Europe 1 with AFP 11:05 a.m., April 16, 2022

A time considered "helped" by global warming, a new study from the University of Arizona points out that nearly 90% of cacti could actually be threatened with extinction by 2070. In question, climate change and habitat loss. 

About 60% of cactus species will face less hospitable climates in the coming decades due to global warming, according to a study by researchers at the University of Arizona which challenges the hypothesis according to which these plants will thrive with rising temperatures.

If we add other factors (disappearance of habitats, degradation of the natural environment, etc.), up to 90% of cacti could be threatened with extinction by 2070, three times the current estimate, believe the researchers in this study published Thursday in Nature Plants.

Some 1,500 cactus species spread across the Americas live in different climates, ranging from sea-level deserts to high Andes mountains, from arid ecosystems to tropical rainforests.

Species-rich biodiversity hotspots include central Mexico and the Atlantic Forest along the coast of Brazil.

"A pessimistic future"

To test the hypothesis that cacti would benefit from a warmer, more drought-prone world, the researchers, led by Michiel Pillet of the University of Arizona, examined data on more than 400 species, and used models to predict their evolution at the mid-century horizon and beyond, according to different scenarios of greenhouse gas emissions.

The results "paint a more pessimistic future", according to the study.

Currently, cacti are mainly threatened by the expansion of agriculture, the degradation of the natural environment, the loss of biodiversity and their harvesting for various purposes.

Even without climate change, cacti "constitute one of the most threatened groups of organisms on the planet", with more than 30% of them classified as threatened with extinction, the authors note.

"60 to 90%" of cacti impacted by global warming

And global warming will soon become a threat too, if emissions are not drastically reduced.

"Our results suggest that climate change will become a major driver of cactus extinction risk, with 60-90% of assessed species negatively affected," the researchers said.

By 2070, around 25% of cactus species could experience an unknown climate over a quarter of their current range.

Previous studies have shown that photosynthesis - the process by which plants use sunlight to grow from CO2 and water - is compromised by warming.