re AGW - if we see methane concentrations rise sharply on a global scale in the next couple of years. Personally, I fear for the absolute worst.
  4. Foster and Rahmstorf Measure the Global Warming Signal
    KR @7 - in general I don't find Bob Tisdale's analyses very good either, but I do give him credit for criticizing poor posts on WUWT like this one quite frequently. He's one of the few 'skeptics' willing to point out the errors made by his fellow 'skeptics'.
  5. Foster and Rahmstorf Measure the Global Warming Signal
    Joe Romm over at Climate Progress also posted an article about the Foster and Rahmstorf paper. Romm's Dec 13 post includes a reprint of the Tomino article cited by Dana. The title of Romm's post is: Sorry, Deniers, Study of “True Global Warming Signal” Finds “Remarkably Steady” Rate of Manmade Warming Since 1979. To access it, click here.
  6. Foster and Rahmstorf Measure the Global Warming Signal
    Sphaerica, This is a statistical approach to removing the effects of exgenous variables. As such it is rather "stiff" in how it implements lags. In reality, dynamical considerations could shift the effective lag in any one instance of ENSO forward or backward from the mean lag. As a consequence, I think one can only hope to remove some of the natural variation using these methods. Only a proper dynamical model would truly be able to account for ENSO effects and the such. However, what Foster and Rahmstorf sacrifice in statistical efficiency is more than made up for by the clarity such an approach affords. Clearly warming has proceeded pretty much apace once much of those effects have been removed from the data. The average lags make sense based on modeling as well, I believe. That's a nice consistent picture.
  7. Foster and Rahmstorf Measure the Global Warming Signal
    John Hartz - Takeaways? My personal opinion here, but I see the takeaways as: * Major portions of mid-term climate variability can be attributed to (with statistical significance) various exogenous (outside) factors. * Accounting for those exogenous factors shows a very clear linear warming trend over the last 32+ years, with all temperature records in agreement. * Not incidentally, accounting for the exogenous factors shows a warming trend demonstrating statistical significance of warming over periods as short as 11 years, since 2000! * Related skeptic memes that this is evidence against: It hasn't warmed since 1998, Climate is chaotic, "It's internal variability", It's a natural cycle, etc.
    Moderator Response: [DB] Fixed text per request.
  8. Foster and Rahmstorf Measure the Global Warming Signal
    dana1981 - I would have to agree. I've read through that WUWT thread, and the singleton removals are numerically invalid for a multiple contribution case like this. You really need to perform a multiple simultaneous regression, or you overemphasize the contributions of the factor(s) you identify first. Interestingly enough, Bob Tisdale (a person whose work is sometimes criticized on Tamino's blog) has been posting on that WUWT thread objecting to Lansner's analysis on much the same grounds. It's good to see that at least a few of the people considered 'AGW skeptics' are willing to critique the opinions of others with that worldview.
  9. Foster and Rahmstorf Measure the Global Warming Signal
    dana1981: In plain Englsih, what are the take-away points of your post?
    Response:

    [dana1981] The main point is the last sentence of the post - the warming trend has remained very steady when these short-term factors are filtered out. I've added a concluding statement from F&R to clarify this point.

  10. Foster and Rahmstorf Measure the Global Warming Signal
    Somebody left a comment which was deleted due to a violation of the Comments Policy - it was just a link to a post on this paper by Frank Lasner on WUWT, suggesting that people should read his post for the sake of 'balance.' I don't agree - Lasner's analysis was extremely poor. For example, he tried to remove the factors one at a time rather than simultaneously (as Foster and Rahmstorf did) with multiple linear regression. This is a statistically poor approach. And in the end his results were effectively the same as F&R. Most of his criticisms of the paper were not valid. Another was the F&R use of TSI rather than sunspot number, but F&R clearly stated that they also did the analysis with sunspot number (and SOI rather than MEI, and a different measure of volcanic activity) and it didn't change their results significantly. As I said, it's a very poor analysis, and shouldn't be read just for the sake of "balance."
