By Claire Bates
These awe-inspiring images of glaciers are helping scientists to determine just how quickly our planet is heating up. The huge ice fields are thought to be one of the most reliable indicators of climate change and are best studied from space.
The features form when snow accumulates on an area of land over tens to hundreds of years. It eventually becomes so thick and heavy that it forms dense glacial ice. When enough ice is compacted it beings to flow downhill or spread across flat land.
Nasa scientist Dorothy Hall said: ‘Glaciers that tend to be good climate indicators are small-land based, non-surge type glaciers. They respond directly to both regional temperature and snow.’
She and a team of scientists from around the world have used satellites to monitor changes in these glaciers in Europe, Iceland and Alaska. Glaciers tend to extend in many different directions with one part retracting while another part stays still. Therefore satellites such as Landsat 5 are essential as they can measure the entire rim by analysing the different wavelengths of light bounced back from the ice.
However, it is not known for certain whether glaciers that are receding around the edges are also becoming thinner near the centre because visible satellite sensors cannot penetrate the surface of the ice. Most scientists assume that receding glaciers are also losing mass.
(L) Mount Rainier in Washington hosts the Emmons Glacier. It is considered the most hazardous volcano in the U.S because of the risk of flooding from melting glaciers during an eruption. (R) Bear Glacier in Alaska, 2006: The hue is caused by the silt that is finely ground away from the valley walls. The stripes down the middle are formed from rocks and debris when two glaciers merge. In 2008 the lake broke through and drained into Resurrection Bay
Professor Hall said: ‘It is very hard to measure volume changes in glaciers. People are required to put stakes in the glacier and come back a year later to see how much of a change there is in the height of the glaciers.’
On average scientists are finding that glaciers across the globe are steadily shrinking, which confirms suspicions that the world is heating up.
An expert at Nasa’s Earth Observatory said: ‘Researchers generally believe the warming trend may be the result of natural, cyclical changes of the Earth’s climate, and possibly in combination with effects of the large-scale burning of fossil fuels by humans since the industrial revolution.’
The last time Earth warmed extensively was 120,000 years ago. The Greenland ice sheet drained into the ocean and the sea rose 20ft above current levels. If this happened today it would flood coastal communities and countries including Holland and Bangladesh.