A 1.5°C overshoot would leave irreversible damage

The United Nations Environment Programme’s Limiting Overshoot report concludes that the world is expected to cross 1.5°C above pre-industrial temperatures, though the height and duration of the overshoot remain uncertain.[2] Even if temperatures later fall, sea-level rise will continue for centuries and some losses involving ecosystems, biodiversity and glaciers will persist.[2] Why it matters: For small island states, overshoot means escalating saltwater intrusion, coral loss, coastal flooding and pressure on limited adaptation and recovery resources well before islands are submerged.[2] Key insights: Returning global temperatures to 1.5°C would not restore all conditions that existed before the threshold was crossed.[2] | Many current adaptation approaches were designed for gradual, one-directional warming rather than temperatures that rise, plateau and potentially decline.[2] | Fixed strategies could become ineffective or increase vulnerability as conditions change, supporting a shift toward flexible and evolving adaptation.[2] Cheatsheet facts: What changed: Crossing the 1.5°C threshold is now expected rather than treated solely as an avoidable scenario.[2] | Why now: UNEP’s report examines how societies must manage a period above 1.5°C and the damage that would remain after temperatures decline.[2] | Watch next: Track how far temperatures rise above 1.5°C, how long the overshoot lasts and how quickly temperatures can be brought back down.[2]