It’s been an interesting year for climate scientist Judith Curry, who after Climategate split with most of her peers and called for reform in the climate science community. She did this most publicly via a letter published by Climate Audit, a noted skeptic web site. Curry called for more transparency in climate research.
But it’s difficult to paint Curry as a skeptic, especially when considering her scholarly work, the most recent of which was published this week in Proceedings of the National Academy of Sciences (see abstract). It delves into the question of why the Antarctic sea ice hasn’t been melting, and builds upon the consensus climate view.
Given the new paper I thought it a good time to speak with Curry about the last year. Here’s a transcript of our discussion.
We’ve seen rapid melting in the Arctic, but not in the Antarctic. Is this something that has concerned climate scientists?
It’s sort of a paradox. The paradox of why the Antarctic isn’t melting and the Arctic is has gotten a lot of attention, and it’s become one of the skeptics’ arguments. The climate models have generally matched the observations, so scientists have said that’s what the climate models predict, and people haven’t been too bothered by it. But trying to understand exactly what has been going on has not been intuitive. It’s not like there’s been a big debate in the climate community, or a lot of worry about this, because observations have agreed with the models. But that didn’t really explain anything. So in this paper we’ve tried to dig in and find out what really has been going on.
What did you find?
The answer is tied up in a combination of natural variability and global warming. But the most important part of the story is it’s not so much the direct heating from above, but how the precipitation modulates the heating both from below and above. The explanation we’ve found doesn’t translate into a simple sound bite.
So give me a non-sound bite answer.
Sea ice can melt from both above and below, either heating from the ocean below or the atmosphere above. In the case of the Arctic most of the melting is driven from the warmer atmosphere above. In the Antarctic most of the melting has been driven from the ocean below. What our study has identified is that there’s been increased precipitation over the last few decades that has freshened the upper ocean, which makes it more stable so the heat below doesn’t make it up to the sea ice to melt it.
Freshens the upper ocean?
It decreases the saltiness. When you have a fresh layer on top that’s less dense it acts as a barrier to prevent the mixing of warmer water from below. It insulates the ice to some extent. We’ve also seen a big role of natural variability, over the past 30 years or so the dominant climate signal has been from the Antarctic Oscillation rather than from global warming. The net effect of all this has been an increase in precipitation, mostly snow. This diminishes the melting both from below and above. It stops the melting from above because snow has a higher albedo and reflects more sunlight.
At some point does this result in a net loss of ice rather than gains?
What happens in the 21st century projections is that the global warming signal begins to dominate. We still have the freshening of the upper ocean, but the upper ocean is getting warmer because of a warmer atmosphere. And the precipitation starts to fall more as rain than snow. Rain falling on ice speeds the melting from above.
Three different models show Antarctic ice beginning to recede around 2060.
Aside from the new paper, you’ve certainly had an interesting year as a climate scientist.
Oh my gosh, I stepped into it with that little essay I put out. I figured, in for a penny in for a pound.
You have been among the most outspoken scientists in the wake of the Climategate e-mails. Most sought to downplay their significance. You took a position that this was a teachable moment for climate science. Has you gotten any traction on this?
The thing that’s getting traction, the most important thing, is the need for transparency, to get the methods out there and the data out there. There’s a real public demand for accountability on this subject and it’s just plain good science. With the World Wide Web it’s just easy to do. The whole transparency thing, everyone agrees on that, and it’s slowly happening. The other thing I’m seeing is that two of the professional societies, the American Meteorological Association and the American Geophysical Union, are talking about ensuring that skeptical papers get through if they’re of the right quality. Some people were getting their papers rejected because they disagreed with the IPCC. That’s not the way it’s supposed to work. Papers were getting rejected for the wrong reason. It’s good that professional societies are taking this seriously. Those are some good things that have happened in the science community.
What about on the policy side?
On the policy side of it everything seems to have fallen apart. A year ago it seems like we were on track for something to happen, but everything’s fallen apart for a whole host of reasons. It’s not like Climategate caused all that. There were a whole bunch of political and economic issues, like the developed world versus developing countries. Frankly I think this is a good thing that it’s fallen apart in the short term so everyone can sit back and reflect a little bit more on what we should be doing — to try and really understand where our common interests lie and maybe get away from the UN Model and understand the unintended consequences of some of the policies people are talking about. There’s some no-brainer things that people can be doing, and I hope some of this can get started. But in terms of these big, huge far-reaching policies … the work that needs to be done is really in the economic and political arena to figure out what actually makes sense to do.
Solutions that make sense to a broad range of interests?
Exactly. Otherwise it’s just not going to happen.
Have the positions you’ve taken affected your standing in the climate science community?
I have no idea. I haven’t had any obvious ostracism. A few people who were directly involved in Climategate e-mailed me and weren’t particularly happy about it. But I’ve gotten encouragement from other people, and other people don’t seem to be particularly aware of it. I’ve gotten a fair amount of positive feedback but there’s probably a lot going on out there among people who don’t directly communicate with me. I think it’s fair to say it’s pretty unpopular in certain circles.
Oh yes. Those guys are directly involved in Climategate so that’s not a huge surprise. (note: Joe Romm, of Climate Progress, was not directly involved in Climategate as his private e-mails were not published. Gavin Schmidt, of RealClimate, points out that he was the victim of a crime and not guilty of anything.)
Do you think those kinds of sites are helpful in trying to build public confidence in climate scientists?
That’s a tough one. Real Climate, I think they’ve damaged their brand. They started out doing something that people liked, but they’ve been too partisan in a scientific way. Their moderation hasn’t been good. There was a lot of rudeness toward me on one thread that was actually encouraged by the moderators. I don’t think that has served them well.
Why have you been so conversant with some of the so-called skeptical sites, sites that are certainly outside mainstream climate science?
One of the other positives that I think has come out of Climategate is a realization of what other bloggers like (Steve) McIntyre (of Climate Audit) are actually up to. This isn’t a Merchants of Doubt, oil-company-funded effort. It’s a grassroots effort. These are people who are interested, they want to see accountability. They have a certain amount of expertise and they want to play around with climate data. There’s no particularly evil motives behind all this.
We really don’t understand the potential or impact the blogosphere is having. I think it’s big and growing. The sites that are growing in popularity are Watts Up With That, which really have huge traffic. I think there’s a real interest in the subject. I think there’s a hunger for information. I think there’s a huge potential here for public education. People say it’s polarizing, and sure, you have Climate Progress and Climate Depot on the two extremes, but in the middle you’ve got all these lukewarmer blogs springing up. So I can also see a depolarizing effect. There seems to be a lot more stuff building up in the middle right now. With the IPCC, and the expectation that scientists hew to the party line, it was getting pretty evangelical. When I speak up about maybe there’s more uncertainty, some people regard that as heresy. That’s not a good thing for either science or policy. We’ve got to lose that.