Ice Cores a Record of Past Climates

We often hear strong opinions in the media about climate change. People cast themselves as "believers" or "sceptics" (although I prefer the term "deniers") -- often without a clear understanding of the evidence upon which scientists base their interpretations of how the climate is changing. As a scientist who is using ice core data to study climate change, I would like to explain this fundamental research technique that underlies our understanding of our modern climate. This is part of a larger body of research that provides a detailed context for understanding the climate changes that we are seeing and experiencing today.

Ice sheets are analogous to miles-thick layer cakes of snow that have been compressed under their own weight. Each year, snow falls on the surface of an ice sheet and over time, these layers become buried and are crushed into ice. At the depth where compressed snow transitions fully to ice, the little spaces of air between the grains are sealed off. These wee bubbles have trapped small samples of the air found at this depth. As if sealed in a bottle made of ice, this ancient air still exists. Just like our atmosphere today, these fossil air bubbles contain nitrogen, oxygen, carbon dioxide (CO2), methane (CH4) and other trace gases. To get at these ancient air bubbles, researchers drill a borehole into a glacier or ice sheet to remove a cylindrical "plug" of ice:…

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