A US Geological Survey study released today suggests that snowpack declines in the Rocky Mountains over the last 30 years are unusual compared to the past few centuries. Prior studies by the USGS and other institutions attribute the decline to unusual springtime warming, more precipitation falling now as rain rather than snow and earlier snowmelt.
The warming and snowpack decline are projected to worsen through the 21st century, foreshadowing a strain on water supplies. Runoff from winter snowpack – layers of snow that accumulate at high altitude – accounts for 60 to 80 percent of the annual water supply for more than 70 million people living in the western United States.
What’s most worrisome is that we now have three major trends driven by human emissions of greenhouse gases that threaten to significantly worsen drought and water problems in the West and Southwest:
- Less precipitation in many areas (see NCAR analysis warns we risk multiple, devastating global droughts even on moderate emissions path)
- Less snowpack, as this USGS study found
- Hotter temperatures (see SW could see a 60-year drought like that of 12th century — only hotter — this century)
Assuming the anti-science disinformers continue to block any serious action, these catastrophic changes will last a long, long time (see NOAA: Climate change “largely irreversible for 1000 years,” with permanent Dust Bowls in Southwest and around the globe).
For the record, it was the possibility of losing the Sierra snowpack in the second half of the century that led our Nobel prize-winning Energy Secretary to warn in 2009, “Wake up,” America, “we’re looking at a scenario where there’s no more agriculture in California.”
Here’s more on the new study: