Global Climate Bulletin of the American Meteorological Society

Globally, 2023 was the warmest year since records began in the mid-1800s to mid-1900s, according to all seven global temperature datasets. The prolonged La Niña that began in 2020 faded at the start of 2023 and was replaced by a strong El Niño by the end of the year. The change to El Niño conditions contributed to exceptionally high temperatures worldwide, especially in the latter part of the year as the El Niño strengthened. The pervasive warmth was highlighted by widespread and intense temperature extremes, with record numbers of warm days globally and the third-highest land fraction experiencing record numbers of warm days. Also, globally averaged lake surface temperatures in the warm season were the highest since records began in 1995. Over the oceans, night-time air temperatures likewise reached record values. Not only was the near-surface affected, but the lower troposphere average had record temperatures, with particularly exceptional values over the tropics in the latter part of the year. The stratosphere, which usually cools in response to anthropogenic carbon dioxide (CO2) increases, also warmed this year, reflecting a recovery from the Hunga Tonga–Hunga Haʻapai (HTHH) eruption in 2022. Grant no. NA22OAR4320151 Grant no. NA19NES4320002