Researchers have said that one in three plant and animal species could face extinction by 2070 because of climate change. The study, published in the journal Proceedings of the National Academy of Sciences, estimated broad-scale extinction patterns from climate change by incorporating data from recent climate-related extinctions and from rates of species movements.
"By analysing the change in 19 climatic variables at each site, we could determine which variables drive local extinctions and how much change a population can tolerate without going extinct," Cristian Roman-Palacios from the University of Arizona said.
"We also estimated how quickly populations can move to try and escape rising temperatures. When we put all of these pieces of information together for each species, we can come up with detailed estimates of global extinction rates for hundreds of plant and animal species," Roman-Palacios added.
For the findings, the researchers analysed data from 538 species and 581 sites around the world and focused on plant and animal species that were surveyed at the same sites over time, at least 10 years apart.
They generated climate data from the time of the earliest survey of each site and the more recent survey. They found that 44 per cent of the 538 species had already gone extinct at one or more sites.
The study identified maximum annual temperatures -- the hottest daily highs in summer -- as the key variable that best explains whether a population will go extinct.
Surprisingly, the researchers found that average yearly temperatures showed smaller changes at sites with local extinction, even though average temperatures are widely used as a proxy for overall climate change.
"This means that using changes in mean annual temperatures to predict extinction from climate change might be positively misleading," said study researcher John J. Wiens.
Previous studies have focused on dispersal -- or migration to cooler habitats -- as a means for species to "escape" from warming climates.
However, the authors of the current study found that most species will not be able to disperse quickly enough to avoid extinction, based on their past rates of movement.
Instead, they found that many species were able to tolerate some increases in maximum temperatures, but only up to a point.
They found that about 50 per cent of the species had local extinctions if maximum temperatures increased by more than 0.5 degrees Celsius, and 95 per cent if temperatures increase by more than 2.9 degrees Celsius.
"If we stick to the Paris Agreement to combat climate change, we may lose fewer than two out of every 10 plant and animal species on Earth by 2070," Wiens said.
"But if humans cause larger temperature increases, we could lose more than a third or even half of all animal and plant species, based on our results," Wiens added.