  11. The End of the Hothouse
    C B Dunkerson writes at 23:44 PM on the 16th of December, 2011: "But, in my hypothetical, there are these people who deny it is happening and oppose any action to address it." Not so hypothetical: http://www.washingtonpost.com/national/health-science/virginia-residents-oppose-preparations-for-climate-related-sea-level-rise/2011/12/05/gIQAVRw40O_story.html To paraphrase Haldane: People are not only more stupid than we imagine, they are more stupid than we can imagine. sidd
  12. Arctic settles into new phase – warmer, greener, and less ice
    This all fits with the report of giant (one kilometer dia) methane plumes rising to the surface in the Artic that have been discovered by Russian scientists. That's the trouble with tipping points, they slip by so silently - a bit like crossing the event horizon of a large black hole, you don't realise until it's too late. (I have never put a hyperlink in before and after reading in the tips section that if I get it wrong, it will screw up the page, I won't try this time either. The address off my computer is: http://news.yahoo.com/blogs/sideshow/giant-plumes-methane-bubbling-surface-arctic-ocean-163804179.html. I imagine that there is a more academic report somewhere.)
  13. Foster and Rahmstorf Measure the Global Warming Signal
    A few observations of interest, looking at the animated graph: 1) Tropospheric temps (RSS and UAH) seem much more susceptible to ENSO events. The smoothing brings them much more closely in line with the surface observations in terms of variability. 2) Even after adjustment, the tropospheric temps still seem to be more susceptible to "dips" (particularly UAH). 3) MEI is clearly not a perfect indicator of ENSO events, as the timing of those peaks and valleys is still somewhat visible in the final graph. I wonder whether another measure of another ENSO-related variable would smooth things further. I'm not asking you to do the work (Dana), but now that I look at it and try to appraise it... it would have been nice to see the graphs from figure 2 and figure 3 separated and stacked (much like figure 2), but with the x-axis lined up, to let one visually see the factor, before and after graphically.
  14. Arctic settles into new phase – warmer, greener, and less ice
    Given the Arctic ice volume trend, it appears the ice cannot exist other than purely seasonal at present climate conditions already. I disagree with the title "Arctic settles into new phase" entirely. There is no 'settlement' - yet.
    Moderator Response: [John Hartz] The headline was written by NOAA's press office.
  15. Models are unreliable
    Eric - I am not sure where you see 0.3 on Soden. It says ~0.5K (text above Fig1) and that seems to match Fig 2a as well. The GCM predictions are helpfully on the same graphs and seem to match my assessment of "very accurate".
  16. Sea level fell in 2010
    In addition to Tom's comment above, mace, please note that it can take several months to years for rainwater deposited into catchments and watersheds to return to the sea. A compounding factor is the replenishment of depleted aquifers. A nice, open-access, recent review is by Church & White 2011: Sea-Level Rise from the Late 19th to the Early 21st Century John A. Church • Neil J. White Surv Geophys (2011) 32:585–602 DOI 10.1007/s10712-011-9119-1 [Source]
  17. Infrared Iris Never Bloomed
    EOttawa @18 – That Seed article is very relevant. Gavin’s comment hit the nail – Lindzen sounds like a contrarian but he actually agrees with most of the mainstream science. Like many others that seek to sew doubt, he likes to throw stuff in the fan in the hopes…
  18. Foster and Rahmstorf Measure the Global Warming Signal
    I have two questions: do you have the data in excel file (I don't want to run de R script even it is on the web) and do you know if there is a database of spatial temperature anomaly. I think there is some residual signal that could be removed from the data and I would like to check what it might be.
    Response:

    [dana1981] I have the data provided by tamino, which includes the raw and adjusted data.  Some of it was in the Excel file he provided, and some was in a .dat file.  I didn't run his R programs.

  19. Foster and Rahmstorf Measure the Global Warming Signal
    Dana: Is the version of Figure 2 with "Enso, Volcanic, Solar Removed" identical to Figure 1?
    Moderator Response:

    [dana1981] Almost but not quite.  The points in Figure 1 are annual averages.  For Figure 2, I just took a 12-month running average.  So rather than having 1 point per year, Figure 2 has 1 point per month, each point being the average of the surrounding 12 months.

  20. Foster and Rahmstorf Measure the Global Warming Signal
    Dana: SkS readers who are not well-versed in climate science acronyms and terminology will have a hard time understanding the information presented in this article.
