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Full IPCC AR4 report now available

Filed under: — group @ 29 April 2007

The complete WG1 IPCC 4th Assessment report (AR4) is now available online. It’s missing the index and some supplemental data, but all should be available by May 7.

Over the next few weeks we’ll try and go through the report chapter by chapter, but since this is likely to the key reference for a number of years, we can take a little time to do it properly. Happy reading!

205 Responses to “Full IPCC AR4 report now available”

  1. 1
    Scaramanga says:

    Thanks, I am looking forward for your comments to the chapters.

  2. 2
    arnd says:

    IPCC missed the opportunity again! What is Climate? A question which should not be ignored when going through the full Report. It is interesting to see what IPCC can do with the term: CLIMATE. That the term climate is used demonstrates the new Technical Summary, AR4WG1_TS, which states on page 21, that: “The Earth’s global mean climate is determined by incoming energy from the Sun and by properties from the Earth”. But IPCC has never even tried to define the term. As part of WMO and UNEP it is also responsible for the UN Framework Convention on Climate Change, which did not define the term at all, but referes instead to: Climate Change, and Climate System. While one can only wonder to read in the FCCC that: Climate change means the change of climate…; the new Policy Summary is just introducing its own understanding: Climate change in IPCC usage refers to any change in climate over time, whether due to natural variability or as a result of human activity. (see Footnote 1, of the SPM-Report).
    It should to be not so difficult for IPCC to realise that one can not define climate change if climate has not been defined in the first place. Further papers discussing this question since 1992, e.g. Sea Law Inst., 1994, or Nature 360, p.292 (1992) on: Many thanks for making the TS available so quickly.

  3. 3
    saveEarth says:

    Thanks, just like to mentione that a WIKI as a quick reference is always more handy than those pdf’s. Also the content is even more accessable.

    A quick summary maybe even a speaken youtube video would be great for educational purpose.


  4. 4
    Vern Johnson says:

    Gavin, your approach is sound. The only cautionary would be that where there is not incontrovertible evidence for conclusions reached, that you bring forward, exhaustively, counter-arguments, and when, having done that, you also state, in non-technical language, why you think that particular conclusion may have over-reached and try, in effect, not to negate that majority conclusion but to raise some reasonable doubt about it no matter how many scientists in your area of expertise may disagree with you. Doubt, after all, is the beginning of knowledge. I look forward to your discussions. Thanks for your efforts. My approach, basically, is the medical one, because even if there may be uncertainty, we must take care to always err on the side of caution as the planet itself is the patient.

  5. 5
    pete best says:

    I believe that there is a entire document dedicated to how to mitigate climate change and I personally would like Scientists to comment on this subject. I know that RC are not energy scientists but maybe they can get a few of them to write an article for RC because from what I can tell and from what I have read the entire situation is a big mess strategically and a lot of the technology being pushed seems premature anc could even make climate change worse. We need some clarity on the matter. Maybe RC will comment on these matters now that the debate on climate change is becomming old and worn.

  6. 6
    Timothy Chase says:

    Well, if you are going to be covering this in depth, I will be sure to set aside some time for it. I would certainly like to learn more, particularly if you take it slow so that I can digest. And what the heck – it will give some more purpose to my life. The first moral obligation of anyone human is to understand. We will see what happens after that.

    Thank you!

  7. 7
    Ike Solem says:

    RE#5, pete we can at least try and break the complicated topic of enegy supply and energy technologies down into a couple of categories:

    1. Already existing technology: Wind turbines, solar thermal systems, solar photovoltaic systems, fuel-efficient hybrids, ethanol and biodiesel from crops (which can be used in existing diesel and gasoline engines).

    2. “Dead-end” carbon-neutral technology – for example, nuclear and hydropower. Dams silt up and nuclear is not a long term soultion (waste disposal, limited fuel, and high cost of dealing with aging nuclear power plants).

    3. Future technologies that need R&D: high-efficiency photovoltaics (say, 50% conversion) (as well as lowering the cost of PV), energy storage systems for intermittent sources like solar and wind (hydrogen storage, other methods), advances in biofuel technology (for example, hydrogen production from algae, cellulosic ethanol, etc.)

