Global warming could briefly exceed 1.5 degrees by 2026 – report

WMO warns of dangers linked to breaching long-term target set by Paris Agreement

The world faces a 50 per cent chance of warming by 1.5 degrees above pre-industrial levels – if only briefly – by 2026, the World Meteorological Organization (WMO) has predicted.

That does not mean the world would be crossing the long-term warming threshold of 1.5 degrees, which scientists have set as the ceiling for avoiding catastrophic climate change. But a year of warming at 1.5 degrees could offer a taste of what crossing that long-term threshold would be like including more extreme weather events.

The 1.5-degree global heating limit is set by international governments under the Paris Agreement. The study, which was led by the UK Met Office, shows that as recently as 2015, there was zero chance of this happening in the following five years but this surged to 20 per cent in 2020 and 40 per cent in 2021 – the global average temperature was 1.1 degrees above pre-industrial levels in 2021.

Projected warming in excess of 2 degrees this century is predicted by some studies based on current trends and global commitments to reduced greenhouse gases (GHGs).


It is also close to certain – 93 per cent – that by 2026 one year will be the hottest ever recorded, beating 2016, when a natural El Niño climate event supercharged temperatures.

"The 1.5 degree figure is not some random statistic. It is rather an indicator of the point at which climate impacts will become increasingly harmful for people and indeed the entire planet," said WMO head Prof Petteri Taalas, which published the new report.

“For as long as we continue to emit greenhouse gases, temperatures will continue to rise,” he added. “Alongside that, our oceans will continue to become warmer and more acidic, sea ice and glaciers will continue to melt, sea level will continue to rise and our weather will become more extreme.”

Climate cycles

Natural climate cycles can nudge global temperatures up or down in a given year. But the Paris Agreement requires states to hold the underlying rise, driven by human activities, to below 2 degrees, as well as pursuing efforts to limit the increase to 1.5 degrees.

The world’s scientists through the UN Intergovernmental Panel on Climate Change warned in 2018 that 1.5 degrees of global heating will bring severe impacts to billions of people.

"The possibility of surpassing the 1.5 degree threshold, even if only for a year, is worrying," said Dr Andrew King at the University of Melbourne.

“Our greenhouse gas emissions are still at near-record highs and until we get emissions down to net zero we’re going to continue to see global warming. Rapid and drastic emissions reductions are needed urgently.”

Prof Steven Sherwood at the University of New South Wales said the WMO report is looking at year-on-year natural variations in global-mean temperature (due for example to El Nino cycles) and the chance that in the near future a single warm year might pop above the Paris target warming threshold, which is a significant possibility.

“However, if that happened it would not mean that we exceeded the target, because the target refers to the underlying average temperature with year-on-year natural variability excluded,” Prof Sherwood noted.

“To actually exceed the [Paris] target we’d have to be above 1.5 degrees even in a ‘normal’ year” – unaffected by natural climate variations, he added.

Prof Taalas also warned of especially rapid heating at the North Pole: “Arctic warming is disproportionately high and what happens in the Arctic affects all of us.”

Shrinking of sea ice and its knock-on effects have been linked to extreme weather events in Europe, the North America and Asia, including heatwaves, floods, sea-level rise and even snowstorms.

The forecast indicates the rise in Arctic temperatures will be three times greater than the global average over the next five years. – Additional reporting: Guardian

Kevin O'Sullivan

Kevin O'Sullivan

Kevin O'Sullivan is Environment and Science Editor and former editor of The Irish Times