Here comes Plan C

摘要

Crucial climate talks in Paris are fast approaching, hailed as the last chance for a deal to avert dangerous warming. The good news is that the talks are already a success, in the sense that national pledges on emission reductions would change our current worst-case trajectory - we'd go from expecting a 4 ℃ increase by 2100 to being on track for closer to 3 ℃. The bad news is that the pledges won't avoid 2 ℃ of warming, the point where dangerous climate shifts loom large. Existing greenhouse gas concentrations commit us to a 1.5 ℃ rise, and the size of the changes needed to decarbonise the global economy makes it look inevitable that we will breach 2 ℃ this century.