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All the Ice on Greenland

Audio Commentary

There’s a lot of ice on Greenland — and this image shows what would happen if it all melted and rained down on the Lower 48 states, with high imaginary walls to keep the water from flowing into the ocean, Canada or Mexico. Of course this is impossible; but the point is to give an idea of just how much ice there is. Enough, also, to raise global sea level by 23 feet if it all melted into the ocean. Greenland is now losing ice at what appears to be a quickening rate; but even with continued acceleration, it would take many centuries for all the ice to disappear.

This graphic shows Greenland’s ice sheet as a cloud, in the shape it would take if the bottom side were made flat — just like a cloud. In fact, the ice sheet’s underside follows the contours of Greenland’s bedrock. Knowledge of these contours, plus detailed measurements of ice elevation taken by NASA’s ICESat satellite, and estimates of ice compression and density, can be combined to estimate the total amount of ice, or water content, on the island.

The graphic also shows the Lower 48 filling according to actual topography.

ICESat: Launched in January 2003, NASA’s Ice, Cloud and land Elevation Satellite (ICESat) carries laser altimeters capable of measuring the height of objects on and above Earth within an accuracy of roughly one inch, from an orbit over 400 miles high. The final laser out of three stopped working in October 2009; together, the lasers have completed just shy of two billion measurements, tracking small and large changes over time in the elevation of Arctic sea ice and of Greenland and Antarctic ice sheets, as well as cloud and aerosol heights, land topography, vegetation, and more.