What if the IPCC is Wrong?

Looking at this title, what do you imagine my implications to be?

By “wrong” do you think I mean “global warming turns out to be natural/nonexistent/a global conspiracy”?

A very interesting sociological phenomenon……In the popular media, we hear so much from people who think that the dangers of climate change have been overstated by the IPCC, and virtually nothing from those who think the dangers have been understated. In fact, I can’t remember ever reading the latter viewpoint in the popular press, while the former presents itself almost weekly on the editorial page.

See, for example, this gem. I haven’t even looked into the quoted statistics (as they’re all from the Science and Public Policy Institute, truly the epitome of credibility….) and already I can guess what sorts of tricks are being played. Picking two convenient years from the last decade, calculating a linear regression, extrapolating that to rate of change per century, comparing that to the IPCC’s worst-case future predictions, and saying “oh look, the IPCC is wrong!” Works for temperature, CO2 concentration, and sea levels.

When the public reads “the IPCC is wrong” enough times in this context, they start to unconsciously equate it with “the IPCC is overestimating the dangers of global warming”. That’s my knee-jerk reaction, too.

I wasn’t even aware of this phenomenon, however, until I read an as-yet-unpublished poll of scientists’ opinions on the IPCC. The abstract says that “there is not a universal agreement among climate scientists about climate science as represented in the IPCC’s WG1”, “there remains substantial disagreement about the magnitude of [climate change’s] impacts”, and “there are….a significant number of climate scientists who disagree with the IPCC WG1 perspective”.

Reading this abstract, it sure sounds like the report found a lot of scientists who think the IPCC has overstated global warming. However, the report found that the IPCC perspective was the mean opinion of climate scientists, and there was a fairly equal minority on each side. 18% thought the IPCC was overestimating, 17% thought the IPCC was underestimating, and the rest thought it was about right.

I am in no way endorsing the findings of this study – as, not being peer reviewed, it wouldn’t pass our comment policy. I am simply using it as an example of how “significant disagreement with the IPCC” really has to be spelled out. The public has been so indoctrinated with the idea that “the IPCC is wrong” equates to “the IPCC is overestimating”, while in reality, it can mean exactly the opposite too.

(To be honest, I’m quite glad that this report wasn’t published without changes to the abstract, because it would be all-too-easy for WUWT et al to take the abstract quotes out of context and parade around saying “look the IPCC is wrong!” A furious blogging storm would begin. We’d be hearing the quotes out of context for years. Peter Sinclair would have to make a video about it.)

There certainly is a chance that the IPCC is overestimating or underestimating the impacts of global warming. In particular, the lag time between collecting data for a publication and the release of the IPCC report could increase error. Gwynne Dyer, in his book Climate Wars (review coming soon), estimated that “most of the data that formed the basis for the IPCC’s 2007 report actually refer to 2002 and earlier.” As few things become out of date faster than climatology data (for example, my chem notes still say that CO2 is at 350 ppm), what we’ve learned in the past 7 or 8 years would likely alter the findings of the IPCC. If we were somehow able to produce a new report instantly, it would interesting to see how the new data made it differ from the AR4. (Does anyone know of a good resource which compared the TAR to the AR4 in this way?)

Another way that the IPCC may seem to underestimate global warming is really very tricky. A lot of their future projections, understandably, are unable to model all the aspects of climate change. Many feedbacks cannot be modelled, especially the release of methane hydrates, so greenhouse gas levels don’t include such feedback processes. The collapse of ice sheets cannot be modelled, so sea-level predictions only account for thermal expansion.

Most of what they can’t model would make the projections a lot worse, but they have no way of knowing how much worse, so they just include, “not including uncertainty in carbon cycle feedbacks”. If you weren’t looking for this disclaimer, you wouldn’t know it was there. And try finding it in the summary for policymakers, which is the only part of the report most people will read.

Gwynne Dyer says it best:

“Leaving the biggest potential feedbacks – methane and carbon dioxide release from thawing permafrost in the higher latitudes, and carbon dioxide release from warming oceans – out of the climate change scenarios that the IPCC generates is defensible in scientific terms, for the did genuinely lack the ability to model them accurately. But, in a report intended for non-scientists, this omission ought to have been highlighted in warning yellow, not buried in the footnotes.”

Does anyone know of a peer-reviewed source which has attempted to include such feedbacks in future projections? In an interview with Dyer, Dennis Bushnell from NASA mentions a rough estimate which calculated a 6 to 12 C warming by 2100 if feedbacks were included. However, I can’t seem to track this down….

The IPCC may seem extreme in some circles, as it supports the drastic notions that the Earth is warming and carbon dioxide is a greenhouse gas. This basic support for the mechanisms of anthropogenic climate change has led the IPCC to be boxed in to the “climate change is real” camp in the general media, which faces off with an omnipresent “climate change is fake” camp. However, we must realize that there is also a camp that says “climate change is real and even worse than the IPCC estimates”. The IPCC, really, is the median scientific opinion – the “truth somewhere between the two extremes” that the public so wholeheartedly supports. Newspapers obviously aren’t too good at averaging.

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51 thoughts on “What if the IPCC is Wrong?

  1. Picking two convenient years from the last decade, calculating a linear regression,

    Calculating linear regression? Come on, that’s serious work, and requires knowledge of elementary statistical techniqes or looking them up on Wikipedia. The usual preferred technique is to calculate a line that connects those two convenient points.

