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Further comment on the Supreme Court briefs

Filed under: — group @ 7 December 2006

Comment from Scott Saleska (elevated from previous post). The discussion refers to the brief submitted in support of the EPA position organised by CEI in opposition to the ‘Scientists’ brief‘ that Scott was a party to.

Was there was a reply to CEI brief?

There was no formal venue for a reply, at least not before the court. The general consensus of those of us who discussed it was that the CEI brief was pretty poor anyway. For what it is worth, below are some comments I emailed to my colleagues after I reviewed the CEI brief, followed by comments by Dr. Curt Covey, whose work was cited in the CEI brief:

— begin quoted excerpts of my email —

Our climate scientist brief focused narrowly and conservatively on two questions: (1) whether the state of the science was accurately represented by the EPA and by the lower court, and (2) whether the science is sufficiently compelling to support a judgement that the legal standard for regulation is met (i.e., may greenhouse gas emissions “reasonably be anticipated to endanger public health or welfare”?)

A relevant claim that our scientists brief is wrong or misleading would therefore have to consist of an argument that either (1) the state of the science was in fact accurately characterized by the EPA or the Appeals Court, or (2) that in fact, greenhouse gas emissions may NOT be reasonably anticipated to endanger public health or welfare. The CEI brief does neither, so I suspect it will not have much relevance to the case at hand.

The CEI brief discusses a range of broad questions on which the Climate Scientist’s brief takes no position (e.g. whether the “net” effects of CO2 emissions “will” endanger public health or welfare, or what history would have been like if industrial development had taken a less CO2-intensive trajectory), and quibbles with technical details which have little or no effect on the answer to the overall question no matter how they are resolved (e.g. whether the NRC/NAS statement in 2001 that post-1950 ocean warming was 0.050C is meaningfully different from the Levins et al. 2005, more recent figure of 0.037C).

As far as the technical details, a quick survey convinces me there is not much there. Just to cite a few, taken more or less at random (I have not had time to look at all):

CO2 growth rates (CEI, p. 11): arguments about what growth rates for CO2 emissions that some models use are besides the point of what the science says about the climate sensitivity of the earth system (emissions growth rates are if anything an economic question). It is well-recognized that many of the original emissions scenarios in IPCC overstated the trajectories that were actually realized (indeed, this was a minor point made in the NRC/NAS 2001 report that was picked up on, and misunderstood or misrepresented, by the Appeals Court), but so what? Unless they are arguing that actual BAU emissions will be so low as to prevent CO2 from any further significant build up (or at least stay under a doubling), this is a detail entirely irrelevant to climate science, and almost entirely irrelevant to the question about “reasonable anticipation of endangerment”.

Hurricanes (CEI, p. 16). We barely mention this, as a parenthetical (not as a “prediction” but as a citation of IPCC TAR’s reference to “likely increases” in tropical storm intensities). I am surprised they went after this, with all the recent work showing that the evidence for this has only gotten stronger since 2001. Yes, there is still debate about whether it has reached canonical levels of statistical significance (95% confidence), and there are problems with data quality yet to be fully resolved, but the standard in the law is lower (“may reasonably anticipate” endangerment). Are they arguing, in the light of Emanual 2005, and Webster et al., 2005, that it would be entirely unreasonable to anticipate stronger hurricanes in the future? If not, what is the point?

Satellite and surface temp records (CEI p. 23). The main substantive thing we said with respect to this is that “all available data sets show that both the surface and the troposphere have warmed,” which the CEI brief criticizes. But the quote they criticize is not ours, it is from the U.S. CSSP (2006) re-assessment (the subtitle of which is “understanding and reconciling differences”). An author of the CSSP (and of the Executive Summary, from which our quote is taken) is John Christy, who is an amicus on the CEI brief. Is he arguing against himself? Perhaps he didn’t realize this CEI comment was in there when he signed on.