  21. 2011: World’s 10th warmest year, warmest year with La Niña event, lowest Arctic sea ice volume
    44, mace, The NOAA has a simpler approach. Here is their ENSO Education page. Here is their general ENSO page.
  22. 2011: World’s 10th warmest year, warmest year with La Niña event, lowest Arctic sea ice volume
    44, mace, This isn't the one I was looking for, but this post at Real Climate is a good introduction.
  23. 2011: World’s 10th warmest year, warmest year with La Niña event, lowest Arctic sea ice volume
    44, mace, There's a lot to be learned about ENSO events to be able to answer your own question. I suggest you start with the National Weather Service Climate Prediction Center, although it's a bit "thick." I recently saw a simpler tutorial (there are a few around), but I can't remember where. If I dig it up, I'll add the link.
  24. 2011: World’s 10th warmest year, warmest year with La Niña event, lowest Arctic sea ice volume
    What's causing this La Nina effect? Is the effect intermittent in some way. The dates in the article don't seem right. Looking at the records, it doesn't look like she kicked in until December 2010 and finished her merry dance in March 2011:- August 2010 3rd warmest September 2010 8th warmest October 2010 8th warmest November 2010 2nd warmest December 2010 17th warmest January 2011 17th warmest February 2011 17th warmest March 2011 13th warmest April 2011 7th warmest May 2011 10th warmest June 2011 7th warmest
  25. Sea level fell in 2010
    mace @16, the inland area of Eastern Australia, approximately the entire area of Queenland, New South Wales and Victoria inland of the Great Dividing Range, consists of three very large flood plains. The largest is the Murray Darling Basin, with an area of just over a million square kilometers. The Darling and tributaries drains nearly all of inland NSW, and a large section of southern Queensland, with a river system that drains into the Murray, and then into the sea in South Australia. Next largest is the Cooper Creek Catchment, with an area of 297,000 km^2. The Cooper Creek Catchement reaches as far north as my birth place, Mount Isa and drains into Lake Eyre, a normally dry salt pan below sea level. The area in Queensland drained by Cooper's Creek and the Diamantina (a tribuatary) is called the channel country because of the very large number of normally dry river beds that cross it. (Click on picture for full sized photo, which is well worth the look.) North of the Cooper Creek Catchment is the Gulf Country, a wide area drained by a number of intermittently flowing rivers into the Gulf of Carpentaria. The area of the gulf country is about 186,000 km^2. Combined, all three flood plains have an area approximately half of the Mississipi Basin, but unlike the Missisipi basin, most of the area is arid with only intermittently flowing rivers. It is also exceptionally flat. Floods in the Cooper Creek in Queensland take 9-10 months to travel its 1,300 km length to Lake Eyre. The land is so flat that raging floods travel at the glacial pace of 0.2 km/hour. Water traveling to the Murray down the Darling takes a similarly long time. Consequently much of the 2010 Queensland flood is either just now reaching the mouth of the Murray, or reached Lake Eyre a month or so ago, where it will now sit until it evaporates away. The land was so wet that the rivers in the channel country still have water in them. In addition to this natural storage, many of Australia's dams where at very low capacity before the floods, but are now very full. Wivenhoe Dam near Brisbane, for example, would have captured a volume of water close to that of Sydney Harbour (mostly during 2010). Combined that means a truly staggering quantity of water is being stored in Australia's river systems and dams which was not there 2 years ago. Dikran Marsupial is correct. The amount of water involved is not enough to account for the dip in sea level in 2010 by itself (and Australia was certainly not the only area flooded in 2010). Never-the-less, that water which is stored in Australia's rivers will not return to the sea as quickly as it was taken from it. It will be five or more years before Australia dries out (assuming we do not have ongoing rainfall, which we currently have). I suspect similar stories can be told in many other regions of the world, so while I expect sea levels to resume their inexorable rise, it will not be an immediate turn around.