    Although I’ve got to give them credit — they say it’s only been cooling for seven years, rather than 11 (since 1998!), so maybe they are doing regression and just ignoring significance tests.

    Oh, and I love this technique for misrepresenting IPCC projections (popularized by Monckton):

    According to the August report by the Science and Public Policy Institute, average global temperature is rising at 1.40C per century, not the 3.90C indicated by the Intergovernmental Panel on Climate Change models.

    In fact, the IPCC does claim on page 804:

    For a higher-emission scenario, for
    example, the SRES A2 scenario, the global mean temperature
    is projected to rise by 3.9°C above 1980 to 2000 levels in 2100.

    But, that is not a projection for how quickly it should be warming right now. You can take your pick of graphs from the document, but they predict an accelerating warming due to the accelerating CO2 concentration in this scenario. They do not suggest it should be warming at that rate now.

    [If you’re interested in debunking his arguments, and have the time, I suggest writing a letter to the newspaper that published the editorial. It’d be great. -Kate]

  2. Actually Monckton’s calculations of IPCC trends were more complicated than just dividing their 2100 number by ten. The numbers just happened to be similar. Lucia went through it at The Blackboard, and found it to be flawed, since it was not related to any IPCC projections.

  3. I have got to agree with Gwynne Dyer that the uncertainties with the carbon cycle and exclusion of dynamic factors of ice melt (for sea level calculations) should have been in bold.

    The end result is that the IPCC’s projections are the least bad of the possibilities for given levels of emissions.

    Compounding the problem is the slow nature of peer reviewed science and the very conservative attitude of scientists, not at all like my mate with the hot tips that “can’t loose”. Too many of us have had experience with hot tips and are assessing solid science with an unfairly biased eye.

  4. MikeN,

    I was referring to this letter from Monckton, where he does draw straight lines to 2100 as the IPCC prediction. Although I now see that he got that graph from Science and Public Policy, the same source for the editorial Kate points out, so apparently I gave Monckton too much credit, but we should not let this diminish his other acheivements in the area of developing techniques to misrepresent IPCC predictions.

  5. Many feedbacks cannot be modelled, especially the release of methane hydrates, so greenhouse gas levels don’t include such feedback processes.

    Kate, the issue of methane hydrates is overhyped in my opinion. Its the perfect mechanism for speculating that climate change could be much worse than predicted. But there’s an awful lot of handwaving and very little evidence. What does the literature actually suggest?

    The US Climate Change Science Program (CCSP, 2008) came to some of these conclusions:

    •There are a number of suggestions in the scientific literature about the possibility of catastrophic release of methane to the atmosphere based on both the size of the hydrate reservoir and indirect evidence from paleoclimatological studies. However, modeling and detailed studies of ice core methane so far do not support catastrophic methane releases to the atmosphere in the last 650,000 years or in the near future.

    •Observations show that there have not yet been significant increases in methane emissions from northern terrestrial high-latitude hydrates and wetlands resulting from increasing Arctic temperatures.

    •Catastrophic release of methane to the atmosphere appears very unlikely in the near term (e.g., this century). However, it is very likely that climate change will accelerate the pace of chronic emissions from both hydrate sources and wetlands. The magnitude of these releases is difficult to estimate with existing data. Methane release from the hydrate reservoir will likely have a significant influence on global warming over the next 1,000 to 100,000 years.

    http://www.climatescience.gov/Library/sap/sap3-4/final-report/default.htm

    Yes, there’s still a lot of uncertainty. And methane hydrates are expected to provide some positive feedback. But it seems that the contribution will be much less significant than CO2 over the next century or two.

    This is another good paper:

    http://geosci.uchicago.edu/~archer/reprints/archer.2007.hydrate_rev.pdf

    Final line of the abstract:

    On geologic timescales, it is conceivable that hydrates could release as much carbon to the atmosphere/ocean system as we do by fossil fuel combustion.

    In other words, hydrates aren’t expected to double the impacts of climate change on anything less than a millennial time scale.

    [I still think it’s scary. -Kate]

  6. The IPCC, by its very nature, will almost always give a very conservative summary. The IPCC tries to include the vast majority of scientists’ opinions and the summary must be approved by international government representatives. This can only happen with a very conservative summary. As you know, Spencer R. Weart discusses this in his superb book The Discovery of Global Warming.

    Regarding consensus and polls, I think the Doran and Zimmerman (2009) survey is a better survey than the Brown, Pielke, and Anaan (2007) survey.

    48% of Americans think most climate scientists do not agree that the Earth has been warming in recent years, and 53% think climate scientists do not agree that human activities are a major cause of that warming (Doran and Zimmerman, 2009). A poll performed by Peter Doran and Maggie Kendall Zimmerman at Earth and Environmental Sciences, University of Illinois at Chicago of 3,146 Earth scientists showed 96.2% of climatologists who are active in climate research believe that mean global temperatures have risen compared to pre-1800s levels, and 97.4% believe that human activity is a significant factor in changing mean global temperatures. Among all respondents, 90% agreed that temperatures have risen compared to pre-1800 levels, and 80% agreed that humans significantly influence the global temperature. Petroleum geologists were among the biggest doubters, with only 47 percent believing in human involvement.

    Doran and Zimmerman conclude:
    Debate on the authenticity of global warming and the role played by human activity is largely nonexistent among those who understand the nuances and scientific basis of long-term climate processes. The challenge, rather, appears to be how to effectively communicate this fact to policy makers and to a public that continues to mistakenly perceive debate among scientists.

    Brown, F., Peilke, R. Sr., Anaan, J. (2007). Is there agreement amongst climate scientists on the IPCC AR4 WG1?. Retrieved August 27, 2009, from Climate Science: Roger Pielke Sr. Research Group News Web site: http://www.climatesci.org/publications/pdf/Brown.pdf

    Doran, Peter T. & Zimmerman, M. K. (2009, January). Examining the scientific consensus on climate change. EOS 90 (3): 22–23. doi:10.1029/2009EO030002

    http://tigger.uic.edu/~pdoran/012009_Doran_final.pdf

  7. Scott, I disagree that the Doran and Zimmerman (2009) survey is a better survey than the Brown, Pielke, and Anaan (2007) survey. The reason is simple.

    The Brown survey gauges the respondents agreement with the IPCC. This is very useful. We find the majority agree with the IPCC and we get 2 minority groups who think they overstate and understate the impacts respectively.

    The Doran survey on the other hand simply asks whether temperatures have risen compared to pre-1800s levels and if human activity is a contributing factor. These questions seem crafted to elicit a highly positive response even from those skeptical of the IPCC. Even the most determined skeptic would agree that temperatures have risen since the Little Ice Age and many also believe that CO2 and land use changes will have some impact on climate. Not asking to what degree makes the question ineffective. Heck, someone that thinks CO2 cools the Earth would answer yes to that question.

    I should go and read the responses to the other 7 questions in that Doran survey, but from the links you provided I find the Brown one much clearer.

  8. Adding one resource to Scott’s list:

    Another bone of contention was the sentence saying that human activities were “very likely” responsible for warming global temperatures. China and Saudi Arabia asked that “very likely” (90% probability) be replaced by “likely” (66%) – effectively keeping the same conclusion as the last IPCC report, in 2001.

    The suggestion was resisted by New Zealand, UK, Norway, Switzerland, Argentina, US, France, Canada, Australia, Germany, Austria, Japan, Kenya, Sweden, and the scientists. Not much of a chance of winning there, then. As a consolation prize, a footnote was added: “consideration of remaining uncertainty is based on current methodologies.” (I leave it to you to decide what that means.)

    New Scientist: Feb.2007 (contemporary with the AR4)

    Because, of course, China and Saudi Arabia have no vested interest in keeping conclusions uncertain and unchanged for years.

  9. Joel: Methodologically, the Brown et al survey is a disaster. The attempt to set up a 7-point Likert scale to measure agreement with the IPCC AR4. So far so good. But then it all goes horrible wrong:

    1) If the intent is to measure agreement with the AR4 position, then central position should be “IPCC got it right”. Instead, they have this as point 5 on the scale, which immediately introduces a bias because there are more response modes available in to the left of this position than to the right.

    2) They then go on to give detailed descriptive labels to each position on the scale. Although its generally regarded as a good idea to give clear labels to each point on a Likert scale, the idea is that this be done only to help users understand that the intervals on the scale are to be interpreted as roughly equivalent. The set of labels in this study end up conflating a whole bunch of different ideas (each of which should be tested with a different question and a separate scale). For example, the labels in include ideas such as fabrication of the science, false hypotheses, natural variation, validity of models, politically motivated scares, divertion of attention, uncertainties, scientists who know what they’re doing, urgency of action, damage to the environment, and so on. Conflating all of these onto a single scale makes analysis impossible, because you don’t know which of the many ideas each respondent is agreeing or disagreeing with.

    3) Point 5 on the scale includes the phrase “the lead scientists know what they are doing”. Yet the survey is sent out to select group that is likely to include such lead scientists. This form of wording would immediately bias them towards this response, regardless of what they think about the overall IPCC findings.

    4) The sampling method is very suspect. Although the authors acknowledge that they didn’t do random sampling, and that this limits the kinds of analysis they can do, it also makes any quantitative summary of the responses hard to interpret. There’s plenty of reason to suspect that significant clusters of opinion chose not to participate because they saw the questionnaire (especially given some of the wording) as suspect. Given the context for this questionnaire, within a public discourse where everything gets distorted sooner or later, many climate scientists would quite rationally refuse to participate in any such study. Which means really we have no idea if the distribution shown in the study represents the general opinion of scientists at all.

    This means the only conclusions that can be drawn from the study are existence ones: there exist some scientists who think the IPCC underestimated, there exist some who think it over estimated, and there exist some who think the IPCC got it about right. The results really say nothing about the relative sizes of these three groups.

  10. MacDonald, G.M., Kremenetski, K.V. and Beilman, D.W. 2008. Climate change and the northern Russian treeline zone. Philosophical Transactions of the Royal Society B

    Have Northern Russian temperatures higher 1000 years ago than now, but not by much. SO how much warming do your sources say is needed for these other effects to kick in?