—- end Saleska quotes —-

With regard to the CO2 scenarios, the CEI brief cited a paper by Curt Covey. My colleague and co-amici David Battisti inquired of Dr. Covey if he had any comments about the way CEI cited his work, and he responded, saying we were free to circulate his comments. Here they are:

— begin quote of Covey email —-

Dear Prof. Battisti,

Part of my job here at LLNL is to accurately communicate the results of my work to scientific colleagues and the public. Accordingly, you should feel free to share the comments below.

Page 11 of the brief begins, “As shown below, computer models predicting future warming must overestimate warming, because they generally use an incorrect increase in carbon dioxide concentration of 1% per year.” It is not true that models “generally use” this rate of increase. Model
simulations of 20th century global warming typically use actual observed amounts of atmospheric carbon dioxide, together with other human (for example chloroflorocarbons or CFCs) and natural (solar brightness variations, volcanic eruptions, …) climate-forcing factors. Model simulations of future global warming use analogous input; of course it is not possible to observe the future, so a variety of scenarios involving possible atmospheric concentrations of carbon dioxide, etc., are employed. These range from stabilization of atmospheric carbon dioxide at twice its pre-industrial value by the end of this century (IPCC SRES B1) to continuously increasing atmospheric carbon dioxide at the rate of a bit less than 1% per year (IPCC SRES A2). Each climate model simulating the future is run several times, with several different scenarios. All of this has been standard practice in climate modeling for the past ten years.

Pages 11-12 quote my 2003 review paper correctly regarding idealized simulations in which atmospheric carbon dioxide is assumed to increase at the precise rate of 1% per year. Note that in the end of the quoted passage, I say that this rate of increase could “perhaps” be considered realistic “as an extreme case in which the world accelerates its consumption of fossil fuels while reducing its production of anthropogenic aerosols.” I’m no expert on scenarios, but from what I hear about China and India I wonder if the world is already on that track. In any case, the purpose of the 1%-per-year scenarios is to compare different models’ responses to identical input — not to produce realistic possibilities of future climate. For the latter purpose, climate model output from the IPCC SRES B1, A2 and other scenarios has been widely used for several years and has been publicly available for
over two years on my group’s Web site at http://www-pcmdi.llnl.gov/ipcc/about_ipcc.php.

Finally it is not true, as implied on Page 12, that “sole reliance on models to the exclusion of observed behavior” is the basis of future climate prediction. As noted above, modern climate models are used to
retrospectively simulate the 20th century as well. Simulation of 20th century global warming is an important confidence-builder for climate models. Indeed, the observed warming during the 20th century cannot be explained other than by assuming that the models are reasonably accurate
in their response to greenhouse gases. This point was clearly made by the IPCC report published in 2001. Pages 12-13 ignore all this and instead use “a constant-rate warming” of 1.8 degrees C per century “based on actual observations.” A constant-rate (i.e. straight-line) extrapolation of global warming from the 20th to the 21st century, as in the brief’s Figure 2, is a favorite technique of one of the authors, Pat Michaels. This technique gives 21st century warming at the low end of the spectrum of possibilities resulting from the different model-input scenarios. It is one possible future, but it’s never been clear to me (or to anyone else I know besides Pat) why the other possibilities — all of which involve more global warming — should be ignored.

Sincerely,
Curt Covey

—- end of Covey email —

Hope that is helpful to you and other interested parties.

Best,
Scott


14 Responses to “Further comment on the Supreme Court briefs”

  1. 1

    Regarding Dr. Covey’s comment

    A constant-rate (i.e. straight-line) extrapolation of global warming from the 20th to the 21st century, as in the brief’s Figure 2, is a favorite technique of one of the authors, Pat Michaels. This technique gives 21st century warming at the low end of the spectrum of possibilities resulting from the different model-input scenarios. It is one possible future, but it’s never been clear to me (or to anyone else I know besides Pat) why the other possibilities — all of which involve more global warming — should be ignored.

