Some glaciers have expanded in the past decade, but concerns remain about growing glacial lakes in the region
By Summit Voice
SUMMIT COUNTY — Glaciers in the Himalaya are not shrinking as fast as once predicted by the Intergovernmental Panel on Climate Change.
Some glaciers in the Karakoram Range have grown slightly in the past decade, according to a team of European researchers who recently completed one of the most detailed surveys of the region to-date.
But there are still valid concerns about variability that could leave some valleys dry, at least on a seasonal basis.
“The majority of the Himalayan glaciers are shrinking, but much less rapidly than predicted earlier,” said Tobias Bolch, of the University of Zurich and Dresden University of Technology.
Bolch said the earlier predictions were based on erroneous mapping. The newest study, published in Science, is based on satellite data showing that glaciers in the Himalayas and Karakoram cover a total area of about 40,800 square kilometers — about twenty times larger than all glaciers of the European Alps put together,but as much as twenty percent smaller than was previously assumed.
Along with satellite data, the researchers added all existing measurements of length, area and volume changes and mass budgets into their calculations.
Some of the measurement series on length changes date back to 1840, and measurements of glacier mass budget that instantaneously reflect the climate signal are rare. Overall, the researchers recorded average length decreases of 15 to 20 metres and area decreases of 0.1 to 0.6 percent per year in recent decades, as well as an average 40 centimeter lowering of glacier surfaces.
“The detected length changes and area and volume losses correspond to the global average,” Bolch said.
For the regions in the northwestern Himalayas and especially in the Karakoram Range, the researchers noted very heterogeneous behavior in the glaciers. Many of them are dynamically unstable and prone to surges that largely occur independently of climatic conditions.
For the last decade on average, even a slight volume increase was detected. Based on their analyses, the researchers assume that glacier shrinkage will not have a major impact on the water drainage of large rivers like the Indus, Ganges and Brahmaputra in the coming decades.
Bolch and his colleagues also said they see a very serious threat to the local population in newly formed or rapidly growing glacial lakes. The deluge of water and debris from potential outbursts of these lakes could have devastating consequences for low-lying regions. According to the scientists, increased efforts are urgently needed to monitor the lakes as well as changes in the glaciers and the climate in the Himalayas.