Guest essay by Eric Worrall
UCLA thinks that by the end of the century, Climate will reduce the Sierra Nevada snowpack by 85%.
Climate change puts California’s snowpack in jeopardy in future droughts
UCLA research shows how warming trends affect the Sierra Nevada now and in the future
Belinda Waymouth | March 09, 2017
Skiing in July? It could happen this year, but California’s days of bountiful snow are numbered.
After five years of drought and water restrictions, the state is reeling from its wettest winter in two decades. Moisture-laden storms have turned brown hillsides a lush green and state reservoirs are overflowing. There’s so much snow, Mammoth Mountain resort plans to be open for business on Fourth of July weekend.
The Sierra Nevada snowpack, which provides 60 percent of the state’s water via a vast network of dams and reservoirs, has already been diminished by human-induced climate change and if emissions levels aren’t reduced, the snowpack could largely disappear during droughts, according to findings in the study published today in the journal Geophysical Research Letters.
“The cryosphere — frozen parts of the planet — has shown the earliest and largest signs of change,” said UCLA climate scientist Alex Hall, who along with study co-author Neil Berg modeled what future California droughts will look like in terms of snowpack loss. “The Sierra Nevada are the little piece of the cryosphere that sits right here in California.”
During a drought we see less overall precipitation. Adding in warmer air caused by climate change a greater share of precipitation falls as rain, and snow melts more rapidly. So a frozen resource that gradually melts and recharges reservoirs is particularly vulnerable to a warming climate and droughts that are expected to become increasingly severe.
To protect California’s future from the threat of warming temperatures California needs to rapidly reconfigure its water storage systems and management practices.
“I think there are serious questions about the suitability of the current water storage infrastructure as we go forward,” said Hall, a professor of atmospheric and oceanic sciences said.
Besides offering a window into the future, the UCLA study revealed some climate effects that are already happening. Hall and Berg found that the Sierra Nevada snowpack during the 2011 to 2015 drought was 25 percent below what it would have been without human-induced warming. The effect was even worse at elevations below 8,000 feet, where snow decreased by up to 43 percent.
“Seeing a reduction of a quarter of the entire snowpack right now — not 20, 30 or 40 years from now — was really surprising. It was almost as if 2015 was the new 2050 in terms of the impacts we were expecting to see,” said Berg, who is a scientist at RAND Corp.
The abstract of the study;
Anthropogenic Warming Impacts on California Snowpack During Drought
Authors Neil Berg, Alex Hall
Accepted manuscript online: 9 March 2017
Sierra Nevada climate and snowpack is simulated during the period of extreme drought from 2011 to 2015 and compared to an identical simulation except for the removal of 20th century anthropogenic warming. Anthropogenic warming reduced average snowpack levels by 25%, with mid-to-low elevations experiencing reductions between 26-43%. In terms of event frequency, return periods associated with anomalies in 4-year April 1 SWE are estimated to have doubled, and possibly quadrupled, due to past warming. We also estimate effects of future anthropogenic warmth on snowpack during a drought similar to that of 2011 – 2015. Further snowpack declines of 60-85% are expected, depending on emissions scenario. The return periods associated with future snowpack levels are estimated to range from millennia to much longer. Therefore, past human emissions of greenhouse gases are already negatively impacting statewide water resources during drought, and much more severe impacts are likely to be inevitable.
Read more (paywalled): http://onlinelibrary.wiley.com/doi/10.1002/2016GL072104/abstract
Climate scientists regularly embarrass themselves with “end of snow” predictions, because they are an inevitable consequence of the “projections” (don’t say predictions) of their runaway climate models.
“End of snow” is one of the funniest and most revealing manifestations of this silliness, though at least some scientists appear to have learned from previous red faces to put the date of their predictions well into the future, presumably so they will never have to answer for their accuracy.