  11. Steve, the question is do you think the Doran survey is any better regarding scientists opinions? I don’t think so.

  12. Joel writes:

    “The Doran survey on the other hand simply asks whether temperatures have risen compared to pre-1800s levels and if human activity is a contributing factor. ”

    You left out the key word “significant”. While one could argue that’s still subjective, do you really think your average skeptic like Lindzen would answer “yes” to that question? Skeptics among scientific circles tend to argue it’s not significant. One weakness in their EOS article is they only quantify in numbers who answered “yes” to both questions. A bit revealing from the graphs is how few actually answered “no”. Some, particularly non-experts, answered “I’m not sure”, which is not surprising. One wonders if that was the default for those who simply didn’t answer the question, either intentionally or not. To do a full analysis of their published survey, one would have to view the full study, which I think is only available through subscription.

    Now to the Brown et al. survey. I find this to be a decent survey – better and more clear than the von Storch stuff (although neither ended up published). Assuming a reasonable sampling methodology, there are still problems with their questions. They ask scientists to choose between 7 choices. Choice 5 is implied to be essential agreement with the IPCC results, leaving 4 choices (1-4) believing it overestimates the human impact and only 2 choices (6-7) underestimating it. #2 and #3 are almost the same. I wonder if this sort of spectrum leads to a few more #4 selections. Those not spending too much time on a survey might assume #4 out of 7 choices is mainstream agreement when the wording actually implies greater skeptism.

    A second problem is the “IPCC agreement” selection #5 is worded as:

    “The scientific basis for human impacts on climate is well represented by the IPCC WG1 report. The lead scientists know what they are doing. We are warming the planet, with CO2 as the main culprit.”

    The 2nd sentence seems not necessary. The 3rd isn’t even an accurate representation of the climate forcings covered by the IPCC, which includes a variety of greenhouse gas forcings balanced to a degree by sulfate aerosols. So if the question isn’t based on an accurate representation, those answering the survey might be torn between 2 inadequate responses or might not answer at all. The phrasing of some of these questions seems very Pielke-ian. Some evidence of question problems can be seen by noting that 6 of the 140 respondents selected choice 5, but wrote in the notes that they agree with elements of choice 7.

    Not surprisingly, a statistically-insignificant number (4 out of 140), chose clearly skeptical options 1 through 3. Most of the “skeptism” was centered in option #4. See above for a discussion on this. Lastly, the response rate on mail-based surveys is never that high, but was particularly low for this one(140 of 1,807) with very low response rates in other countries, speculated to be related to the survey being written in English only. In contrast, the Doran survey had a 31% response rate, and a larger sample size, although a similar sample for “active climatologists”.

    [I got a hold of the full article from EOS, which is actually no more than what Doran posts on his web page. The other questions that were asked aren’t posted, more detailed methods aren’t included, etc. Kind of disappointing, especially when we know that there was more to the survey…. -Kate]

  13. I missed Steve Easterbrook’s reply. Part of my critique of the Brown survey echoes in his first point. #2 is also a good observation. They would have been better served asking a few more questions rather than shoving a variety of ideas into each choice in one question, guaranteeing the choices are not mutually exclusive.

    If a scientist chooses #6 or #7, does that imply scientists don’t “know what they are doing”?

  14. The new paper
    Analysis of Climate Programs Under Uncertainty

    http://globalchange.mit.edu/pubs/abstract.php?publication_id=1989

    says that to keep temperature rises from going past 2.2C
    there needs to be an 80% cut in the US and other wealthy countries, and developing countries like China have to follow suit within a few decades.
    That doesn’t seem very likely.

    [It certainly won’t be easy, but I’d much rather give it our best shot than risk the upheaval of civilization. The longer we wait, the harder it’ll get. -Kate]

  15. Just reading the abstract, it says the treeline reflects temperatures and growing season length, and that the treeline hasn’t reached the levels of the Medieval Warm Period or the Holocene Thermal Maximum

  16. MikeN said:

    Just reading the abstract, it says the treeline reflects temperatures and growing season length, and that the treeline hasn’t reached the levels of the Medieval Warm Period or the Holocene Thermal Maximum.

    It seems you just read the abstract.

    If you had read the paper you might have noticed that they say exactly the opposite of what you claim:

    The late nineteenth and twentieth centuries are characterized by generally increasing temperatures that in recent decades appear to have exceeded those experienced during the MWP.

    You might also have noticed that it takes for the treeline to advance — it doesn’t respond to temperature increase instantly — and for trees with poor seed dispersal it can take even longer:

    As of yet, the treeline has not been reached or exceeded its limits from the MWP, probably owing to poor seed dispersal by Larix (Shiyatov 2003).

    All you did was draw the conclusion you wanted, one which is contradicted by the paper itself.

    [Very, very important to read the full article. The Anaan et al study was similar, where the abstract could be misinterpreted quite easily. Larix is the larch/tamarack genus, am I correct? -Kate]

  17. Oh, I forgot the last part of that. How much warming is needed for those feedbacks you speak of to kick in?

    You say you’d like to give it a best shot, but I think it is foolish to chase after windmills. I’d like to pursue cheaper renewable energy as the best chance.
    I’d ahve to go through the study’s scenarios to have a better idea of what they say the probabilities are.

    [Our ultimate goal needs to be to reduce CO2 concentration as much as possible and as fast as possible. I don’t particularly care whether we do that through wind energy, nuclear, or CSS. Whatever works, and doesn’t compromise our ultimate goal for the benefit of a few industries. -Kate]

  18. The original post here hits on something important. People, especially conservatives, tend to think in binaries – good vs bad, right vs. wrong, liberal vs. conservative, etc. It’s simply easier to process the complexity of the world when you can reduce it into a few distinct categories. It doesn’t leave room for complexity, caveats, or “direction of wrongness” (i.e. are we under- or over-estimating).

