“It’s a popular image of cacti,” said David G. Williams, a professor of botany at the University of Wyoming who was not involved in the new research. “‘Ah, we don’t have to worry about cacti. Look at them, they’ve got spines, they grow in this terrible environment.’” But cactuses, like most plants, exist in delicate balance with the ecosystems around them, he said. “There are a lot of these tipping points and thresholds and interactions that are very fragile and responsive to changes in the environment, land use and climate change.”
The new study is “pivotal,” Dr. Williams said, for showing how broadly such changes could affect cactus communities.
Around a decade ago, when Dr. Goettsch was preparing a comprehensive global assessment of the threats to cactuses, there were only a few scientific studies looking at climate change’s potential impacts specifically on cactuses, she said.
But, she said, other cactus experts kept telling her during their field visits, “You know, we go back now, and a lot of plants are dead. There’s no real reason, so we think it might be climate change.” The evidence has only piled up further since then, she said.
Brazil is a hot spot for cactus diversity. As the country’s northeastern drylands experience hotter temperatures, more intense droughts and desertification, that plant wealth is in jeopardy, said Arnóbio de Mendonça, a climate and biodiversity researcher at the National Institute for Space Research in Brazil who did not work on the new study.
“Species either adapt or they will go extinct,” he said. “As adaptation is a slow process and current climate change is occurring rapidly, it is likely that many species will be lost.”