    Pat argues that it is the general tendency of climate models when forced with exponentially increasing CO2 concentrations (as were the models used in Dr. Covey’s CMIP project) to produce a nearly linear temperature rise into the future. He argues that CO2 concentrations have been increasing at a marginally exponential rate, just at a rate that is only about 1/2 the 1%/year rate. Thus, he continues, the observed rate of warming, according to model projections, should be linear, with a slope somewhat less than the slope produced by feeding the models 1%/yr. And the observations tell him that this is exactly the case. The observed warming rate during the past several decades has indeed been constant at about 0.18C/dec–just as models indicate that it should be. And since models typically maintain a linear warming rate into the future (under exponentially increasing CO2 concentrations), Pat maintains the observed warming rate into the future–and projects a warming of about 1.8C by 2100. This does NOT mean that he doesn’t think that the CO2 concentration in the atmosphere will stop increasing, just the opposite–he assumes it will continue to exponentially increase as it has been.

    I hope that this clarifies Pat’s argument, so that others besides Pat, understand it. You all may not agree with it, but it is really not that difficult to understand. This is the scenario that he believe is the most likely, and thus the one that he focuses on.

    -Chip Knappenberger
    to some degree supported by the fossil fuel industry since 1992

    [Response: Hmmm…. Well, Michaels has been using this argument for almost two decades. If it had much validity, one would presumably have expected him to have been predicting 0.18 C/dec the whole time. Only that isn’t the case. The earliest use of the argument that I can find has him predicting 0.10 C/dec, then 0.13 C/dec (1999) then later 0.15 deg/C and now 0.18 deg/C. To anyone else, that would imply that simple linear extrapolation probably doesn’t have much predictive power. – gavin]

  2. 2
    Lynn Vincentnathan says:

    Wish the Court could have read these responses. That last sentence is important, the one wondering whether all but the lowest GW scenario should be ignored.

    Folk wisdom teaches us “to hope for the best, and expect [& try to avert] the worst.”

    And I still get this niggling feeling that we aren’t talking enough about the worst of the worst possibilities, bec it’s less probable and/or science isn’t really up to snuff yet about all that could possibly go wrong….since the system is so extremely complex.

    Throw into the equation militant humans who go on the warpath if their material base is a bit threatened, and the worse possible scenario is probably beyond our wildest imaginations.

    So why are the powers-that-be so adamently opposed to lowering C02 emissions a bit. If they’re so opposed to lowering the small amount indicated in the case, then that indicates they don’t want any action taken against this problem at all, but to just wait & see whether the worse of the worse actually happens. Like some fascination with watching disasters, some death wish for the world.

    I read the Native Alaskan brief. I hope the SC justices also did so.

  3. 3

    Re #1. Hmmm, Gavin. Good point! A quick check of Pat’s The Satanic Gases (2000) show that he projected a rate of 0.13C/decade from CO2 rise alone based upon the argument that I outlined above. I think since that time, I have convinced him that most unadulterated GHG warming began after the PDO shift in 1977, and thus 1977 should be the starting point in his temperature analysis of the impacts of rising GHGs. If you use 1977 as a starting point, you get around 0.18C/decade. In The Satanic Gases (and probably in any writing prior to that) he used the trend during the prior 30 years, which included temperature data, which in my view, was still part of the cooling (or steady) period prior to the PDO shift and when the GHG warming clearly began to manifest itself.

    That is the difference.

    -Chip

  4. 4
    Sonja Christiansen says:

    If you mention one person’s sources of income, you should mention everybodies, including you own.

    Government or NGO funding does not necessarily come without strings and could be used as a ‘label’ of bias. Self-censorship, or going with the crowd – be it the prevailing left, right or green ideology – may also be involved. Scientists are human and believers….You do yourself no favour at all by harping back to fossil fuel funding.

    Most fossil fuel people here now love carbon taxes, regulations for they increasingly improve profits, reduce risks or involve subsidies to investors. We need to replace fossil fuels in a hurry, here in Europe, and this has little to do with climate but a lot – in public rhetoric -with the ‘global warming ‘ threat. The real reasons are more complex.