    4. Identifying where fossil fuel reductions can be made – #1 is in agricultural production. Massive amounts of fossil fuel are used in industrial agriculture, from diesel for machinery to natural gas for fertilizers and herbicides to the fuel used for long-distance transport and refrigeration. #2 is in transportation, from airlines to cars to ships to trains. Electric vehicles that use solar and wind for energy are one example. One airline company is experimenting with new biofuels for airplanes (biodiesel won’t work as it freezes at altitude).

    The important thing is to convince governments to get behind such plans, and to convince individuals to use less energy. The existing value of fossil fuel infrastructure is estimated at something like $10 trillion dollars, and that needs to be replaced by renewable energy infrastructure. That does seem like a very large amount of money, but in comparison to other recent expenditures it isn’t so large.

    Still, there’s a huge gap that needs to be filled. For example, the amount of renewable energy research that is carried out in US universities is miniscule compared to the amount of pharmaceutical research that goes on (i.e. the entire NIH budget, more or less). A 1000-fold increase in funding for renewable energy research would be a good first step.

  8. 8
    AlBreingan says:

    Re #5 & #7, I also feel this is becoming a critical part of the whole debate, though we still need to advance the climate science.

    Much of the fear uncertainty & doubt (and downright bullshit) that has mainly left the climate arena is well entrenched in the energy debate, and is more likely to stay there due to the much greater commercial interest.

    We very definitely need a partisan but scientific viewpoint expressed by experts in the field (as RC has been doing – thank you).

  9. 9
    Craig Allen says:

    Re #5, #7 & #8: Perhaps we need a sister website called RealClimateSolutions that is run by energy engineers. I for one am watching the various low-emission energy solutions with the will of a football fan desperately hoping to win the grand final – ” c’mon, score a goal, score a goal “. The greenhouse science is fascinating, but sooo depressing.

    My favorite teams at the moment are:
    * hot dry rock geothermal
    * solar tower technology (see animated rendition here )
    * Pelamis wave energy generators

    And of course all the energy efficiency technologies such as LED bulbs, and the various intelligent policy options that will be critical to driving down energy use.

    Don’t forget to boo the umpire when he unfairly favors opposition teams.

  10. 10
    Chris C says:

    Re: #2

    From the Third Assessment Report, Appendix I – Glossary:

    “Climate in a narrow sense is usually defined as the â��average weatherâ��, or more rigorously, as the statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands or millions of years. The classical period is 30 years, as defined by the World Meteorological Organization (WMO). These quantities are most often surface variables such as temperature, precipitation, and wind. Climate in a wider sense is the state, including a statistical description, of the climate system.”

    A definition is clearly stated.

  11. 11
    Bob Reiland says:

    Re #5, #7 & #8,

    Note that existing nuclear power plants in this country are lasting much longer than had been expected and new designs could be even better. They aren’t the ultimate solution, but they can be an important part of it for some time.

    While looking at the other energy sources and increasing efficiency in energy use, don’t ignore really creative solutions such as what the Heat Island Group at Berkeley have been working on: . Better roofing materials can greatly reduce energy usage while directly reflecting more energy into space. They have many other ideas that are worth looking into.

  12. 12
    Ron Tuckwell says:

    Could you please respond to a news report from Dab Elliott of Denver, quoting William Gray, a Colorado State University researcher and hurricane forecaster, who has said that global warming is all down to ocean currents and will reverse itself within 10 years.
    The news article was headlined “Ocean currents to blame for warming: expert”.
    Has he submitted a paper on the subject for peer review by climate scientists? I’m actually assuming that the answer to my question is, No!

  13. 13
    Pat says:

    Is there any chance that the new IPCC reports will be put into html, like the 2001 reports are currently? (The pdfs are so slow – not that it isn’t worth the wait, but…)

  14. 14
    Chuck Booth says:

    Re # 4 [bring forward… counter-arguments, and…state…why you think that particular conclusion may have over-reached …to raise some reasonable doubt about it]

    Hmmm…sounds like you are already convinced that the report presents incorrect conclusions, and you want Gavin to do the skeptics’ work for them?
    What if Gavin agrees with the conclusions of the report?

