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Unforced variations

Filed under: — group @ 20 December 2009

Open thread for various climate science-related discussions. Suggestions for potential future posts are welcome.

(Continued here).

1,159 Responses to “Unforced variations”

  1. 151
    Anne van der Bom says:


    that CO2 […] can certainly (and probably has) biased the climate in a warming direction

    You are hereby nominated as contender for the ‘euphemism of the year’ award. ;-)

  2. 152
    NoWayOut says:

    Although it (unfortunately) still is a bit outside the “standard” climate change debate, i’d love to see an update on ocean acidification and/or in general on the ocean sink. I can’t understand why it is so neglected.

  3. 153
    John Mason says:

    Gavin et al,

    You asked for ideas for new posts. Can I suggest one please?

    As a bit of a severe weather photography buff I am often asked what events will be “caused” by AGW. Now, I reply that AGW does not cause weather events as such but instead it influences them and their outcome – an example being the recent Cumbrian floods. In this case, a well-understood synoptic set-up – the Warm Conveyor – gave record-breaking totals. I am at ease with suggesting that these will trend towards ever higher precip intensities as things warm up. But how about convective storms? Has any work been done that has modelled trends with thunderstorms, and especially with respect to the essential wind-shear that is required to generate supercells and tornadoes? Other than suggesting that convective storms that form in the tropical maritime airmasses that sometimes make it to the UK are liable to generate more intense precipitation due to greater available moisture, I know not what to say on the matter either way!

    So a post delving into current effects of AGW would be of great interest.

    Cheers – John

  4. 154


    Brazil has done more than most other countries to fight global warming by switching its cars from gasoline to sugar cane ethanol. On the other hand, it is allowing ranchers and loggers to cut down the Amazon rain forest far too rapidly and too indiscriminately, adding to the problem.

  5. 155

    Mesa: There is a large community of scientifically educated individuals whose intuition does not buy the positive feedback, disaster scenario heating arguments on a planet where difficult periods of climate have been typically marked by severe cold…

    BPL: People who decide scientific issues on intuition tend to make large, glaring mistakes. It is intuitively obvious that the world is flat on average, that the sun and the whole sky orbit the Earth, that when you push on something it goes faster in proportion to how hard you push, that women’s menstrual periods are related to phases of the moon, that some races are more intelligent than others, and that there’s no way a people as primitive as the ancient Egyptians could have built the pyramids without help. Surprise! All those intuitions turn out to be wrong.

  6. 156
    Spaceman Spiff says:

    re. #134 Edward Greisch

    Yeah, I am vaguely aware of such catastrophic events having occurred, but that wasn’t my question. Here it is restated:

    Many of the past climate variations were driven via radiative forcings due to variations in the absorbed solar radiation (Earth spin axis/orbit characteristics). Presumably, this coupled with ice/albedo and water vapor feedbacks eventually led to pumping/removing of carbon from our atmosphere, acting as yet another feedback (it’s likely more complicated than that, but never mind). But now we are using carbon as a hammer to Earth’s climate (we’re coming at it from the reverse direction), and I wondered what this difference informs us regarding predictions of future climate (e.g., climate sensitivity to CO2, or the H20 feedback effect to the C02 forcing, for example). I have a substantial physics/maths background and a general interest in planetary climates, I am asking an honest question.


  7. 157

    Jim B: it [climate science] strikes me as a science in relative infancy compared to physics.

    Let’s see… Aristotle divided the world into torrid, temperate, and frigid zones around 300 BC. Torricelli invented the barometer in the early 1600s and discovered that pressure falls with altitude. Hadley mapped the Earth’s large-scale atmospheric motions in the 1750s. Fourier showed that sunlight alone couldn’t keep the Earth as warm as it is in 1824. Tyndall identified the major greenhouse gases in the Earth’s atmosphere as water vapor and carbon dioxide in 1859. And Arrhenius proposed the theory of anthropogenic global warming, complete with quantitative predictins, in 1896.

    On the other hand, while Newton came up with good mechanics in the late 1600s and electromagnetism and celestial mechanics were well developed by the 1900s, quantum theory wasn’t even proposed until Planck suggested it in 1900, it wasn’t put in an easily usable form until Heisenberg’s work in the 1920s, and the theories of relativity weren’t published until 1905 (special) and 1915 (general). So you could say modern climatology is older than modern physics, though of course the two fields are intimately intertwined. They both deal with reality, now, don’t they?

