California's butterflies and climate change

Climate Change
‘There’s No Ambiguity. It Will Be Gone.’ How Animals Will Feel the Warming Climate
by Jane Braxton Little, September 20, 2019

"A blue copper butterfly perches waist height on a buckwheat blossom blooming in the cloud dunes near Bodega Bay. In the thick fog its gossamer wings are folded, keeping its sky-blue hues to itself and the milk-white flower. Normally found at higher elevations in California’s Sierra Nevada and Cascade mountains, this colony of blue coppers exists in this chilly coastal prairie because of the low clouds that drip with moisture.
If the fog belt burns off permanently, this butterfly population will become extinct. “There’s no ambiguity. It will be gone,” said Arthur Shapiro, an evolution and ecology professor at University of California, Davis.

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"In inland California, butterflies at various elevations have shown mixed responses to record-setting temperatures. During the state’s five-year drought, researchers found the number of butterfly species and individuals observed per year increased at lower elevations but decreased at higher elevations. A 2018 study documented those at sea level reversing long-term declines, while butterflies in the Sierra Nevada were severely harmed, said Shapiro, the UC Davis professor.
Butterflies generally do not do well in warm, wet winters, he said. During the drought, species at low elevation sites benefitted from hot sunny days and cold nights with minimal humidity. But the drought reduced the high-elevation snowpack that helps overwintering butterflies survive until spring. It may also have caused them to emerge earlier in the season, which could have put them out of sync with the flowers and other resources they depend upon. When ecosystems warm to the extent that they are no longer capable of supporting these and other species, “it’s bye bye,” Shapiro said.

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"Of the state’s 300 at-risk species, those already gone include two populations of the Bay Checkerspot butterfly. California’s Fourth Climate Change Assessment predicts temperatures will climb another 5 to 8 degrees Fahrenheit by 2100. Glaciers will continue to melt. In the San Francisco area, where sea level is already 8 inches higher than a century ago, the 2018 assessment projects it will rise an additional 4.5 feet by 2100 – and possibly as much as 9 feet along the California coast. Northern California farmers will face water shortages of up to 16 percent in some regions. Winter storms will likely become more intense in a boom-bust cycle with very wet and very dry years. And in the Sierra Nevada, the snowpack will decline by two-thirds over the next century and temperatures will increase up to 9 degrees Fahrenheit, according to an assessment led by David Ackerly, a biology professor at University of California, Berkeley.
As scientists continue to document the sometimes surprising ways that animals respond to heat, blue coppers will continue to lay eggs and nibble on buckwheat as caterpillars before spreading their bright blue wings as butterflies. But for how long? These are uncharted times in a hot and entirely novel climate regime.

About the author Jane Braxton Little:
Based in the northern Sierra Nevada, Jane Braxton Little is an independent journalist covering science and natural resource issues for publications that include Scientific American, National Geographic, Audubon, Discover, High Country News and, with this story, Bay Nature.

https://baynature.org/2019/09/20/theres-no-ambiguity-it-will-be-gone-how-animals-will-feel-the-warming-climate/

Publicado por andreacala andreacala, 25 de septiembre de 2019

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