evidence: The long-term trend towards higher temperatures is being driven by man-made global warming. However, year-to-year rankings are likely to reflect short-term natural variability. In 2023, an emerging El Niño event combined with other natural and man-made factors discussed below to create a record-breaking warm year. By contrast, 2021 and 2022 had somewhat lower temperatures due to a persistent a La Niña event. The cyclic warming and cooling due to El Niño and La Niña is one of the largest sources of year-to-year internal variability in the global average temperature, often adding or subtracting 0.1 °C from the global average. 2023 was a highly unusual year in several respects, including record warmth in most ocean basins and a large deviation from the historical trend. Warmth in 2023 greatly exceeded expectations, and was much stronger than normal this early in an El Niño. Some studies have recently argued that the pace of global warming may be accelerating, and some of the evidence for this is discussed below. However, given historical variability in surface temperatures, it still remains too early to conclude whether or not the pace of surface warming has increased. [...] - New national record high annual averages for an estimated 77 countries, including Bangladesh, Brazil, China, Germany, Japan, and Mexico - Record annual average warmth in both the land-average and ocean-average - Record warmth in most ocean basins, including once-in-a-century levels of warmth in the North Atlantic - Record low Antarctic sea ice during the Antarctic winter - An emergent strong El Niño event, contributing significantly to the record warmth