  8. 158

    Jim B,

    You want p values? Try here:

    I have to agree with Ray. I don’t think you’re really a physicist. I’ve never known a REAL physicist who wouldn’t give his name when talking to colleagues, even in another field. Ray is a Ph.D. physicist. I’ve just got a bachelor’s in the field, but even when I was a teenager writing to astronomers in the USSR and RSA, they were always polite enough to call me “Doctor” and even send me reprints with commentary. You, on the other hand, have yet to identify your name, where you got your degree, where you work, or even what your specific field is.

    And as for precision… do you know for how many, many decades astrophysicists couldn’t agree whether the value of the Hubble constant was closer to 50 km sec^-1 Mpc^-1 or 100? Is that what you call “precision?” And let’s not forget that the early values were 500-600. It took what, 70 years, to pin the value down with 5% error bars?

  9. 159

    ccpo: in no other field are scientists so summarily dismissed.

    BPL: Evolutionary biology?

  10. 160
    Greg Leisner says:


    There is lots of talk about the temperature of the atmosphere and some about the temperature of the ocean’s upper layer. There is almost no talk about the temperature of the land’s surface and nothing about Earth’s total surface heat content.

  11. 161
    drew3000 says:

    1. Don’t get too drawn into the bickering. Keep with the science blogging. While it’s probably not a good idea to ignore the skeptics entirely, let’s give equal time to the facts rather than the “sides” of the debate. Show the science that refutes the claims, but don’t blow them out of proportion.

    2. Posts on some of the supposed “solutions.” I’d like to see some science posts on the impact of nuclear energy sources as well as possible outcomes from carbon emission trading schemes, both of which seem to put the problems off rather than dealing with them.

    3. Open source data projects. It would be good to see more innovation in mashed up projectsions based on the data, using google maps and predicted scenarios and that sort of thing.

    Happy new years folks.

  12. 162
    Ray Ladbury says:

    James MacDonald asks, “Why is it so hard to find a terse, cogent explanation of the CRU controversy?”

    Because providing context for anything takes more time and space than taking it out of context and constructing a lie in which to embed it. Because people would rather believe what they want to believe than confront reality. Put another way: Reality is more complicated and often more disturbing than bedtime stories.

  13. 163
    Ed Hawkins says:

    Re #53 (MapleLeaf)

    At a recent meeting of the Royal Meteorological Society (UK), Adrian Simmons from ECMWF presented exactly what you suggest. He showed global mean temperature from ERA-40 (and ERA-Interim) reanalysis estimated in two different ways. Firstly he subsampled the surface in the same manner as HadCRUT, and got essentially the same answer for global temperatures over the past 40 years. He then averaged over the whole surface and got a larger warming in recent years. In fact, both 2005 and 2006 were warmer than 1998 in that reanalysis, mostly because HadCRUT does not include the Arctic.
    The details of the presentation are not online yet, but are in a submitted paper.

  14. 164

    I have a suggestion, if this is do-able. You currently have RSS feeds for the main blog, and another for the comments. Would you consider having an RSS feed for the “inline response” comments?

    I find following your inline responses are a useful way to get a bit more out of the blog.

  15. 165
    Cinoom says:

    I would like to hear RealClimate take on peak oil.

  16. 166
    Completely Fed Up says:

    Cinoom says: I would like to hear RealClimate take on peak oil.”

    Try “The History Of Oil” by Robert Newmann

  17. 167
    Anne van der Bom says:

    Paula Thomas,

    ‘Without hot air’ is nuclear propaganda. Prof. MacKay holds renewables to a higher standard than nuclear.

    Let me explain. In the first chapters he starts building his stacks of consumption vs. generation. He ends up with a 125 kWh per person per day consumption stack and then concludes renewables can never accomplish that. Current electricity consumption in the UK is ~18 kWh per person per day.

    But see what happens when he introduces the nuclear option. The 125 kWh per person per day is nowhere to be seen. All of a sudden he switches to a much more reasonable 18 kWh per person per day, based on current electricity consumption.

    Ask yourself why he does that.

    The other misleading part is consistently equalling electricity to heat. We all know that electricity is a higher grade form of energy than heat from the burning of fossil fuels. This difference is very easily dismissed by him.

    I do not say his facts are wrong, but they are presented in a misleading way.

