Print This Post
By Alex Shoumatoff
A somewhat different version of this appeared in the September-October 2005 Audubon Magazine.
In the l970s I was the resident naturalist at a nature sanctuary in Mount Kisco, New York, an hour north of the city. On our Sunday morning bird walks we noticed species that were unusual in this far north, : mockingbirds, tufted titmice, Carolina wrens, turkey vultures. They were moving up and becoming part of the local mix. One morning, drawn to juicy clucks, punctuated by drilling, coming from a massive dead chestnut oak, we spotted the first red-bellied woodpecker ever reported in Westchester County. What is driving these new arrivals ? I wondered. A paper was published in l976 about birds that were moving north in Europe, and attributing it to the warming trend that Europe, like North America, was experiencing, but the warming was assumed to be natural, and that was the main theory about what was happening in Westchester as well : that we were still in the upward arc of an interglacial warming period. These birds had been here long ago, before the last glaciation, and they were returning. These cyclical range shifts were all parts of nature.
There was already speculative talk that something else was driving up the temperature : the “greenhouse effect” from all the carbon dioxide being spewed into the atmosphere by enormous fires in the Amazon, tens of millions of cars on the road in America at any given moment, and a host of other human activities. Scientific evidence that the global warming trend was anthropogenic, not natural, began to appear in the late seventies and early eighties, but it was not until l996 that hard scientific evidence of an animal’s range moving northward was provided by an ecologist at the University of Texas delightfully named Camille Parmesan. Parmesan had been tracking a species of butterfly called the Edith’s checkerspot, which ranges on the PACIFIC coast, west of the Rockies, from Baja California to southern British Columbia and up along the continental divide with Alberta, to the east. She reported that it was almost extinct in Mexico and was thriving in Canada. The progress of this shift could only be explained by the greenhouse model of climate change.
Having spent four and a half years studying this one species, Parmesan then tracked 52 species of butterfly in Europe and found that thirty-four of them were also moving northward. The message these insects were sending, as indicator species, was clear : the entire global ecology is being destabilized by man-induced climate change. Last year, Parmesan was the lead author of a metanalysis for the Pew Center on Global Climate Study of the impacts of climate change on North American wildlife. It reports that pikas, rufous hummingbirds, starfish, and red foxes and many other species across the zoological spectrum are doing the same. About half the species on earth, Parmesan estimates, are having poleward shifts or other responses to global warming.
Parmesan’s seminal work catapulted her into the news. Hundreds of newspapers around the country have run stories about her, and she has become a frequent guest on radio and t.v. talk shows. Thomas Lovejoy, the tropical and conservation biologist who coined the term “biodiversity,” and includes two papers by Parmesan in his new book, Biodiversity and Climate Change, commends her for presenting “some of the very first nicely documented examples of responses in nature. What this does is to take the subject from single example and anecdote to statistical significance and sound generality.”
The implications of her findings are very disturbing. For some species, there is no viable habitat to the north. It has been usurped by agriculture, cities, or sprawl, or in the case of many displaced British birds and butterflies, all there is is the Atlantic Ocean. Other species are being pushed up and off mountaintops, and unless there are more mountains to the north that they can get to, they, too, are doomed. The monarch, North America’s best-loved butterfly, which makes the longest migration of any insect, may be doomed, because north of the volcanic mountains of Michoacan, Mexico, where it overwinters, but will not be able to much longer, there is nothing but desert for four hundred miles.
So global warming is another cause of the extinctions that are occurring worldwide at a rate unprecedented in the historical record– a subtler, more insidious one, because it can’t be stopped and is much harder to detect, than outright habitat destruction, contamination by pollutants, or outcompetition by introduced species.
Recently I spent twelve hours, spread over two days, talking with Parmesan, mainly at her lab in Austin, at the university’s Department of Integrative Biology, where she is an associate professor. Built in the twenties, the rooms are high-ceilinged and spacious. Parmesan, a handsome, raven-haired, petite woman in her early forties, spends her time of her time there at the computer, managing and analysizing databases, writing up her findings and doing graphics. She is rearing checkerspots in an environmental chamber. We sat in the cozy little area where she meets with her students.
Parmesan grew up in Houston, the grandchild of Sicilian and Swedish immigrants. “My mother was a geologist with a minor in botany,” she recalled, “and every summer she would take me and my sisters hiking for two weeks and would tell us every rock and plant.”
Parmesan enrolled as a pre-med at the University of Texas, but “I realized that I was not any good at anesthetizing cute little white rats and cutting them open to learn from them, so I switched to animal behavior. I studied the social behavior of captive primates, bees’ foraging behavior, and the belted kingfishers along the Little Colorado River [which flows through Austin], to see if the kids could recognize their mother’s specific song. In the summer of l983, before her senior year, she went to California with Mike Singer, a lepidopterist at the university who specialized in the Edith’s checkerspot, and “I fell in love with butterflies and eventually with him.”
