IRA FLATOW, host:

You're listening to Science Friday on NPR News. I'm Ira Flatow. We were just talking with Dr. Fuchs a little bit about dyslexia, and I feel like I had a dyslexia moment right before the break, talking about Antarctica, when I said there was research that Antarctica was cooling instead of warming, when it's just the opposite because that's what's in a new research paper that's come out this week. It turns out that Antarctica, according to satellite data, is actually warming up instead of cooling. And that's bad for Antarctica skeptics and global warming skeptics, who've always pointed to Antarctica and the data from Antarctica as saying, look, you see? Global warming's not happening. Antarctica is getting colder instead of warming.

Well, here to talk about it and how that has been turned on his head is maybe - and no longer a topic of discussion - although I doubt it - is Eric Steig. Dr. Steig is professor in the Department of Earth and Space Sciences and director of Quaternary Research Center at the University of Washington. Welcome to Science Friday, Dr. Steig.

Dr. ERIC STEIG (Professor, Director, Quaternary Research Center, University of Washington): Thank you, Ira. It's very nice for you to have invited me.

FLATOW: You're very welcome. Tell us about your research. Tell us why we thought Antarctica was cooling all these years.

Dr. STEIG: Well, one thing I might start out with is I didn't think that.

(Soundbite of laughter)

FLATOW: All right, you're on record now.

Dr. STEIG: You know, it's very easy for general ideas to get out there that have an inkling of truth to them that aren't really quite right, that over-simplify their problem. It actually doesn't make sense to talk about a huge continent like Antarctica as doing one thing. Just to put this in perspective - West Antarctica, which is an area that we focused on in our paper, because it's the area that's warming faster than realized, is about the size of Texas, California and Alaska combined. It's actually a bit bigger than that. And East Antarctica is twice as large as West Antarctica.

So, the - where did - the first question then is where did this idea that Antarctica's cooling come from? Well, the answer is that in the decades of the '80s and '90s and a little bit into the thousands, the East Antarctic ice sheet was in fact cooling, particularly in certain seasons - summer and especially fall. And when that was first recognized, it wasn't clear why that was. And that was looked into by some of the leading scientists in the world, including Susan Solomon at the NOAA Aeronomy lab, who was also the lead coordinator for the entire IPCC report.

And what they showed is that there's a very strong relationship between the ozone hole and the temperature on the surface of East Antarctica. So, that paper got a lot of press; it was published in Science. They may have even been on your program; I don't recall. And that sort of morphed into all of Antarctica has been cooling for the last 50 years, which was never true, nor did they say that in their paper.

So, what we did is we said, well, OK, that's fine. East Antarctica's cooling. But actually, we've been working in West Antarctica, and we've been working there drilling ice cores. And at least 10 years ago, when we started this work, I realized there are very few weather stations in West Antarctica. We'd really like to have a better idea what is happening there.

And to make a long story short, we took a look at the satellite data, which has been measured - the NOAA satellite, which looks at the infrared radiation emitted from the snow, which is a function of temperature - and noticed that those data actually showed a different thing going on in West Antarctica than East Antarctica, namely, it was warming up there. And so, our paper is essentially taking those satellite data and doing a bit of additional work to establish confidence levels in that finding.

FLATOW: Mm hmm. And can you apply it to the whole continent?

Dr. STEIG: OK. So, let me back up a minute and say a little bit more about the satellite data and also elaborate a bit on why other people haven't used them in this way. That's an overstatement actually, that they haven't been used, because in fact, Joey Comiso, one of our co-authors from NASA, published several papers in the past. And I think one of his papers was in fact influential in Dave Thompson and Susan Solomon's work, because he again was looking just at this period.

At the time, it was just 1982 to 99, which is actually the period of strongest cooling in East Antarctica. And this is very obvious in the satellite data, and so, that supported interest in what is going on in East Antarctica, which again, is the largest part of the continent. So, looking at those temperature changes, it's the most obvious feature. Those satellite data also show very clearly that there's been significant warming on the Antarctic Peninsula, which is a relatively small bit of land that sticks up as a sort of finger towards South America.

