In his latest essay on my stupidity, climate modeler James Annan made the helpful suggestion that I consult a “a numerate undergraduate to explain it to [me].” So I looked outside my office, where things are quiet out on the quad this time of year, but as luck would have it, I did find a young lady named Megan, who just happened to be majoring in mathematics who agreed to help me overcome my considerable ignorance.

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[Update: The ever helpful David Roberts of Grist Magazine points out that an op-ed in the Washington Times yesterday makes the same logical error that I point out in this post below made by Patrick Michaels -- namely that short-term predictive failures obviate the need for action. The op-ed quotes me and says that I am "not previously a global warming skeptic," which is correct, but implies that somehow I am now . . . sorry, wrong. It also quotes my conclusion that climate models are "useless" without the important qualifiers **for decision making in the short term when specific decisions must be made**. Such models are great exploratory scientific tools, and were helpful in bringing the issue of greenhouse gases to the attention of decision makers. I've emailed the author making these points, asking him to correct his piece.]

Here I’d like to explain why one group of people, which we might call politically active climate scientists and their allies, seek to shut down a useful discussion with intimidation, bluster, and name-calling. It is, as you might expect, a function of the destructive politics of science in the global warming debate.

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James Annan, a climate modeler, has written a post at his blog trying to explain why it is inconceivable that recent observations of global average temperature trends can be considered to be inconsistent with predictions from the models of the IPCC. James has an increasing snarky, angry tone to his comments which I will ignore in favor of the math (and I’d ask those offering comments on our blog to also be respectful, even if that respect is not returned), and in this post I will explain that even using his approach, there remains a quantitative justification for arguing that recent trends are inconsistent with IPCC projections.

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Lucia Liljegren has wonderfully clear post up which explains issues of consistency and inconsistency between models and observations using a simple analogy based on predicting the heights of Swedes.

She writes;

I think a simple example using heights is helps me explain the answer to these questions:

1. Is the mean trend in surface temperature over time predicted by the IPCC consistent with the temperature trends we have been experiencing? (That is: is 2C/century consistent with the trend we’ve seen? )
2. Is the lowest uncertainty bound the IPCC shows the public consistent with the trend in GMST (global mean surface temperature) we have seen since 2001?

I think these questions are important to the public and policy makers. They are the questions people at many climate blogs are asking and they are the questions many voters and likely policy makers would like answered.

I think the answer to both questions is “No, the IPCC predictions are inconsistent with recent data.”

Please go to her site and read the entire post.

She concludes her discussion as follows:

The IPCC projections remain falsified. Comparison to data suggest they are biased. The statistical tests accounts for the actual weather noise in data on earth.

The argument that this falsification is somehow inapplicable because the earth data falls inside the full range of possibilities for models is flawed. We know why the full range of climate models is huge: It contains a large amount of “climate model noise” due to models that are individually biased relative to the system of interest: the earth.

It will continue to admit what I have always admitted: When applying hypothesis tests to a confidence limit of 5%, one does expect to be wrong 5% of the time. It is entirely possible that the current falsification fall in the category of 5% incorrect falsifications. If this is so, the “falsified” diagnosis will reverse, and not we won’t see another one anytime soon.

However, for now, the IPCC projections remain falsified, and will do so until the temperatures pick up. Given the current statistical state ( a period when large “type 2″ error is expected) it is quite likely we will soon see “fail to falsify” even if the current falsification is a true one. But if the falsification is a “true” falsification, as is most likely, we will see “falsifications” resume. In that case, the falsification will ultimately stick.

For now, all we can do is watch the temperature trends of the real earth.

The folks at Real Climate have produced a very interesting analysis that provides some useful information for the task of framing a falsification exercise on IPCC predictions of global surface temperature changes. The exercise also provides some insight into how this branch of the climate science community defines the concept of consistency between models and observations, and why it is that every observation seems to be, in their eyes, “consistent with” model predictions. This post explains why Real Climate is wrong in their conclusions on falsification and the why it is that two decades of cooling can be defined as “consistent with” predictions of warming.

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UPDATE: Real Climate has already dismissed the paper linked below as a failed effort.

Climate Audit provides a pointer to this paper (PDF) by Koutsoyiannis et al. which has the following abstract:

As falsifiability is an essential element of science (Karl Popper), many have disputed the scientific basis of climatic predictions on the grounds that they are not falsifiable or verifiable at present. This critique arises from the argument that we need to wait several decades before we may know how reliable the predictions will be. However, elements of falsifiability already exist, given that many of the climatic model outputs contain time series for past periods. In particular, the models of the IPCC Third Assessment Report have projected future climate starting from 1990; thus, there is an 18‐year period for which comparison of model outputs and reality is possible. In practice, the climatic model outputs are downscaled to finer spatial scales, and conclusions are drawn for the evolution of regional climates and hydrological regimes; thus, it is essential to make such comparisons on regional scales and point basis rather than on global or hemispheric scales. In this study, we have retrieved temperature and precipitation records, at least 100‐year long, from a number of stations worldwide. We have also retrieved a number of climatic model outputs, extracted the time series for the grid points closest to each examined station, and produced a time series for the station location based on best linear estimation. Finally, to assess the reliability of model predictions, we have compared the historical with the model time series using several statistical indicators including long‐term variability, from monthly to overyear (climatic) time scales. Based on these analyses, we discuss the usefulness of climatic model future projections (with emphasis on precipitation) from a hydrological perspective, in relationship to a long‐term uncertainty framework.

