An international group of more than 11,000 scientists warned in a letter published Tuesday of an ongoing “climate emergency” that could lead to “untold suffering” if it is not turned back.

In their letter five scientists, and thousands of co-signatories, said not only has the climate crisis already begun, but it is “accelerating faster than most scientists expected.”

“It is more severe than anticipated, threatening natural ecosystems and the fate of humanity,” Drs. William Ripple, Christopher Wolf, Thomas Newsome, Phoebe Barnard and William Moomaw wrote in the letter published on the Bioscience peer-reviewed scientific journal.

“Especially worrisome are potential

Read more: Over 11K scientists warn of global 'climate emergency'