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Climate change emerges as third major threat to global wildlife, scientists warn

New published in BioScience reveals that climate change is rapidly emerging as a third major threat to Earth's wild animals, joining habitat alteration and overexploitation in what scientists call a shift from "twin to triple threats."

The research team, led by William J. Ripple of Oregon State University, analyzed data for 70,814 animal species from 35 classes, using two publicly available biodiversity datasets to assess climate change vulnerability among the world's wild animal populations.

Their findings indicate that 5.1% of all assessed animal species are threatened by climate change, with six animal classes having at least 25% of assessed species at risk. The researchers note that these figures likely underestimate the true scale of the crisis.

"We are entering an existential crisis for the world's wild animals," say the authors. "Although some species might benefit, increases in global temperature can lead to a variety of impacts on wild animals, including changes in their physiology, behavior, life cycle, distribution, and interactions among species."

In the Special Report, the authors document numerous recent population collapses linked to climate change, including the disappearance of over 10 billion snow crabs in the Bering Sea since 2018, 7,000 heat-wave-related humpback whale deaths in the North Pacific, and the unprecedented mortality of 4 million common murres off the west coast of North America in 2015–2016.

The assessment revealed stark disparities in research attention among animal groups. While 72.6% of vertebrate species have been assessed for conservation status through the International Union for Conservation of Nature Red List process, only 1.6% of invertebrates have received similar attention, despite constituting the vast majority of animal biodiversity.

The authors emphasized the urgency of climate action: "We may be approaching tipping points regarding the impact of climate change on Earth's animals. We anticipate future extinction risks and mass mortalities due to climate change not only to rise but also greatly accelerate with each fraction of a degree increase in global temperatures."

The researchers recommend establishing a global database to track climate-related mass mortality events, accelerating assessments of vulnerable but understudied species (particularly invertebrates), and integrating biodiversity and climate change policy planning at the global scale.

The American Institute of Biological Sciences, which publishes BioScience, has facilitated the development of national level databases for the study of biological diversity over multiple decades.

"Rapid and effective climate mitigation is crucial now more than ever for saving the world's biodiversity," the authors conclude.