Support Provided ByLearn More
Planet EarthPlanet Earth

In the race against climate change, many animals may not keep up

A sobering analysis suggests that animal species aren’t adapting fast enough to maintain their numbers in the face of rising temperatures.

ByKatherine J. WuNOVA NextNOVA Next
iStock-1124546863.jpg

European roe deer (Capreolus capreolus) are among the animals at risk of declining as a result of climate change. JMrocek

In the blink of an eye, a fire can fell a forest. With the push of a button, a city can be razed to the ground. There’s little limit, it seems, to the speed at which an environment can change.

Unfortunately, the same can’t be said for the animal species adapting in response.

A sobering new report published today in the journal Nature Communications suggests that our world is now warming at a pace that far outstrips many animals’ ability to adapt. Though the authors’ findings support the idea that some species remain capable of changing their genes or behavior to accommodate the changing times, few are doing so quickly enough to ensure their long-term success.

Support Provided ByLearn More

The analysis, which compiled data from 58 independent publications, evaluated only 17 species—most of which were commonly studied birds—and focused primarily on the relationship between temperature and animals’ life cycle events, such as breeding times.

Despite the study’s relatively narrow scope, the authors argue that the results likely apply to other creatures, including those rare and vulnerable species already imperiled by habitat fragmentation, pollution, and other human-caused disruptions. They also hint that, for many species, the countdown toward climate-driven extinction may have already begun—and even an immediate course correction may come too late for some.

“The take home here is that the wheels of climate change are now turning too fast for many critters to keep up,” says J. Drew Lanham, a wildlife conservationist and ornithologist at Clemson University who was not involved in the study. “It’s going to be critical to obtain more of these long-term datasets that enable us to say more concretely what’s happening with [the world’s animals].”

iStock-1143306966.jpg

The Eurasian magpie (Pica pica), a bird commonly seen in the northern part of the Eurasian continent. Research monitoring this bird's rates of adaptation to climate suggests its numbers will likely decline in the future. Image Credit: mauribo, iStock

It’s well understood that human-driven climate change has taken its toll on biodiversity. But in the fight for wildlife preservation, researchers need to know how individual species cope with changing conditions—and few studies have been able to put hard numbers to whether these responses are helpful or harmful in the long-term.

To quantitatively assess animal adaptations to the changing climate, an international team of scientists led by Viktoriia Radchuk, an evolutionary ecologist at Leibniz Institute for Zoo and Wildlife Research in Germany, scoured datasets from more than 10,000 previously published reports. Their goal was to incorporate data for as many species as possible, Radchuk says. But in the end, only 71 studies met the team’s crucial criteria of measuring an aspect of climate change, while also keeping tabs on a population of arachnids, insects, amphibians, reptiles, birds, or mammals for at least six years.

It’s well understood that human-driven climate change has taken its toll on biodiversity. But in the fight for wildlife preservation, researchers need to know how individual species cope with changing conditions—and few studies have been able to put hard numbers to whether these responses are helpful or harmful in the long-term.

To quantitatively assess animal adaptations to the changing climate, an international team of scientists led by Viktoriia Radchuk, an evolutionary ecologist at Leibniz Institute for Zoo and Wildlife Research in Germany, scoured datasets from more than 10,000 previously published reports. Each study measured an aspect of climate change, like temperature or precipitation, while also keeping tabs on the wellbeing of an arachnid, insect, amphibian, reptile, bird, or mammal for at least six years.

The goal was to incorporate data for as many species as possible, Radchuk says. But in the end, only 71 studies met the team’s crucial criterion of actually showing whether a species’ response to climate change was adaptive.

That’s because adaptation is difficult to rigorously quantify, Radchuk explains, as it requires tracking how a specific trait—like an animal’s body size or the timing of its breeding season—affects its survival and ability to produce offspring. Do this for a population over a long period of time, she says, and you might get a sense of where on the spectrum the best adapted creatures fall. They might be those with smaller builds, for instance, or those who mate or hatch earlier in spring.

