Graphic: Dramatic glacier melt
Muir Glacier, Alaska: August 13, 1941 and August 31, 2004
There’s nothing quite like historical photos of glaciers to show what a dynamic planet we live on. Alaska’s Muir Glacier, like many Alaskan glaciers, has retreated and thinned dramatically since the 19th century.
This particular pair of images shows the glacier’s continued retreat and thinning in the second half of the 20th century. From 1941 to 2004, the front of the glacier moved back about seven miles while its thickness decreased by more than 2,625 feet, according to the National Snow and Ice Data Center.
While historical photos like these show change over many decades, satellites are giving us a better understanding of how Earth’s ice cover has changed in the more recent past. The satellite era, beginning in the 1970s, has given us a picture of accelerating ice changes in places like Alaska, Greenland and Antarctica, where the loss of land-based ice is contributing to global sea level rise.
Forty-six gigatons of ice from Alaskan glaciers was lost on average each year from 2003 to 2010. That’s according to data from NASA’s GRACE satellite, as analyzed by a team of scientists from the University of Colorado at Boulder.
Graphic: Earth's temperature record
Each year, four international science institutions compile temperature data from thousands of stations around the world and make independent judgments about whether the year was warmer or cooler than average. “The official records vary slightly because of subtle differences in the way we analyze the data,” said Reto Ruedy, climate scientist at NASA’s Goddard Institute for Space Studies. “But they also agree extraordinarily well.”
All four records show peaks and valleys in sync with each other. All show rapid warming in the past few decades. All show the last decade has been the warmest on record.