  15. 15
    Eli Rabett says:

    Why am I tempted to respond to Chuck by asking if he wants to bet on that? Unless you can find a countervailing forcing opposite in sign to that of CO2, and Gray cannot (nor can Lindzen and he has been trying to decades) you cannot handwave accelerating global warming away. Increased greenhouse gases, principally CO2, are by far the largest forcing in the climate system today and are getting larger. It is the elephant in the room.

  16. 16
    SCM says:

    Re: #12
    William Gray’s wiki entry answers your questions. He has a hypothesis about thermohaline circulation being responsible for recent warming, and forecasts future cooling.

    Has has no peer reviewed papers on this ideas re GW (no surprise there) but claims to be ‘working on it’. He was renowned for his earlier work on hurricanes but seems to have gone off the rails a bit.

    Gray’s ideas have already been given the realclimate treatment.

  17. 17
    Lynn Vincentnathan says:

    RE #4 & 14, I’d like to see some mention of scientific studies and articles that didn’t make the cut off date for the IPCC (or were excluded on technicalities or the politics of trying to get everyone to agree), and how they might be showing things are even worse than the IPCC portrays.

    It’s not that I want it to be worse; I pray everyday GW is not real, or is not as serious as they say. It’s just that I have this niggling feeling that it may actually be or could be worse, and we need to know.

  18. 18
    Nereo Preto says:

    There is now a public understanding that global warming is real, and man-made, at least here in Italy. I suppose the reason is this IPCC report is so sound that objections are unreasonable. This does not imply, however, that average people understand all of what is going on.

    So I have a proposal for oceanographers and atmospheric scientists (and geologists, for that matter) who wish to do some spreading of recent scientific achievements. The proposal is to start contribute to the Citizendium ( ), which is sort of a wikipedia with an editorial system. Or, post in wikipedia.

    Think about that: when you look for a definition in Google, wikipedia or other wikis are almost always in the first page. People knowing nothing of, e.g., global warming, will end up learning about it from wikis, most probably. I believe posting in such wikis is a primary way to do scientific culture.

  19. 19
    Louis Hazard says:

    Re # 12 – Ron, see if this section from April last year helps.

  20. 20
    Nils Simon says:

    #12: roughly speaking, you can have two kinds of temperature variations: in one version the global heat content keeps unchanged, but the heat is redistributed differently, leading to changed temperature patterns. This is what happens when you have a very cold winter in, say, Russia. It is then warmer somewhere else, and the global average temperature doesn’t change.

    The other version shows an increase in the global heat content, due to greenhouse gases. There we have globally increasing average temperatures, including the oceans AND the atmosphere. This is what happens right now under the conditions of global warming.

    If global warming was due to warmer ocean currents, then this energy has to come from somewhere. Therefore, we should be able to find it in in the form of lower temperatures somewhere else (the deep ocean??), but we don’t. Therefore Gray should come up with some REALLY good explanation regarding his claim, but I doubt it will be convincing. As Eli said: Ask Gray to bet a few thousand dollars, and you’ll see whether he’s up to it.

  21. 21
    pete best says:

    Re 18, The USA produces 25% of all global emissions and has a relatively small population (5%) and it is here that real climate and others are making their case because in the USA they are having trouble getting the whole idea through to their people and politicians. I believe that the way that the US political system is set up and works means that the greens nees money to lobby and seduce politicians just like the ultra rich fossil fuel lobby does. Alaska will be a waste land and the middle east a war zone before this argument is ended.

  22. 22
    James Davey says:

    #5 – I’m sitting in the ‘Mitigation’ chapter closing negotiations now. Obviously I can’t say what’s going on, but I think it’s safe to say that the final report will offer some new insights on how we move from where we are today to where we need to be in a few decades time.

    It would be /extremely/ interesting to see some discussion on mitigation on RealClimate. I realise it’s not Climate Science per se, but it’s as hotly debated an area and as important.

  23. 23
    Tibor Kiss says:

    How would you change your private life to protect the environment?

