Ex-diplomats sketch out two visions of climate change in 2050

Two architects of the Paris Climate Agreement present a pair of possible scenarios for the global climate in 2050 — one in which we've met the carbon reduction targets laid out in the agreement, and one in which we've failed.

Why it matters: The authors argue that we have a decade left to pick which path the planet will take: catastrophe or hope.

Former United Nations Framework Convention on Climate Change head Christiana Figueres and climate diplomat Tom Rivett-Carnac were instrumental in guiding the Paris Agreement, which committed countries to reducing carbon emissions sufficiently to keeping global temperature rise below at least 2° C by 2100.

• In their new book The Future We Choose: Surviving the Climate Crisis, the pair sketch out what the climate could look like by mid-century, depending on whether we meet the Paris goals.
• If we succeed, they foresee a world where forests cover half the land surface, air pollution has disappeared and fossil fuels have been eliminated.
• If we fail, warming will be on a pace for a 3°C increase by 2050, the air will become unbreathable and the very future of human civilization will be in doubt.

What they're saying: "If we continue where we are now, we are going to be irreparably going down a course of constant destruction," Figueres told the Guardian.

• Altering that path will require sharp technological and political change, especially in the U.S. The choices made in 2020 will help decide the climate in 2050.