UN sees higher global warming, even in best-case scenario

Global warming is now projected to exceed previous estimates, with even the most optimistic scenario seeing average temperatures rise to 1.7-1.8 degrees ‌Celsius above pre-industrial levels by mid-century, a UN report showed on Wednesday.

Despite a rapid expansion of renewable energy and climate policies that are reducing emissions in many countries, the report said "urgent and stringent" cuts were still needed to achieve that ‌best-case outcome. The UN Environment Programme's report said greenhouse gas emissions would need to fall 18% from 2025 levels ‌by 2030, 45% by 2035 and 69% by 2040. Current national plans would cut emissions by only 5-8% by 2030 and 11-15% by 2035.

The report projected global warming of 2.8 Celsius by 2100 under current policies, or 2.6 C if countries fully implement existing climate ⁠pledges. Both ​estimates are higher than last year's ⁠projections, reflecting the US withdrawal from the Paris Agreement and revised assessments of historical emissions. As countries prepare for the next round ⁠of climate talks in Turkey, COP31, UN Secretary-General António Guterres said it was crucial not to give up on efforts to rein ​in the emissions that are fuelling floods, fires and other natural disasters.

"Overshoot is not surrender. We can ⁠still keep it as small and as short as possible – and bring temperatures back below 1.5 degrees by the end of the century," ⁠he ​said. Under the 2015 Paris Agreement, countries agreed to try to keep the average temperature increase at well below 2 degrees and ideally 1.5 C.

As limiting warming to 1.5 C with no or limited overshoot was no ⁠longer considered possible, the UN Environment Programme said its new "lowest possible" overshoot scenario gives roughly a 50% chance that temperatures ⁠could return to 1.5 ⁠C or below by 2100. The report said climate plans submitted since last year had made virtually no difference to future warming projections, and that returning to 1.5 C would ‌depend on large-scale ‌carbon removal, the feasibility of which was uncertain.