Unweird Science

For the past two weeks, conservative commentators including Matt Drudge and Glenn Beck have feasted on the scandal known as "ClimateGate," arguing that leaked emails and documents from a British university reveal global warming as a hoax. Let’s turn down the heat and take a closer look. It’s true the emails have revealed unprofessional conduct among certain scientists and have called into question particular datasets of the University of Anglica’s Climate Research Unit. But have they discredited the entire field, or turned our understanding of climate change upside-down? Not at all, says prominent climate scientist Michael MacCracken. No more than a scandal in JAMA would undermine the credibility of modern medicine as a whole.

MacCracken, the chief scientist for climate change programs at the Climate Institute in Washington, D.C., has been working in the field for more than 25 years. He was senior global change scientist to the interagency Office of the U.S. Global Change Research Program in Washington D.C., from 1993 to 2002. He also coordinated the official U.S. government reviews of several of the assessment reports prepared by the Intergovernmental Panel on Climate Change (IPCC). On the eve of the U.N. climate summit in Copenhagen, which begins next week, MacCracken explains why everything we thought we knew about climate change, we still do know.

Foreign Policy: Have you been following the ClimateGate email saga closely?

MM: No. I think it’s largely a distraction from the bigger picture on climate change, and especially ill-timed right before Copenhagen.

FP: The main charges revolve around the professional conduct of some scientists and allegations that certain data sets in the possession of the University of East Anglia are flawed. For instance, their data on surface temperature readings are in question. Do these charges, if true, alter our basic understanding of climate change?

MM: No. The skeptics seem to have this view that it [climate-change science] is a house of cards — you pull one thing out, and the whole thing collapses. But the truth is that it’s more like a pyramid, and the basic building blocks remain solid. Whatever the revelations reveal about [the University of East Anglia’s Climate Research Unit], our trust in the science produced by many other credible sources remains intact. The climate is clearly changing; I don’t think there is any doubt.

FP: A few days before the U.N. climate summit begins in Copenhagen, please remind us what those basic facts are. What’s the big picture?

MM: The first point is that human activities are changing atmospheric composition. This is supported by observations gathered by scientists from all over the world — there’s no way this ["ClimateGate"] discussion is changing that in any way.

The second is that if you change atmospheric composition by increasing greenhouse gas concentrations, that will exert a warming influence on the planet. There are some questions about exactly how much warming you’ll have, but most forecasts predict a few degrees of warming in response to the equivalent of a doubling of the CO2 concentration. That isn’t changed.

The third is that the climate has actually been changing in recent history. There are a host of reliable indicators, not just temperature change, by which we know this is occurring — from the fact of Arctic sea ice retreating and sea-level rise, to the habitat ranges of plant and animal species shifting over time. Moreover, temperature is actually one of the harder things to try to keep track of because it varies so much from place to place, and varies even from the sun to the shade; you have to be very careful with the observations and do a fair amount of adjustments.

The fourth is that if we keep emitting more greenhouse gases into the atmosphere, we’re going to have significantly more change. Right now there is no indication that we’re going to just suddenly stop putting CO2 into the atmosphere. 

The fifth is that climate change has visible and important impacts — changes you can already see if you visit the Arctic, or many other places. This isn’t in dispute.

The sixth is that if you want to stop this, you have to make large cuts in emissions.

All these basic points are unchanged by these arguments that they’re having in the ClimateGate discussions. It really doesn’t affect the large scientific interpretation of what’s going on.

FP: Much of the discussion has focused on disputed temperature readings. Are temperature readings the only or best way to monitor long-term climate change?

MM: Temperature is actually one of the harder things to try to keep track of because it varies so much from place to place, and varies even from the sun to the shade; you have to be very careful with the observations and do a fair amount of adjustments.

In some sense, what’s being argued about is the fact that global temperature rise is only one of the elements that’s indicating the climate is changing. All these other factors are changing as well. And they’re all changing in a roughly consistent way, so it doesn’t appear that there are really significant errors [about whether climate change is really happening] there.

The climate responds to lots of different things, including changes in solar heat and volcanoes; there is some internal variability. So the Earth’s temperature is responding to those factors, as well as to human activity and greenhouse gases. In any given year, one factor or another may dominate.  For temperature readings over shorter periods, you can get some kind of variability. But if you go back and you look at the warming pattern we’ve seen over the last several decades, you can pick out some years where it looks like temperature wasn’t rising, or where it even went down a little bit. But then of course it started up again. The broad trend is clear. The American Metrological Society in its report about the climate of 2008 addressed this question.

FP: Which data sources can we still trust?

MM: Many well-respected groups have excellent data. They use different approaches, but come to similar broad conclusions. NASA, NOAA, and the NASA Goddard Institute for Space Studies, where Jim Hansen works, are all great sources. Those three are tracking surface temperature, among many other factors. Some significant indicators which remain unquestioned are loss in snow cover and sea ice and also what’s happening to permafrost.

FP: Why do you think ClimateGate become the media circus that it has?

MM: Because we’re getting close to actually doing something significant. And there’s a lot of people who seem somehow resistant to change. So if you don’t like the message then you go after the messenger. This has been going on for quite some time.

I remember when there were people who said all scientists take orders from Al Gore, or that the only reason they’re [coming to meetings of the Intergovernmental Panel on Climate Change] is they get these big international trips. The truth is, climate science isn’t very glamorous or high-paying. First of all, the IPCC doesn’t pay any of the authors. And [with] a group publication like [one of the IPCC’s reports], you have a bunch of authors and everything is not usually given much credit in academic circles as far as promotion is concerned.

FP: Do you have particular hopes or expectations for Copenhagen?

MM: That’s a big question. My view of the right agreement, or a very useful agreement, would be to get in the first phase the developed countries working very hard to improve CO2 emissions down and the developing countries working to improve their carbon efficiency or intensity.

It seems to me if you try to force China and India to actually reduce their CO2 emissions from their present levels, given how much lower per capita emissions are than we have in the U.S., that’s just overlooking the huge equity issues of poverty.

We need to have comparable challenges. Countries won’t all do the same thing, but we do something that is comparably challenging our societies, to try to make things happen. I don’t want to try to specify details I think negotiators have to work on.