This is Scientific American's 60-second Science, I'm Christopher Intagliata.Greenland is the biggest island in the world. And the ice sheet that sits atop it is massive.“The pile of ice is so thick, it extends more than 10,000 feet above the ocean.And if all that ice were to melt and go into the ocean, global sea levels would rise by 24 feet everywhere around the world.”Jason Briner, a geologist at the University at Buffalo.The ice sheet is melting, of course. But just how much, compared to the past?Briner’s team did a computer simulation of the southwest portion of the Greenland ice sheet―which he says is a good proxy for ice melt across the entire ice sheet.The researchers plugged past climate data into that model to “hindcast,” rather than forecast, the past activity of the ice sheet.They then checked the model’s predictions of the past shape and size of the ice sheet by looking at piles of rocks and boulders and dirt on Greenland today, which outline the edges of ancient ice.And the simulation was in good agreement with the actual situation.Using that reconstruction of the ice sheet over time, the team could compare the ice sheet’s historic losses to those happening today under human-caused global warming.And they determined that Greenland is on track to lose more ice this century than during any century in the past 12,000 years―possibly four times as much.The results appear in the journal Nature.
