A new study published in Nature Ecology & Evolution predicts when and where climate change is likely to expose species across the globe to potentially dangerous and unprecedented temperatures.

The research team – from the University of Connecticut, University College London, the University of Cape Town, and the University at Buffalo – analyzed data from over 35,000 species of animals (including mammals, amphibians, reptiles, birds, corals, fish, whales, and plankton) and seagrasses from every continent and ocean basin, alongside climate projections running up to the year 2100.

The researchers investigated when areas within each species’ geographical range will cross a threshold of thermal exposure, defined as the time when temperatures consistently exceed the most extreme temperatures experienced by a species across its geographic range over recent history (1850-2014).

“Our most critical finding was that when a species starts to be exposed to unprecedented temperatures, it happens in a coordinated way across most of the range at once. Across almost all the 35,000 species examined! That could mean that species have little opportunity to move or evolve, compared to a scenario where exposure is gradual,” says UConn Department of Ecology and Evolutionary Biology researcher Cory Merow.

Once the thermal exposure threshold is crossed, the species is not necessarily going to die out, but there is no evidence that it is able to survive the higher temperatures – that is, the abrupt loss of habitat due to future climate change could be disastrous for many species.

“We focused on exposure to thermal risk because it’s something we know we can forecast well. We’re not sure what a species’ responses to that risk will be, but we can use our forecasts to prioritize monitoring to determine those responses,” says Merow.

The researchers found a consistent trend that for many animals, the thermal exposure threshold will be crossed for much of their geographic range within the same decade.

Lead author Alex Pigot from the University College London Centre for Biodiversity & Environment Research, UCL Biosciences says:

“It is unlikely that climate change will gradually make environments more difficult for animals to survive in. Instead, for many animals, large swathes of their geographic range are likely to become unfamiliarly hot in a short span of time. While some animals may be able to survive these higher temperatures, many other animals will need to move to cooler regions or evolve to adapt, which they likely cannot do in such short timeframes. Our findings suggest that once we start to notice that a species is suffering under unfamiliar conditions, there may be very little time before most of its range becomes inhospitable, so it’s important that we identify in advance which species may be at risk in coming decades.”

The researchers found that the extent of global warming makes a big difference: if the planet warms by 1.5°C, 15% of species they studied will be at risk of experiencing unfamiliarly hot temperatures across at least 30% of their existing geographic range in a single decade, but this doubles to 30% of species at 2.5°C of warming.

“Our study is yet another example of why we need to urgently reduce carbon emissions to mitigate the harmful effects climate change is having on animals and plants, and avoid a massive extinction crisis,” says Pigot.

The researchers hope their study could help with targeting conservation efforts, as their data provides an early warning system showing when and where particular animals are likely to be at risk.

A previous study by the same lead authors found that even if the progress of climate change is halted, so that global temperatures peak and start to decline, the risks to biodiversity could persist for decades after. In another analysis similar to the current study, they found that many species facing unfamiliar temperatures will be living alongside other animals experiencing similar temperature shocks, which could pose grave risks to local ecosystem function.

“The next phase of our research plan is to develop this for all species across the planet as part of an automated global monitoring program powered by NASA satellite observations of extreme events,” says Merow. “This work is just the tip of the iceberg.”

The study was supported by the Royal Society, the Natural Environment Research Council, the National Science Foundation (US), the African Academy of Sciences, and NASA.