Because there were no weather station data, or very few, in West Antarctica with which to validate the satellite data, which have potential problems in them, which I can elaborate upon, if you like, people, I think, have tended to believe only those data for which they have direct local evidence that the data are right. So, the East Antarctic weather stations, where people on the ground measuring the temperature agreed with the satellite data in East Antarctica, the satellite data also agreed with the weather stations on the Antarctic Peninsula, and so, those are the areas that people focused on.

For some reason, there wasn't much attention being paid to the fact that on these maps from the satellite, West Antarctica was the same color - red - when scaled, where temperature warming is red and cooling is blue, as the Antarctic Peninsula. So, what we had to do is establish that there was a meaningful relationship between the satellite's recordings and the surface temperatures. And we did this essentially by creating a statistical model which says if we have weather station data, can we add it up, can we use it to…

FLATOW: I don't mean to cut you short, Doctor, (Laughing) but - it's an interesting explanation; we don't have that much time.

Dr. STEIG: I apologize.

FLATOW: No, no, that's OK, and I like the details, but we just can't get it at this point.

Dr. STEIG: Right.

FLATOW: But the bottom line, does this mean - finally put to rest the idea that Antarctica is cooling - that argument?

Dr. STEIG: It puts to rest the idea that the entire continent has been cooling monotonically for the last 50 years. I really want to emphasize, it does not change whatsoever the results that showed that East Antarctica has been cooling in the last few decades. That's still true, our understanding of why that is remains - the best explanation remains the ozone hole.

It's important also that our results actually support that, because they show that the continent has been warming on average for these 50 years. The cooling in East Antarctica, according to our analysis, didn't really begin until the late 1970s at the earliest, which is right about the time you'd expect if the cause is the ozone hole, which didn't get going until then.

FLATOW: Why would the ozone hole be the cause for this?

Dr. STEIG: Well, the long and the short of it is, ozone is a greenhouse gas, just like CO2, but there's less of it, not more of it. And it's in the stratosphere, of course. With less ozone in the stratosphere you get stratospheric cooling. And that has two effects. In a sort of simplistic way, the stratospheric air sometimes actually makes it down towards the surface in East Antarctica, which is very high. So, that leads to cooling. But in addition, the change in the vertical temperature gradient over the continent that results from this tends to act like a change - it tends to create a change in pressure, which causes a change in the winds - the circumpolar winds surrounding the continent. And that limits the ability of warm air from low latitudes to get into the continent.

FLATOW: So, it's not a question of - that the scientists were wrong before. It's just that they just didn't have enough data to make a good decision about it.

Dr. STEIG: Yeah. I would actually put it even slightly differently, which is that there was very little attention being paid to a very large part of the continent - West Antarctica - because of a tendency to be skeptical of the satellite data, without, I think, very careful work being done to ask, well, how good are they?

FLATOW: And now that you have the dependable satellite data - or it's being considered shown to be dependable - you're now very much more certain that Antarctica is warming up as - in general?

Dr. STEIG: Yes, absolutely. I won't try to give you all the details here, because we clearly don't have time. But in the paper, we outline very carefully how we test the fidelity of our methods. I would just add that there's corroborating evidence in at least two papers published just in the last week, which get exactly the same result as we do, that are not based on those satellite data. So, it's a red herring to continue to argue about how good the satellite data are. It's actually irrelevant.

FLATOW: All right, I want to thank you. It's quite an interesting paper and probably historic, too, I think.

Dr. STEIG: I think so, thank you.

FLATOW: I want you to take you - thanks for taking time to be with us today.

Dr. STEIG: You're welcome, my pleasure.

FLATOW: Eric Steig is professor in the Department of Earth and Space Sciences and the director of the Quaternary Research Center at the University of Washington. And he joined us by phone from Seattle. Transcript provided by NPR, Copyright NPR.