SAN FRANCISCO — The glaciers surrounding Mount Everest have lost far more ice than once thought, declassified spy satellite photos have revealed.

Using these decades-old images — along with recently-collected data — researchers generated digital surface-elevation models of the glaciers, creating a highly detailed record of melt. From 1962 to 2018, the glaciers along Mount Everest’s flanks had shrunk significantly from the top down, according to research presented on Dec. 13, 2019, here at the annual meeting of the American Geophysical Union.

Decades-old images

During the late 1950s, U.S. intelligence officials devised a plan to take to the skies to peek behind the Iron…