Scientists are in broad agreement that warming above 1.5C relative to pre-industrial times risks catastrophic consequences, and every effort must be made to stick as close as possible to this safer threshold.
But the world is set to blow past 1.5C in a matter of years and planet-warming emissions keep rising, hitting a new record high in 2024, according to a report by the UN Environment Programme (UNEP).
The sobering assessment was published just days before world leaders gather in Brazil on Thursday and Friday ahead of the COP30 climate summit in the rainforest city of Belem.
With an overshoot of 1.5C now inevitable, focus has shifted to how quickly temperatures can be returned to less-risky levels.
“Our mission is simple, but not easy: make any overshoot as small and as short as possible,” UN Secretary-General Antonio Guterres said Tuesday at the launch of UNEP’s Emissions Gap report.
Big polluters most responsible for the crisis have been urged to pledge faster and deeper emissions cuts to bend the curve back to 1.5C by the end of the century.
Instead, the latest round of carbon-cutting targets announced ahead of the UN climate talks “have barely moved the needle”, concluded UNEP’s latest assessment.
“Ambition and action are nowhere near the levels needed globally or collectively,” Anne Olhoff, the report’s chief scientific editor, told AFP.
The latest assessment projects that the world’s collective commitments to tackle climate change, if enacted in full, would result in 2.3C to 2.5C of warming by 2100.
That poses an unacceptable threat to the survival of nations most at risk by rising seas and extreme weather, and the global failure to rise to this challenge will loom over COP30.
Scientists have strong evidence that warming above 1.5C — let alone a degree or more — increases not only the intensity of hurricanes, floods and other disasters, but the likelihood of catastrophic climate tipping points.
At 1.4C above pre-industrial times, the Earth is already too warm for most tropical coral reefs to survive, while ice sheets and the Amazon rainforest could suffer severe and lasting changes below 2C, with consequences for the entire planet.