    In climate science, this leads to some interesting feats of illogic. Take this post on WUWT: http://wattsupwiththat.com/2009/07/14/there-appears-to-be-something-fundamentally-wrong-with-the-way-temperature-and-carbon-are-linked-in-climate-models/

    The original paper found that models are underestimating the impact of positive feedbacks, and that therefore warming will be worse than predicted. But Watts goes through this chain of reasoning:
    models underestimate warming –> underestimation is a type of wrongness –> models are wrong –> global warming is wrong

  19. Joel: I just got a chance to read the Doran paper. Methodologically, it seems much better, although not enough detail is given in the paper to judge. One obvious problem in the presentation is to include the “general public” on the same graph as the survey respondents; given that this number was derived from an opinion poll with a different question and different sampling technique, it is very misleading to plot them on the same graph without clearly indicating they came from a very different study.

    However, the questions are pretty pointless, because they are really questions of fact, not opinion. The fact that publishing climatologists overwhelmingly agree just means that these are established facts in that field. The really alarming thing is that non-negligible numbers of other earth scientists don’t accept these as fact. That level of ignorance seems stunning!

    But it still doesn’t leave us with an idea of what any of these scientists think about how big a problem climate change is likely to be in the future. Which is, of course, the interesting question.

  20. If the host wants to put up a post about Arctic temperature history and hockey sticks, that’s up to her. Otherwise, I’m not going to get into what I’m projecting or not projecting, or what the temperatures were in the past. I asked a question about how much warmer the Arctic needs to get. I could be wrong that it’s not the Arctic where these feedbacks happen.

  21. First MikeN said:

    MacDonald, G.M., Kremenetski, K.V. and Beilman, D.W. 2008. Climate change and the northern Russian treeline zone. Philosophical Transactions of the Royal Society B

    Have Northern Russian temperatures higher 1000 years ago than now

    It was pointed out that

    If you had read the paper you might have noticed that they say exactly the opposite of what you claim:

    Now MikeN says:

    If the host wants to put up a post about Arctic temperature history and hockey sticks, that’s up to her. Otherwise, I’m not going to get into what I’m projecting or not projecting, or what the temperatures were in the past.

    How ironic that one of the focal points of this blog is: credibility.

    [When someone cites an article, I trust that they’re not misrepresenting the conclusions of the paper. I don’t have time to investigate every citation that someone makes. To all readers, in future, please make sure you read more than the abstract! -Kate]

  22. Steve,

    You stated: The really alarming thing is that non-negligible numbers of other earth scientists don’t accept these as fact. That level of ignorance seems stunning!

    I can speak for the meteorologists as to why many are not convinced. Those who use weather forecast models see that it is quite difficult to forecast more than 3 to 5 days out. Therefore, to those that do not understand the difference between forecasting weather and forecasting climate, it can appear to be hubris when folks discuss the future of climate. BTW, I am not one of the skeptics. :)

    As another example, when I posted a comment on WUWT stating that hockey sticks are shown by many different proxies, a supposed particle physicist claimed that trees are a bad proxy and therefore all hockey sticks are bogus. So, even a Ph.D in Physics chose not to read but believes she is entitled to a credentialed opinion.

    I have a colleague with an MS Geology who routinely teaches Heartland Institute “facts” in his classes. What are we to do?

  23. I did read the full article, and saw the parts in question. You are right that I am interpreting it the way I want. They have a contradiction between their data, and other studies, and did not resolve the contradiction. If it satisfies you, I’ll say they didn’t conclude the MWP was warmer than now. For the purposes of my original post, I still think based on that paper that the MWP was warmer than now, but not by much, for the reasons in the abstract(even the parts you quote have qualifiers like probably and appears), and am wondering how much more warming is needed for these feedbacks to kick in. That was the point of my post, how much more warming is needed?

  24. Steve: Perhaps my post could have been written better. What I meant was that because hindcasting of models is one of the “smoking guns” for AGW and is a strong reason that there is such a consensus among those that understand climate science, meteorologists have trouble accepting climate forecasting and are therefore more likely to be skeptical.

    Wow, what a run-on sentence that was.

  25. If you must have more, Hiller et al 2001, Seppa 2001, Hulden 2001, all had higher medieval warm periods, by about 1C, again not relevant to my point of how much warming is needed.

    [Mike, can you please clarify what journals these papers were in? I’m getting multiple hits for each on Google scholar, none of which are about paleoclimate. E&E, as usual, is off limits.

    The question of when feedbacks will really kick in is one of the great frontiers of climate science right now. I haven’t seen any definitive literature on the topic, perhaps someone else has? -Kate]

  26. Silly me, the full citation is at the end of the paper.

    Hiller, A., Boettger, T. & Kremenetski, C. 2001: Medieval climate
    warming recorded by radiocarbon dated alpine tree-line shift on
    the Kola Peninsula, Russia. The Holocene 11, 491–497

    Seppa¨, H. 2001: Long-Term Climate Reconstructions from the Arctic
    Tree-line. A NARP Symposium. The Arctic on Thinner Ice.
    10–11 May 2001, Oulu, Finland, Abstracts, p. 29.

