On the Eve of Extinction
In 1996, a biologist named Camille Parmesan observed that an obscure breed of butterfly living in the Western mountain ranges of the U.S. — the Edith’s checkerspot — had shifted its migratory range about 60 miles north in search of cooler temperatures. It was one of the first studies to document “the fingerprints of climate change,” as Parmesan put it — evidence that global warming was being felt in the animal kingdom. Twenty-four years later, these ripple effects are so common, says Wendy Foden of the International Union for the Conservation of Nature, they’re barely even publicized. In 2016, Foden and other scientists took inventory of climate change’s impact on our entire ecosystem, and found that 83 percent of all biological processes had already been altered. Foden calls these dramatic changes the “bootprints of climate change.”
Global warming has set off a cascade of disruptions to the web of life, changing animals’ breeding habits, food supply, and their very DNA. They are in distress not only from climate instability but also from the loss of habitat and pollution produced by unchecked human consumption. In the past century, species have been wiped out at a pace 100 times greater than the natural rate of extinction, and as many as 1 million species are at risk of going extinct in the coming decades, according to a United Nations report released last spring. There is perhaps no better bellwether of the peril we face than this dwindling biodiversity. “The evidence is crystal clear,” said Sandra Díaz, one of the co-chairs of the U.N. report. “Nature is in trouble. Therefore, we are in trouble.”
Rolling Stone, aided by illustrator Lisel Jane Ashlock, explored the myriad ways that climate change can threaten species. We examined the challenges of a dozen different animals, from the wee coqui frog to the great gray whale.
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Coquí
Habitat: North Caribbean islands
Threat: Temperature riseAnyone who’s been to Puerto Rico knows the insistent chirp of the coquí, a singsong trill that echoes through the warm island air, especially at night. What you might not know, unless you’re a herpetologist, is that the tiny frog, about the size of a ping-pong ball, is fast disappearing. Among the 17 species of coquí native to Puerto Rico, three are already extinct, and 13 are considered endangered or at-risk. And in recent years, the coquí’s signature call — which sounds just like its name — has actually been an alarm: A 2014 study found that as temperatures in Puerto Rico have risen, coquís’ bodies have gotten smaller and their chirps higher-pitched. This seemingly innocuous modification could ultimately make it more difficult for females to recognize mating calls, causing an already fragile population to decline even faster. Sadly, the news is part and parcel of sweeping changes in the amphibian world, whose vulnerable species, dependent on both land and water habitats, have been on the decline for decades. Last year, scientists announced that climate change had enabled a disease in the common frog that could wipe out entire populations in the next 50 years.
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Green Sea Turtle
Habitat: Warm waters in the Atlantic, Pacific, and Indian oceans, with nesting beaches in more than 80 countries
Threats: Temperature sensitivity, habitat lossGentle giants that can clock in at 700 pounds, green sea turtles cross entire oceans to reach their preferred nesting beaches, where they bury their eggs in coastal sandy pits. But strong storms can destroy the nests, and rising seas threaten to erase beaches altogether, a problem compounded by fancy hotels and waterfront vacation homes. “Beaches everywhere are constrained by development,” says Aimee Delach, policy analyst at Defenders of Wildlife. “[Turtles] can’t migrate inshore.” On the U.S. endangered species list since 2016, these turtles face another dilemma. The temperature of the nesting site decides the sex of their hatchlings — the hotter it is, the more babies are born female. A 2018 study on Australia’s Great Barrier Reef found “virtually no male turtles are now being produced” on the warmer northern beaches, home to one of the largest green sea turtle populations in the world. (More than 99 percent of juvenile turtles were female.) Other reptiles, including crocodiles and some lizards, also have temperature-dependent sex determination, so the problem is expected to increase as global warming escalates.
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Ringed Seal
Habitat: Arctic ice floes
Threat: Habitat lossThe ringed seal’s entire life cycle is tied to the Arctic ice: They mate under it, give birth on top of it, and dig caves in the snow on its surface to keep their young warm. As Arctic temperatures rise, the decrease in snowfall has made digging those caves impossible in some places. And the shortened life span of ice sheets — which are forming later and melting earlier every year — is forcing seal pups into the ocean before they’re mature, making them especially vulnerable to predators. A 2004 study projected that more than 80 percent of the seals’ ice in the Baltic Sea would be gone by 2100. In 2012, in an effort to protect that habitat, ringed seals were listed as threatened under the Endangered Species Act. As they struggle, so too will their fellow ice dwellers — and primary predator — polar bears. “We’re maybe not seeing population declines immediately, but we know with certainty it is going to happen,” says Nikhil Advani of the World Wildlife Fund. “For ice-dependent species like polar bears and ice seals, they’re basically facing a total loss of habitat.”