  18. 168
    Completely Fed Up says:

    “There will come a point when the pendulum begins to swing in the direction of truth as a result of what is observed in the real world”

    The problem is that will come so late it’s far too late to stop the collapse.

    Although it would be nice to rub Mad Max’s face in it and go “SEE YOU WERE WRONG”, it’s not going to make up for the end of the world (as we know it). E.g. if we’re committed to 50 years warming and we delay another 20 as BAU, that could tie in 100 years warming no problem.

    That puts us at “West Antarctic and most of Greenland melt”. NYSE and the LSE will be borked, land will become a premium. And many of those pissing in the pool will have gotten out “scott free”.

    It’s not a good trade.

  19. 169
    Jim B: says:

    Ray, frankly to frame the issue as me not wanting to discuss the “successes” of the area assumes what you are trying to prove so dramatically way that I don’t even know how to respond.

    Bart – your reply is fun, of course, but non-responsive. I was specific what I meant by maturity which is not a timeline. I never said nor implied in any way that climate was not “dealing with reality”.

    So! It seems the motto of the day is strawmen, perhaps in an attempt to bait, and perhaps that is simply the motto of the internet, but it seems prudent to now bow out. I suppose you are both just “staying on message”. Not having much familiarity with the comment threads here a quick look back makes me think you both somewhat in the realm of shedding more heat than light, at least in your tone. Small sample bias in this conclusion admitted, but I do not have time for a more thorough vetting. Good luck to both of you, though.

  20. 170
    Ray Ladbury says:

    ccpo, Your post #130 raises an interesting point–dealing with the complexity of climate change for a lay audience.

    Yes, the physics of greenhouse gasses is complicated–thermal radiation, line broadening, collisional relaxation, equipartition, etc.

    However, what climate change really comes down to is energy balance–at equilibrium, you have it and temperature is stable, while now we have a mechanism that takes a chunk out of the outgoing radiation, so the system MUST heat up.

    How much must it heat up? Well, the short answer is until we have energy balance again. The long answer is again complicated, involving equilibrium between many heat reservoirs, complicated feedbacks, etc. It could be a career understanding all of these intricacies. However, fortunately, we already know what the answer to this question is to a large extent: Every time you double CO2, you raise the average global temparature by 3 degrees. This is known empirically and constrained by 10 different lines of evidence:

    What is more, we know that CO2 sensitivity can’t be as low as 2 degrees per doubling given the same evidence.

    I don’t see anything there that I couldn’t explain to an intelligent 12 year old. I don’t see that this high-level explanation does violence to the truth. And it is evidence based, so any denialist disputing it would be forced to confront the evidence–which, as we know, they are reluctant to do, for obvious reasons. What do you think?

  21. 171
    CM says:

    I *wouldn’t* like to hear RealClimate take on peak oil. Or solar vs. nuclear. The energy business is not their specialty.

    Well, actually, if the RC contributors did comment on these issues, I’d probably read with interest, because they’re bright people, probably follow these issues a bit, and can do the math. But I don’t think it’s the best use of anybody’s time.

  22. 172
    Hank Roberts says:

    > I find following your inline responses are a useful
    > way to get a bit more out of the blog.

    Yes yes yes yes.

    And, how about a sticky button at the top of each page that says “Nuclear Power, Boon or Bane? (This Way to the Egress!)”–> linked to BraveNewClimate

  23. 173
    Christopher Hogan says:

    I’d like to see an update on arctic methane. You last prior posts were fairly sanguine on the issues of catastrophic release from menthane hydrates, and on the overall role of arctic GHG releases in amplifying global warming. I’d like to see if your judgment about these issues has changed.

    Second, I’d like to see a general overview of the long-term quasi-period cycles that get mentioned from time to time (pacific decadal oscillation; atlantic multidecadal oscillation). I occasionally do time-series econometric work, and I find it hard to grasp how people can claim evidence for (e.g.) a 90-year cycle out of a instrumental record that is only (say) 150 years long. (But I’m not so interested in it that I want to ferret out the answers myself, so I was hoping for a cogent discussion here.)

    Third, since the decline of the arctic sea extent seems to be one of those unabiguous, hard numbers; and since the ice extent is down to almost exactly to the low 2007 level (as of today); and since the predictions for “an ice free summer Arctic” vary so widely, and since the US Navy appears to have picked 2030 as the date to play for an ice-free arctic; and since the information on age and thickness suggests that the decline is greater than the data on extent alone suggest; … well, I’d like to see a nice synthesis of current information.

