IN PICTURES: Disappearing glaciers
That's about 12 million Olympic-sized swimming pools.In 2008, a total of 79 Swiss glaciers were in retreat, while 5 were advancing, the Swiss Glacier Monitoring network says.
"There are a very small number of glaciers that are monitored," said veteran glaciologist Ian Allison, pointing to less than 100 globally for which there are regular "mass-balance" measurements that reflect how much a glacier grows or shrinks from one year to the next.
Such measurements are the benchmark and several decades of data is regarded as the best way to build up an accurate picture of what's happening to a glacier.
Glaciers originate on land and represent a sizeable accumulation of snow and ice over the years. They tend to carve their way through valleys as more and more ice accumulates until the point where more is lost through melting than is gained.
THAT SHRINKING FEELING
"We probably know less about the total volume of glaciers than we do about how much ice there is in the big ice sheets in Greenland and Antarctic because a lot of it is in small mass areas and a lot of it is inaccessible," said Allison, leader of the Australian Antarctic Division's ice, ocean, atmosphere and climate program.
The World Glacier Monitoring Service in Switzerland analyses mass balance data for just over 90 glaciers and says their average mass balance continues to decrease.
