00:01There is a place that sometimes appears in dreams on hot, sweltering days.
00:16Knowing when the Greenland ice sheet was present and when it was gone
00:21are absolutely critical questions as we look out in the next couple hundred years
00:25to what's going to be probably the most massive change that we've ever seen as a species.
00:31Paradoxically, our ability to look forward in time is best aided by looking backwards in time.
00:37We are looking back in time. We could, for instance, see what kind of cycles there are.
00:44This starts back in the Cold War, believe it or not, with the collection of the very first ice core
00:49that was drilled all the way through the entire thickness of the ice sheet of Greenland.
00:55And they recovered about three and a half meters of frozen sediment.
00:58These sediments were forgotten about.
01:03When we opened these boxes, it was just like finding, you know, gold or something better than gold.
01:09I said, I think there's fossil plants in here.
01:11Boom, there's a twig. I couldn't believe it.
01:13Every single sample has plants in it, which was surprising. And then we look at these and we're like, oh my God, there's bugs in it.
01:19The only way you're going to get light on those sediments underneath almost a mile of ice is if the ice is gone.
01:26Just what was the threshold that caused that part of Greenland to not have ice on it anymore?
01:30If you can have much lower CO2 and melt the Greenland ice sheet, what will happen if we have very high CO2?
01:39How long will it take to get how much smaller and how much sea level rise over the next century?
01:45The sea level rise could be more than five meters.
01:50Had that core been taken apart and used up in the 1960s, we'd never know what we know now.
01:56Because the analyses that every one of us on this team does didn't exist.
02:00That archive of sediment holds precious clues about the rhythm of the ice sheet, its patterns of ice retreat and advance, the memory of darkness, light and ice.
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