Hopar glacier in Pakistan. Melting ice outside the two largest caps -
Greenland and Antarctica - is much less than previously estimated, the
study has found. Photograph: Paula Bronstein/Getty Images
The world's greatest snow-capped peaks, which run in a chain from the
Himalayas to Tian Shan on the border of China and Kyrgyzstan, have lost
no ice over the last decade, new research shows.
The discovery
has stunned scientists, who had believed that around 50bn tonnes of
meltwater were being shed each year and not being replaced by new
snowfall.
The study is the first to survey all the world's icecaps and glaciers and was made possible by the use of satellite data. Overall, the contribution of melting ice outside the two largest caps – Greenland and Antarctica
– is much less than previously estimated, with the lack of ice loss in
the Himalayas and the other high peaks of Asia responsible for most of
the discrepancy.
Bristol University glaciologist Prof Jonathan Bamber,
who was not part of the research team, said: "The very unexpected
result was the negligible mass loss from high mountain Asia, which is
not significantly different from zero."
The melting of Himalayan glaciers caused controversy in 2009 when a report from the UN's Intergovernmental Panel on Climate Change mistakenly stated that they would disappear by 2035, instead of 2350. However, the scientist who led the new work is clear that while greater uncertainty has been discovered in Asia's highest mountains, the melting of ice caps and glaciers around the world remains a serious concern.
"Our results and those of everyone else show we are losing a huge amount of water into the oceans every year," said Prof John Wahr of the University of Colorado. "People should be just as worried about the melting of the world's ice as they were before."
His team's study, published in the journal Nature, concludes that between 443-629bn tonnes of meltwater overall are added to the world's oceans each year. This is raising sea level by about 1.5mm a year, the team reports, in addition to the 2mm a year caused by expansion of the warming ocean.
The
scientists are careful to point out that lower-altitude glaciers in the
Asian mountain ranges – sometimes dubbed the "third pole" – are definitely melting. Satellite images and reports confirm this. But over the study period from 2003-10 enough ice was added to the peaks to compensate.
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