  24. 24
    pete best says:

    Re #21, I would hope that there is emphasis on how to get there rather than just the end product. For instance the UK has committed itself to a 60% reduction from 1990 levels by 2050 but as yet the document on how it is going to get there is missing, in other words they can make progress during the early years (obvious reductions) and get a 1/3 or CO2 removed but then it gets progressively harder to remove the other 2/3rds as that requires greater and greater strategic planning and it is this that becomes politically unsettling. The worlds population is increasing, the worlds most populous countries want what we have and have the means to get it now that the the west in preapred to invest and as yet there is no technology solutions currently available to either remove CO2 or not produce it at all that are mature and commercially available. We all know that we have to reduce demand and not increase supply so much.

    I reckon that it cannot be done and presently I side with James Lovelock. Some of the changes required need new energy infrastructures like a new decentralised grid, things have to be redesigned and that will cost trillions.

  25. 25
    Bob Schmitz says:


    A lot of good reading ahead. I read chapter 6 on paleo climate. Too bad there is not more about the Miocene climate (would love to see an article on RC about this one day). I could not help myself to point out this typo: page 464 :’A likely cause for the 8.2 ka event is an outburst flood during which pro-glacial Lake Agassiz drained about 1,014 m3 of freshwater into Hudson Bay extremely rapidly (possibly 5 Sv over 0.5 year; Clarke et al., 2004).’
    Lake Agassiz was larger than the average fish pond??

  26. 26

    In the Summary for Policymakers on page 10:

    It is likely that there has been significant anthropogenic warming over the past 50 years averaged over each continent except Antarctica (see Figure SPM.4). The observed patterns of warming, including greater warming over land than over the ocean, and their changes over time, are only simulated by models that include anthropogenic forcing. The ability of coupled climate models to simulate the observed temperature evolution on each of six continents provides stronger evidence of human influence on climate than was available in the TAR.

    The figure shows computer model output with and without anthropogenic effects for all continents except Antarctica. Does this mean that the models can’t account for the data there, or that such data isn’t sufficient to make a judgment? It seems like the omission needs more explanation.

  27. 27
    Paul Dietz says:

    nuclear is not a long term soultion (waste disposal, limited fuel, and high cost of dealing with aging nuclear power plants).

    The first is not a difficult problem (indefinite surface storage is acceptable), the second is very likely surmountable (for example, by extraction of uranium dissolved in seawater), and the third is demonstrably not a problem at all.

    What has held nuclear back is capital cost of the plants themselves, but the renewable alternatives face this problem in an even stronger form.

  28. 28
    Timothy says:

    #24 – Mostly it is because there are very few observations of what the climate is doing on Antarctica, due to the fact that the continent is only inhabited by a small number of scientists (and penguins and possibly whalers in the past?). There simply isn’t the observational data to compare the models with.

    Remember that the Summary for Policymakers is just that: a summary. I expect there is a reference to the full chapter, where you would expect this to be discussed.

    Indeed, 3.2 is referenced and I can now find the sentence in that section of the full report: “..substantial gaps in data coverage remain, especially in the tropics and the SH, particularly Antarctica.”

  29. 29
    Walt Bennett says:

    #23 – The implication of that question seems to be “how much pain are you willing to incur to leave a smaller GW footprint?” Correct me if I misinterpreted.

    My personal answer: it’s a question of cost. I stretch one high-tech income to cover me, my wife, our 5 children and our two cats. I buy energy efficient appliances and flourescent light bulbs, I insulate my doors and windows, and I keep electric devices which are not in use turned off. I still drive to work, mainly because biking in this hilly area would get me to work sweaty. I do not own a hybrid, because I cannot afford a new car at all and they are too new to be readily available in the used car market.

    If ‘renting’ solar (a la CitizenRe) becomes feasible, I will jump on that. If my utility offers me the option to ‘purchase’ energy from renewable sources, and is within 10% of my current costs, I will do it.

    I strongly believe that innovation will lead mankind away from spewing CO2 into the atmosphere. What will lead to better management of land use, and what will lead to less impact from livestock? These answers are less clear and will be more complex to manage.

