Globally, CO2 emissions and climate change are accelerating. 2023 saw the highest temperatures in the atmosphere and in the oceans ever recorded, the least sea ice ever observed, and a rapid increase in sea level.
Atmospheric CO2 concentration increased by 2.6 ppm, which is 41% faster than the previous year and 16% faster than the average 2000–2022 growth rate. The rapid increase was due to a combination of ever-increasing fossil fuel emissions and a change to El Niño conditions during 2023.
The average CO2 concentration reached 421 ppm, a 33% increase from 1960. Global average air temperature was the highest on record by a considerable margin. It was 0.32 °C higher than the previous year and 1.18 °C above the 20th-century average. The last ten years (2014–2023) all rank as the ten warmest on record.
The maximum ozone hole extent was 2% smaller than the previous year. It was 5% larger than the 2000–2022 average but 13% below the maximum extent observed in 2000. The ozone hole has not shrunk over the last two decades but may have stabilised.
Oceans absorb 93% of excess heat from climate change. Global ocean heat content increased by 4.8% compared to the previous year. Globally, sea surface temperatures were the highest on record in 2023. The global mean sea level rose by 11.7 mm in 2023; the most rapid rise since 2015. Sea level has increased by 85 mm since 2000 and 101 mm since 1993.
Sea ice extent was 2% less than the previous year in the Arctic and 8% less around Antarctica, where it broke the record set the previous year. Ice extent on both hemispheres combined was 5.0% less than the previous year, the lowest on record and 9.5% lower than the 2000–2022 average.
