Nature Climate Change | Climate Feedback

Judith Curry and Michael Mann speak out

The current issue of Discover has a couple of interesting interviews with prominent climate scientists Judy Curry of Georgia Tech and Michael Mann of Pennsylvania State University.

Not surprisingly, the two express quite different views on recent events and ongoing discussions in the broader climate science community.

Here are some excerpts:

Judith Curry

Where do you come down on the whole subject of uncertainty in the climate science?

I’m very concerned about the way uncertainty is being treated. The IPCC [the United Nations’ Intergovernmental Panel on Climate Change] took a shortcut on the actual scientific uncertainty.

Are you saying that the scientific community, through the IPCC, is asking the world to restructure its entire mode of producing and consuming energy and yet hasn’t done a scientific uncertainty analysis?

Yes. The IPCC itself doesn’t recommend policies or whatever; they just do an assessment of the science. But it’s sort of framed in the context of the UNFCCC [the United Nations Framework Convention on Climate Change]. That’s who they work for, basically. The UNFCCC has a particular policy agenda—Kyoto, Copenhagen, cap-and-trade, and all that—so the questions that they pose at the IPCC have been framed in terms of the UNFCCC agenda. That’s caused a narrowing of the kind of things the IPCC focuses on. It’s not a policy-free assessment of the science. That actually torques the science in certain directions, because a lot of people are doing research specifically targeted at issues of relevance to the IPCC. Scientists want to see their papers quoted in the IPCC report.

You’ve talked about potential distortions of temperature measurements from natural temperature cycles in the Atlantic and Pacific oceans, and from changes in the way land is used. How does that work?

Land use changes the temperature quite a bit in complex ways—everything from cutting down forests or changing agriculture to building up cities and creating air pollution. All of these have big impacts on regional surface temperature, which isn’t always accounted for adequately, in my opinion. The other issue is these big ocean oscillations, like the Atlantic Multidecadal Oscillation and the Pacific Decadal Oscillation, and particularly, how these influenced temperatures in the latter half of the 20th century. I think there was a big bump at the end of the 20th century, especially starting in the mid-1990s. We got a big bump from going into the warm phase of the Atlantic Multidecadal Oscillation. The Pacific Decadal Oscillation was warm until about 2002. Now we’re in the cool phase. This is probably why we’ve seen a leveling-off [of global average temperatures] in the past five or so years. My point is that at the end of the 1980s and in the ’90s, both of the ocean oscillations were chiming in together to give some extra warmth.

Michael Mann

Public opinion, at least in this country, has shifted toward the skeptical.

It has moved in that direction.

What should scientists do about that?

Right now, there’s the largest disconnect that has ever existed between the confidence that we have scientifically and where the public is, at least in the United States. (…) Some people say climate change became too closely associated with a partisan political figure and that polarized the debate. We’ve had a cold winter. We’ve got a bad economy. It’s a bad time to be talking about major changes in our energy economy that some argue could be costly.

What is the worst-case scenario? Are we talking about the risk of our demise as a species?

That’s what scares me, yeah. Now it appears that the antiscience side is in a much better position from a public relations point of view than the scientific community is. I see nothing to change that dynamic. The way our system works, it almost ensures that as an environmental threat grows, there is an institution in place that acts in a way to thwart the attempt by civilization to confront that threat. I fear that it isn’t just a short-term thing. If that is our future, I worry. I have a 4-year-old daughter, and I care about the world that she grows up in.

How do you do research in an environment that is so politicized?

It’s difficult. And needless to say, I’m not getting a lot of science done right now. Half my job involves defending myself against attacks.

Has the political polarization had a detrimental effect on progress in climate science?

It has. Here’s the most basic example: Scientists like to communicate by e-mail. It’s much more efficient. You can respond whenever you want. Scientists aren’t going to be doing that as much anymore. When you do write an e-mail, you’ll probably take twice as long because you want to make sure that every word can’t be cherry-picked and distorted. You’re second-guessing yourself at every stage and, sure, that slows everything down.

[Judith Curry] was referring to a rise and fall in temperatures in the 1930s and ’40s that might have been caused by a coincidence of (…) oscillations in the Atlantic and Pacific, and another that could account for a lot of the warming in the 1990s. She was saying that it looked bad that you were trying to smooth out the bump in the ’30s and ’40s but not the one in the 1990s. Is that a valid critique?

The way you characterize it, it sounds like nonsense. I’m not sure how much familiarity she has, for example, with time-series smoothing. I’ve published a number of papers on this topic, and in fact, the approach that I take was used in the most recent IPCC report. I actually take a very objective approach to the problem of time-series smoothing. I’m not sure she understands the problem. It is very much the mainstream view in the climate research community that you cannot explain the warming of the past few decades without anthropogenic and human influences on climate.

The full text of the interviews is here.

Quirin Schiermeier


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    Ron Manley said:

    I’ve read the full interviews and I particularly liked Judith Curry’s distinction between Scientific Sceptics and Political Sceptics.

    What struck me most forcibly was Michael Mann’s stubborn refusal to acknowledge Judith Curry’s basic point: that the temperature changes in the 1920 and 40s showed marked similarities to those of the 80s and 90s and that factors which may have driven the early temperature rise were present at the time of the later rise. That models do not represent natural fluctuations well was summed up by Kevin Tranberth when he said (in one of the CRU emails) “The fact is that we can’t account for the lack of warming at the moment and it is a travesty that we can’t.”

    Models show an almost monotonic increase in temperature, give or take an occasional volcano, and don’t accurately represent the late 19th century and mid-20th century cooling or the early 20th century warming. .

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    Wilf Schaefer said:

    This must be the same Mann whose hockeystick graph appeared in the IPCC report a few years ago.