History Reveals Greenland Ice Might Melt Much Faster Than Believed

2016-12-12

Another uh-oh fact emerging, this time from historical records versus climate models projecting into the future.

We watch those science shows on TV or read about the giant drills that poke deep beneath the surface of the earth and haul up tubes of ice and rocks and soil. From those samples, we learn. This is one of those learning moments: the rocks hauled up show that they weren’t covered in ice during previous warming periods.

Excerpt:

Scientists found that Greenland rocks now buried under 10,000 feet of ice were ice-free for long stretches during the past 1.4 million years, leading them to predict the Greenland Ice Sheet could melt more suddenly than previously believed.

That could raise global sea level far beyond current projections over the next few centuries, including recent estimates from the Intergovernmental Panel on Climate Change, according to a new study published Wednesday in the journal Nature. The research challenges the prevailing idea that the ice sheet remained relatively intact during the recent geological past, showing even the thickest ice had vanished during warm periods between ice ages.

Columbia University paleoclimatologist Joerg Schaefer, who co-authored the study, said the findings show the Greenland Ice Sheet may be much less stable than scientists thought.

“Over the last 15 years, it looked like we wouldn’t have to worry too much about the Greenland ice sheet melting too fast,” Schaefer said. “Most of the climate models treated it as a solid ice cube sitting on bedrock. With climate warming, it melts off the top, but it takes a long time. Compared to other ice sheets like West Antarctica, is looked pretty strong and resilient to warming.”

New, direct samples of the bedrock pierced that belief.

If the ice sheet had persisted across most of Greenland during those warm periods, there was hope that it could stay mostly intact despite the Earth’s thickening blanket of greenhouse gases. The new study suggests that, because it mostly melted, there’s little doubt the planet’s warming trajectory will melt the Greenland Ice Sheet in the centuries ahead.