  26. Sea level fell in 2010
    Hi Daniel Bailey, thanks for letting me post on more threads but I think I'll stick to just this one as I need to internalize my thoughts. The topic's about sea level falling, and the articles saying that this is because of more rain falling on the land than is normal. Obviously, rain would normally run off the land in to the rivers and oceans pretty quick, so I'm trying to think up why this hasn't happened in 2010. It dawned no me that it might be that it's being sucked in to the land, so I looked at the countries in figure 2 of the GRACE diagram, and Australia looked a likely candidate for this sponge effect. There definitely seems to be slightly more dark blue than dark orange in that picture, and the two can't be convoluted because the dark blue indicates higher quantities of surface lying water but it doesn't factor in how much has been absorbed in to the earth. The direct link is here:- http://grace.jpl.nasa.gov/news/index.cfm?FuseAction=ShowNews&NewsID=53 A Nasa climate scientist, Josh Willis, has put it more eloquently than I can, but I reckon he's saying the same thing. I guess we'll have to wait until next year for an update of the sea level data. Even if it doesn't show a bounceback, I think this could be due to a lagging effect as the water has to penetrate through the rock to get back to the sea.
  27. Sea level fell in 2010
    mace, you are welcome to post comments to as many threads as you feel capable of carrying on a dialogue on with any who participate with you, provided you are on-topic for that particular thread and that your comments comply with the Comments Policy (here). That being said (per Dikran above), for better internalization of things learned, fewer is probably best. Also note that this is a science-based website, so any hypothesis one wishes to float would need be accompanied by supportive references to the peer-reviewed literature.
  28. Arctic settles into new phase – warmer, greener, and less ice
    CBD, I believe you refer to the Tietsche et al 2011 paper. Note that a limitation of Tietsche is that the presumption is that stable CO2 concentrations have been achieved and equilibria with temps then reached. We are far, far from those conditions. Tietsche thus remains an academic construct.
  29. Sea level fell in 2010
    Sorry about that Dikran. I kind of see your point now about Australia but I read the article and previous posts so just wanted to launch a hypothesis out there to see if any fellows felt it was plausible. The article also identifies Columbia, the US, Brazil and Pakistan as having some heavy flooding. I don't think it's quite so dry in those places, though, so I agree my hypothesis is probably falling down. I think I've only posted to 2 threads, so far but apologies again. I will confine my posts to just 1 thread in the future.
  30. Dikran Marsupial at 23:40 PM on 19 December 2011
    Sea level fell in 2010
    mace@12 Please try to use some self-skepticism when putting forward a new hypothesis and at least apply a sanity check before posting. The surface area of the worlds oceans is ~3.6×10^8 km2, the surface area of Australia is only 7,617,930 km2, 1/47th of the surface area of the oceans. So for Australia as a sponge absorbing a 6mm rise in seal levels would be equivalent to absorbing 282mm of rainfall over its entire surface (most of which doesn't get much rainfall). Do you think that is at all plausible? If mean sea level were that sensitive to local flooding, it would bounce up and down like a yo-yo. Also I would suggest that you should confine yourself to discussion on a smaller number of threads. Your posts rather suggest a lack of basic knowledge on a number of basic topics, and posting wild theories like this gives the impression of trolling/spamming, especially when posted to multiple threads. This is intended as friendly advice, there is plenty of time to discuss these topics, and science is better served by depth of discussion rather than breadth.
  31. Models are unreliable
    mace wrote: "Can we conclude, that if the ice melts in Greenland, rather than the sea level increasing as many may expect, the global warming will cause seawater to evaporate and hang in the atmosphere." No. A warmer Earth does mean more water vapor, but the increased atmospheric water vapor content is much smaller than the increase in liquid water due to ice melt. The planet would have to get very hot (c.f. Venus) in order for that to stop being true. As to cloud feedbacks... there has been alot of research on the positive and negative feedback effects of clouds which you elude to. The exact net value is still uncertain, but it has been narrowed down to 'small'. That is, whatever the exact value it isn't going to have a major impact on the climate compared to the more prominent factors; CO2 forcing, water vapor feedback, and ice albedo feedback.
  32. Arctic settles into new phase – warmer, greener, and less ice
    I don't think there is any chance of the Arctic 'stabilizing' to a 'new normal' any time soon. Even if greenhouse gas levels magically leveled off we'd continue to see continued ice loss and related changes for decades, if not centuries, to come. I recall a study a year or two ago which concluded that if Arctic temperatures/conditions returned to 'normal' the sea ice could recover and therefor there was no 'death spiral'... which never made much sense to me because it should be obvious by now that there isn't going to be any 'return to normal'. That 'normal' is gone. The conditions which allowed it no longer exist.