Singer, a long-time professor in the department, showed me three raggedy live Euphydryas editha he had in his greenhouse. They were small, with inch-and-a-quarter wingspans, but strikingly mottled, with bands of red, brown, and yellow spots— warning coloration, Parmesan explained. Checkerspots mainly eat plants in the snapdragon family that are chock-full of nasty compounds, so birds leave them alone.
The Edith’s checkerspot, she continued, spends its entire life in an area the size of a football field. It is only a butterfly for two weeks. For most of its life cycle, almost eleven months, it is a caterpillar. It is highly variable, with at least fourteen subspecies, and is one of the best-studied butterflies in the world, by legions of lepidopterists, including Singer, going back to l959.
Parmesan followed individuals in the rubicunda subspecies on the wing at two sites in the Sierra Nevada, and her work was so good that it was published in Behavioral Ecology and Animal Behavior—a rare honor for an undergraduate. “I was encouraged to go into graduate work in the editha system, but I wasn’t sure what I wanted to do with my life,” and it wasn’t until l987 that she returned to Austin, butterflies, and Singer, whom she married.
NASA had put an RFP, a research funding priority, for science on biological responses to global warming, and Parmesan got a three-year grant to study the whole editha complex. It was the ideal species, because its biology was so well known, and because you could start in Mexico in March and end up in Canada in July and hit half a dozen subspecies during their month- to six-week-long flight seasons (the individual butterflies emerge at different times for their fortnight with wings) so you could get a lot of data in one field season. A l962 study already reported that editha’s populations were driven by climate. They are wiped out fairly frequently by extreme weather events—drought, sudden freezes at weird times of the year, very heavy snow—and such events, especially on the hot and dry end of the weather spectrum, are becoming more frequent and intense because of the greenhouse effect.
Parmesan started with the southernmost subspecies, Euphydryas editha quino, which lives in the coastal foothills of southern California and Baja California. “I read in a diary from the fifties how quino used to be so thick at times that you had to run your windshield wipers to be able to see,” she told me. “There were so many populations that no one bothered to mark them. Quino was simply described as ‘ubiquitous.” Each mesa top in San Diego had a population, but they were all wiped out by housing development. Now quino is down only six pathetic populations, from literally hundreds.”
The populations on the densely settled coast were gone, but it was impossible to say how much this was attributable to climate change and how much to land use change. She needed to find pristine habitat, with no statistical “noise.” Combing the records of collectors in the thirties, she did– on federal and ranch land in the interior of Baja California and of Riverside County—gorgeous quino habitat. But there were no quinos. .“Crawling down on my hands and knees during what should have been quino’s flight season, I looked under thousands of little grass-like plantanes and Indian paintbrushes and other potential food plants, and just didn’t find any butterflies or larvae, except in a couple of places. Most of the populations in Mexico had gone extinct. I couldn’t say what had caused the extinctions or when they had happened, but there was evidence of 80% extinction on the southern edge of editha’s range. Matching them with the extinction records for the last forty years that Mike was compiling, I could see a definite correlation with what you would expect from global warming. It was very likely that the warming and drying trend had shortened the window of time in which the host plant was green, so that it was out of phase with quino’s life cycle. Quino’s hatching as a half-grown caterpillar is triggered by rain, and so is the greening of its food plant. But now the plants were shriveling up, because no further rain was falling, or they weren’t coming out at all, and the caterpillars were starving. There had been droughts in the past, of course, but rarely ones so frequent or severe. The precipitation data for northern Mexico and southern California showed that it was gradually going down. The region had always been marginal for quinos. They had had lots of crashes and booms, as is typical at the edge of any organism’s range, but most years they had been able to make it. But now they had been pushed over the edge, out of their climate envelope.
Parmesan then went to the northern edge of editha’s range, in southern Alberta . Here the main subspecies is beani. She found the extinction rate in the known populations to be only 20%, within the sustainable range of what many butterfly species normally experience over the years. There had not been enough collecting to be able to talk about colonization or expansion. Throughout editha’s entire range, the various subspecies had moved on average two degrees of latitude north from the places where they had first been identified. So Parmesan had evidence of a biological response from editha and she suspected that it wasn’t an isolated case, but part of a general trend affecting flora and fauna around the world. She wanted to assemble the big picture, and the place to do it, if you were using butterflies, which were admirably suited to the task, was Europe. “It took me four and a half year to get data on a single species here, but in Europe everything was in place,” she told me. “There are records in the northern countries going back to 1760. Collecting is much more part of British and German culture. It was the Victorian thing to do on your vacation. The governments provide money for thousands of amateur lepidopterists every spring to monitor the state of the butterflies.”