    At a personal level, however, if we all make changes which, for example, average 10% better energy efficiency, we won’t notice much pain, we will lower our energy expenses, and the cumulative impact will be quite meaningful.

  30. 30

    I wonder if RealClimate could help me with the key logic components that generate rising temperature forecasts. There’s a disparity between the temperature increases that Hansen and others predict, and the numbers I get from two of the core formulas that are said to be at the heart of this issue.

    One formula links radiative increases to rising greenhouse gases. For rising CO2, delta R = 5.35 * log(new PPM/original PPM). [This formula from NOAA’s AGGI webpage.] With new PPM = 382, original PPM = 280, this CO2 formula implies radiative forcing of 1.66 watts/meter^2.

    The second links temperature to rising radiative energy. Roughly, R = constant * T^4, where T is degrees Kelvin. I use 235 watts/meter^2 as the starting R, and 286 Kelvin as the starting T. Probably not exactly right, but pretty close I think.

    To go from PPM to rising temperature, I first calculate the radiative forcing. Then I add the radiative forcing value to the R in the second formula, and solve for T.

    When I do this, I don’t get a very fast increase in Temperature Kelvin. In fact, I’m surprised at how slowly the T value seems to rise as a function of rising PPM for CO2.

    Here’s what I do get:

    382 PPM –> +1.66 watts/meter^2 –> +0.50 Kelvin.
    450 PPM –> +2.54 watts/meter^2 –> +0.77 Kelvin.
    560 PPM –> +3.70 watts/meter^2 –> +1.12 Kelvin.
    740 PPM –> +5.20 watts/meter^2 –> +1.57 Kelvin.

    Each of these new Kelvin values are delta values from the starting number, 286 Kelvin (13 Celsius). Though 740 PPM vs 280 PPM represents a tripling of atmospheric CO2, the formulas cited imply an overall temperature increase of 1.57 Celsius, from 13 C to 14.57 C. Not an earthshaking result, I shouldn’t think.

    Are these formulas wrong? Am I using them improperly?

    I’d like to be able to make the case – for those of my friends who don’t believe GW is a priority – in as mathematical a way as possible. The math I’ve just cited, though, doesn’t seem especially compelling. Thanks for any help you can provide.

    [Response: Steven–those formulas provide the radiative forcing from co2 alone, i.e. they assume no feedbacks! It is the positive feedbacks, primarily water vapor feedback and ice-albedo feedback, that lead to significantly greater warming than would be predicted by the radiative forcing from co2 alone. Indeed, it is precisely the role of these positive feedbacks that is at the heart of discussions of climate sensitivity. A good primer is Gavin’s recent article Learning from a simple model. -mike]

  31. 31
    Jamie says:

    in the mid 1970s we where told that the earth is cooling down. know we are told its warming up who do we, or what do we belive..?

    The governments of the world have put money in research into “global warming” co2 levels etc, could it be something else but this. I must admit the evidence point towards higher co2 levels in future. But if that’s all you’re paying the scientist to find that what they will find. If your in a court of law what’s the evidence on the opposing side …?
    Could it be the earth is in a “natural cycle” could it be sun spots.
    All the computer models are based on human in put and not fact based on history. But what if the records don’t go far enough for the information that needs to be generated and is that accurate …. Questions questions questions

  32. 32
    Ray Ladbury says:

    Jamie, I’m gonna go way out on a limb and guess that maybe you aren’t a scientist. Am I right. First, climate scientists do not just look at CO2. They look at solar output. They look at water vapor. They look at cloud formation. They don’t look much at galactic cosmic rays because, frankly, nobody can come up with a coherent theory of how this mechanism might work.
    Your court of law in this case is the scientific community. Anybody who has relevant evidence is welcome to present it to that community and see if it holds up. So far, no alternative explanation has even come close to being able to explain what we’re seeing.
    As to the climate models, yes, they are the product of human beings, but they are constrained by the best data we have–both historical and current. Moreover they work very well. And the records–they go back 650000 years with fair accuracy, or if you want to include fossil evidence, even further. We KNOW humans are causing climate change. We KNOW it with as much certainty as we know that Einstein’s General Theory of Relativity is a good description of gravity. If you have “questions, questions, questions,” then go find “answers, answers, answers”, but go to a reasonable source of information or you won’t know anything more than you do right now. Misinformation does not fill the void of lack of information.