Birds, it turns out, are relatively easy to monitor in this way, and ended up dominating the list of 17 species that made the cutoff, which included great tits (Parus major), Eurasian magpies (Pica pica), and Arctic terns (Sterna paradisaea). The only mammal was the European roe deer (Capreolus capreolus).

When the researchers examined the available data, the outlook wasn’t as bad as Radchuk was expecting: To meet the demands of an increasingly warming world, many species had simply shifted certain life events, like seasonal nesting or egg laying, earlier in the year—the seemingly appropriate response.

In an absolute sense, these species were adapting in the right direction. But things got far less rosy for these early birds when the team took into account the speed at which these changes were occurring. Pitted against accelerating rates of global warming, rates of animal adaptation are simply too slow, Radchuk says. According to the team’s model, many animals aren’t even adapting rapidly enough to maintain steady population numbers, putting them at higher risk of future extinction. On the whole, she says, things are looking “pretty dire.”

That life adapts in response to ever-shifting environmental conditions is a universal truth—and Earth’s climate has certainly been in flux before. But the past century of human activity has plunged the planet into unprecedented territory. Our climate is currently changing at a rate unprecedented in the past 65 million years, since all non-avian dinosaurs went extinct. Some estimates put the current rate of change at 10 to 100 times anything observed in that period.

In effect, this puts Team Adaptation at a deep disadvantage on an already uneven playing field. Adaptation is, by definition, a response to an environmental change—and life needs time to take notice and adjust, whether it’s by tweaking an outward behavior, crystallizing a shift in a population’s gene pool, or both. Now, these results suggests this inevitable lag is widening, and the consequences could be severe.

Climate change has always been something of a moving target, Lanham says. But with a boost from humankind, its recent sprints have already begun to leave some species in the dust.

iStock-680778870.jpg

Great tits (Parus major) nesting. The study's results suggest this bird is among the many species that aren't adapting quickly enough to keep pace with the changing climate. Image Credit: mauribo, iStock

All this is further complicated by the fact that life on Earth isn’t infinitely adaptable, says Stepfanie Aguillon, an evolutionary biologist and bird genomicist at Cornell University who was not involved in the study. Breeding seasons can only shift so far forward; an animal can only get so much smaller. Some species may already be hitting the point of diminishing returns. “There’s a hard limit on how much an organism can change,” Aguillon says, “and it’s difficult to know where that limit is until it’s been reached. That’s a pretty scary thing.”

And, of course, climate change isn’t the only variable at play, says study author Céline Teplitsky, a researcher at the Center for Functional and Evolutionary Ecology in France. Species attempting to weather the impending storm may find their options more limited than before, as available habitats around the world continue to disappear. What’s more, the effects felt by individual species will inevitably ripple through the ecosystems they occupy, leaving other organisms who may not feel the direct repercussions of climate change reeling by proxy.

It’s also worth noting that many of the species profiled in the paper are pretty abundant, even in human-dominated environments, Lanham says. “This doesn’t take into account a lot of species that are on the brink,” he says. And while the data in this study can’t be extrapolated directly or definitively to other creatures, “if we’re seeing negative impacts with common species, then these issues will probably be even further exacerbated in rare and threatened animals.”

In a way, Lanham adds, this underscores the need for more long-term studies of the world’s wildlife. Looking at species in aggregate can provide broad perspective, he says. But, he suggests, it’s important to not lose sight of the trees for the forest (so to speak). Each species’ interactions with its unique environment will differ from the next, and those subtleties will be crucial for researchers and conservationists to understand if they are to forestall and ultimately counteract climate change’s impacts on biodiversity.

Ultimately, the message shouldn’t be one of despair or hopelessness, Teplitsky says. “It can be hard to stay optimistic,” she says. “Although some species are definitely doomed, I’m hopeful that some species can still adapt.”

That’ll only be possible if humans start pulling their weight, Radchuk says. “We need to take action now to prevent further aggravation of the climate,” she says. “The results of these studies show why.”

Receive emails about upcoming NOVA programs and related content, as well as featured reporting about current events through a science lens.