In short order Parmesan learned that the showy white Parnassius Apollo, an alpine species, had moved 200 kilometers in only ten years. The spectacular purple emperor, Apatura iris, had arrived in Sweden in the early l990s, and now there was a strong population and the butterfly was spreading inland. African species like Danaus chrysippus, a cousin of the monarch, had come up to Spain, while a blue called Glaucopsyche alexis and the sooty copper, Heodes tityrus were disappearing from the southern edges of their ranges. “This tells you that it’s not just editha,” explained Parmesan. “It’s a much more systematic response of wildlife.
Habitat destruction was even more of a problem in Europe than it had been on the west coast. Parmesan found the least disturbed habitat in the mountain valleys and meadows of Spain and France, where traditional haymaking was still widely practiced—the grass was cut only once a year with a scythe, and the sheep were moved in and out, and there was more continuity and harmony in the way things were done—than in Germany and Austria, “where they want everything to be tidy. Tidy destroys nature.”
In l999 Parmesan and twelve European published a paper called “Poleward Shifts in Geographical Ranges of Butterfly Speices Associated with Regional Warming.” “The Europeans were thrilled because all their running around and spotting butterflies with binoculars– what they loved to do– had meaning. Museum people came up to me and said the paper legitimized their collections, which they had been getting a lot of flak about. [During her long run as prime minister, from l979 to l990] Margaret Thatcher had said something to the director of the British Museum like ‘Why do we need all this old dead stuff ?’” referring to the rooms after rooms full of pinned butterflies, birds skins, and other mouldering specimens.
So why should we care if editha and a bunch of butterflies in Europe are moving north ? I asked. “Because it’s more significant that just editha. Editha is an indicator species. It’s being affected so anybody who is empathetic to other forms of life needs to be worried. Do you want there to be bears in the Rockies, dolphins in Monterey Bay ?
“Editha is also important to study because it’s a bioindicator for other insects, and insects carry a lot of diseases. Mosquitoes are as temperature-sensitive as butterflies.
The West Nile virus as of last year is already carried by 22 of the roughly 50 species of mosquito in Quebec, and it only arrived in the U.S. in l999. The U.S. and Europe are going to get malaria in the wild. So humans are affected by wildlife, like it or not.
“In the past,” she continued, “when there weren’t humans around, there was a lot of shifting. Between each of the Pleistocene glaciations, whe there was a four to six-degree centrigrade shift, species of shrews and picas were moving a thousand kilometers north and shifting back again, spruces and oaks were going up and down mountains. The problem is that we’ve taken all the habitat away. It’s not possible any more for an animal or a plant to shift gradually through the scenery and end up in some spot thousands of miles away.
Parmesan showed me a graph in the IPCC, the U.N.’s Intergovernmental Panel on Climate Change’s most recent, 2001 report, which concludes that current, ongoing warming trend is definitely human-induced. The graph showed a vertiginous, nearly vertical spike beginning in l971. “As you can see,” she said, “we are very close to the point where it is going to be hotter than any time in the last 400,000 years.
“Climate change is fundamentally different from the other causes of extinction,” she went on, “because it is the only one you cannot locally do anything about. There is no restoration technique or local management option that allows you to reverse it. It will take a huge collective effort, globally, and that makes it very scary for conservation. With enough money you can deal with other problems. We are recovering quino’s habitat, for instance, and reintroducing it on protected land, so there will be new, healthy populations. But all that will come to naught if climate change continues. The formula is one meter up equals one kilometer north, and a rise of one degree centrigrade equals 150 meters up or 150 kilometers north.
“You can’t stop it but you can keep the progressive warming to a minimum. If we can keep it down for another two degree until 2100, then we may lose some species, but I’m hoping we can still maybe keep coral reefs. I’m crossing my fingers. But if it goes over that by much we will simply lose coral reefs, because their little algal symbiot can’t persist above a certain temperature. And alpine environments will no longer exist because there will be no more mountain for them to go up.
“The sea level has risen from four to eight inches in the last century (estimates vary) and will keep rising anywhere from five inches to a meter in the next one. When New York City, Florida, Houston, and San Francisco Bay are flooded, people are going to finally demand action, but by then it will be too late. The climate system has a long lag time and we can’t reverse the effects that are happening or are in motion even now. So climate change is unlike any other environmental crisis we face in that it is global and slow-moving. It’s like trying to stop the trajectory of a planet. It has a lot of momentum, and once it gets going you’re not going to stop it. Carbon dioxide stays in the atmosphere for hundreds of years. What we’ve already put up we’re not feeling the full effects of, so even it we stop it now, we will still feel its effects.
“But global warming is also the thing that the individual can do most about, without asking anybody’s permission, like trading in their SUV for a Honda Civic that gets forty miles per gallon. If everyone just did that, it would make a huge dent.”
Parmesan struck me as a basically up-beat person. She was just someone who by the typically circuitous route that our lives take, happened to come into possession of this information. As she flipped through the massive, two volume IPCC report, with its disturbing graphs and maps, she was actually humming to herself. I wondered if she was trying keep her spirits up. People in this line of work must do a lot of humming.