Thousands of animal species face an imminent threat of extinction from climate change

Climate change is rapidly joining overexploitation and habitat destruction as a third major driver of global biodiversity loss, forcing thousands of animals onto the endangered species list.

A sweeping analysis recently identified at least 3,500 animal species already deemed directly threatened by rising temperatures, intensifying storms, droughts, and other climate-related stresses.

The research, led by Oregon State University ecologist William Ripple, draws on international databases to show that risk is especially acute for invertebrates.

Marine species, in particular, face heightened danger because they cannot easily move away from warmer waters.

The study also warns that true vulnerability is likely far greater because scientists have not formally assessed most animal groups for climate danger.

“We’re at the start of an existential crisis for the Earth’s wild animals,” Ripple said. “Up till now, the primary cause of biodiversity loss has been overexploitation and habitat alteration. As climate change intensifies, we expect it to become a third major threat to the Earth’s animals.”

Climate threats to animal species

Ripple and colleagues analyzed records for 70,814 species across 35 taxonomic classes, relying on the International Union for Conservation of Nature’s (IUCN) threat categories.

The team discovered that in six whole classes – arachnids, centipedes, anthozoans, hydrozoans, and two other invertebrate groups – climate change threatens at least one-quarter of species.

Other classes, including mammals, birds, and reptiles, contain smaller but still significant proportions of climate-imperiled members.

The oceans stand out as a danger zone because seawater absorbs most excess heat from greenhouse forcing.

“We are particularly concerned about invertebrate animals in the ocean,” Ripple said. “Those animals are increasingly vulnerable because of their limited ability to move and promptly evade adverse conditions.”

Understanding the IUCN Red List

The IUCN Red List of Threatened Species is like the world’s pulse check for wildlife. It tracks the health of thousands of species – plants, animals, fungi – and tells us who’s thriving, who’s struggling, and who’s on the brink of extinction.

Scientists use a detailed set of criteria to evaluate risk, ranging from population trends and habitat range to actual threats like poaching or climate change.

When a species lands in categories like “Endangered” or “Critically Endangered,” it’s not just a label – it’s a cry for help backed by data.

Governments, conservationists, and communities use the Red List to make decisions about land use, funding, and protection strategies. It influences environmental policies and helps prioritize where to focus resources.

When we protect what’s on that list, we’re safeguarding ecosystems, cultures, and future generations.

Climate disasters kill millions of animals

In recent years extreme climate events have delivered dramatic proof of these vulnerabilities. Off Israel’s coast, a 90 percent crash in mollusk abundance followed a jump in sea-surface temperature.

During the 2021 Pacific Northwest heat dome, billions of intertidal mussels, clams, and snails died in a matter of days. A severe marine heatwave in 2016 bleached nearly 30 percent of Australia’s Great Barrier Reef.

Terrestrial and pelagic vertebrates have suffered too. An extreme warm spell in 2015-2016 altered the marine food web in the North Pacific, starving four million common murres, slashing Pacific cod numbers by 71 percent, and contributing to the loss of roughly 7,000 humpback whales.

Ripple noted that such mass mortality events reverberate through ecosystems. “The cascading effects of more and more mass mortality events will likely affect carbon-cycle feedbacks and nutrient cycling.”

Missing data on a massive scale

Although the headline figures are sobering, the authors emphasize that they represent only a fraction of the problem.

Sixty-six of the planet’s 101 recognized animal classes have not had any species evaluated for climate risk by the IUCN. The 70,814 species examined in the study account for just 5.5 percent of all described animals.

“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 Red List itself is heavily skewed toward vertebrates, which make up fewer than six percent of named animal species, leaving the vast majority of invertebrates – essential to pollination, soil health, and marine food webs – largely unexamined.

Merging climate and conservation

Ripple argued that policymakers must couple improved risk assessments with policies that synchronize biodiversity conservation and climate mitigation.

“There is also a need for more frequent climate risk assessments of all species and better consideration of adaptive capacity,” he added. “We need the integration of biodiversity and climate change policy planning on a global scale.”

Ripple and his co-authors call for real-time monitoring of die-off events and expansion of citizen science initiatives to cover overlooked taxa.

They also advocate incorporating species’ dispersal abilities and genetic diversity into risk models.

Only with such knowledge can policymakers design interventions that help vulnerable species stand a fighting chance.

Saving animals with climate action

With global temperatures already flirting with the 1.5°C threshold that scientists warn will unleash accelerating hazards, the time for closing data gaps is rapidly shrinking.

The new study shows that climate change is no longer a distant or incremental danger for wildlife; it is a present crisis that compounds longstanding threats.

Whether governments heed the warning will decide how many species remain confined to the 3,500-strong endangered column – and how many more quietly slide into it as the planet continues to warm.

The study is published in the journal BioScience.

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