Critical 1.5C threshold breached over 12-month period for first time

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The average global temperature has for the first time breached the critical benchmark of 1.5C above pre-industrial levels over a 12-month period, according to data from the European earth observation agency showing that last month was the hottest January on record.

As countries contend with bouts of extreme weather events, including floods and wildfires, the Brussels-based Copernicus Climate Change Service (C3S) said the global mean temperature for February 2023 to January 2024 was the highest ever at 15.02C, 1.52C above the 1850-1900 pre-industrial period.

The 1.5C level is a crucial threshold in the 2015 Paris agreement, in which countries agreed to limit global temperature rises to well below 2C and ideally to 1.5C above pre-industrial levels.

Although the record-breaking temperatures of the past 12 months were above 1.5C, scientists emphasised that the breach did not mean a failure to uphold the Paris accord, which is based on a longer-term temperature increase of more than a decade.

“Having reached this level for such a sustained period . . . may imply that the time between now and when the Paris agreement limit is breached is shrinking,” said Francesca Guglielmo, senior C3S scientist, citing the “abrupt” rise in global mean temperatures over the past nine months.

Sir Brian Hoskins, chair of the Grantham Institute at Imperial College London, said the data was “a stark warning of the urgency for the action that is required to limit climate change at anything like the Paris targets”.

January marked the eighth month in a row that temperatures were the warmest on record, as heatwaves, wildfires and flooding devastated many regions. Last year was the hottest on record.

Samantha Burgess, deputy C3S director, called for swift action to tackle rising global temperatures.

“Rapid reductions in greenhouse gas emissions are the only way to stop global temperatures increasing,” she said.

Richard Betts, head of climate impacts research at the Hadley Centre of the UK’s Meteorological Office, said the past 12 months’ record-breaking temperatures showed the “profound changes” in the global climate.

January’s average surface air temperature was 13.14C, 0.12C above the temperature of the previous warmest January in 2020. It was also 1.66C warmer than an estimate of the January average for 1850-1900.

Temperatures in January were well above average in eastern Canada, north-western Africa, the Middle East and central Asia, as well as much of the south of the European continent.

But in the Nordics, western Canada, the central US and most of eastern Siberia, temperatures were well below average. Temperatures dropped below -40C in parts of Sweden and Finland last month.

Large parts of Europe, western and south-eastern US, south-eastern South America, south-east Africa and northern and eastern Australia were wetter than average. But southern UK, Ireland, parts of Spain, most of Scandinavia and the eastern Balkans were drier than usual.

Drier than usual seasonal conditions in the Horn of Africa, the Arabian peninsula, south-central Asia, Australia and South America contributed to wildfires in places such as Chile, the scientists said.

Scientists said the global sea surface temperature also reached a record high of almost 20.97C for January. It was the second-hottest sea surface temperature recorded for any month ever, with only August 2023 surpassing it at 20.98C.

The El Niño phenomenon, which heats the Pacific Ocean surface and exacerbates global warming caused by greenhouse gas emissions, has contributed to sea temperature rises in recent months.

But they warned that sea surface temperatures had already reached “new absolute records”, with a level of 21.12C recorded on February 4 surpassing the previous high reached last August.

Last May the World Meteorological Organization said there was a 66 per cent chance that the mean global temperature would temporarily surpass 1.5C above pre-industrial levels in “at least” one year by 2027.