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Atlantic Puffin
Habitat: Rocky coasts and islands of the North Atlantic
Threat: Food scarcityThe Atlantic puffin feeds on long, narrow fish — white hake and herring are favorites. But a key part of their habitat, the Gulf of Maine, which stretches from Cape Cod to Nova Scotia, is experiencing the warming effects of climate change at a faster rate than 99 percent of the global ocean, sending puffins’ choice fish into colder, deeper, and more out-of-reach waters. As a substitute, the adaptable, foot-tall birds have been diving for wide, flat butterfish instead. The problem: Butterfish are too round for young puffins to swallow, leading chicks to die of starvation. In 2012, according to a study by the Audubon Society, only 31 percent of puffin pairs successfully raised a chick at Maine’s largest colony, compared with the typical 77 percent. “We could certainly be looking at losing puffins from Maine,” Delach says. “Sea birds are tremendously susceptible to climate change, because their dietary patterns are based on where their prey has always been, and it’s pretty easy for the prey to move, but not for the birds to move. Puffins have a really high site fidelity — they won’t shift where their colony is.”
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Gray Whale
Habitat: Mainly the Pacific Ocean; they make a yearly 12,000-mile round-trip migration from Northern Mexico to Arctic waters
Threat: Food scarcityIn 2019, the gray whale experienced what the National Oceanic and Atmospheric Administration defined as an “unusual mortality event.” In a heartbreaking sight that repeated along the Pacific coast from Mexico to Alaska, carcasses of the majestic creatures washed ashore at four to five times the typical rate. Many died emaciated. While the whale was removed from the endangered species list in 1994, it is clearly in peril again. The likely culprit? Global warming. The spring melting of Arctic ice releases nutrients that trigger a plankton bloom. Small animals such as krill feed on the plankton, and gray whales, in turn, feed on the krill, following their feast north with the retreating ice. In 2018, however, unexpectedly warm southerly winds caused ice in the Bering Sea to reach record lows; insufficient ice, scientists theorized, depleted the food supply along the whales’ journey. The situation is not forecast to improve — the Arctic has warmed 0.75 C in the past decade alone, altering migrations for several species of whale.
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Reindeer
Habitat: Arctic tundra and adjacent boreal forests of Greenland, Scandinavia, Russia, Alaska, and Canada
Threat: Food scarcityYou could be forgiven for thinking the reindeer is just a mythical creature of holiday lore. The iconic sled-hauler, called caribou in the United States, went extinct in the lower 48 just this past winter, when the last remaining herd in the Pacific Northwest was found to be down to its last member. They’re also struggling farther north. Through the Arctic winter, when the grasses and vegetation that comprise their usual diet are long dead, these herbivores survive by digging up nutrient-rich lichen from underneath the snow. But as the Arctic warms twice as quickly as the rest of the globe, there’s less snow and more rain in winter, which creates hard, icy layers that block the deer from reaching the lichen. Over the past two decades, the Arctic reindeer population has plummeted by half; 200 of them died of starvation this past winter alone. “How many species can we pull out before the metaphorical Jenga tower collapses?” says Delach. “We shouldn’t be thinking in terms of how many species we should let go extinct. We should be trying to save as many as we can.”
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Koala
Habitat: Bushland on the east coast of Australia
Threats: Dehydration, rising temperatures, fireWhen wildfires tore through 25.5 million acres of Australian bushland earlier this year, koalas did the one thing they know how to do when they’re in danger — climb high into the trees and curl into a tight ball. But their only defense mechanism was completely ineffective against climate-change-fueled fire and smoke. By one estimate, more than 25,000 koalas may be dead in the wake of the fires, as much as half the population. That disaster was only their most recent challenge in adapting to the climate crisis: In 2018, Australia faced its worst droughts in 400 years. The marsupial typically doesn’t drink water — it gets all of the moisture it needs from the eucalyptus it eats. But as the drought dried up the country’s plant life, stories emerged of koalas wandering into bird baths or simply dropping out of trees from dehydration.
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Bramble Cay Melomys
Habitat: An island off the coast of Australia
Threat: Habitat lossThis tiny rodent was the world’s first mammal to be wiped out by climate change. The entire species lived on a 12-acre island above the Great Barrier Reef called Bramble Cay, which it is thought to have colonized via driftwood or a land bridge lost to sea rise. In 2008, when its population dipped below 100 after decades of decline, the Australian government created a recovery plan. But when scientists returned in 2014, they didn’t find a single melomys; it is believed to have been wiped out by storm surges and rising sea levels. “The Bramble Cay melomys was a little brown rat,” said Tim Beshara of the Wilderness Society. “But it was our little brown rat, and it was our responsibility to make sure it persisted. And we failed.”
