Another Year of Record Heat for the Oceans

Changes in ocean heat content (OHC), salinity, and stratification provide critical indicators for changes in Earth's energy and water cycles. These cycles have been profoundly altered due to the emission of greenhouse gasses and other anthropogenic substances by human activities, driving pervasive changes in Earth's climate system. In 2022, the world's oceans, as given by OHC, were again the hottest in the historical record and exceeded the previous 2021 record maximum. According to IAP/CAS data, the 0-2000 m OHC in 2022 exceeded that of 2021 by 10.9 ± 8.3 ZJ (1 Zetta Joules = 1021 Joules); and according to NCEI/NOAA data, by 9.1 ± 8.7 ZJ. Among seven regions, four basins (the North Pacific, North Atlantic, the Mediterranean Sea, and southern oceans) recorded their highest OHC since the 1950s. The salinity-contrast index, a quantification of the "salty gets saltier-fresh gets fresher" pattern, also reached its highest level on record in 2022, implying continued amplification of the global hydrological cycle. Regional OHC and salinity changes in 2022 were dominated by a strong La Niña event. Global upper-ocean stratification continued its increasing trend and was among the top seven in 2022.由于人类活动排放温室气体, 全球能量和水循环已经发生了显著的变化, 驱动了气候系统的一系列变异. 海洋热含量、 盐度和层结变化是地球系统能量和水循环的重要指针. 2022 年, 全球海洋上层 2000 米热含量再破记录, 海洋成为有现代记录以来最热的一年. 据中国科学院大气物理研究所的测算, 2022 年 0–2000 米海洋热含量超过 2021 年 10.9 ± 8.3 泽塔焦耳 (1 泽塔焦耳= 1021焦耳). 与之一致, 美国国家海洋和大气管理局国家环境信息中心的测算为 9.1 ± 8.7 泽塔焦耳. 在所研究的 7 个海盆中, 北太平洋、 北大西洋、 地中海、 南大洋这 4 个海盆的 2022 年度热含量均创下了自上世纪 50 年代以来的新记录. 此外, 定量化测算海洋盐度 “咸变咸, 淡变淡” 变化趋势的 “盐度差指数” 也在 2022 年达到过去半世纪以来的最高值, 反映了全球水循环在不断加速. 在区域尺度, 海洋热含量和盐度变化显示出较强的拉尼娜事件的影响. 最后, 全球上层 2000 米海洋层结也持续加强, 2022 年全球海洋层结处于有现代记录以来的第 7 高位.