Himalayan glaciers are losing ice faster



by LORENZO CIOTTI

Himalayan glaciers are losing ice faster

The Himalayas and other mountain ranges of Central Asia have large icy regions. These important glaciers supply water to the arid regions of Mongolia, western China, Pakistan, Afghanistan and India. As with all other glaciers around the world, those of Asia are suffering a loss of their mass, which suggests a tremendous impact on the ecosystem of the region.

The glaciers of the Mount Everest region of the Himalayas are all in a state of recession. The Rongbuk glacier, which flows from the north side of Mount Everest towards Tibet, has been retreating by 20 m per year. In the Khumbu region of Nepal along the main front of the Himalayas, of 15 glaciers surveyed from 1976 to 2007 all were retreating significantly, averaging 28m per year.

The most famous of these, the Khumbu, retreated at a rate of 18m per year over the period 1976-2007. The Gangotri glacier has retreated by 1 km over the past 30 years, and with an area of ​​286 km² it provides up to 190 m3 / second.

For the Indian region of the Himalayas, the retreat ranges from -19 meters per year for all 17 glaciers. In Sikkim, 26 glaciers examined were receding at an average rate of 13.02 m per year, from 1976 to 2005. For the 51 glaciers in the main Himalayan range of India, Nepal and Sikkim, 51 are receding, at an average rate of 23 m per year.

In the Karokoram of the Himalayas there is a mixture of advancing and retreating glaciers. Many of the Karakoram glaciers are advancing. Accelerated mass loss of Himalayan glaciers since the Little Ice Age, published on the Scientific reports, said: "Himalayan glaciers are undergoing rapid mass loss but rates of contemporary change lack long-term (centennial-scale) context.

Here, we reconstruct the extent and surfaces of 14,798 Himalayan glaciers during the Little Ice Age (LIA), 400 to 700 years ago. We show that they have lost at least 40% of their LIA area and between 390 and 586 km3 of ice; 0.92 to 1.38 mm Sea Level Equivalent.

The long-term rate of ice mass loss since the LIA has been between - 0.011 and - 0.020 m we / year, which is an order of magnitude lower than contemporary rates reported in the literature. Rates of mass loss depend on monsoon influence and orographic effects, with the fastest losses measured in East Nepal and in Bhutan north of the main divide.

Locally, rates of loss were enhanced with the presence of surface debris cover (by 2 times vs clean-ice) and / or a proglacial lake (by 2.5 times vs the nd-terminating). The ten-fold acceleration in ice loss we have observed across the Himalaya far exceeds any centennial-scale rates of change that have been recorded elsewhere in the world. "