The paper provides the following conclusions:

*All examined long records demonstrate large overyear variability (long‐term fluctuations) with no systematic signatures across the different locations/climates.

*GCMs generally reproduce the broad climatic behaviours at different geographical locations and the sequence of wet/dry or warm/cold periods on a mean monthly scale.

*However, model outputs at annual and climatic (30‐year) scales are irrelevant with reality; also, they do not reproduce the natural overyear fluctuation and, generally, underestimate the variance and the Hurst coefficient of the observed series; none of the models proves to be systematically better than the others.

*The huge negative values of coefficients of efficiency at those scales show that model predictions are much poorer that an elementary prediction based on the time average.

*This makes future climate projections not credible.

*The GCM outputs of AR4, as compared to those of TAR, are a regression in terms of the elements of falsifiability they provide, because most of the AR4 scenarios refer only to the future, whereas TAR scenarios also included historical periods.

The Real Climate guys have offered odds on future temperature changes, which is great because it gives us a sense of their confidence in predictions of future global average temperatures. Unfortunately, RCs foray into laying odds is not as useful as it might be.

The motivation for this bet is the recent Keenlyside et al. paper that has caused a set of mixed reactions among the commenters in the blogosphere. Some commenters here have stridently argued that the predictions in the Keelyside et al. paper are perfectly consistent with predictions of climate models in the IPCC. However, when one such commenter here was asked to show a single IPCC climate model run showing no temperature increase for the 2 decades following the late 1990s he submitted an irrelevant link and disappeared. Others have argued that the Keenlyside et al. projections (and this includes Keenlyside) are inconsistent with the IPCC predictions. Real Climate apparently falls into this latter camp.

The Real Climate Bet (and there is also one for a later period) is that the period 1994-2004 will have a higher average temperature than the period 2000-2010. Since the periods have in common 2000-2004, we can throw those out as irrelevant. Thus, the bet is really about whether the period 1994-1998 will be warmer than the period 2005-2010. And since we know the temperatures for 2005 to present, the bet is really about what will happen in 2009 and 2010. (Using UKMET temps here.)

It is strange to see the Real Climate guys wagering on 2-year climate trends when they already taught us a lesson that 8 years is far to short for trends to be meaningful. But perhaps there is some other reason why they offer this bet. That reason is that they are playing with a stacked deck, which is what you do when looking for suckers. The following figure shows why.

For the Real Climate guys to lose the bet global average temperatures for 2009 and 2010 would have to fall by about 0.30 from the period 2005-present (and I’ve assumed Jan-Mar as the 2008 value, 2008 obviously could wind up higher or lower). Real Climate has boldly offered 50-50 odds that this will happen. This is a bit like giving 50-50 odds that Wigan will come back from a 3-0 halftime deficit to Manchester United. Who would take that bet?

Another interpretation of the odds provided by RC is that they actually believe that there is a 50% chance that global temperatures will decrease by more than 0.30 over the next few years. Since I don’t think they actually believe that, it is safe to conclude that they’ve offered a suckers bet. Too bad. When Real Climate wants to offer a 50-50 bet in which the bettor gets to pick which side to take in the bet (i.e., the definition of 50-50) then we’ll know that they are serious.

Here is a very thoughtful comment sent in by email on the ““consistent with chronicles”. I haven’t identified the author, since he didn’t ask me to post it. But it is worth a read about how climate science is received by one rancher in West Tennessee. I appreciate the feedback.

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Scientists are fond of explaining that recent observations of the climate are “consistent with” predictions from climate models. With this construction, scientists are thus explicitly making the claim that models can accurately predict the evolution of those climate variables. Here are just a few recent examples:

“What we are seeing [in recent hurricane trends] is consistent with what the global warming models are predicting,” Thomas Knutson, a research meteorologist at a National Oceanic and Atmospheric Administration laboratory in Princeton, N.J., said Friday.
link

In a change that is consistent with global warming computer models, the jet streams that govern weather patterns around the world are shifting their course, according to a new analysis by the Carnegie Institution published in Geophysical Research Letters.
link

Francis Zwiers, the director of the climate research division of Environment Canada, said research consistently showed the addition of sulfate aerosols and greenhouse gases such as carbon dioxide into the atmosphere has changed rainfall patterns in the Arctic. Zwiers and his colleagues made their findings using 22 climate models that looked at precipitation conditions from the second half of the 20th century. Writing in the journal Science, Zwiers said these findings are consistent with observed increases in Arctic river discharge and the freshening of Arctic water masses during the same time period.
link

The fact that we are seeing an expansion of the ocean’s least productive areas as the subtropical gyres warm is consistent with our understanding of the impact of global warming. But with a nine-year time series, it is difficult to rule out decadal variation. link

All of this talk of observations being “consistent with” the predictions from climate models led me to wonder — What observations would be inconsistent with those same models?

