The fate of the mountains under climate change: a ray of hope for the Sierra?

In his inimitably far-sighted way, John Muir considered the fate of the Sierra Nevada in an era of climate change, long before global warming even began to take hold.

In August 1875, in his journal, he wrote: 

I often wonder what man will do with the mountains…Will human destructions like those of Nature — fire and flood and avalanche — work out a higher good, a finer beauty? Another universal outpouring of lava, or the coming of a glacial period, could scarece wipe out the flowers and shrubs more effectively than the sheep. And what then is coming? What is the human part of the mountains' destiny? 

Most of the prognostications about climate change and the mountains have been, indeed, dire — more drought and higher temps forcing species up the slopes. As ecologist Tim Flannery wrote in his excellent book about climate change, The Weather Makers, alpine species globally have moved about twenty feet up the montane slopes per decade, and "the implications are outrageous" for tropical rainforests. 

But it's possible — stress on possible, not known for certain — that the Sierra may be spared. For reasons still unclear, the second half of the 20th century was wetter in California mountains than the first half, and the rising temps of climate change have resulted in many mountain species moving not upslope, as expected, but downslope, towards wetter, colder local environments, as discussed in a Science study, and noted in Bettina Boxall's excellent LA Times story

For whatever reason, [researcher] Abatzoglou said the Sierra was 5% to 10% wetter in the final half of the 1900s than in the first half, allowing tree and shrub species to take hold at lower elevations.

Comparing historic vegetation data from 1905 to 1935 to information gathered from 1975 to 2005 by researchers and federal agencies, the study found that about five dozen species had on the whole migrated downhill an average of about 264 feet.

This may be what climate researcher Kevin Trenberth calls "local embroidery," and of little long-term meaning. Or it might mean the survival of species, such as the pika, that some researchers think are doomed. Researcher Connie Millar, with the US Forest Service, is surveying the pika population, which she suspects is not doomed, at least in the Sierra. She has found the same trend — pika moving downslope, towards shadier, cooler areas — in their populations. 

Pika_5972np If you're a backpacker or mountain-climber who recalls seeing pika in the mountains, Millar would love to hear from you about the critters you saw, where and when and how many. 



Published by Kit Stolz

I'm a freelance reporter and writer based in Ventura County.

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