The researchers assembled the most detailed look to date at the last 40 years of Himalayan ice loss to date, combining contemporary satellite information with data from declassified U.S. spy satellites. They found that average ice-loss per year had doubled between the periods 1975 to 2000 and 2000 to 2016, and that the glaciers had lost more than 25 percent of their ice in the study period, The Guardian reported.
“This is the clearest picture yet of how fast Himalayan glaciers are melting since 1975, and why,” research leader Joshua Maurer of Columbia University’s Lamont-Doherty Earth observatory told The Guardian.
Melting since 2000 has been especially dramatic, The New York Times reported. The glaciers lost a foot and a half of ice every year since then, and have lost a total of eight billion tons of water each year recently, the equivalent of 3.2 million Olympic size swimming pools. Most of this melting was caused by the climate crisis. While researchers said some ice lost was due to soot from the burning of fossil fuels, most was due to warmer temperatures, which rose by higher rates on average between 2000 and 2016 across the more than 1,200 mile range.
Study co-author Joerg Schaefer, as at Columbia, told CNN that unless we act to reduce greenhouse gas emissions and cool the planet, we would see a “pretty devastating scenario for Himalayan glaciers.”
University of Leeds glaciology specialist Duncan Quincey, who was not involved in the research, explained why.
“In the short-term, such rapid melt rates will mean summer floods become more frequent as river discharge is increased, but the long-term prospect is one of drought as the glacier reservoir becomes depleted,” he told CNN.
Around 800 million people across Asia now rely on Himalayan glaciers for energy, agriculture and drinking water. But this study is part of a growing body of evidence showing how much climate change threatens these glaciers, and the communities they support. A February study found that even if world leaders managed to limit global temperature increase to the Paris agreement goal of 1.5 degrees Celsius above pre-industrial levels, one third of the ice in the Hindu Kush Himalaya (HKH) region would still melt by 2100. If temperatures hit two degrees, half of the ice would melt, and if temperatures rose to four or five degrees Celsius, two thirds would disappear.
University College London climate science Prof. Chris Rapley, who was not involved in the study, said ice loss was “already undermining the viability of small communities in the Himalayas as they suffer ever more serious water shortages.” If it continued, it would displace a significant number of people.
“Better for all of us to accelerate to net zero as a matter of the highest priority,” he told CNN.