Logically, for a claim of observations being “consistent with” model predictions to have any meaning then there also must be some class of observations that are “inconsistent with” model predictions. For if any observation is “consistent with” model predictions then you are saying absolutely nothing, while at the same time suggesting that you are saying something meaningful. In other contexts this sort of talk is called spin.

So I have occasionally used this blog to ask the question — what observations would be inconsistent with model predictions?

The answer that keeps coming up is “no observations” — though a few commenters have suggested that a temperature change of 10 degrees C over a decade would be inconsistent, as too would be the glaciation of NYC over the next few years. These responses certainly are responsive, but I think help to make my point.

Others, such as climate modeler James Annan, suggest that my goal is to falsify global warming theory (whatever that is):”no-one is going to “falsify” the fact that CO2 absorbs LW radiation”. No. James is perhaps trying to change the subject, as I am interested in exactly what I say I am interested in — to understand what observations might be inconsistent with predictions from “global warming models,” in the words of climate modeler Tom Knutson, cited above.

Others suggest that by asking this questions I am providing skeptics with “talking points.” The implication I suppose is that I should not be looking behind the curtain, lest I find a little wizard at the controls and reveal that we are all actually in Oz. How silly is this complaint? If the political agenda of those wanting action on climate change is so sensitive to someone asking questions of climate models that it risks collapsing, then it is a pretty frail agenda to begin with. I actually do not think that it is so frail, and in fact, my view is that the science, and policies justified based on scientific claims, will be stronger by openly discussing these issues.

A final set of reactions has been that climate models only predict trends over the long-term, such as 30 years, and that anyone looking to examine short-term climate behavior is either stupid or willfully disingenuous. It is funny how this same complaint is not levied at those scientists making claims of “consistent with,” such as in those examples listed above. Of course, any time period can be used to compare model predictions with observations — uncertainties will simply need to be presented as a function of the time period selected. When scientists (and others) argue against rigorously testing predictions against observations, then you know that the science is in an unhealthy state.

So, to conclude, so long as climate scientists make public claims that recent observations of aspects of the climate are “consistent with” the results of “global warming models,” then it is perfectly appropriate to ask what observations would be “inconsistent with” those very same models. Until this follow up question is answered in a clear, rigorous manner, the incoherent, abusive, and misdirected responses to the question will have to serve as answer enough.

For a while now I’ve been asking climate scientists to tell me what could be observed in the real world that would be inconsistent with forecasts (predictions, projections, etc.) of climate models, such as those that are used by the IPCC. I’ve long suspected that the answer is “nothing” and the public silence from those in the outspoken climate science community would seem to back this up. Now a paper in Nature today (PDF) suggests that cooling in the world’s oceans couldthat the world may cool over the next 20 years few decades , according to Richard Woods who comments on the paper in the same issue, “temporarily offset the longer-term warming trend from increasing levels of greenhouse gases in the atmosphere”, and this would not be inconsistent with predictions of longer-term global warming.

I am sure that this is an excellent paper by world class scientists. But when I look at the broader significance of the paper what I see is that there is in fact nothing that can be observed in the climate system that would be inconsistent with climate model predictions. If global cooling over the next few decades is consistent with model predictions, then so too is pretty much anything and everything under the sun.

This means that from a practical standpoint climate models are of no practical use beyond providing some intellectual authority in the promotional battle over global climate policy. I am sure that some model somewhere has foretold how the next 20 years will evolve (and please ask me in 20 years which one!). And if none get it right, it won’t mean that any were actually wrong. If there is no future over the next few decades that models rule out, then anything is possible. And of course, no one needed a model to know that.

Don’t get me wrong, models are great tools for probing our understanding and exploring various assumptions about how nature works. But scientists think they know with certainty that carbon dioxide leads to bad outcomes for the planet, so future modeling will only refine that fact. I am focused on the predictive value of the models, which appears to be nil. So models have plenty of scientific value left in them, but tools to use in planning or policy? Forget about it.

Those who might object to my assertion that models are of no practical use beyond political promotion, can start by returning to my original question: What can be observed in the climate over the next few decade that would be inconsistent with climate model projections? If you have no answer for this question then I’ll stick with my views.