Almost 14,000 high-altitude lakes in Sierra Nevada, California, are showing signs of extreme stress caused by global warming. Whether or not they survive is dependent on their ability to stay below ice and snow during spring-time. New study shows that summer air at Emerald Lake is warming up at the rate of 1.5 degrees Fahrenheit every 10yrs. This is one of the fastest rates of warming up worldwide and is consistent with warming up rates in other mountainous and hilly areas.
The smaller alpine lakes are popular for their mirror-like surfaces and rugged remoteness. They are partly cushioned from the warming air as they primarily answer to snowpack variations that then act as a sort of protective blanket against rising temperatures. Steven Sadro said that during drought years the role of snow is smaller. It is then that a warming trend is found which is consistent with warming rate seen in other lakes across the globe. These findings come at a time when studies are indicating a decline in snowpack in Western America.
Snowpack data collected in 1982 was recently analyzed. It showed that 13% of the total snowy regions across the West lost great amounts of snow over the past few decades, the average decline rate of which was 41%. It has also been noted that snow seasons seem to be growing shorter throughout mountainous regions, shrinking by 34 days on average across 10% of the nation since 1980s.
Early arrival of spring temperatures in the West has been cited as a reason for shorter snow seasons. Snowpack changes further affect phytoplankton growth and nutrient delivery in Sierra Nevada lakes. Effects of increase of phytoplankton however remain unclear. Researchers of UC Davis are attempting to understand more about Emerald and Castle lakes as they could unveil much about entire mountain range of Sierra Nevada. The recent findings have been published in Limnology and Oceanography Letters.