June 20, 2019

Andrew Campbell 

Joshua M. Maurer, a Ph.D. candidate at Columbia University’s Lamont-Doherty Earth Observatory, who led the new research published in the journal Science Advances on June 19 with the other three co-others, J. M. Schaefer, S. Rupper, and A. Corley, said, “This is the clearest picture yet of how fast Himalayan glaciers have been melting since 1975, and why.”

The study finds the Himalayan glaciers have been losing 20 vertical inches of ice per year since 2000, which doubles the melting rate of the late 20th century. In other words, the amount of ice lost each year is enough to fill 3.2 million Olympic-size swimming pools and more than enough to supply water to every human being for longer than a lifetime.

The researchers analyzed 40 years of satellite images of 650 Himalayan glaciers spanning 1,200 miles across India, China, Nepal, and Bhutan. Surprisingly, much of the 20th-century data came from images taken by US spy satellites in cold war. They then created an automated system to transform these images into 3D models in order to measure the changing elevations of glaciers over time. They also compared these images with more recent data from newer satellites to determine ice volume changes.

Maurer pointed out that human-caused climate change is the main reason for the fast melting. From 2000 to 2016, temperatures in the Himalayan region have increased by 1.8 degrees Fahrenheit as compared to the period from 1975 to 2000. Maurer said the melting "looks just like what we would expect if warming were the dominant driver of ice loss."

Photo:Webshot.