  33. 33
    tamino says:

    Re: #31 (Jamie)

    in the mid 1970s we where told that the earth is cooling down.

    Told by whom?

  34. 34
    Ike Solem says:

    RE#27, Paul – to repeat, it still seems to be that if you have $4 billion to spend on non-CO2 producing energy sources, the better investment would be to build 40 solar-cell manufacturing facilities at $100 million apiece; for example see Honda Solar Factory; this would result in some 1,100 megawatts of solar cell capacity being produced per year, in comparison to a single nuclear power plant (typical power level: 600-1200 MW) being built.

    While some may claim that nuclear power is far cheaper, if you look at the history of nuclear power cost overuns, you see that $4 billion for a single plant is an underestimate; for example the Shoreham Nuclear Power station came in at $6 billion. At the end of the lifetime of a nuclear plant, you have a huge, toxic mess to clean up; after 30 years of comparable solar cell manufacturing, you have 30 MW of installed solar power (assuming good PV panel lifetimes). Solar PV is a far better approach, with immediate payoffs.

  35. 35
    Ike Solem says:

    RE#31 – The IPCC report addresses that in chapter one, pg 98:

    Not all theories or early results are verified by later analysis. In the mid-1970s, several articles about possible global cooling appeared in the popular press, primarily motivated by analyses indicating that Northern Hemisphere (NH) temperatures had decreased during the previous three decades (e.g., Gwynne, 1975). In the peer-reviewed literature, a paper by Bryson and Dittberner (1976) reported that increases in carbon dioxide (CO2) should be associated with a decrease in global temperatures. When challenged by Woronko (1977), Bryson and Dittberner (1977) explained that the cooling projected by their model was due to aerosols (small particles in the atmosphere) produced by the same combustion that caused the increase in CO2. However, because aerosols remain in the atmosphere only a short time compared to CO2, the results were not applicable for long-term climate change projections. This example of a prediction of global cooling is a classic illustration of the self-correcting nature of Earth science.

    This just shows the lengths some people will go to – repeatedly citing a few papers from the 1970’s as evidence that no one understands climate… can you imagine a similar claim regarding, say, HIV and AIDs? “In the 1970s, scientists didn’t know about HIV and AIDs, so why should we believe them now?”

  36. 36

    Re #31


    In the 1970s the earth was cooling down, now it is warming up. Is that so hard to believe?

    In the 1970s it was discovered that when the climate changes it usually does so abruptly, and so a rapid cooling was thought to be the main danger. Now, however, no one seems to have worked out that a rapid warming is the most likely catastrophe!

  37. 37
    tamino says:

    In the 1970s the earth was cooling down …

    Let’s dispel this myth once and for all.

    Analyzing GISTEMP data for the 1970s gives a positive rate of global temperature change — warming! — of 0.05 deg.C/decade. But the error bars are +/- 0.19 deg.C/decade, so the trend is not statistically significant.

    In fact the much-vaunted “global cooling 1940 to 1970” is not real either. Then trend for that time period is -0.25 +/- 0.3, again not statistically significant. The cooling is from about 1944 to 1951, the rest of that time shows no sign of any significant change.

    The only isolated decades which have statistically significant trends are (all in deg.C/decade):

    1930s: warming +1.8 +/- 1.2
    1940s: cooling -1.6 +/- 1.0
    2000s: warming +3.1 +/- 2.1

    The much higher error range for the 2000s is mainly due to the fact that we have less data (the 2000s aren’t over yet).

  38. 38
    Ed G. says:

    My favorite recent source on mitigation is ‘Heat’ by George Monbiot. While it is very UK centric and, I believe, wrong about a few issues, it is the only work I’ve seen that specifies changes to create an industrial society with vastly (90%) less carbon emissions. I’d like to know what folks here think.

  39. 39
    tamino says:

    Re: #37 (tamino)

    Correction to my previous post: all the numbers are deg.C/century, not deg.C/decade

  40. 40
    Ike Solem says:

    Typo – re#34, that should be 30,000 MW installed after 30yrs, not 30!