  24. 174
    Blair Dowden says:

    My questions:

    1) The most basic consequence of global warming is the poleward shifting of climate zones. This means an expanded tropical zone, which I understand has already been detected. My question is does the semi-tropical dry zone only change position, or does it also expand in size?

    2) Climate models predict increased intensity of precipitation, because warmer air holds more moisture. In today’s world precipitation intensity increases as we move toward the equator. Is the predicted increase only because more of the Earth will be warmer, or is there some reason that a region with a given temperature in the new climate regime will receive more precipitation than a region in the old climate regime with the same temperature?

    3) Ocean acidification due to increased carbon dioxide in the atmosphere is reducing the pH of the oceans. This is supposed to reduce the ability of organisms to produce calcium carbonate shells, impacting plankton and coral reefs. Precipitation of calcium carbonate from dead plankton is a major cause of carbon removal, creating limestone deposits.

    Carbon dioxide levels have been much higher in the past, particularly during the Cretaceous. Yet there is a lot of evidence for Cretaceous coral reefs, and a lot of limestone and chalk deposits, as a visit to the south coast of England demonstrates. The explanation I have heard is that is because the rapid rate of carbon dioxide increase means the ocean does not have time to transfer the carbon dioxide to the deep ocean, so the surface gets acidified. So my question is how long does it take the ocean to turn over, so it comes into equilibrium? If it is less than a few million years, then the Cretaceous ocean had plenty of time to come into equilibrium, and the entire ocean should have been more acidic than today. Which does not seem consistent with coral and limestone formation.

  25. 175
    David Miller says:

    I’m with #74 and 83 and others – I’d like to know more about what is likely to happen to NH weather systems as a result of the arctic ice cap melting.

  26. 176
    Christopher Hogan says:

    I’d also like to know more about the effects of soot and other particulates. My proximate interest is that I’ve converted to heating with wood. Now I wonder whether the sootiness of wood fuel relative to natural gas fuel offsets the fact that it’s biomass not fossil fuel, and if so, by how much. I had the impression that the particles in woodsmoke were fairly large (and thus ought to drop out locally, when emitted from a residential chimney), but I’d really like to see a discussion of the issue.

    Not just my small issue, but the global issues as well. I see that a significant portion of arctic warming has been attributed to particulates, but I’d like to have somebody explain how. Intellectually, I grasp that it can change the albedo of the snow it falls on. And I get that most of it is from burning coal. And I see that forest fires contribute. But am I adding to that with my modern, airtight, high-efficiency woodstove? If so, if there any way for me, the lay reader, to estimate the net benefit (if any) of converting from natural gas to wood.

    As an aside, the one great advantage of heating with wood is that I am constantly reminded of how many tons of fuel I consume over a typical winter. Whereas, with natural gas, the mass of the fuel is similar, but it’s totally obscured. Having to tote around a couple of cords of wood gives me a much more serious attitude toward air leaks and insulation.

  27. 177
    Knut Witberg says:

    To Ray Ladbury @ 97
    You write:
    “Knut Witberg @75
    What a load of post-modernist, looneytarian crap. The whole point of science is to take a huge pile of data and use it to illustrate the truth.”
    With other words: from that “huge pile of data” you can select data as you please to illustrate “the truth”!

    Thanks Ray, I believe that you have most convincingly illustrated my point.

    I am not a “post-modernist” regarding my view on science. If you read what I have written, you will see that I acknowledge that there is a “truth”, only that we don’t know the (exact) truth. When we want to get closer to that exact truth, we just can’t discard data as we please in order to illustrate the truth, simply because we don’t know that (exact) truth. It may be an effcient illustration, but it is not proper science. I am surprised that you have problems with understanding this.

    [edit – not]
    and I will therefore present my own background. I have an MBA in economics and statistics and I have a degree in mechanical engineering. I have taught statistics at an university and I been doing research. From my background, you can probably figure out that yes – I have done Maximum Likelihood analysis and estimates. As I am sure you appreciate, statisticians are very seldom “post-modernists” in their views on science, that would be schizophrenic. They are trained in the choice of methods and in meticulous scientific procedures.

