Interview with Roger A. Pielke, The controversial climatologist

…MJ: So it's not that you are a "global warming skeptic"; it's that you think that global warming has been hyped at the expense of other problems.

RAP: That's exactly right. I would also add that climate change is much more than global warming. We have altered the climate significantly, say by land-use change, without changing the global average surface temperature, yet it has big impacts. So I definitely think that we humans have altered the climate system. I think we have a strong component that has been warming—for some reason, it has stopped. And I don't understand the reasons why. …

…MJ: So which environmental problem should we be most worried about, on a global level?

RAP: With respect to human impact on the climate system? I think first we need to identify which of these problems has the largest effect on drought and flood patterns. Because of human input of aerosols, from biomass burning in the tropics, from industrial activity, it's spatially concentrated. And what we found out was when we compared the effect of these aerosols in altering wind circulations versus the effect of the greenhouse gases affecting wind circulations, the aerosol effect was 60 times greater. That number could change, but the bottom line is it's a much greater impact, because the greenhouse gases are more spatially dispersed. And in fact, if one is concerned with CO2 addition, which I think is justifiable, it's actually not global warming that people should focus in on, but the biogeochemical effect of added CO2, because it's a fertilizer. And plants respond differently.

I don't think we know the consequences of what we're doing. But our footprint on the environment is more than just CO2: It's nitrogen deposition, it's the other black carbon, the aerosols, it's land-use change. And so we put all of these things together and say, "How can we come up with a policy that reduces our impact on the environment?" Because we don't know the consequences. …

…MJ: Even if you're not just talking about global warming, there's a point where there's no going back. Do you have any sense of how long we have to get all of this under control?

RAP: The problem is, we don't know if we're pushing ourselves toward or away from some negative impact. That's the problem. We could be making ourselves actually less likely to have some drought pattern, but since we don't know, to me the prudent pattern is to try to minimize our impact. Don't have too much CO2 in the atmosphere, but also limit our nitrogen deposition; try to get our landscape back to as close to the natural state as we possibly can. And if we can't do that because we're growing crops, try to understand the consequences.

MJ: Don't we know that there are negative impacts already? There are more storms. The sea ice is melting. Couldn't we look at those effects and say we do know that there are negative impacts?

RAP: I don't think there are more storms. That's actually in terms of tropical cyclones. There's a lot of controversy in the tropical storm community, and I think that a lot of the claims for increase in tropical cyclone activity are flawed. [It seems like there are more now] because they didn't have any satellites in the past.

In terms of sea ice, if you look at Antarctic sea ice, it actually has been well above average, although in the last couple days it's close to average, but for about a year or longer, it's been well above average, and the Arctic sea ice is not as low as it was last year. So in the global context, the sea ice has been fairly close to average. It doesn't mean it can't happen because we are altering the climate system. But whenever I look at the data, I see a much more complicated picture than what you typically hear about.