Glacier melting a key clue to tracking climate change
Glaciers now occupy the center stage in the debate over causes and impacts of climate change.
(Page 2 of 3)
Gallery Disappearing glaciers
Lego figures to Jupiter on Juno spacecraft. Why send toys into space?
Paul the Octopus gets own memorial
Paul the Octopus has died. Who will predict the next World Cup outcome?
San Diego whale unearthed at the zoo
Killer shrimp assault British shrimp, threaten ecosystem
Subscribe Today to the Monitor
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.
Since 1980, cumulative thickness loss of the reference glacier group is about 12 meters of water equivalent, it says in its latest 2007/08 report. Estimates vary but glaciers and mountain caps could contribute about 70 cm (2.3 feet) to global sea levels, a 2009 report authored by Allison and other leading scientists says.
The "Copenhagen Diagnosis" report from the Climate Change Research Center at the University of New South Wales says there is widespread evidence of more rapid melting of glaciers and ice-caps since the mid-1990s.
That means run-off from melting glaciers and ice-caps is raising sea levels by 1.2 millimeters a year, translating to up to 55 cm (1.8 feet) by 2100 if global warming accelerates.In Nepal, the International Center for Integrated Mountain Development says "mass-balance" measurements would provide direct and immediate evidence of glacier volume increase or decrease.
"But there are still no systematic measurements of glacial mass balance in the region although there are promising signs that this is changing," the center said in a recent notice.
It said that based on studies, the majority of glaciers in the region are in a general condition of retreat.
"Small glaciers below 5,000 meters (16,500 feet) above sea level will probably disappear by the end of the century, whereas larger glaciers well above this level will still exist but be smaller," it said.
Glaciers have almost vanished from New Guinea island and in Africa and many on Greenland, the Antarctic Peninsula and West Antarctica are also melting quickly, dumping large amounts of ice into the sea.