  28. 178
    Completely Fed Up says:

    “Carbon dioxide levels have been much higher in the past, particularly during the Cretaceous. Yet there is a lot of evidence for Cretaceous coral reefs, and a lot of limestone and chalk deposits,”

    When the sun was cooler and the corals differently evolved. Remeber, even crocodiles and horseshoe crabs have evolved even though they have apparently been unchanged for millions of years.

    Your genes have to run fast just to keep still.

    “1) The most basic consequence of global warming is the poleward shifting of climate zones.”

    And it’s seen.

    Or are gardeners in on the scam (and why?):

  29. 179
    Completely Fed Up says:

    Ray, the problem is that if you simplify the climate then the denialists complain where you’re missing out “important information that proves you’re wrong”. If you fill the gaps in the simple argument, you’re going to lose the layman.

    Heads they win, tails they lose.

    I think the only way to win is not play.

  30. 180
    meteor says:

    hi gavin

    sorry, but this is the second post I sent concerning past temperatures reconstruction.
    for the latter this concerned Man et al 2009, and I asked why the proxies temperature did’nt go to the end of the figure 1 graph.
    Is the reconstruction problem not interesting since few days, or, more likely, is there a technical problem, another, which avoid my posts to appear on the comments list?

    [Response: The methodology is described in in the Supplemental Material and in Mann et al (2008). As I understand it, these methods use a Climate-Field-Reconstruction approach which uses the proxy data to fill in for the instrumental data – but only where this doesn’t already exist. Thus there is no ‘proxy reconstruction’ in the modern period. However, you can tell how well this procedure works using separate validation/calibration intervals (for instance fig 2 in Mann et al 2008). – gavin]

  31. 181
    Hank Roberts says:

    The UK Met Office press release
    “… The study, carried out by ECMWF (the European Centre for Medium-Range Weather Forecasts) with input from the Met Office, performs a new calculation of global temperature rise.”

    points to this site, though I didn’t find a press release there:

  32. 182
    SecularAnimist says:

    ccpo wrote: “The funny thing is, in no other field are scientists so summarily dismissed. Only climate. Why? Vested interests.”

    Parapsychologists are often “summarily dismissed”. Indeed, I would venture to predict that perhaps a majority of the scientists from other fields who comment on these pages will be inclined to “summarily dismiss” parapsychologists. They might even be inclined to suspect parapsychologists as a group of fraud or incompetence and to take offense at the very mention of the field in the same breath as climate science. Yet these are attitudes analagous to those of AGW deniers towards climate scientists, typically based on just as little actual knowledge of the science and the scientists involved, and typically “informed” by organized “skeptic” groups that are hostile to the science itself. Lord Monckton, meet The Amazing Randi. Heritage Foundation, meet CSICOP.

    And why the hostility? Again, “vested interests”. But obviously not vested financial interests as is the case with climate science — rather, vested ideological interest in a world view that classifies certain types of human experiences as a priori “supernatural” and therefore illegitimate for scientific study, and thus views any scientific study of them as necessarily illegitimate.

    As to possible subjects for RealClimate articles:

    I am particularly concerned about drought. It seems to me that quite a lot of attention is given to questions about sea level rise. And yet, it seems likely that global warming-driven drought is likely to become a serious, even catastrophic, problem for human civilization long before sea level does. Even in what I understand to be the plausible worst-case scenarios for sea level rise, it would take decades before we would be evacuating major coastal cities. But a decade-long, continent-wide megadrought could strike any of the world’s major agricultural regions any time, and we could have worldwide food shortages or even famine within a few years. There are signs that this is already starting to happen is some areas.

    So I am very interested to know what climate science can tell us about the prospects for drought.

  33. 183
    Curmudgeon Cynic says:

    Hi Chaps

    Firstly a declaration – I am Joe Soap member of the public. I am not a scientist. I care whether we are making the planet fry – I also care if I am being conned. I have read and listened to the output from the “alarmists” and the “deniers”. It is impossible for a layman to come to a conclusion based upon such conflicting, heart felt opinions from both sides.

    Therefore, as a layman, but as a middle aged curmudgeon and cynic (WMDs, Swine flu, end of boom and busts, etc)can we check the “consensus” please?

    It is oft quoted that 2500 scientists can’t be wrong and that the science is settled. The denier camp casts doubt on this and claims that the IPCC report is written by just a few scientists and that anyone that disagreed was cut out but still quoted as “contributors” (thus including them and discounting them at the same time).

