UN warns of ‘irreversible damage’, even if global warming peaks at 1.5C

Global temperatures are set to rise by 1.5°C above pre-industrial levels and will lead to possibly permanent effects even if the damage is reversed, according to a new UN climate study. The UN environment programme’s report, published on Wednesday (2 September), highlights the damages of a temperature overshoot even in the best-case scenario of a 1.5°C peak and later decline. And it finds that even with immediate global mobilisation on sustainable climate action, “some losses will be irreversible,” according to South African climate scientist professor Debra Roberts, co-author of the report. Government action would still mean stronger pressure “on those who have been at the source of the problem to put in place ambitious adaptation and mitigation,” Roberts told EUobserver. “We live in an unequal and unjust world, that will be exacerbated by [temperature] overshoot,” she added. Some of the irreversible damage will be experienced by small-island developing states, such as Samoa and Barbados, expected to lose their habitability long before they become completely submerged by rising sea levels. “This collapse of habitability has already begun,” the report warns. Storm surges are pushing many island inhabitants further inland, while the global trend of urbanisation is pushing more and more people to migrate to cities in search of work, despite high-population areas suffering some of the harshest effects of heatwaves. According to the report, effects may include “skyrocketing energy demand and consumer costs, and shifting risk for insect-borne diseases.” Low-income urban residents will face the greatest threats, especially the one billion-strong inhabitants of informal settlements. The first individual year with a global mean temperature above 1.5°C was 2024. Scientists at the UN now expect the world to keep this mean temperature for a 20-year period. To limit long-term average warming below this threshold, the report advises immediate action to ensure this overshoot is followed by a peak and decline, encouraging that “countries with greater historical responsibility for climate change should act the hardest and fastest.”