Snow atop Arctic sea ice has thinned dramatically since the mid-20th century, declining by over a third in the western Arctic and by more than half in the Chukchi and Beaufort Seas, reports a new study led by researchers at the University of Washington and NASA.

The study crunched numbers collected in a variety of ways over the decades -- from simple handheld meter sticks poked into snow at Soviet ice stations as early as 1937; from modern, depth-recording poles thrust into the snow by researchers traveling to the ice pack in recent years; from measurements taken from instruments on buoys mobilized by Cold Regions Research and Engineering Laboratory; and from a sophisticated aerial radar system used by NASA's Operation IceBridge program.

The results? Spring snowpack on sea ice in the western Arctic went from average depths of about 14 inches in the 1954-1991 period to about 9 inches in the 2009-2013 period. On the Chukchi and Beaufort seas, the decrease was bigger, from 13 inches to 6 inches.

Read more: Snowpack atop Arctic sea ice has dwindled since 1950s, study says