    Hulde´n, L. 2001: Ektunnor och den medeltida va¨rmeperioden i
    Satakunda. Terra 113, 171–178.

  27. Kate: The best summary of various feedbacks and when they might kick in is the Lenton et al paper:
    http://www.pnas.org/content/105/6/1786

    And there’s a beautiful (and scary) graph in Ramanathan & Feng that summarizes the likely warming we’re already committed to, and where the feedback effects might start:
    http://www.pnas.org/content/105/38/14245

    Although not everyone agrees with R&F’s analysis:
    http://www.easterbrook.ca/steve/?p=692

    (let me know if you can’t get access to the full papers, and I’ll send you them)

  28. The exact timing and geogrphical distribution of the warming is the great challenge for modelers, and as I understand it probably isn’t amenable to anything like a complete solution. It’s interesting to discuss such things in the abstract, but we should keep in mind that “the science is settled” more than enough for us to know that we need to put the brakes on very hard indeed. As Jim Hansen notes, the case for climate action should be understood to be based on (in declining order of importance) paleoclimate studies, modern observations and modeling. It’s true that policymakers seem to want to know exactly what’s likely to happen when, but IMHO that’s rather like a pre-schooler negotiating the limits of tolerable behavior.

    Kate, have you read Hansen et al’s “Target CO2” (which BTW was incorporated into the Rockstrom et al paper published a couple of weeks ago in Nature)? (And while I’m on that subject, Charlie Veron, Ove H-G and co-authors just put out a review paper supporting the 350 ppm limit from the standpoint of coral. Plus check this out.)

    [Target CO2 is fairly terrifying. And Jim Hansen has such a good track record…..chances are he’s right about this. I’ll check out those other links, thanks. -Kate]

  29. “The really alarming thing is that non-negligible numbers of other earth scientists don’t accept these as fact. That level of ignorance seems stunning!”

    I wonder how many non-biologist scientists doubt evolution? I suspect it’s very small but non-negligible. Ironically, Roy Spencer (climate change “skeptic”) is one. I think even if a theory has overwhelming evidence in favor of it, it will naturally have dissent, even among apparently competent educated individuals, if the issue has some strong policy implications or ideological challenges. Evolution is often seen as a direct challenge to some religions. Manmade global warming implies a shift away from heavily-entrenched industries and government action, including possibly international agreements and cooperation, to mitigate. That generates a whole series of irrational fears and a fervent desire and demand to find reason to doubt the science. Many are willing and able to meet this demand.

    This partly implies that if the scientific community is to convince the public that manmade global warming is real, they are going to have to convince them that moving away from fossil fuels and preventing deforestation isn’t going to lead to a one-world government, destroy the economy, double or triple their electric bill, or make them give up their SUV in favor of horse and buggy.

  30. Andrew:

    People, especially conservatives, tend to think in binaries…

    Is this based on anything other than your own observation?

    In climate science, this leads to some interesting feats of illogic.

    It appears that Anthony faithfully reproduced the Rice University press release here:

    http://www.media.rice.edu/media/NewsBot.asp?MODE=VIEW&ID=12794&SnID=1419357327

    Some quotes:

    – Unknown processes account for much of warming in ancient hot spell.
    – There appears to be something fundamentally wrong with the way temperature and carbon are linked in climate models.
    – …something other than carbon dioxide caused much of the heating during the PETM.
    – Some feedback loop or other processes that aren’t accounted for in these models — the same ones used by the IPCC for current best estimates of 21st Century warming — caused a substantial portion of the warming that occurred during the PETM.

    I’m afraid you might be showing your own binary nature in regards to climate skeptics with your comment. Maybe you don’t like his choice of title, but it was a direct quote from the press release.

  31. Joel,

    Sometimes spin has several levels. It starts with the article:

    “Unknown processes account for much of warming in ancient hot spell.”

    “something other than carbon dioxide caused much of the heating during the PETM.”

    Neither of these statements are quotes from any scientist. The first leaves out “feedback” the 2nd leaves out “forcing”.

    Here is the direct quote from a scientist:

    “Some feedback loop or other processes that aren’t accounted for in these models…”

    Why would they leave out the phrase “feedback loop” at the top of the article and then go on to claim CO2 had nothing to do with the excess warming? Potentially underestimated feedbacks are kind of a key implication of the study.

    The Watts title sets the tone for his politically-oriented readers. However, I’ve seen much worse from Watts than that particular post.

  32. MarkB:

    Neither of these statements are quotes from any scientist.

    I didn’t say they were. They are statements from the Rice University press release, which is the University where one of the authors is from and where the news articles originated:

    http://www.media.rice.edu/media/NewsBot.asp?MODE=VIEW&ID=12794&SnID=1419357327

    As I said before, Watts faithfully reproduced the press release. If there any gripes it should be with the university’s media department.

  33. Joel –

    Two things.

    First, my problem isn’t with Watt’s reporting of the press release. It is with the (il)logical conclusion being drawn from the press release that global warming isn’t real. You can’t jump from “there appears to be something fundamentally wrong with the way temperature and carbon are linked in climate models” to “global warming isn’t happening.” The reason is, “wrong” can mean that models over-estimate CO2’s impact on climate, but it can also mean they underestimate the impact. In this case, the study Watts was reporting on concluded that models UNDER-estimate the effect of CO2 on climate, because they understate positive feedback loops; that the models are wrong implies that global warming will be stronger than expected, not that it doesn’t exist. So Watts is being deceptive here – reporting the study’s facts accurately, but drawing illogical conclusions.