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Rufa Red Knot
Habitat: Annual migration from the southernmost tip of South America to the central Canadian Arctic
Threat: Food scarcityThis small, robin-size shorebird flies 19,000 miles per year in its sweeping migration from Tierra del Fuego, at the very tip of South America, to the Canadian Arctic tundra, where it breeds, and then back again. To fuel this epic journey, the knot carefully times its spring break with horseshoe-crab mating season in the Delaware Bay, where it stops to feed on the crabs’ pebble-like eggs, doubling its weight in the process. But warmer temperatures are now prompting horseshoe crabs, already struggling due to overfishing, to lay their eggs earlier in the year. By the time the knots arrive, they’re left with scraps. And the crab-egg feast isn’t the only meal these birds are missing: In Virginia, rising ocean acidity is depleting the population of blue mussels that knots feed on, and in the Arctic, warmer temperatures are causing insects to hatch earlier, depriving knot chicks of their first meals. In 2014, after its population bottomed out at just 12,000 birds, the rufa red knot was listed under the Endangered Species Act, the first bird to have climate change named as its “primary threat.” According to the National Audubon Society, two-thirds of North American birds are threatened from global temperature rise. “Birds are important indicator species,” said Audubon’s director of climate watch, Brooke Bateman, in a report on the study, “because if an ecosystem is broken for birds, it is or soon will be for people too.”
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Moose
Habitat: Northern United States and Canada
Threat: PestsWeighing in at around 1,800 pounds, with antlers that can span six feet from end to end, adult bull moose have few predators to worry about. But thanks to milder winters, a deceptively small pest is threatening their young. With less snowfall and warmer temperatures over the past 10 to 15 years, ticks are thriving. A study tracking moose calves in New Hampshire and Maine counted an average of 47,000 of the blood-sucking parasites on any given calf — a problem that puts them at severe risk of death by anemia. Seventy percent of the calves being tracked perished over the course of three years. Moose populations in the U.S. are declining, and “the abundance of pest species is seriously concerning,” says the IUCN’s Foden, who notes that warmer weather in Hawaii has brought malaria-carrying mosquitoes to higher elevations than before, and proliferating tsetse flies have rendered large parts of Africa unfit for cattle farming. “The stress of climate change will make all species more susceptible to diseases and parasites.”
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Monarch Butterfly
Habitat: North America, Hawaii, Portugal, Spain, Australia, New Zealand, and elsewhere in Oceania
Threat: Habitat lossLike most butterflies, monarchs are highly sensitive to weather and climate. The species’ famous 3,000-mile migration from Canada to their winter home in Mexico is a trip made in search of optimal conditions: They need temperatures between 55 F and the low 70s along the route, and rain while they hibernate; an ideal body temperature is also crucial for mating, fertility, and egg-laying, which they must do where their caterpillars’ only food source, milkweed, is abundant. But storms and extreme temperatures are disrupting the monarchs’ routines. Once a summertime fixture, dappling backyard gardens from coast to coast, these crucial pollinators are disappearing. “They’re experiencing freezes in their wintering habitat, and drought and heat waves along their route,” Advani says. Higher temperatures may also be driving monarchs’ summer breeding grounds farther north, making their migrations longer and more difficult. One study recorded a 4.9 percent increase in their wing size over the past century and a half — an adaptation that likely arose to help them make the longer journey. Though monarchs aren’t endangered yet, their numbers are dropping. In 2018, there was a 15 percent decline in butterflies in Mexico compared to the previous year, and an 80 percent decline over the previous 20 years. One set of models predicts the population may drop so steeply in the next two decades, it won’t be able to recover.
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Snowshoe Hare
Habitat: North American mountain ranges
Threats: Compromised camouflage, habitat lossOccupying a lower rank of the forest food chain — a meal for lynx, foxes, coyotes, and birds of prey — the snowshoe hare must hide to survive. Its coat changes from brown during warm months to bright white in winter to match the snowy landscape. This camouflage, however, is becoming less effective as the planet warms. When snow arrives late and melts early, the hares end up “mismatched” to their surroundings — think bright white on a dark forest floor of dirt and leaves — making them extra vulnerable to predators. (Researchers in Montana have seen mismatched hares die at a rate seven percent higher than those that blend into their environment.) In response, the animals are moving to colder climes. While the effect is not yet profound, WWF’s Advani says it’s just a matter of time: “They’re pretty maladapted.”