A study of more than 400 species of cold-blooded animals has shown that due to rising average temperatures around the world, marine animals are more at risk of extinction than their terrestrial counterparts.
The journal Nature published a study noting that marine animals are disappearing from their habitats at twice the rate of land animals due to fewer ways to find shelter from warmer temperatures.
The study, led by scientists at Rutgers University in New Jersey, is the first to compare the effects of warmer ocean and land temperatures on all types of cold-blooded animals, from fish and shellfish to lizards and dragonflies.
Previous research has already shown that warm-blooded animals are better able to adapt to climate change than cold-blooded ones, but this study highlights the particular risk to marine creatures. As the oceans continue to absorb heat released into the atmosphere due to carbon dioxide pollution, the waters reach the highest temperature in decades – and the inhabitants of the underwater world simply cannot afford to hide from warming in a shady place or in a hole.
“Marine animals live in an environment where the temperature has always been relatively stable,” says Malin Pinsky, an ecologist and evolutionary biologist who led the study. “Sea animals seem to be walking along a narrow mountain road with temperature rocks on both sides.”
Narrow margin of safety
The scientists calculated “thermal safety margins” for 88 marine and 318 terrestrial species, determining how much warming they can tolerate. Safety margins were narrowest at the equator for ocean dwellers and at mid-latitudes for terrestrial species.
For many species, the current level of warming is already critical. The study showed that the rate of extinction due to warming among marine animals is twice as high as among terrestrial animals.
“The impact is already there. This is not some abstract problem of the future,” says Pinsky.
Narrow safety margins for some species of tropical marine animals average around 10 degrees Celsius. “It seems like a lot,” says Pinsky, “but it actually dies out before the temperature warms up by 10 degrees.”
He adds that even modest increases in temperatures can lead to problems with foraging, reproduction and other devastating effects. While some species will be able to migrate to new territory, others – such as corals and sea anemones – cannot move and will simply disappear.
“This is a really important study because it contains solid data that supports the long-standing assumption that marine systems have one of the highest levels of vulnerability to climate warming,” says Sarah Diamond, an environmentalist and assistant professor at Case University Western Reserve in Cleveland, Ohio. . “This is important because we often overlook maritime systems.”
Pinsky notes that in addition to reducing greenhouse gas emissions that cause climate change, halting overfishing, restoring depleted populations, and limiting ocean habitat destruction can help combat species loss.
“Establishing networks of marine protected areas that act as stepping stones as species move to higher latitudes,” he adds, “could help them cope with climate change in the future.”
beyond the sea
According to Alex Gunderson, assistant professor of ecology and evolutionary biology at Tulane University in New Orleans, this study reflects the importance of measuring not only changes in temperature, but also how they affect animals.
This is also important for terrestrial animal species.
“Terrestrial animals are at less risk than marine animals only if they can find cool, shady places to avoid direct sunlight and avoid intense heat,” Gunderson emphasizes.
“The results of this study are another wake-up call that we need to protect forests and other natural environments that help wildlife adapt to warmer temperatures.”