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Kurtz: So we’re looking at data that’s just

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north of Greenland and Ellesmere Island. So there’s a very

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narrow passage called the Nares Strait, and an ice arch forms there most

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years, and it broke up very early this year.

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So what we’re seeing in the data is ice that’s very smooth and flat.

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This is new ice that had grown as the ocean had been exposed, and then

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we’re seeing a lot of the thick, older, ridged ice. That’s these photon

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clouds that look a bit rougher. And so what we’re doing with ICESat-2

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is really looking for thickness changes in the ice.

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So the Arctic icepack has been thinning quite a bit. It’s lost about half its thickness

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since the 1980s when we measured it with submarines.

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And so what we’re looking at is measuring changes in the thickness of the ice.

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And then that change in the sea ice, that has an impact on the

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overall climate of the Earth. The polar regions act as an air conditioner

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for the planet. Because when there’s sea ice there—especially snow-covered sea

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ice—it reflects a lot of the Sun’s energy and so that helps keep the planet cool.

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