  33. Models are unreliable
    Hansen has said in this paper that water vapour is the dominant greenhouse gas, rather than CO2 or methane. Can we conclude, that if the ice melts in Greenland, rather than the sea level increasing as many may expect, the global warming will cause seawater to evaporate and hang in the atmosphere. Not sure if more cloudy conditions would cause the earth to cool due to sunlight being unable to penetrate or to warm, as it acts like a blanket keeping the land warm. Any thoughts on this?
  34. Models are unreliable
    scaddenp, Hansen et al 1992 predicted a 0.5C drop and the observed drop was 0.3 (see http://paos.colorado.edu/~dcn/ATOC6020/papers/Soden_etal_727.pdf) The difference is usually attributed to El Nino in 1992 (see fig 2a in Soden). I am not so sure since that figure shows the model preceding the observed-ENSO drop by about 6 months and that is not explained.
  35. Sea level fell in 2010
    6mm drop in sea level may sound like a lot when you consider all of the world's oceans, but Australia was bone dry prior to the recent floods, so rather than the rain run off the land in to the rivers/oceans as you'd expect, it soaked it up like a sponge.
  36. Arctic settles into new phase – warmer, greener, and less ice
    As the average winter max is somewhere at 13-14 Mkm2, extrapolating the running average graph to somewhere between 6.5-7 Mkm2 would mean the earliest year of ice free summer (at least in sept) up there. Just guessing here, of course, a major volcano would likely delay that for a couple of years, and an enormous eruption somewhat longer still. http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2003# discusses of the meteorological effects of ice free arctic.
  37. Arctic settles into new phase – warmer, greener, and less ice
    that's the running average of Ice up north. don't know where that part of the text went.
  38. Arctic settles into new phase – warmer, greener, and less ice
    Let's see if that shows:

    Cryosphere Today, ~365 day running average of Arctic Ice

    The X-axis is the fraction of the year. It looks like the Arctic Ice amount is affected little by ENSO events, if at all, so Atlantic heat transport and general atmospheric warming would be the largest melters of the Arctic Ice.
  39. There is no consensus
    I dont think Hansen 2000 establishes a crack in the consensus. The uncertainties were quickly resolved and in Hansen et al, 2002: "Climate forcings in Goddard Institute for Space Studies SI2000 simulations" Hansen was able to conclude: "The greenhouse gas forcings are known with reasonably good accuracy. CO2 (1.4 W/m2) has the largest forcing, but the CH4 forcing is half as large when its indirect effects on stratospheric H2O and tropospheric O3 are included, and the sum of non-CO2 greenhouse gas forcings exceeds the CO2 forcing." AR4 papers improve on that. The current knowledge on greenhouse attribution can be found in Schmidt et al 2010. Got anything that challenges that paper?
  40. Arctic settles into new phase – warmer, greener, and less ice
    TomC: That's something we discussed on prior Arctic ice threads - summer minimum extent is dropping like a rock, winter maximum extent less so. That has to translate to a more rapid or an extended melt season. Consistent with the results described by Jeff Masters here. As Earth's climate has warmed over the past 30 years, the Northern Hemisphere has seen a dramatic drop in the amount of snow cover in spring (April, May, and June.) Spring is coming earlier by an average of three days per decade, and the earlier arrival of spring has significantly reduced the amount of snow on the ground in May. Less snow on the ground means the land surface can heat up more readily, and May temperatures in Arctic have increased significantly over the past 30 years. Consistent, too, with Arctic amplification and feedback due to the increased area of exposed sea water for more of the year. BTW, my questions in #2 were rhetorical.
  41. Models are unreliable
    Further on volcano predictions - in fact climate modeller did make very accurate predictions about the effects of the Pinatuba eruption as it happened. See Potential climate impact of Mount Pinatubo eruption Hansen et al 1992.
  42. There is no consensus
    Jdey #497 It's hard to forecast the weather more than a few days ahead, yet amazingly we can have (in the NH) real confidence that June will be warmer than December, and that June's temperature will lie within a particular range. GHGs play the role of the height of the Sun in the climate version of this analogy - the strong longer-term forcing that does not immediately dominate the vagaries of day-to-day weather, but inevitably wins in the end. Scientific theories are the best we have (read up on what a theory is). What are scientific 'facts'?
