We hear a lot about the species that could be wiped out by global warming. But a number of animals—including the endangered polar bear—are quickly adapting to a hotter world.
Researched by: Rachel John & Aarthi Ramnath
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First thing to know: Extinction is normal
The first organisms were formed 3.7 billion years ago. And the great explosion of plants and animals occurred 541 million years ago. All of which was followed by five mass extinction events—mostly caused by extreme climate change:
- The first mass extinction occurred about 440 million years ago—and wiped out many small organisms of the sea.
- More sea organisms were wiped out in the next mass extinction event 365 million years ago by an asteroid.
- Then came the Great Dying—which ended 90% of all species around 250 million years ago.
- But new species flourished as did large animals like the first dinosaurs—who went extinct 210 million years ago.
- But later dinosaurs flourished and ruled the earth until they were all killed when an asteroid hit the planet around 66 million years ago. Around 75% of all species were erased in the fifth mass extinction event.
In other words, mass extinctions are part of the evolutionary cycle:
In each of these cases, the mass extinction created niches or openings in the Earth’s ecosystems. Those niches allowed for new groups of organisms to thrive and diversify, which produced a range of new species. In the case of the Cretaceous extinction, the demise of the dinosaurs allowed mammals to thrive and grow larger.
But, but, but: Species do evolve all the time and those who happen to possess the ‘right’ traits will survive dramatic changes in their environment. For example, avian dinosaurs or what we call birds. The reason they survived is because they had already developed teethless beaks: “Some bird lineages started to specialise on fruit, seeds, and other plant foods. Instead of teeth to catch, the birds evolved beaks to pluck and pick.” When the asteroid hit, those beaks proved very handy for at least some of the bird species:
These birds weren’t specialized on insects or other animal food, and so they were able to pluck up hard food items like seeds and nuts. And in the aftermath of the extinction, when animal life was severely cut back, those hard, persistent little morsels got beaked birds through the hard times. Beaked birds were able to feed on the seeds of the destroyed forests and wait out the decades until vegetation began to return.
And that is true of animals that live today. One in four species are facing extinction—mostly due to global warming. But a number of them will survive—and some will thrive.
Key point to remember: Contrary to misleading headlines, species that will survive have not evolved traits in response to climate change. Like the birds, they already possess certain genetic traits that will prove to be an advantage in a warming world: “When species do evolve, it is not out of need but rather because their populations contain organisms with variants of traits that offer a reproductive advantage in a changing environment.”
The likely winners
We can’t say for sure which species will survive. But there are certain traits that offer an advantage.
‘Mobile generalists’: These species are able to move and adapt to different environments:
[They] might do well under climate change because they thrive in states of change and transition. For example, deer (in the US) are common in suburban areas and thrive where forests have been removed or are regularly disturbed.
Also adaptable: pesky invasive species that often move across the globe and wipe out local flora and fauna. Example: Cane toads.
The ‘well buffered’: Some creatures like cockroaches have the “ability to hide and protect in buffered conditions”—i.e they can burrow into the ground to escape the heat. Others already live in buffered zones called “climate change refugia”. Example: species that live in the deep sea habitats:
They are pretty much uncoupled from the surface of our planet and I doubt that climate change will impact them in the least. Humanity didn’t even know they existed until 1977. Their energy comes from the core of our Earth rather than from the Sun, and their already extreme habitat is unlikely to be altered by changes happening at the ocean surface.
Another example: Blind cave fish that live in pools under the ground—and far away from the surface heat. They are so well-protected that we didn’t even know they existed in Europe until 2015.
Early migrators: Some migratory species are doing better than others. For example, pink salmon that leave early from the ocean to the streams are thriving and increasing their numbers:
The team found that between 1983 and 2011, the frequency of a genetic marker for late migration dropped significantly. By 2011, late migrating fish only made up about 10 percent of the population. Over that same time period, the local water temperature has increased by about one degree Celsius on average, an uptick that’s linked to climate change. The researchers argue that earlier migrating fish are better fit to handle warmer waters. Auke Creek salmon populations have held steady over the last few decades, and this adaptation may have made them more resilient.
Point to note: Plant species are also “migrating” in search of a more habitable environment. Some trees are moving south and west in pursuit of moisture. But plants that rely on ocean currents or the wind to spread their seed are more likely to survive—than those who depend on birds or other animals. After all, these carriers might go extinct.
Non-fussy eaters: Animals with a diverse diet will likely survive. That’s the other reason why cockroaches, rats and raccoons will be just fine—but picky koalas that only eat eucalyptus will not thrive. These leaves are becoming less nutritious due to increasing carbon dioxide levels. And they are therefore at greater risk of starvation.
Warmer blood: Mammals will do better than reptiles because of how they regulate their body temperature. They either expend energy to maintain a particular temperature like warm-blooded animals. Or they slow or speed up their metabolism to match their conditions—like cold-blooded animals. One is far more advantageous than the other when temperatures rise:
Unlike lizards or fish, warm-blooded animals don’t fall apart as quickly in extreme heat. To stay cool, they’ve developed different strategies like panting, pooping (yes, pooping), or even controlling the air around them with big ears. A few of us, primates and horses, evolved to evaporate water through the skin (sweating) to stay cool. To clear that moisture, our bodies spend energy which in turn, heats up our insides even more.
Just behave: Animals often adapt to changing temperatures by changing their behaviour. So cold-blooded anoles—a kind of lizard—have started hiding in the shade in hotter parts of the world:
On the rich landscapes of islands, freckled with all manner of rocks and vines and trees, an anole can avoid overheating by just skittering into the shade, Michael Logan, an evolutionary biologist at the University of Nevada at Reno, told me. Unlike evolution, this quick-fix change can work within a single generation, without the rigmarole of sex or the gamble of genetics; in the span of a single day, it can toggle on and off. Behaviour, Logan said, is all it takes to “maintain the temperatures they want to be at.”
About those polar bears: They are the most popular symbol for the threat of extinction due to global warming—at risk of being wiped out due to melting Arctic ice. And yet they seem to be doing well in Svalbard—the “most rapidly warming part of planet Earth”:
There is growing evidence that the bears are switching hunting practices – targeting reindeer as well as seals, a change that was first documented on the archipelago in 2021. “Denning” – behaviour around making dens – has changed and bears are swimming long distances, but, says Aars, there is still enough sea ice in the spring for the bears to hunt successfully.
This doesn’t mean that polar bears are thriving as a species. Just that some subpopulations seem to have adapted to the disappearing ice—and aren’t quite as vulnerable as others.
As for humans: Most experts think we are doomed for extinction. The reason: We simply don’t make babies fast enough:
Even with our extraordinary capacity for innovation and adaptability, humans, it turns out, probably won’t be among the survivors.This is partly because humans reproduce agonisingly slowly and generally just one or two at a time – as do some other favourite animals, like pandas. Organisms that can produce many offspring quickly may have a better shot at avoiding extinction.
The bottomline: Future life on the planet will look very different than it is today: “The winners will be very small, preferably [warm blooded] endotherms if vertebrates, highly adaptable, omnivorous or able to live in extreme conditions.” Of course, we may all be living on Mars instead.
Reading list
BBC Future has the best overview of traits that can survive global warming. Smithsonian has a useful list of species that seem to be adapting better to climate change. Also in Smithsonian: Why birds survived the dinosaurs. We did a detailed Big Story on evolution. The Guardian explains why polar bears are not a good symbol for the threat of extinction. National Geographic sums up previous extinction events.
