Thousands of animal species threatened by climate change, novel analysis finds
Oregon State University
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Hawai'ian green sea turtle.
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CORVALLIS, Ore. – A novel analysis suggests more than 3,500 animal species are threatened by climate change and also sheds light on huge gaps in fully understanding the risk to the animal kingdom.
The study was published today in BioScience.
“We’re at the start of an existential crisis for the Earth’s wild animals,” said Oregon State University’s William Ripple, who led the study. “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, distinguished professor of ecology in the OSU College of Forestry, and collaborators in the U.S. and Mexico used publicly available biodiversity datasets to examine animal data for 70,814 species from 35 existing classes. They categorized the species by class and climate change risks as assessed by the International Union for Conservation of Nature.
The researchers found that at least one-quarter of the species in six different classes are threatened by climate change; these classes include arachnids and chilopodans (centipedes) as well as anthozoans and hydrozoans (marine invertebrates related to jellyfish and corals). Smaller percentages of other classes’ species are also directly at risk from a warming climate.
“We are particularly concerned about invertebrate animals in the ocean, which absorbs most of the heat from climate change,” Ripple said. “Those animals are increasingly vulnerable because of their limited ability to move and promptly evade adverse conditions.”
Sudden impacts on animal communities can take the form of mass mortality from extreme events like heat waves, wildfires, droughts and floods.
“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.”
The 90% reduction in mollusk populations along Israel’s coastline because of escalating water temperatures shows how susceptible invertebrates are, he said. Other examples include the deaths of billions of intertidal invertebrates during the 2021 Pacific Northwest heat dome, and the catastrophic die-off of corals across 29% of the Great Barrier Reef following a severe 2016 marine heat wave.
Mass mortalities have not been limited to invertebrates, Ripple notes. In 2015 and 2016, about 4 million common murres off the west coast of North America starved to death via an altered food web caused by an extreme marine heat wave.
The same heat wave caused a 71% decline in Pacific cod because of an increase in metabolic demand and a reduced prey base, and marine heat waves have likely played a role in the deaths of approximately 7,000 humpback whales in the North Pacific.
Further cause for concern, the authors note, is the comparatively small amount of information that’s been gathered regarding climate change risk to wildlife. Most wildlife classes (66 of 101) have not yet had any species assessed by the IUCN, and the 70,814 species that have been assessed represent 5.5% of all described wildlife species alive today.
“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. We need a global database on mass mortality events due to climate change for animal species in all ecosystems, and an acceleration in assessing currently ignored species.”
The IUCN Red List of Threatened Species, he notes, has a bias toward vertebrates, which make up less than 6% of the Earth’s named animal species.
“There is also a need for more frequent climate risk assessments of all species and better consideration of adaptive capacity,” Ripple said. “We need the integration of biodiversity and climate change policy planning on a global scale.”
Roger Worthington, an attorney in Bend, Oregon, provided partial funding for this study, which also included Christopher Wolf and Jillian Gregg of Terrestrial Ecosystem Research Associates and Erik Torres-Romero of the Biotechnology Engineering-Polytechnic University of Puebla in Puebla, Mexico.
Australian corals
Credit
Justin Smith
Journal
BioScience
Method of Research
Data/statistical analysis
Subject of Research
Animals
Article Title
Climate c hange t hreats to Earth’s w ild a nimals
Article Publication Date
20-May-2025
Climate change emerges as third major threat to global wildlife, scientists warn
American Institute of Biological Sciences
New research 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, 7000 heatwave-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 the last many decades.
"Rapid and effective climate mitigation is crucial now more than ever for saving the world's biodiversity," the authors conclude.
Journal
BioScience
Method of Research
Literature review
Subject of Research
Animals
Article Title
Climate change threats to Earth’s wild animals
Article Publication Date
20-May-2025
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