The survival of more than 3,500 animal species is in jeopardy thanks to the impacts of climate change, a new study has found.
This threat applies to at least a quarter of the species in six different classes, including arachnids and chilopodans (centipedes), as well as anthozoans and hydrozoans (marine invertebrates related to jellyfish and corals), according to the study, published on Tuesday in BioScience.
“We’re at the start of an existential crisis for the Earth’s wild animals,” lead author William Ripple, a professor of ecology at Oregon State University, said in a statement.
“Up till now, the primary cause of biodiversity loss has been the twin threats of overexploitation and habitat alteration, but as climate change intensifies, we expect it to become a third major threat to the Earth’s animals,” Ripple warned.
Along with collaborators across the U.S. and Mexico, Ripple used publicly available biodiversity datasets to evaluate the potential threat to 70,814 species across 35 existing classes. The researchers categorized species by class and climate change risks, designated by the International Union for Conservation of Nature.
While the scientists found that at least a quarter of the species were at risk in the six classes of highest concern, they also identified smaller percentages of species under threat in other classes, due to the impacts of a warming climate.
Ripple expressed particular fears about invertebrate animals in the ocean, which is absorbing most of the heat generated by climate change. These animals, he explained, are becoming increasingly vulnerable because of their limited mobility — and resultant struggle to evade adverse environmental conditions.
Certain sudden and extreme weather events, such as heat waves, wildfires, droughts and floods, can cause mass mortality events on some animal communities.
“The cascading effects of more and more mass mortality events will likely affect carbon cycle feedbacks and nutrient cycling,” Ripple said. “Those effects also likely will have an impact on species interactions such as predation, competition, pollination and parasitism, which are vital for ecosystem function.”
Among the specific examples reviewed in the study was a 90 percent reduction in the mollusk population along Israel’s coastline, where water temperatures have escalated. The authors also pointed to the deaths of billions of intertidal invertebrates during the 2021 Pacific Northwest heat dome, as well as a catastrophic die-off of corals along 29 percent of the Great Barrier Reef, in the aftermath of a 2016 marine heat wave.
Although invertebrates might be especially vulnerable to these effects, Ripple noted that plenty of other animals are facing dire consequences from climate change. In 2015 and 2016, for instance, about 4 million common murres — a heavy-bodied seabird known for its powerful but labored flight ability — starved to death off the west coast of North America when the food web was altered by a heat wave.
That same event caused a 71 percent decline in Pacific cod, and other heat waves have likely contributed to the deaths of about 7,000 humpback whales in the Pacific, according to the study.
The authors emphasized that their assessment of just 70,814 species represented just 5.5 percent of all described wildlife species today — meaning, the full scope and scale of the threat posed by climate change remains unclear.
“Our analysis is meant to be a preliminary effort toward assessing climate risk to wildlife species,” Ripple said. “Understanding the risk is crucial for making informed policy decisions.”
