The Paris Agreement in 2015 established a 1.5 degrees Celsius goal as a rallying point for every nation in the world, and the Costa Rican diplomat Christiana Figueres was one of its chief architects. With the release of Monday’s latest report from the Intergovernmental Panel on Climate Change, she’s faced with the increasingly probable outcome that the temperature threshold she helped establish as former executive secretary of the U.N. Framework Convention on Climate Change will be passed in the years ahead.

"I don’t have words to explain. ‘Concerning’ is not enough. This is frankly a terrifying report,” Figueres told Bloomberg Green a few days ahead of the report’s official release, speaking with apparent familiarity with its findings. "It’s not really about megatons,” she said, speaking of rising levels of greenhouse gas emissions. "It is fundamentally about the long-term well-being of the entire web of life on this planet.”

Figueres is a founder of the Global Optimism Group and co-author of "The Future We Choose: Surviving the Climate Crisis." Her remarks in reflecting on the IPCC climate assessment have been edited and condensed for length and clarity.