    Second, has anyone estimated blog comment threads’ impact on productivity and GDP? I’m sure it’s much more economically damaging than cap-and-trade.

  34. Joel,

    “As I said before, Watts faithfully reproduced the press release. If there any gripes it should be with the university’s media department.”

    By your logic, it would be ok if a blogger “faithfully reproduced” a press release on Martians abducting children. It’s the responsibility of a self-proclaimed blogger on science to the discerning about what stories are covered, do objective analysis when appropriate (pointing out where the article’s wording is wrong), and of course, be more careful about the titles of their posts, which many knee-jerk readers don’t read beyond.

    I disagree with Andrew, though. While Watts has a habit of doing pseudo-analysis and misleading his readers (who are quite easily mislead) and sometimes trying to weasel his way out of clever distortions long after the fact,

    http://wattsupwiththat.com/2009/03/26/galactic-cosmic-rays-may-be-responsible-for-the-antarctic-ozone-hole/

    http://wattsupwiththat.com/2009/03/26/galactic-cosmic-rays-may-be-responsible-for-the-antarctic-ozone-hole/

    in this case, Watts is guilty of selecting a misleading title and failing to properly vet an article, which is already sufficiently misleading for this agenda. Some of his readers (apparent in the comments) have interpreted his ambiguous title in such a manner that is indicative of “seeing what you want to see”.

  35. Ooh, a little late to this reply.

    OK, if we’re going to be critical of every blog post that has ever had a misleading title, I could be here all day quoting Romm. Here’s an example:

    http://climateprogress.org/2009/03/03/pielke-in-nature-clearly-since-1970-climate-change-has-shaped-the-disaster-loss-record/

    Pielke’s response:

    http://sciencepolicy.colorado.edu/prometheus/another-response-to-joe-romm-5023

    The conclusion of the Hohenkammer consensus was:

    Because of issues related to data quality, the stochastic nature of extreme event impacts, length of time series, and various societal factors present in the disaster loss record, it is still not possible to determine the portion of the increase in damages that might be attributed to climate change due to GHG emissions.

    But Romm knowingly takes Pielke’s quote out of context in the post title: Pielke in Nature: “Clearly, since 1970 climate change…has shaped the disaster loss record.”

    Romm has cherrypicked a quote, misrepresented the results of the Hohenkammer consensus, and then cited a non-peer reviewed and older commentary by Mills to contradict the findings of the consensus.

    Let’s see you rake Romm over the coals for that.

    Now none of this excuses any misquotes from Watts, but it clearly shows that its not simply a conservative failing. At least in Watts’ case the study was behind a pay wall, where as I’m sure Romm had access to the conclusions of the Hohenkammer consensus.

  36. Joel,

    I took a look at your links. I don’t see where the misrepresentation is. Romm cites Pielke saying that climate change has shaped the disaster loss record. Hohenkammer verifies this with:

    “Climate change and variability are factors which influence trends in disasters.”

    Pielke’s beef then is with the phrase that it’s not possible to determine the specific portion of disaster costs attributable to greenhouse gas emissions. I think that’s always going to be elusive. Determining disaster cost attribution seems an order of magnitude more complex than say, measuring trends in intensity of hurricanes. This is because of population growth, land use changes, and regional variation in climate. Pielke has attempted to do this but not adequately in my view.

    You also didn’t note that Pielke Jr. is making a false assertion:

    “There are no peer-reviewed papers documenting a link between GHG emissions and the long-term trend in disasters.”

    Perhaps what he meant to say is “there are no very recent peer-reviewed papers co-written by me that documents such a link when processing the data with some shaky assumption-filled normalization technique” but that’s a stretch. Pielke doesn’t count the Mills paper because he doesn’t like it (see his link).

  37. MarkB,

    I find it amusing that various people (Romm, Mills) are linking to papers or consensus documents authored by Pielke Jr. and then coming to the opposite conclusion that he does.

    I think Mills paper is more of a commentary or essay then a peer reviewed paper, but in any event, I think Pielke thoroughly demolishes it with this [a blog post – Joel, to show that there is adequate criticism of a peer-reviewed paper, please cite another peer-reviewed paper, or at least a letter published in a journal. Thanks. -Kate]

  38. Fine:

    http://eetd.lbl.gov/emills/pubs/pdf/mills-pielkejr.pdf

    Again, I don’t think the section in Science labelled “Viewpoint” is considered the same as a peer reviewed paper.

    And again, MarkB you are selectively quoting Hohenkammer with “Climate change and variability are factors which influence trends in disasters.”

    That’s it? That’s all you’ve got? There’s no quantitative analysis in that or in Mills piece. Here’s the quantitative analysis:

    Because of issues related to data quality, the stochastic nature of extreme event impacts, length of time series, and various societal factors present in the disaster loss record, it is still not possible to determine the portion of the increase in damages that might be attributed to climate change due to GHG emissions.

    I’m not interested in predictions or models of increasing disasters if we can’t even perform an attribution study. This is not science. We can do attribution studies of global warming because of the length of the temperature record and measurements of external forcings, but at present this is not possible for disasters most notably because there is no statistically significant trend.

