Wood rats have large ears. Australian parrots have high bills. And the changes are happening very quickly, the researchers say.
The climate crisis is sending natural selection into rapid motion, forcing animals to cope with increasingly warmer temperatures by physically morphing, or “shape-shifting,” a new study suggests. This raises a piercing question: can development continue with the consequences of human-driven carbon emissions?
Over the past 150 years, Australian parrots, such as gang-gang cockatoos and red-rumped parrots, have shown an average 10% increase in bill size along with rising temperatures in their natural habitats, according to research published Tuesday in the journal Trends Is. in ecology and development.
“It is worrying that we are seeing these responses so early in the climate crisis,” said study author Sarah Riding, a researcher in the School of Life and Environmental Sciences at Deakin University in Australia. “We don’t know whether they will be able to survive when the crisis worsens.”
Puffy parrots laden with bright colors aren’t the only victims of the hot world. An increase in bill size has been observed in several other species of birds in North America and Australia, wood rats have larger ears, and some bats are showing an advanced, larger set of wings.
Those larger appendages are expected to help animals manage warmer climates because they provide more surface area to release body heat. “It’s not necessarily a growth visible to the naked eye,” Riding said, “but it’s still functionally important.”
Although evolution has occurred since the beginning of life on Earth, Riding worries that it is happening too quickly.
“I don’t want the takeaway to be, ‘Oh, animals are evolving in response to climate change, that means they’ll be fine,’ because that’s not true,” she said.
The team’s study, which scoured through already published papers to compare trends in animal shape-shifting against climate change, recognized that large-scale adaptations are occurring relatively quickly along the projected timeline of the climate crisis. Huh.
That timeline doesn’t shrink for a while.
Already many countries call the previous goal of limiting global warming to 1.5 degrees, or even 2 degrees, “beyond reach” over the next decades. That is unless there are “immediate, rapid and massive reductions in greenhouse gas emissions,” reads the group’s report from August, which the panel considers a “reality check”.
“Climate change is happening at a faster rate than ever before,” Riding said. “Although evolutionary change may be a slow process, taking thousands — or more — years, we also know that strong selection can drive rapid evolutionary change.”
By strong selection, riding is referring to the intensity with which natural selection occurs. If only one in 10 members of a species can survive in a warm climate by having a large appendage, the other nine will not survive long enough to pass their genes on to the next generation.
So we are seeing new groups of species with heavy appendages riding the trajectory of global warming.
“Given how widespread this phenomenon is on a geographic scale—and across a wide range of animals—climate change is what unifies us,” Riding said.
The correlation makes sense, because of a theory first developed by American zoologist and ornithologist Joel Asaf Allen in 1877. It basically says that animals living in warmer climates will have larger, longer appendages than those in colder regions.
“Animals can release excess body heat through their appendages, so the larger appendages allow them to let in even more body heat, which is beneficial as the climate warms,” Riding explained.
Allen’s law has been widely studied by scientists, including a paper from 2020 that aimed to establish its benefits as a predictive tool for climate change outcomes. However, widespread coverage of riding work reinforces the phenomenon of rapid development as a far-reaching issue.
“I hope these findings really shed light on how climate change is affecting animals,” Riding said, “and how important it is that we reduce our emissions and combat the climate crisis as much as possible.” Work to avoid