Global warming mystery: Why are some glaciers growing?
Glaciers around the world are slowly melting, and scientists are quick to point their fingers at manmade climate change. But new research suggests that a few glaciers aren't shrinking at all, and may even be growing. Here, a brief guide to this counterintuitive phenomenon:
Which glaciers are growing?
A few glaciers in the Karakoram mountain range along the India-China-Pakistan border are gaining mass, according to a report published in the April issue of the journal Nature Geoscience. "The rest of the glaciers in the Himalayas are mostly melting," lead researcher Julie Gardelle tells LiveScience. "This is an anomalous behavior."
How are scientists so sure?
Researchers used satellite imaging to "analyze the extent of the ice in about a quarter of the range — about 2,167 square miles," says Jennifer Welsh at LiveScience. Photos taken in 2008 were compared to images taken in 1999, and scientists discovered that glaciers grew an estimated 0.36 to 0.72 feet each year.
What makes a glacier change in size?
Snow fall and temperature are the primary factors. And as the world gets warmer, most glaciers are shrinking and melting, causing sea levels to rise about 0.04 millimeters per year on average. Scientists estimate that the melting of glaciers, ice caps, and ice sheets around the world has caused more than 1,000 cubic miles of ice to disappear from 2003 to 2010.
So why are these Himalayan glaciers getting bigger?
No one's certain, but scientists have a few ideas. Stephan Harrison of the U.K.'s University of Exeter thinks it may have something to do with avalanches from surrounding mountains, which can pack on ice. Others think it could be that the climate in the Karakoram mountains is cooling, even as the rest of the world warms. "Records from weather stations between 1961 and 2000 showed that there had been an increase in winter precipitation and a decrease in average temperatures during the summer," says PlanetSave.