  43. There is no consensus
    Jdey123, what do you make of that paper from Hansen et al. 11 years ago? Did you read the whole thing, and do you think that Hansen currently thinks that CO2 is not the dominant forcing where recent warming is concerned? It's easy to point to abstracts and say, "see! see!," but perhaps you can tell us what you think the paper says. I do note that it does say that CO2 and CH4 are the principal GHGs.
  44. Models are unreliable
    Let's be clear about what happens in the modelling process. There is the famous George Box statement. "Essentially, all models are wrong, but some are useful". When you hindcast, you find models capture some observations but all. So what do you do to improve the model? In a physics model, you add more physics. Beyond bugs in the code, a failure in the model is physics not working. A lot of that has to with simplifications necessary for hardware of the time, so it's choose the important stuff. In 1975, "Broecker, W.S. 1975. "Are We on the Brink of a Pronounced Global Warming?" used Manabe's model to make a very good fist of predicting the 2010 temperature. However, the Manabe model was so primitive, that it had little to say of use about a great many other parameters. Improving computer power allows better spatial and temporal resolutions; more direct physics calculations rather than parameterisations etc. You will have no trouble finding things that the models still dont capture well - ask the modellers - but more and more of the important stuff go in. What doesnt happen in the process is tweaking numbers to fit a line. There are parametrizations made from empirical data - eg evaporation as function of temperature,humidity and wind speed - but the fitting is done in terms of data on evaporation, temperature and windspeed, not fiddling the function to make achieve say a particular global temperature curve.
  45. Arctic settles into new phase – warmer, greener, and less ice
    Muoncounter @2, the fluctuations are largely due to seasonal variations. However, between 1997 and 2007 the difference between the winter and summer anomalies was around 1 million square kilometers. Post 2007, it is closer to 1.75 million square kilometers. That is partly because the winter anomaly has not declined since 2007, while the summer anomaly continues its death spiral. However, contrary to DeWitt Payne, I think 5 years is two short an interval to suggest that this is a new seasonal pattern rather than just noise. On the other hand, at some stage in a continuing death spiral of summer ice, we would expect this pattern to emerge. In the near term limit, winter ice will still form extensively, while the summer ice will shrink to near zero. In the medium term we would then expect the winter ice to gradually shrink in area as the summer water temperatures start to climb in the absence of ice. Consequently the pattern over the last few years may be this pattern (continuing winter ice, and low or no summer ice) starting to assert itself. It is just too early to say IMO.
  46. Arctic settles into new phase – warmer, greener, and less ice
    If you are talking about this Cryosphere Today graph, aren't the 'big spikes upward and downward' the seasonal variation? And isn't the very-well defined trend down?
  47. Arctic settles into new phase – warmer, greener, and less ice
    There has certainly been a shift in the seasonal behavior of NH sea ice area. The new seasonal pattern that appears to have been established in 2007 is significantly different from that observed by satellite from 1979-2006 and appears to be reasonably stable, at least through 2011. That's why the anomaly data for NH sea ice area at Cryosphere Today calculated using the 1979-2008 average, for example, shows big spikes upward and downward starting in 2007.
  48. Models are unreliable
    431, mace, Not based on, but tested with. The models are physics based, but may be run over past periods so that the outcomes of the model can be compared to what we know already happened. And GHG's are a significantly stronger forcing agent on climate scales, but not simple monthly to inter-annual variability. The swings from one year to the next or over several years are still large. Consider the monthly and annual changes in temperatures here, versus the trend, using the BEST data:
  49. Dikran Marsupial at 10:44 AM on 19 December 2011
    Models are unreliable
    mace@431, GHG may be the dominant forcing, but that doesn't mean that their effect on climate dominates unforced variability on short timescales (e.g. 15 years). GCMs are just approaching the point where decadal predictions are beginning to be interesting. There was a good article at RealClimate on this recently.
  50. Models are unreliable
    Stephen Baines, the article to which these comments are attached says that the model is based on hindcasting. I thought GHGs were already large enough to be a significantly stronger forcing agent than natural sources. It's only deniers who claim otherwise.

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