Roger Pielke Jr: The Implications of the CRU Affair

  • Date: 01/12/09

The New York Times: Roger A. Pielke Jr. is a political scientist at the University of Colorado who has long focused on climate and disasters and the interface of climate science and policy. He has been among those  seeking some clarity on temperature data compiled by the  Climatic Research Unit of the University of East Anglia, which is now at the center of a storm over thousands of e-mail messages and documents  either liberated or stolen from its servers (depending on who is describing the episode).

On Monday, I asked him, in essence, if the shape of the 20th-century temperature curve were to shift much as a result of some of the issues that have come up in the disclosed e-mail messages and files, would that erode confidence in the keystone climate question (the high confidence expressed by the Intergovernmental Panel on Climate Change in 2007 that  most warming since 1950 is driven by human activities)?

This is Dr. Pielke’s answer. (I added boldface to the take-home points.):

Here is my take, in a logical ordering, from the perspective of an informed observer:

The circumstances:

1. There are many adjustments made to the raw data to account for biases and other factors.2. Some part of the overall warming trend is as a result of these adjustments.3. There are legitimately different ways to do the adjusting. Consider that in the e-mails, [Phil] Jones writes that he thinks [James] Hansen’s approach to urban effects is no good. There are also debates over how to handle ocean  temperatures from buckets versus intake valves on ships and so on. And some of the procedures for adjusting are currently contested in the scientific literature.4. Presumably once the data is readily available how these legitimate scientific choices are made about the adjusting would be open to scrutiny and debate.5. People will then be much more able to cherry pick adjustment procedures to maximize or minimize the historical trends, but also to clearly see how others make decisions about adjustments.6. Mostly this matters for pre-1979, as the  R.S.S. and U.A.H. satellite records provide some degree of independent checking.

Now the implications:

A. If it turns out that the choices made by  CRU, GISS, NOAA fall on the “maximize historical trends” end of the scale, that will not help their perceived credibility for obvious reasons. On the other hand, if their choices lead to the middle of the range or even low end, then this will enhance their credibility.

B. The surface temps matter because they are a key basis for estimates of  climate sensitivity in the models used to make projections. So people will fight over small differences, even if everyone accepts a significant warming trend. (This is a key point for understanding why people will fight over small differences.)

C. When there are legitimate debates over procedures in science (i.e., competing certainties from different scientists), then this will help the rest of us to understand that there are irreducible uncertainties across climate science.

D. In the end, I would hypothesize that the result of the freeing of data and code will necessarily lead to a more robust understanding of scientific uncertainties, which may have the perverse effect of making the future less clear, i.e., because it will result in larger error bars around observed temperature trends which will carry through into the projections.

E. This would have the greatest implications for those who have staked a position on knowing the climate future with certainty — so on both sides, those arguing doom and those arguing, “Don’t worry be happy.”

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