Scientists say there are close to even odds that the average global temperature will increase by 1.5 C from pre-industrial levels in one of the next five years, which means the world would temporarily exceed the limit set in the Paris Agreement.

In its annual set of climate predictions, the World Meteorological Organization, or WMO, said that the chance of exceeding 1.5 C has risen steadily since 2015, when it was close to zero. For the years between 2017 and 2021 there was a 10 percent chance, and the probability that exceedance will occur in one of the years between 2022 and 2026 is 48 percent.

In the Paris Agreement, which is a legally-binding United Nations treaty on climate change, countries agreed to limit global warming to within 2 C and 1.5 C this century.

To truly violate the agreement, the temperature would need to remain above 1.5 C for longer than one year, said Leon Hermanson, a predictability researcher at the United Kingdom Meteorological Office who led the report.

"A single year of exceedance above 1.5 C 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," Hermanson said.

The WMO study also estimated that there is a 93 percent chance that one of the years between 2022 and 2026 will exceed the warmest year on record, which was 2016.

WMO Secretary-General Petteri Taalas said that the study shows with a "high level of scientific skill "that the world is getting measurably closer to reaching the lower range of the Paris Agreement.

"The 1.5 C figure is not some random statistic," Taalas said. "It is rather an indicator of the point at which climate impacts will become increasingly harmful for people and indeed the entire planet."

Sustained global warming would cause sea level rise, more frequent heatwaves and extreme weather events, leading to famines, floods and climate migration. In a separate report, the Intergovernmental Panel on Climate Change said that if the world warms by 1.5 C over an extended period, several hundred million people will be exposed to climate-related risks and subsequently plunged into poverty by 2050.

"For as long as we continue to emit greenhouse gasses, temperatures will continue to rise," said Taalas. "And 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. Arctic warming is disproportionately high and what happens in the Arctic affects all of us."