The world is on track for the warmest decade since records began 150 years ago, the UK's Met Office warned on Wednesday.
It forecasted that temperatures are likely to be at or above 1°C over pre-industrial levels between now and 2023. They could even temporarily reach above 1.5°C — considered a critical level.
"A run of temperatures of 1 °C or above would increase the risk of a temporary excursion above the threshold of 1.5 °C above pre-industrial levels. Predictions now suggest around a 10% chance of at least one year between 2019 and 2023 temporarily exceeding 1.5 °C," said Dr Doug Smith, a Met Office Research Fellow.
In the five-year forecast, the Met Office highlighted the first possibility of a natural El Niño phase combined with global warming that could exceed the 1.5°C mark.
The Met Office said 2015 was the year that the global annual average surface temperature reached 1°C above pre-industrial levels. Every year since then, the average temperature has come close to or above the 1°C mark and is set to rise in the next five years.
The Met Office said 2018 was the fourth warmest year on record. Some record extremes seen last year included wildfires in California and Greece, record temperatures in northern Europe over the summer, floods in India, and drought in South Africa.
2015 Paris Climate Agreement
To combat global warming, almost 200 governments signed up to the Paris climate agreement in 2015 to cut carbon and limit the rise in temperatures to 2°C above pre-industrial times while "pursuing efforts" for 1.5°C.
However, the Met Office said temperatures would be close to reaching 1.5°C, but it would be "a temporary exceedance rather than the climatological level of warming in the Paris 1.5 °C threshold."