Temporary overshoot: Origins, prospects, and a long path ahead

The world looks almost certain to reach and then exceed global warming of 1.5°C during the 2030s, given recent trends and limited near-term action. The next-best option still within reach is to ensure this exceedance is both limited and temporary, by bringing global warming levels back down below 1.5°C as soon as possible and by 2100 at the latest. In this primer, we set out the key elements that would make such a “temporary overshoot” trajectory a relevant and feasible prospect. We elaborate on the origins of temporary overshoot as a concept in the scientific literature as well as its emerging role in international climate policy, the need for a typology of risks that a future decline in temperature would reduce or avoid, and the emission pathways that could achieve a return of global warming levels to below 1.5°C, along with their feasibility and implications for climate policy.