    [Response: Not true. Many thousands of scientists have participated in the IPCC process and all had opportunity to critique the text and the conclusions and suggest improvements. Many of them did so. I am only aware of a single case (Reiter) of a contributing author not wanting to be associated with the final product, which given the scope and number of people who have taken part seems a minor thing. – gavin]

    Can someone write (email) each scientist and get their views on the IPCC report conclusions?

    [Response: People have tried to do this, and (no surprise) there is general support for the IPCC conclusions. However, the methodology of these kinds of things and getting enough responses to be meaningful is hard. – gavin]

    It seems to me that the historic data needs to be agreed before we can sensibly form opinions and I am aware (from reading) of, on the one hand the Medeival Warm period and the little ice age theory, and of Michael Mann’s hockey stick graph on the other.

    Which one is a true and fair representation of historic global temperatures? The answer is surely the key to the debate. Can we ask the 2500 scientists which graph they believe?

    [Response: First, you probably overestimate how important these things are. The ‘attribution’ of climate changes in the twentieth century is the key result that gives us cause for concern in the future. The ‘hockey stick’ issues – however much play they get in the blogosphere just aren’t that important. Even if Mann et al were completely wrong (which they aren’t), the warming over the 20th C is clear, and the arguments for what caused it are unaffected. Read the IPCC FAQ linked from the “Start Here” button above for some more background. – gavin]

    As an aside I have some “lay” questions.

    1. I understand that we have launched 100,000 ships in the last century. Is the total displacement of those ships in anyway “material” to increasing world wide sea levels?

    [Response: I wouldn’t think so. Quick calculation – the biggest boats around weigh about 100,000 tons, so 100,000 of them weigh ~10^13 kg, which displaces about 10^10 m3, which spread over the area of the world’s ocean is about 0.03 mm. And this is very much an upper limit. Sea-level rise is about 3 mm every year. – gavin]

    2. I also understand that we pump sea water underground to get oil to come out. Is the amount of sea water that is now “underground” as a result of the years f pumping ina any way “material” to overall sea level?

    [Response: This may be a factor. Depletion of ground water resources is a global problem, and in IPCC AR4 they discuss (p418) some of the estimates but they are quite uncertain. Recent results from GRACE point to a larger contribution than may have been expected. – gavin]

    Sorry if the questions are naive.

  34. 184

    173 Christopher Hogan says: “You last prior posts were fairly sanguine on the issues of catastrophic release from menthane hydrates…”

    I agree, I talked to arguably the top NOAA CO2 researcher here in Boulder, and he is not so sanguine at all.

  35. 185
    Ken W says:

    Jim B (169):
    “I suppose you are both just “staying on message”. Not having much familiarity with the comment threads”

    If you don’t want to be treated with the “respect” that a deniar deserves, they please don’t post like one. Given the frequency of anonymous deniars that come around playing coy in their actual views, surely you can understand the skepticism of regulars when you come along claiming to be a scientist and posting a broad-brushed belittlement of the entire field of climate science. That’s been done far too often by pretenders.

    Scientists from other fields often visit here and post specific doubts or questions on climate science. But they generally use their real names or at least specify their actual field, and post specific questions. They are responded too with due respect and offered resources to help them gain understanding. Perhaps you should reconsider how you initially join discussions. At least, if you really are a scientist and not just another drive-by shooting deniar.

  36. 186
    Chris S says:

    I’d like to see Real Climate’s take on this conference: – particularly Drs. Allen & Swart’s presentations & Prof. Schellenhuber’s opening address.

  37. 187
    Ron R. says:

    Daniel J. Andrews #120: Sourcewatch has a lot of info on these people and groups as well. Though it’s a wiki so ocassionally the info just disappears.

  38. 188
    MapleLeaf says:

    Ed Hawkins @163, thank you for the link and information.

  39. 189
    chris says:

    Another possible subject for RealClimate analysis:

    Hansen has recently suggested that the climate sensitivity on long timescales might be considerably larger than the Charney sensitivity of near 3 oC of warming per doubling of atmospheric CO2.

    Recent analysis of Pliocene CO2 levels and temperature [*] tend to support this interpretation. A discussion of this would be helpful….what are the timescales involved?….what are the physical responses underlying raised sensitivity on the long timescale?

