A Grim Future for Yosemite's Glaciers
Image from glennwilliamspdx
McClatchy News' Tom Knudson has a lengthy, sobering piece on the impact of climate change on Yosemite National Park that is well-worth reading for anybody who has ever had the chance to traipse through its beautiful vistas. As I've noted before, the warmer temperatures have taken a harsh toll on the Sierra Nevada's snowpack, California's largest surface water reservoir (it supplies about 65 percent of the state's freshwater needs), and many of Yosemite's best known glaciers have been equally affected. The park's second-largest glacier, Lyell, could be gone by the end of the century, according to Pete Devine, a glacier observer affiliated with the nonprofit Yosemite Association, and the remaining 100 could suffer a similar fate.
Image from ground.zero
Here's how Knudson described the Sierra's predicament:
More of the Sierra's precipitation is falling as rain instead of snow, studies show, and the snow that blankets the range in winter is running off earlier in the spring. And snow in the Sierra touches everything. Take it away and droughts deepen, ski areas go bust and fire seasons rage longer.
Or, as Greg Stock, a geologist with the park, put it: "All across the Sierra, glaciers are transitioning into ice patches. Ice patches are transitioning to snow fields. And snow fields are transitioning into bedrock."
To make matters worse, the earlier loss of snow in the region could trigger the dreaded albedo effect -- basically a positive feedback loop in which melting snow exposes the ground, leading to more heat being absorbed and, eventually, more warming. Noah Diffenbaugh, a professor of earth sciences from Purdue University, published a much-noticed article in Geophysical Research Letters a few months ago in which he predicted that spring snowmelt could start 2 months earlier by 2100.
It hasn't helped that the region has been suffering through one of the worst drought cycles in recent history, which has only accelerated the Sierra's dramatic meltwater flow:
Clear as vodka, it trickled and tumbled, spilled and splashed. At times, its sound seemed almost musical: steady and sonorous, with a cadence like a chant or a funeral dirge. And with temperatures barely below freezing at night, the music played 24-7 - not a good sign for a glacier.
All glaciers melt naturally. But to remain stable or grow, they must replace meltwater with snowfall. And that's not happening at Lyell or elsewhere. Today, scientists are finding that not only is more precipitation across the region arriving as rain, but also less snow overall is falling. The current drought - now heading into a possible third year - could be catastrophic for California, state officials say.
"With a healthy glacier, we expect to see the upper half covered in snow and the lower half bare ice," Stock said in base camp one morning. "Instead, virtually all of the glacier is bare ice. It's losing a lot more than it's gaining. It's definitely deteriorating."
Very scary stuff and visible proof (as if you really needed it) that climate change is here and only getting worse with time.