Study of 40,000 Sites and 5,100 Species Finds Climate Change Impact Far Worse Than Expected

A Major Reversal in Climate Science Consensus

For decades, climate scientists widely assumed that tropical species faced greater risks from climate change than their temperate counterparts. A landmark new study has completely upended that assumption.

"The world has changed since 2016," said John Wiens, senior author of the study published in Nature Climate Change. "Temperate regions, especially at higher latitudes, are warming more, and this trend may have fully reversed in recent decades."

Researchers are working to understand the drivers behind this reversal. "For animals, we didn't find that tropical extinctions were less common than previously thought — we found that temperate extinctions have now overtaken tropical ones," Wiens said in a press release.

Temperate Regions Warming at Nearly Twice the Tropical Rate

Scientists calculated that over the past 25 years, tropical regions have warmed by approximately 1.8°C (3.3°F), while temperate regions have warmed by roughly 3.3°C (6°F) — nearly twice as much. Temperate zones are heating up at a dramatically faster pace.

"Although the accelerating warming in temperate regions appears to be the primary driver of local extinctions, we also found that temperate species are at least as sensitive to rising temperatures as tropical species," said lead author Gopal Murali.

What 'Local Extinction' Actually Means

'Local extinction' refers to the complete disappearance of a species or population from a specific geographic area or habitat, even if that species survives elsewhere in the world. In practical terms, it means the plants and animals once found on familiar hiking trails are simply gone.

The study shows that these populations can no longer survive under shifting environmental conditions — a trajectory that may ultimately drive entire species to global extinction.

"People often assume that as the climate warms, species will migrate to cooler areas, but we found that more than 70% of species are not doing that," Wiens said.

The reasons are straightforward: animals may be unable to cross highways; aquatic species may be confined to specific lakes or rivers; mountain-dwelling species may have no higher ground left to retreat to. In short, wildlife is rapidly running out of escape routes.

"In the past, we focused too much on the hottest areas," Wiens said. "But it turns out that for many temperate species' populations, there is no truly safe place left."

The Stark Reality Behind the Data

Among the 5,100 plant and animal species examined, the researchers found that 45% had already experienced local extinction at the warmest sites within their known ranges. Even more alarming, this figure exceeded 50% across multiple taxonomic groups, including insects, terrestrial vertebrates, and marine species.

The researchers were also careful to emphasise that this study is not based on future projections — it documents biological changes that have already occurred.

"People often think of climate change impacts as something in the future," said Murali. "But we are seeing these impacts right now, in both tropical and temperate species. The patterns we've recorded show that biodiversity is changing in ways we are still working to understand."

Conservation Strategies May Need to Be Redirected

Notably, a 2016 study covering 976 species reached the opposite conclusion — that local extinctions were more prevalent among tropical species than temperate ones. That understanding has now been completely overturned. Regardless, one fundamental truth remains unchanged: species populations are disappearing, temperatures continue to rise, and climate change is real.

The findings carry significant implications for future conservation planning. Resources and efforts may need to be redirected towards temperate regions. The crisis facing these species may be far more severe than previously recognised.

The study has been published in Nature Climate Change.

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