  5. 5
    lars says:

    [edit]

    [Response: Repeated (and repetitive) cut and pastes from politicised sources are not useful. If you have something you want to say, say it. – gavin]

  6. 6
    Jim Dukelow says:

    Re #4, Sonja Christiansen wrote:

    “Most fossil fuel people here now love carbon taxes, regulations for they increasingly improve profits, reduce risks or involve subsidies to investors. We need to replace fossil fuels in a hurry, here in Europe, and this has little to do with climate but a lot – in public rhetoric -with the ‘global warming ‘ threat. The real reasons are more complex.”

    I don’t get the sense that fossil fuel “people” in the US are supportive of a carbon tax. Europe on the other hand has had a heavy carbon tax (i.e., gasoline tax) for decades, for reasons that are not particularly complex. Europe has little oil or other fossil fuel supplies appropriate for fueling cars and trucks and has to buy it on the world market using hard currency.

    As an economic necessity in the post-WWII years they put in large gasoline taxes to limit use of oil and encourage car/truck makers to produce fuel efficient vehicles. They also have robust public transportation, including electric trains and urban light rail that can be powered by domestic coal and nuclear fuels. Europe has also been a leader in prototyping renewable energy and, in the case of wind power, implementing it on a large scale. France’s move to nuclear power for their electrical power production is part of the same paradigm.

    Best regards.

    Jim Dukelow

  7. 7
    Lynn Vincentnathan says:

    RE the low end projections of CO2 & warming. Are these totally problem-free? Are not these also worth avoiding, if we can? And we don’t hear much about the possible scenarios after 200 years, 500 years, etc. We’d probably still eventually reach very harmful levels, only slower.

    So here’s an idea. Why not end this experiment on planet earth, drastically reduce our GHG emissions (since we can do so profitably anyway), and never really find out which scenario was the most accurate? If the ego needs feeding, I’d even be willing to say, well, it seems you low guys may have perhaps been right. But just as long as we all stop this global warming experiment now.

  8. 8
    Edward Greisch says:

    How do the rest of us make comments to the Supreme Court on this issue?

  9. 9
    Hank Roberts says:

    >How do the rest of us make comments to the Supreme Court on this issue?

    By voting for President and Senator. There’s a rather long lag time in the feedback process.

  10. 10
    John L. McCormick says:

    RE # 8

    You, we, do not.

  11. 11
    Eli Rabett says:

    Actually the option the current US administration favors, is to terraform Mars and test climate theories there. (Why do I keep hearing voices in my head, saying, by then it was to late?)

  12. 12

    Re #8: “How do the rest of us make comments to the Supreme Court on this issue?”

    It is now too late for this particular case for any further comment, the briefs have all been filed and the arguments heard.

    In general, however, anyone can submit an amicus curiae (friend of the court) brief for a case on the Supreme Court docket before the relevant deadline.

    The Supreme Court is very particular about the format and timing, and there are procedural hoops to go through, so most are filed by counsel who are familiar with the details. The Court frowns on briefs that do not directly address the issues presented by the case in a way that presents new information not already part of the record. E.g. Rule 37 of the Supreme Court (about the filing of amicus briefs) begins:

    “1. An amicus curiae brief that brings to the attention
    of the Court relevant matter not already brought to
    its attention by the parties may be of considerable
    help to the Court. An amicus curiae brief that does not
    serve this purpose burdens the Court, and its filing is
    not favored.”

    See the full copy of all Supreme Court rules (about 75 pages) at:
    http://www.supremecourtus.gov/ctrules/rulesofthecourt.pdf

  13. 13
    Halldor Bjornsson says:

    Re #1
    Chip Knappenberger wrote:

    Pat argues that it is the general tendency of climate models when forced with exponentially increasing CO2 concentrations (as were the models used in Dr. Covey’s CMIP project) to produce a nearly linear temperature rise into the future.

    Figure 2 in the brief compares the CMIP 1% experiments (see for instance fig. 9.3 in IPCC TAR [1]) with global temperature data after 1975. – This comparison is both misleading and problematic.

