Mystery of Greenland’s Ice Lingers as Sheet Shrinks

Scientists have cautioned that a warming planet could melt Greenland’s vast ice sheet, a potentially catastrophic event that would raise sea levels and inundate coastal communities around the globe.

Yet while they puzzle over when and whether this might happen, they’re also mystified over how the giant island formed so much ice in the first place. Greenland’s ice sheet is the second largest in the world, behind only Antarctica.

Strangely, other parts of the globe at similar latitudes, including northern Canada and Siberia, don’t have year-round patches of ice anywhere near as extensive or thick.

A new study finds that a mysterious drop in greenhouse gases around 3 million years ago allowed Greenland’s ice to proliferate. The research could help with forecasts about the fate of the ice and the potential for rising seas.

…Here’s the really interesting part: When Greenland was ice-free, carbon dioxide was at 400 parts per million by volume in the atmosphere, Lunt explained via email. The level was 280 ppm before the Industrial Revolution. Now it has climbed back to 385 ppm.

LiveScience