From California to Kyrgyzstan, mountain snowpack is in a state of long-term decline. Over the last 100 years, snowpack has been retreating at unprecedented rates, with ice caps, glaciers, and an ice shelf disappearing altogether. Overall, Earth’s frozen places (the “cryosphere”) are diminishing.
There are variations, of course. Mount Shasta’s glacier shows signs of growth (though not the region as a whole). On the other hand, tropical glaciers of the Andes are being hit especially hard. And each year is different. But on average on the scale of decades, alpine snow is declining everywhere.
The reason, mostly, is climate change, which is caused by greenhouse gas (GHG) emissions which trap energy in the atmosphere. Today we have the highest concentration of such gasses in the past 10,000 years (nearly 400 parts per million), a spike staring at the Industrial Revolution when we began burning fossil fuels .
Image: American Geophysical Union
Updated April 29, 2011.