The Weather Notebook: A Slice of Climate

A Slice of Climate
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Dave Thurlow, Host

Frozen into glaciers around the world, are records of the earth's climate for the past nearly half million years. Layer upon layer of snow and ice reveal much about the climate at the time when the snow actually fell. These layers serve much the way growth rings in trees do, as kind of a natural bookkeeping system of climate.


Ice Core

Hi, I'm Dave Thurlow and this is The Weather Notebook. Professor Cameron Wake from the University of New Hampshire's Climate Change research center, has drilled deep into ice corps in Greenland, Nepal, and Antarctica. He knows how it's done:

CW: We pull them up in 1 meter to 5-meter sections at a time. So we drill those ice cores and then we actually cut those ice cores into slices. And the way that glaciers preserve information is they have this great layer cake stratigrophy...horizontal layers. And as you go deeper in a glacier, you go further back in time. So, when we pull up ice cores and we cut slices out of that ice core, so round slices, discs, what we're actually doing is looking at discrete moments in time when there was deposition on that glacier.

DT: And the composition of the atmosphere at that time is somehow hidden in those little discs?

CW: Absolutely, when the snow falls, it actually picks up a sort of chemical chemistry in the atmosphere and it deposits that on the snow. We can actually extract that air and look at the composition of carbon dioxide or methane or nitrous oxide and we can get an actual measure of what that concentration was in the atmosphere.

By knowing the composition of air samples from the past, information about temperature and atmospheric circulation can be extrapolated, unlocking secrets, frozen in time. Thanks go to the National Science Foundation.