One third of plant and animal species could disappear by 2070

This will be the result if temperatures continue to rise, as species can adapt, however to a certain extent. It has been seen that animals will not be able to move to colder places fast enough to escape extinction.

A new study by researchers at the University of Arizona, recently published in PNAS, concludes that one in three species of animals and plants could disappear in 50 years if global warming is not reduced.

To reach this conclusion, researchers have combined existing information on current climate change extinctions, the rates of movement carried out by the species to escape the rising temperatures and the projected future climate.

Cristian Román-Palacios and John J. Wiens, both from the Department of Ecology and Evolutionary Biology at the University of Arizona, have analysed data 538 species and 581 locations around the world to estimate future extinction rates. More specifically, they have studied local extinctions that have already occurred, based on repeated survey studies of plants and animals over time. Román-Palacios and Wiens generated climate data from the first survey to the last one. What they found was that 44% of the 538 species had already become extinct in one or more places.

"By analyzing the change in 19 climatic variables at each site, we were able to determine which variables drive local extinctions and how much change a population can tolerate without extinction," Román-Palacios said. "We also estimate how quickly populations can move in an attempt to escape rising temperatures. When we gather all this data for each species, we can obtain detailed estimates of the global extinction rates of hundreds of plant and animal species.”

Researchers have concluded that annual maximum temperatures are key to knowing whether a species will become extinct or not. However, it is average annual temperatures, not maximum temperatures, that are most commonly used as indicators of climate change. Scientists point out that using the latter provides extinction data that can be misleading as they have been shown to show smaller changes in sites with local extinction.

Seeking to escape rising temperatures, animals migrate to colder habitats. However, those responsible for the study argue that, given past rates of movement, most species will not be able to disperse quickly enough to avoid extinction.

Many species are able to tolerate a temperature rise, but up to a limit. It has been found that about 50% of species become locally extinct if maximum temperatures increase by more than 0.5 degrees Celsius, and 95% if temperatures rise by more than 2.9 degrees Celsius. It follows that if the temperature trend is to continue to grow, more species will become extinct.

"If we stick to the Paris Agreement to combat climate change, we can lose less than two out of 10 plant and animal species on Earth by 2070. However, if humans cause higher temperature increases, we could lose more than a third or even half of all animal and plant species, according to our results, "said John J. Wiens.

As for the areas most affected by extinctions, experts predict that they will be two to four times more common in the tropics than in temperate regions, a major problem because it is precisely in these areas that more species of plants and animals occur.

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