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| Earth on Oct 04, 2010

Tom Neumann on whether Antarctica is warming or cooling

Antarctica is the only one of Earth’s major continents that hasn’t shown a consistent and clear picture of warming in recent years. One reason might be that data from Antarctica is sparse.

Most climate scientists say Earth is getting warmer. Meanwhile, Antarctica – the coldest place on Earth – is sometimes said to be cooling. But is it?

The fact is, it’s hard to say whether the southernmost continent has been getting warmer or colder – or staying more or less the same – since temperature measurements began just a few decades ago. Plus there are complexities in the overall picture of warming and cooling in Antarctica that make simple conclusions difficult.

That’s according to Thomas Neumann, an ice expert at NASA Goddard’s Space Flight Center. He told us it’s difficult to pinpoint what type of climate change – if any – is happening on Earth’s southernmost continent.

Tom Neumann: Antarctica is a big place, so it’s maybe not surprising that you’d find different parts of it that are warming or cooling.

He said that due to Antarctica’s extreme cold and remoteness, scientists only have about 20 to 30 years of climate data for the entire continent. The lack of data has made it difficult to detect long-term changes in Antarctica. Neumann said that, today, he studies Antarctica using satellite data, weather stations, and direct measurement of ice to assess climate patterns. And it does appear that parts of the continent – especially the outer edges – are warming.

Tom Neumann: Places like the Antarctic Peninsula – that’s that little thumb that sticks up towards South America – is definitely warming, and warming pretty quickly. West Antarctica is another big, big chunk of Antarctica that’s also very clearly warming.

But East Antarctica is a different story, he said. Scientists aren’t sure if East Antarctica is warming or cooling.

Tom Neumann: It’s about the size of The United States roughly. We don’t have a good understanding of what temperature has been doing there. But more recent studies suggest that, yes, parts of East Antarctica might well be cooling. It’s still hard to say.

He said he sometimes compares warming and cooling in Antarctica to a frozen turkey in an oven. The outer parts of the turkey might be heating up, even as the inner part stays frozen. In Antarctica, he said, seasonal changes add complexity to the picture. He said he thought that the particulars of Antarctica’s air circulation might be contributing to a patchwork of warming and cooling over the southernmost continent.

Dr. Neumann told EarthSky more about how he and other scientists measure temperatures in Antarctica.

Tom Neumann: The most direct way to measure how temperature is changing there is to set up weather stations. East Antarctica is a big place. It’s about the size of the United States, roughly. And we have, probably on the order of 20 or 30 automatic weather stations out on the ice sheet, which are recording wind speed and temperature throughout the year.

Most of these stations are around the edges of the Antarctic continent, close to the coast, he said. So data collection is sparse. Dr. Neumann emphasized that climate measurement in Antarctica is limited both in duration and in scope.

Tom Neumann: In terms of weather stations and monitoring sites that go back more than 20 years, there are maybe just two or three. Imagine the size of the United States with, say, a weather station in Utah, one in Vermont, and another one in Missouri. If that were the case, it would be hard to know what’s been happening in California, or other parts that you’re just not measuring. Certainly the advent of satellite date has helped that tremendously. In particular, microwave data can be used to look at how the skin temperature, the upper-most surface of the ice sheet, how that temperature changes through time. We have that data going back to about 1979. So by now we have just over 30 years worth of that data. That’s starting to be a long-enough time series to look for changes through time.