The chance of the global average temperature exceeding 1.5C above pre-industrial levels in one of the next five years is now about 50:50 (48%), according to a new Met Office study.
The Global Annual to Decadal Climate Update, which was produced with the World Meteorological Organisation, also showed a 93% chance that the five-year average global temperature for 2022-2026 will be higher than the average for the last five years (2017-2021).
Dr Leon Hermanson, from the Met Office who led today's report, said: "Our latest climate predictions show that continued global temperature rise will continue, with an even chance that one of the years between 2022 and 2026 will exceed 1.5C above pre-industrial levels.
"A single year of exceedance above 1.5C does not mean we have breached the iconic threshold of the Paris Agreement, but it does reveal that we are edging ever closer to a situation where 1.5°C could be exceeded for an extended period."
In 2021, the global average temperature was 1.1C above the pre-industrial baseline, according to the provisional WMO report on the State of the Global Climate.
The final report will be released on 18 May.
Meanwhile, back-to-back La Niña events at the start and end of 2021 had a cooling effect on global temperatures, but this was only temporary and will not reverse the long-term global warming trend.
Any development of an El Niño event would immediately fuel temperatures, as it did in 2016, which is currently the warmest year on record.
Professor Steven Sherwood, an ARC Laureate Fellow at the ARC Centre for Climate System Science and UNSW Climate Change Research Centre, said: "This 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.
"In other words, to actually exceed the target we'd have to be above 1.5C even in a "normal" year, and that is much less likely. But the report reminds us that we are getting uncomfortably close to this target."
Dr Andrew King, a lecturer in Climate Science at the School of Geography, Earth and Atmospheric Sciences, University of Melbourne, added: "This update highlights how fast we are warming the planet. It's only six and a half years since the Paris Agreement was adopted and we're already seeing forecasts that we may experience brief exceedance of the 1.5°C global warming limit in the near future.
"While the Paris Agreement is about keeping global warming well below 2°C and preferably below 1.5°C in the long-term, the possibility of surpassing the 1.5°C threshold, even if only for a year, is worrying."