2023 confirmed as world's hottest year on record

2023 was the world's hottest year on record, the Copernicus Climate Change Service (C3S) reported on Tuesday. According to the EU's Earth observation programme, the unusually high air temperatures were caused by unprecedentedly high sea surface temperatures, which in turn were caused by rising concentrations of greenhouse gases in the atmosphere, El Niño and marine heatwaves.

In its 2023 Climate Highlights report, C3S charts the climate extremes of the past year. Data going back to 1850 shows that 2023 was the warmest calendar year on record. The global average temperature last year was 14.98° C, 0.17° warmer than the previous record set in 2016. Compared to pre-industrial levels from 1850 to 1900, it was 1.48 degrees Celsius warmer.

"The extremes ... dramatically demonstrate how far we are from the climate in which our civilisation evolved"

For the first time, every day in 2023 was at least 1° C warmer than pre-industrial levels. For almost half of the year, it was at least 1.5° warmer. On 17 and 18 November, it was more than 2° warmer - another first.

This does not mean that the limits set in the 2015 Paris climate agreement, which aim to limit warming to 2° C and preferably 1.5°, have been exceeded. The agreement is based on average temperature changes over periods of at least 20 years.

High sea temperatures

According to the report, the unusually high air temperatures were caused by unprecedentedly high sea surface temperatures in the oceans. These, in turn, are caused by increasing concentrations of greenhouse gases, which reached their highest levels ever recorded in the atmosphere in 2023, and the El Niño climate system, which began in July. Marine heatwaves further contributed to the record-breaking temperatures last year.

"The extremes we have seen in recent months dramatically demonstrate how far we are from the climate in which our civilisation evolved," said C3S director Carlo Buentempo. "If we are to successfully manage our climate risk portfolio, we urgently need to decarbonise our economy while using climate data and knowledge to prepare for the future."

^{A heatwave in Seville, Spain, August 2023 © JORGE GUERRERO / AFP}