    Anyone that proclaims “hurricanes and tornadoes are going to get much worse in the next decade” or “temperatures will be record breaking next year” or even “earthquake frequency expected to increase with global warming” are all doing a disservice to science. All 3 assertions have been made and its just denier fodder when they’re unsupported and don’t happen. Sure, they can be considered in policy (lots of wackier things are) but they must be weighted accordingly.

    [Sorry about that….I didn’t realize that the piece in question was a Science editorial. Due to time constraints, I usually only doublecheck citations that seem really sketchy. -Kate]

  39. Joel writes:

    “I find it amusing that various people (Romm, Mills) are linking to papers or consensus documents authored by Pielke Jr. and then coming to the opposite conclusion that he does.”

    Have you seen the immense dishonest spin from Bob Carter on his recent paper? Pielke Sr. has done the same on occasion. See Annan’s posts on the matter:

    http://julesandjames.blogspot.com/2009_08_01_archive.html

    Pielke Jr. is not above vastly overplaying the implications of his own work (see his recent claims on the surface record). Back to the topic. You write:

    “I’m not interested in predictions or models of increasing disasters if we can’t even perform an attribution study…at present this is not possible for disasters most notably because there is no statistically significant trend.”

    Actually, the topic of discussion is disaster cost trends, not disaster trends, so you might want to rethink your spin. This is an important distinction and your misinterpretation of the implications is perhaps one thing that motivates folks like Pielke, as it gives contrarians some talking points. It’s somewhat easier to measure trends in disasters (hurricanes, extreme precipitation events, droughts, wildfire activity) than to measure normalized disaster cost trends, because the normalization process involves the additional difficult step of making various assumptions about population and land use, which is included in “various societal factors present in the disaster loss record”.

    One of these that Pielke Jr. did not consider in his work is outlined by Mills in his response to Pielke Jr., which you conveniently linked for us.

    “Yet, one can also hypothesize that the various societal responses may have more than compensated for population growth and in fact fewer people are today at risk….”
    The Army Corps of Engineers estimates that flood control measures have prevented
    80% of U.S. losses that would have otherwise materialized (9).”

    These sorts of complicating factors don’t come into play when simply measuring the trends in extreme events, as opposed to attempting to attribute normalized disaster costs. Mills asks the following question:

    “Lastly, why would rising numbers of events (10) not translate into rising costs?”

    All else being equal, it would. Focusing exclusively on disaster costs as a proxy for global warming effects, for the reasons noted above, is obfuscation.

    As for extreme events, including increase in hurricane activity, see the U.S. Climate Extremes Index for starters.

    ftp://ftp.ncdc.noaa.gov/pub/data/cmb/images/cei/dk-cei.tc.01-12.gif

    “Anyone that proclaims “hurricanes and tornadoes are going to get much worse in the next decade” or “temperatures will be record breaking next year” or even “earthquake frequency expected to increase with global warming” are all doing a disservice to science. ”

    I haven’t heard much about tornadoes and global warming and even less about earthquakes. Global warming leading to more intense hurricanes has scientific backing, and the observations to go with it. I refer you to the IPCC AR4 as another starting point. Follow the references.

    http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_SPM.pdf

    Of course some won’t be convinced on the effects of global warming until the ocean is in their living room, even if they live in the mountains. To make a loose analogy, we know that sleepy drivers have a significantly higher risk for car accidents, but attributing precisely the cost to insurers is very difficult, since it’s hard to disentangle driver sleepiness from other causes of distraction. The reasoning of a global warming denier would thus conclude that there’s no significant risk in driving sleepy.

  40. MarkB, first up you’ve linked a blog post refuting a peer reviewed paper…but I don’t really mind. How did we get to Bob Carter though? You didn’t address my main point, which is Mills using Pielke’s papers as references in his Viewpoint while misrepresenting them. No matter.

    I asked if you had anything quantitative and truly you don’t. The first half of your post had Mills hypothesizing and in fact narrowing the field to hurricane losses in the US only. What about globally? This changing of the goalposts is pretty convenient when its global changes we are interested in. As Pielke writes:

    Over recent decades, the IPCC found no long-term global trends in extratropical cyclones (i.e., hurricanes or winter storms), in “droughts or wet spells,” or in “tornados, hail, and other severe weather” (2). Logically, in the absence of trends in these weather events, they cannot be responsible for any part of the growing economic toll.

    If you want to talk just hurricanes (climate extremes undoubtedly includes record cold, heat, flooding, and drought which are not really disasters) we have the North Atlantic Accumulated Cyclone Energy data from Florida State University:

    No dice there.

    Global warming and tornadoes:

    http://www.sciencedaily.com/releases/2007/08/070830105911.htm

    Global warming and earthquakes:

    http://www.livescience.com/environment/070830_gw_quakes.html

    I will draw your attention to one line on page 8 in the Summary for Policymakers document you linked to in regards to human contribution to tropical cyclone activity:

    “Magnitude of anthropogenic contributions not assessed. Attribution for these phenomena based on expert judgement rather than formal attribution
    studies.”

  41. Ooh, I shouldn’t have said floods aren’t disasters…my point was to seperate moderate flooding from increased precipitation from that of hurricane induced flooding. (Flooding in dry parts of Australia is reasonably common but not really unexpected nor a disaster.)

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