    B. Schneider & R. Schneider Palaeoclimate: Global warmth with little extra CO2 Nature Geoscience in press

    M. Pagani et al. (2009) High Earth-system climate sensitivity determined from Pliocene carbon dioxide concentrations
    Nature Geoscience in press

    Lunt, D. A. et al. (2009) Nature Geosci. doi:10.1038/ngeo706 in press

  40. 190
    Former Skeptic says:

    Jim B:

    What Ray said in 149.

    OK, you also claim to have read (almost everything) on AR4 “and a few select papers”…and yet you remain unconvinced. Really? Could you please give us a few specifics, rather than the vague generalities?

    I found the regional projections of impacts in WG2 rather disturbing – especially for the American SW, where I currently reside. What was your reaction, pray tell?

    And yes, I read Hulme’s book too but thought it was rather lightweight in its general treatment of AGW, especially with how it has been politicized (which is well covered by Mooney’s “Republican War on Science” and more recently by Hoggan and Littlemore’s “Climate Cover Up”). At the end of his climate science chapter, Hulme includes Weart’s book as good further reading. I (like the others who have read it here) do recommend it as the primer on climate change.

  41. 191
    Ray Ladbury says:

    Sorry, Knut@177, but your approach is postmodernist whether you’ve realized it or not. Look, science works, and it works and delivers robust approximations of truth for very good reasons. You are alleging that folks are just throwing data out–which would be serious misconduct. You had better have more than vague accusations when you make such allegations. OK so you understand Max Lik. Fine. Now try to understand the physics.

  42. 192
    Didactylos says:

    Anne van der Bom,
    It is true that David MacKay, like some environmentalists, but unlike others, has no disproportionate fear of nuclear power. However, you accuse him baselessly of being against renewables, which is clearly silly, given that the whole book is examining practical ways of implementing renewable energy on a large scale. He not only views renewables as a necessity, his analysis concludes that renewables can generate a far larger fraction of the UK’s power generation than any previous study has concluded.

    You should also remember that the results are specific to the UK. The UK doesn’t have much land to spare for wind generation, so the best energy mix is likely to be very different to, for example, the US.

    James Hansen also views nuclear power as a sensible option.

    Anne, your other claims about the book don’t seem to be true at all. Can you provide references to back up your assertions?

  43. 193
    Radge Havers says:

    Wut the hey. Here’s my half penny’s worth: Although it might be too bureaucratically wonkish for this venue, I’d kind of like to see some discussion of the organizational relation of science and public policy aimed at keeping politics from polluting climate science in particular. It might be a confidence builder for how science is perceived/respected.

    Possible points of interest:

    — the role and structure of the IPCC and agencies like the banished Congressional Office of Technology Assessment

    — firewalls that limit direct public contact with scientific consultants during planning or that filter how dialogue informs policy

    — the status of peer reviewed lit in decision support

    — laws against meddling with reports from scientists (esp. censoring)

    — how public information officers for science departments and agencies interact with the press

    — even lobbying and campaign finance reform

    It would be nice if there were some way to implement a sort of peristaltic policy algorithm able to work the nutters and ne’er-do-wells out of the system and tumble them discredited into foil-lined rubbish bins where they belong.

  44. 194
    Ray Ladbury says:

    Jim B. says, “Ray, frankly to frame the issue as me not wanting to discuss the “successes” of the area assumes what you are trying to prove so dramatically way that I don’t even know how to respond.”

    Fine, since you don’t want to discuss issues or evidence, we’ll just put you under the category “TROLL” shall we? Unfortunately for you, since this is a website about climate SCIENCE, that doesn’t leave much for you to talk about. For future reference, let me enlighten you as to two mistakes you made.

    1)You said you were a physicist, thinking that this was a field sufficiently broad to give you cover for not knowing specifics, and sufficiently general to give you an air of authority. You evidently didn’t anticipate that there would be several phyisicists here waiting for you.

    2)You thought that saying you were a physicist would lend authority to what you said. It doesn’t. If you come on here spouting supercilious twaddle as you did, you could be a frigging Nobel Laureate, and people here would be sufficiently knowledgeable and confident to call you on it.

    If instead you come on here asking sincere questions and really wanting to learn, you will find folks here more than happy to answer any question no matter how elementary or off the wall. And Barton and I would be among the first to try to answer them.

    Here’s the thing, Jim. Climate science is a very broad subject. A lot of climate scientists really were educated as physicists. A lot of them have worked in other areas of physics. And a lot of physicists have been over this research with a fine-toothed comb, because it will impact funding for their subfields of research. And you know what? The American Physical Society has validated what the climate scientists have done. But then, I guess you must have missed that in all the physics journals you read, huh?

