2012: Advent Atmosphere: Ice Cores and Ice Ages

by on December 8, 2012

There are places in Antarctica where the ice hasn’t melted for fifteen million years.

We can’t drill that far down. Our longest ice cores go back about 740,000 years. Long enough to encompass the whole of human history. Long enough to show eight ice ages.

Yeah. Eight. Turns out, the Earth has a cyclical climate. Every so often, the glaciers cover most of the world. Every so often, they retreat. Right now, we’re in a warm patch, called an interglacial period. Which is quite nice for us, because it gives us lots of living space. Not so nice for the woolly mammoth.

The glacial/interglacial cycle is probably caused by our orbit around the Sun not being perfectly regular. Little differences in angles and distances adding up to change the amount of sunlight we get, and the sunlight changing the climate, and feedback loops amplifying the effect into an ice age. Probably. That’s our best theory right now, though we can’t quite make the orbital data line up consistently with the climate. Sometimes one orbital effect lines up, sometimes another.

We don’t understand it well enough to predict. We live on a planet that does its own thing. But the human race has survived an ice age before, and we’ve invented fiberglass insulation since then. I mean, if tomorrow an ice age starts, then you and I are probably dead, but the species will make it, which is some comfort.

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