    You can take a look at the temp record here, which supports tamino’s conclusions.

    It’s also now well understood that large volcanic eruptions have a short-term cooling effect, see GW FAQ: effect of volcanic activity (short-term being the key phrase, after Church et al Nature 2005, and also )

    Thus, a large volcanic explosion this year would result in cooling temperatures for a few years… but the long-term trend would soon override this. This illustrates the natural variability – who wants to bet that there will be a large volcanic explosion this year? Noone can assign a realistic probability to that one, but 1 in 10 is the recent historical average.

  41. 41

    re #30 and Mike’s response to my post. As you suggested Mike, I have re-read Gavin’s earlier post. I think it ends up about where I do. Gavin suggests a sensitivity of 0.3C/(W/m^2) with no feedback, and in an albedo feedback example shows that rising to 0.33C/(W/m^2). Those results are similar to my back of the envelop scratchings in Excel.

    In other words, it takes a forcing increase of approximately 3 W/(m^2) to produce an increase of 1 degree Celsius.

    The simple incremental CO2 forcing that comes from 380 PPM rising to 450 PPM – if NOAA’s formula is right – is only 0.27 W/(m^2). Before any feedbacks are added in. Not much of a Temperature gain in that, is there?

    Even the baseline forcing – 280 PPM to 450 PPM – implies a rise in temperature of only 0.77 degrees Celsius. Before feedbacks are taken into account. Still not much of an implied temperature gain, especially not if the sensitivity is 0.33C/(W/m^2).

    You’ve said you’d be summarizing the IPCC analyses, including, of course, the IPCC temperature forecasts. May I sugggest adding to your summary a table that lines up the variables?
    – CO2 PPM changes expected in coming decades
    – Other GHG changes expected over the same time period
    – Anticipated W/(m^2) from GHG forcings
    – Anticipated W/(m^2) from albedo forcings
    – Anticipated W/(m^2) from water vapor forcings
    – Temperature changes implied by these forcings

    The point is simple. If Temperature change is a function of a forcing change, and a forcing change is a function of a Greenhouse Gas change plus a feedback loop, then it would be cool to have a table that connects the dots. GHG changes + Feedback changes –> Total forcing changes –> Total temperature changes.

    I assume the IPCC estimates will include some forecasts that show temperatures rising by as much as 3 to 4 C. If Gavin is roughly right, that the temperature sensitivity is somewhere around 0.33C/(W/m^2), then it’ll be interesting to see where the forcings come from that yield those predicted temperature increases.

    One last thought. Blackbody temperature changes are interesting. But climate is ultimately about atmosphere, isn’t it? Is it at all likely that temperatures rise first in the atmosphere? That ocean and land temperatures lag the atmosphere? Is it possible for climate effects to outpace ocean & land warming rates?

    Thanks so much for your patience and the teaching you do with this website!

    [Response: I think you’ve misunderstood Mike’s point. My calculations for the simple model are not representative of the real world (as I think I stated multiple times). They are illustrative of the kind of calculations that go on, but they are not a replacement for the more complicated ones. The most likely sensitivity is around 0.75 C/(W/m2), not 0.33. See for observationally based reasons for that conclusion. – gavin]

  42. 42
    steven mosher says:

    RE #34 IKE.

    Before we go off quoting the costs and troubles of a nuclear power plant built over 20 years ago we might have a look around at other more up to date stuff. I figure these guys might have learned something in 25 years. Kinda like GW scientists learned stuff.Just a hunch.

    Not a settled matter you know.. but I found this. again, it’s just one data point, but it’s not 25 years old.

    Now, the IRONIC thing I found was in your very next post, you are JUSTIFIABLY critical of somebody for reaching back to to the 70s for scientific papers. That was FUNNY as hell, but ironic. First( in #34) you reach back to the same period to pull up example to strengthen your case against Nukes and then you slam somebody for doing essentially the same thing. I thought you would find this as humerous as I did. Kind of like running with scissors .

