UN admits 1.5°C limit will be breached, urges plan to cool planet

The United Nations has conceded that the world will soon breach the 1.5°C warming threshold set in the 2015 Paris Agreement, marking a strategic shift in climate policy. A new report from the UN Environment Programme, released Wednesday, outlines a path to "overshoot" the limit and then bring temperatures back down.

Secretary-General António Guterres said humanity is "speeding past the limit to avoid climate catastrophe." The report, the first of its kind, acknowledges that current emissions from fossil fuels will push global temperatures past the threshold within the next few years.

Scientists now calculate the world is already 1.4°C above pre-industrial levels. The most optimistic scenario sees warming peaking at 1.8°C by mid-century if countries adopt ambitious goals. Under current policies, temperatures could rise to 2.6°C by 2100.

Instead of preventing the breach, the UN now urges policymakers to "prepare for and navigate" a future where warming peaks and then gradually cools back below 1.5°C, ideally by century's end. This period of overshoot could last "many, many decades," said report co-author Richard Betts of the University of Exeter.

"It's a reality check," Betts said. "We have to live with this warmer world. But there's still a lot we can do to limit warming."

UNEP Executive Director Inger Andersen stressed that the 1.5°C target remains the goal, but must be approached "from above." She called for limiting the peak temperature and shortening the time spent above the threshold.

During overshoot, the report warns of increased weather disasters, rising seas, extinctions, and melting ice. It also highlights risks of tipping points, such as the loss of major ice sheets and the Amazon rainforest, and notes that some regions could become uninsurable or uninhabitable.

To cool the planet, the report calls for ending fossil fuel use and developing carbon-removal technologies. Planting trees alone can only shave a tenth of a degree, so more novel approaches are needed. However, some scientists question the reliability and cost of such methods.

"We were unable to stop the runaway train of global emissions to avoid 1.5°C of warming," said Stanford's Rob Jackson, who was not part of the report. "Now overshoot scenarios require us to stop the train quickly and to back it up. Is it our best hope? Absolutely. Is it likely? Absolutely not."

Despite the bleak outlook, experts stress that every fraction of a degree avoided reduces damage. "Every tenth of a degree we avoid still means less damage," said University of Victoria's Andrew Weaver.