    The CMIP results show how a number of models warm up relative to their control state as CO2 increases by 1% per year. This change in radiative forcing is described as “idealized” by the CMIP group[2]. The purpose of the experiment was to compare model responses, the goal was not climate prediction. After 80 years of intergration the range of warming obtained in the models is ~ 1.2 – 3.7 degrees, with most models falling somewhere in the 1.5 – 2.5 range. The average is about 2 degrees.

    Figure 2 in the brief overlays the CMIP results with data showing the increse in global temperature from 1975 and also shows a linear fit through the data. This linear fit implies a warming of about 1.3 degrees over the eighty year period.

    It is a bit surprising to see actual data superimposed on a graph from the idealized 1% CMIP experiment (where the x-axis is “Model Years” and starts at zero and goes to 80). For the real data one can ask: why is 1975 year zero?
    The answer can be seen in footnote 10 (bottom p. 12 of the brief) where they say

    The increases [in CO2] in the previous three decades (ending in 2004) have been .49, .42, and .43% per year, respectively.

    Thus, the reason that 1975 is year zero is simply that the brief authors are considering real world “experiment” where CO2 was increased by 0.42 – 0.49% per year from 1975.
    There is also an assumption of linearity, such as the claim made by Chip here above and on p. 11 of the brief that

    …the models respond quite linearly to changes in atmospheric carbon dioxide with respect to percent (i.e., a 1% change in concentration per year produces roughly twice as much warming as 0.5%).

    Now, based on this it is clear that figure 2 in the brief is really comparing two different CO2 forcing histories: In the CMIP history we have a 1% CO2 increase per year and 2 degrees warming over 80 years, in the “real world” history we have 0.42 to 0.49% increase in CO2 per year and extrapolated to 80 years we get roughly 1.3 degrees warming.

    But wait a minute, if the brief authors are correct and a “1% change in concentration per year produces roughly twice as much warming as 0.5%” then we should expect the CMIP models to yield 1 degree warming (over eighty years) with 0.5% CO2 increase per year. This is already less than the brief authors get with 0.42 to 0.49%.

    Using the average of the annual CO2 growth rates given in the brief (0.42, 0.43 and 0.49) and the linearity argument then it follows that under 0.5% growth per year the real world extrapolation would have given about 1.46 degrees over a period of eighty years, which is far more than CMIP.

    In short, the linearity argument and the annual CO2 rates of increase cited by the authors imply that the CMIP models have a reponse that is too low.

    This is why the comparison is misleading. The x axis is wrong. They should be looking at warming rate per percent increase in CO2 rather than Model Year.

    But of course, rather than showing that the models are overestimating the warming, this would indicate that they might be underestimating, turning the brief on its head. “Contra-contrairians” might argue that this shows that actual climate predictions in the IPCC TAR (see for instance summary figure 9.14) were to moderate ;-)

    Now, the comparison is also problematic. First there is an obvious problem with this somewhat haphazard mix of idealized model experiment results and real world data. Second, the relavant forcing is equivalent CO2, so the 0.42 – 0.49% increase per year is to low. Third, to fit global temperatures to CO2 over a period of 30 years and and use a linear trend to extrapolate for the next 50 years is asking for trouble. For one thing, the fit neglects lags in the system (such as those resulting from ocean heat uptake) and it also neglects changes in albedo and other radiative factors.

    To summarize: Figure 2 in the brief makes a dubious comparison between the results from idealized model experiments and real world data. If this comparison is taken seriously and the CO2 growth rate taken into account, it implies that the real world is more sensitive to CO2 increase than the models in the experiment. However, the comparison is problematic so one need not worry. As the comparison forms the core of the arguments in the brief it follows that its conclusions need not be taken seriously.

    References:
    [1] IPCC Third Assessment Report – Climate Change 2001″
    [2] See for instance
    Meehl (2000) The Coupled Model Intercomparison Project, BAMS Vol 81, No. 2, p. 313 – 318″

  14. 14
    Eli Rabett says:

    Very nice and very clear Halldor. Thanks


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