BYE-BYE BUTTERFLIES

11 05 2006

Millions of butterflies are missing in California. University of California entomologist Arthur Shapiro told the San Francisco Chronicle that he has seen fewer butterflies this spring than he has in any of the thirty-five years he has been tracking them in California. He has not found any evidence of half the species he commonly surveys.

One species in particular stands out: the Painted Lady, one of the classic butterflies, with its orange wings tipped in black and flecked with white. Last year the Painted Lady surprised and delighted Californians by appearing in massive numbers; this year, Shapiro and his cadre of butterfly watchers have seen four. Four. From millions to four in just one year.

What’s going on?

Can you say, “Global warming,” boys and girls? Very good. Now, can you say “Mass Extinction”?

Butterflies, like many plant and animal species, need a certain amount of cold weather in the winter. Painted Ladies, whether adults, pupae, larvae, or eggs, will not “wake up” and continue growing unless they get a certain amount of cold weather, and that didn’t happen in California this winter. That killed many of the butterflies—wow, oversleep and die—well, it’s the same for us, just at a subtler level.

Then the few Painted Ladies that did manage to come out of hibernation following unseasonably warm weather in February were greeted with a cold, wet March that gave them no opportunity to eat, pupate, or breed. Oops.

Arthur Shapiro remains optimistic about the butterflies’ future. “They’ve been around for 40—50 million years,” he points out. “They’ve been through it before.” I hope he’s right.

Indeed, the butterflies have been through a lot of weather changes in California. Recent research indicates that the climate there is the wettest it’s been in thousands, maybe tens of thousands of years, and we have built a society there that is utterly dependent on the water supply remaining as it is or growing. Oops again?

One of the mechanisms that makes the weather unpredictable has recently come to light. Research on the intensity of the trade winds, a steady wind that flows from the South American coast towards Indonesia, creating rainfall along the way, has revealed that these winds are weakening, a commonly predicted result of global warming. Weakening winds, of course, slow the movement of frontal systems, causing them to linger in some places and miss others. Just east of Indonesia, the Indian Ocean Monsoon is also weakening, giving India, China, and the Himalayan Ice Sheet less water. Up in Tibet, the permafrost is melting as well as the ice sheet, and that may destroy the railroad to Lhasa that the Chinese have recently, at great expense, completed. That’s good news, I suppose.

More monsoon rain is simply falling back into the ocean, although some of it is actually going west into sub-Saharan Africa, where they certainly need it. So that’s kind of a benefit from global warming, except that, due to global warming and changing rainfall patterns, problems like tse-tse flies and malaria are now spreading into areas where they were previously unknown.

Fewer butterflies, more biting flies and mosquitoes. Ah, the balance of nature.

music: Eliza Gilkyson, “Calling All Angels”

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