A while back, in a post semi-defending Gore et. al’s backing of science showing a connection between hurricanes and climate change, I invoked a study by Tom Wigley and colleagues. It occurred to me that it might be nice to hear what Wigley himself had to say, so I asked him. He responded, and I’m publishing his response below (I added all the links). Note: Wigley made it clear he’d rather spend his time on science than blogging, and doesn’t expect to be available to address any responses. For what it’s worth.


Tom Wigley:

(1) Middle vs extremes. I agree that this misrepresents the science. There is no denial extreme in the credible science literature. The literature differences are a matter of scale — how big will the warming be (or, more technically, what is the range of warming with an associated confidence interval (C.I.))? This can be determined using good science — see below. What to do is a policy issue — but it should be informed by good science (which includes economics).

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(2) Re: the IPCC TAR range of 1.4-5.8C (determined, by the way, using the Wigley & Raper MAGICC model), markbahner said that the probability of warming less than 1.4C was 50% and the probability of warming greater than 5C was zero.

IPCC did not assign a probability to the 1.4-5.8C range. It was recognized that to so may have been useful, but it was beyond the state of the science (insofar as IPCC can only review the science, not do new science). So Sarah Raper and I did the appropriate probabilistic calculations:

Wigley, T.M.L. and Raper, S.C.B., 2001: Interpretation of high projections for global-mean warming. Science 293, 451-454.

We found that there was a non-zero probability of warming less than 1.4C and a non-zero (but smaller) probability of warming above 5.8C. You can estimate the probabilities from the above-cited paper. We found the 90% C.I. to be 1.68C to 4.87C.

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MAGICC can be downloaded as user-friendly software from www.cgd.ncar.edu.

(3) The only paper I have published on hurricane science is the 2006 PNAS paper. Roger Pielke Jr. has published much more on hurricanes, but nothing on hurricane science. The PNAS paper, however, is really about the cause of SST changes in hurricane/tropical cyclone genesis regions. There is little doubt that part of this warming can be attributed to human factors (primarily GHGs). We accept a wealth of scientific evidence that greater SSTs means greater hurricane intensity — but there are considerable uncertainties in the strength of this relationship.

Roger is quite right in saying "so what" to the numbers of papers we may have published on this topic. We are both quite knowledgeable about the issues, so can both claim to give informed opinions.

(4) While I eschew the idea of a "middle", I note that the WRE paper, which determines emissions requirements for CO2 concentration stabilization (and which has been supported by a lot of subsequent economic literature) could be said to represent the middle ground.

Wigley, T.M.L., Richels, R. and Edmonds, J.A., 1996: Economic and environmental choices in the stabilization of atmospheric CO2 concentrations. Nature 379, 240-243.

(5) Al Gore, in his movie, supports the ideas of Pacala and Socolow (who say we can follow a pathway to CO2 concentration stabilization at an acceptable level, at least to 2055, using present technology) …

Pacala, S. and Socolow, R., 2004: Stabilization wedges: Solving the climate problem for the next 50 years with current technologies. Science 305, 968-972.

I (and a number of my colleagues) do not agree with this. We believe that the above paper is flawed (for some insight into this, see …

Gibbs, W.W., 2006: Plan B for energy. Scientific American 295(3), 102-114.)

… and that the technological challenge of achieving concentration stabilization is much greater and more urgent than either Pacala and Socolow, or Gore, seem to think. Two papers dealing with this are …

Hoffert, M.I., Caldeira, K., Jain, A.K., Haites, E.F., Harvey, L.D.D., Potter, S.D., Schlesinger, M.E., Schneider, S.H., Watts, R.G., Wigley, T.M.L. and Wuebbles, D.J., 1998: Energy implications of CO2 stabilization. Nature 395, 881-884.

Hoffert, M.I., Caldeira, K., Benford, G., Criswell, D.R., Green, C., Herzog, H., Jain, A.K., Kheshgi, H.S., Lackner, K.S., Lewis, J.S., Lightfoot, H.D., Mannheimer, W., Mankins, J.C., Mauel, M.E., Perkins, L.J., Schlesinger, M.E., Volk, T. and Wigley, T.M.L., 2002: Advanced technology paths to global climate stability: Energy for a greenhouse planet. Science 298, 981-987.