    Finally, go check the honda numbers again. The plant looks like it is sited on existing corporate property ( so those costs are probably not included), capitalization is 4B Yen. Total investment is 7B Yen. Finally, I’m seeing PV lifespans guaranteed at 10-20 years. I’m not critical of solar, but I would take a bit more care in comparing alternatives.

    Anyways, I always enjoy your posts.

  43. 43
    Roger Smith says:

    Seabrook NH is more recent than that (completed late 80s or early 90s I believe) and United Illuminating Customers in Connecticut are still paying it off.

    There has been almost no reactor construction since the 1970s in the US, so all the domestic datapoints are old.

  44. 44
    Jim Crabtree says:

    It appears (as usual) the IPCC reports are way out of date before they are published. A new paper “Arctic Sea Ice declines – faster than forecast” in Geophysical Research Letters by researchers at NCAR and the U of Colorado National Snow and Ice Data Center show that the Arctic may be ice free by 2020, 30 years ahead of the forecasts by the models. As I stated in an earlier post several months ago, Dr. David Barber (a sea-ice specialist at the University of Manitoba), predicted the Arctic could be ice free in 15 years (Feb 15, 2006). Looks like more people are agreeing with him. Looks like again the models come up real short. Another surprise (and I think more are coming).

    Wish I could remember which paper I read several months ago where the average age of the sea ice in the Arctic is now less than 3 years old (memory fading with age). So apparently the ice is turning over a lot faster than originally thought.

    Also, the models were way off on the melting of the Greenland ice sheet. I can be critical of models since I am a computer scientist (retired) who has done some modeling.

    As I learned in my marine science courses many years ago, the Arctic is our thermostat for the northern hemisphere. Once it is broken, we had better hang on for a wild ride.

  45. 45
    pat n says:

    Re: faster than expected

    Official memorandum by directors of NOAA/NWS and NWS North Central River Forecast Center (NCRFC) states:

    ‘the mission of the NCRFC was operational in nature, and that Global Warming was beyond the time window of our hydrologic forecast mission.’


  46. 46
    Steve Bloom says:

    Re #44: Here’s the link to the press release on the new Arctic sea ice paper. I don’t recall seeing your prior comment on the prediction from Barber, but IIRC Wieslaw Maslowski (the U.S. Navy’s sea ice expert) was saying something similar at least two years, and in a recent AMS presentation noted that simply eyeballing the trend led to the conclusion that the summer sea ice is not long for the world (my phrasing).

  47. 47
    SCM says:

    Re #44 “Arctic Sea Ice declines faster than expected”

    Those that can’t access GRL can check out this recent poster on the same topic by the authors (from the 2nd CIRES Symposium a few weeks ago).

  48. 48

    Re #41 and Gavin’s reply. Thanks Gavin. I followed the link and read the observations. Also your reply to the first post following, in which you say the forcing for a doubling of CO2 is roughly 5.3 * LN(560/280), or 3.7 W/(m^2). This is the calculation I’ve already been guided by.

    I must be making an amateur’s mistake of some kind, though. On the assumption that a doubling of CO2 yields a forcing value of 3.7 W/(m^2), I add 3.7 to the value of G in your Stefan-Boltzmann formula, and I solve for Temperature. The increase in T is only a shade over 1 degree C, not the 2+ degrees that you say is the likely minimum.

    What am I doing wrong? Is it a mistake simply to increase the value of G by 3.7 W/(m^2), and then solve? Or am I wildly off in the value of sigma? (I’m using a sigma that I derived from your numbers, with G ~ 390 and T ~ 288.) Thanks again.

  49. 49
    Dave McFarland says:

    While I was reading Ch 6 of the IPCC report on Paleoclimate I came across the description of the Paleocene Eocene Thermal Maximum 55Ma. They describe a very large step input of carbon into the atmosphere and the ocean. Both Atmospheric CO2 and Ocean Carbon content increased in magnitude similar to what we are seeing today. How do we know that we are not seeing a repeat of the PETM?

  50. 50
    Rod B. says:

    “Alaska will be a waste land and the middle east a war zone before this argument is ended. ”

    I don’t get your point, pete. Save for its oil, I thought Alaska is a wasteland (scenic to be sure…), and the Middle East is a war zone…