  45. 195
    ghost says:

    Virtually every time I want to ask why X hasn’t been discussed, or what the answer to Y is, it usually turns out to have been addressed here, maybe multiple times. If I could request the near-impossible (and be the 10000th person to think of this), it would be to maintain a robust and current link library to papers and external discussions, divided into topic headings. I don’t know if I comprehend how huge a job that would be and how big a can o’ worms it could open, though. From viewing their sites and comments here, I know that the solid and routine posters here encounter rigorous topical material elsewhere. Tamino, BPL, Ray Ladbury, Timothy Chase, Lynn, dhogaza, Hank Roberts, John Reisman, Eli Rabbett, and all the others I cannot recall but whose contributions I cherish no doubt could add important links weekly. Perhaps it could be run as an off-topic section of the site to avoid distracting the mods from the site’s primary mission. Perhaps guest posts from those related climate fields could be rotated on to the main board, and maybe a balance could be found between efficient information flow on the one hand, and watering down the crucial contribution that the core of RC makes on the other hand. I do know that Gavin, Eric, et al spend some amount of time directing queries to previous discussions, and maybe a more comprehensive internal index would help that also (maybe it wouldn’t). An obvious problem with an external link library is how to avoid mis-categorized links, and links to junk. I rather doubt that in-field experts have much free time to volunteer, but some expertise in the field of the linked external material would help. Maybe lay volunteers would cause more havoc than the time savings is worth. Maybe the whole thing’s a terrible time-and-resource-sucking idea, a debasement of science, and another reason why I don’t get invited to these sort of parties :)

  46. 196
    Blair Dowden says:

    Re #178: “Completely Fed Up” (and some others here) should reconsider their hostile and paranoid response to what could be honest questions. Remember, even if the author of the post has an agenda, many of the hundreds of other readers do not, and are put off by what amounts to bullying. These should be exactly the people you are trying to reach.

    I never questioned if global warming is happening, and in fact confirmed it in the next sentence. As for the Cretaceous issue, thanks for the suggestion, but somehow I doubt that thousands of organisms all simultaneously evolved a new method of fixing calcium carbonate. I am sure the answer, if known, is much more complex than that.

  47. 197

    My two post requests would be first, the clearest explanation of stratospheric cooling from GHGs that you can give (I find it confusing) and second, a discussion of whether CO2 transfers absorbed radiation by vibrational quenching instead of re-emission of infrared. Thanks!

  48. 198
    Pete says:

    I’d like to see a more extensive discussion on Global Warming Potential (GWP) for greenhouse gases on different time scales (e.g., 20 year GWP, 100 year GWP).

    Using methane as an example, should I be thinking of GWP as 12 years of methane in the atmosphere (its approximate shelf-life) having a positive forcing equivalent to 79 times that as CO2 would have over 20 years in the atmosphere, and 33 time that as CO2 would have over 100 years in the atmosphere? Are we looking at the shelf-life impact of any particularly greenhouse gas stacked up against CO2 at various time intervals for CO2?

    If this is the case, is that why greenhouse gases with a longer shelf-life than CO2 have higher GWPs for 100 years than they do for 20 years?

    I think part of what makes it confusing (at least for me), is that the way GWP is sometimes described, it sounds like the 20-year or 100-year GWP for methane means that methane is actually in the atmosphere for more than 12 years (20 and 100 years in this instance). Since this is not the case, I’m left with the construct I’ve made above. Am I way off the mark? If so, a discussion on GWP in a post that goes beyond what can be found in the 2007 IPCC report or wikipedia would be fantastic.


  49. 199
    Completely Fed Up says:

    “reconsider their hostile and paranoid response”

    Paranoia is when they aren’t out to get you.

    Check out the paranoid rantings of the denialosphere (oh, hang on, your truth-sensitive glasses block that out) where you’ll read that AGW is just a way to tax everyone. A way to make the third world slaves. A way to siphon off the west’s wealth to the thidr world. A way to create a New World Order with Barak Obama as the new Muslim In Chief.

    They really exist, those arguments.


  50. 200
    Completely Fed Up says:

    “If I could request the near-impossible (and be the 10000th person to think of this), it would be to maintain a robust and current link library to”