Study: Greenland's coastal glaciers are shrinking

HANOVER, N.H., April 28 (UPI) -- A new study explores the relationship between surface meltwater and ice mass loss suffered by Greenland's tidewater glaciers.

Understanding glacial systems is key to predicting the effects of climate change on sea level rise. But as scientists at Dartmouth College point out, it's not just about whether ice is melting, it's about where and how -- it's about quality as much as quantity.

In their paper, newly published in the journal Annals of Glaciology, researchers argue that the relationship between surface meltwater and glacial stability has been largely ignored by the scientific literature.

"Our results show meltwater from these glaciers is playing a larger role in glacier stability than previously thought," lead study author Kristin Schild, an Earth sciences doctoral student at Dartmouth, said in a news release. "A clearer understanding of subglacial hydrology at tidewater outlet glaciers is important for understanding the mechanisms controlling fluctuations in ice flow and submarine melt as well as gauging the impact of rapid freshwater delivery to the fjord system."

According to the latest research conducted by Schild and her colleagues, meltwater significantly weakens glaciers as it flows through and out the bottom. Meltwater also reduces friction beneath a glacier, allowing it move faster. Finally, when it meets the ocean, meltwater attracts warmer saltwater, encouraging further melting from below.

Researchers say all of these meltwater effects are accelerating the loss of ice mass from Greenland's coastal glaciers.

Iceberg calving is the most obvious form of ice mass loss, but melting from within and below are more difficult to monitor.

As part of the new study, Dartmouth researchers used a combination of computer simulations, time-lapse photography, ground sensors and satellite imagery to estimate how much of a glacier is influenced by meltwater runoff.

Their analysis shows a glacier and its terminus can host several intense plumes of sediment-rich meltwater. As these paths spread out, they can encourage calving and melting across a wide portion of the glacier. During the time meltwater passes through the glacier, it adds mass and accelerates the glacier's movement.

The findings only begin to explain the patterns and paths of glacial meltwater, and researchers believe further exploration is vital to predicting sea level rise.

"Subglacial hydrology at tidewater glaciers is of critical importance in understanding dynamics at the ice front," researchers concluded.