National Public Radio (NPR)
January 23, 2009 Friday
SHOW: Talk of the Nation: Science Friday 3:00 PM EST NPR
In Antarctica, Too, Temperatures On The Rise
LENGTH: 1623 words
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.