Another Record: Ocean Warming Continues through 2021 despite La Niña Conditions

Abstract

The increased concentration of greenhouse gases in the atmosphere from human activities traps heat within the climate system and increases ocean heat content (OHC). Here, we provide the first analysis of recent OHC changes through 2021 from two international groups. The world ocean, in 2021, was the hottest ever recorded by humans, and the 2021 annual OHC value is even higher than last year’s record value by 14 ± 11 ZJ (1 zetta J = 10²¹ J) using the IAP/CAS dataset and by 16 ± 10 ZJ using NCEI/NOAA dataset. The long-term ocean warming is larger in the Atlantic and Southern Oceans than in other regions and is mainly attributed, via climate model simulations, to an increase in anthropogenic greenhouse gas concentrations. The year-to-year variation of OHC is primarily tied to the El Niño-Southern Oscillation (ENSO). In the seven maritime domains of the Indian, Tropical Atlantic, North Atlantic, Northwest Pacific, North Pacific, Southern oceans, and the Mediterranean Sea, robust warming is observed but with distinct inter-annual to decadal variability. Four out of seven domains showed record-high heat content in 2021. The anomalous global and regional ocean warming established in this study should be incorporated into climate risk assessments, adaptation, and mitigation.

摘要

人类活动导致大气中温室气体的浓度上升,造成了地球系统的净热量吸收和海洋热含量增加。本文发布了两个国际机构的2021年海洋热含量数据,数据表明:2021年海洋升温持续——成为有现代海洋观测记录以来海洋最暖的一年。相对于2020年,2021年全球海洋上层2000米热含量上升了14 ± 11 ZJ (1 zetta J = 10²¹ J)(IAP/CAS数据)、以及16 ± 10 ZJ(NOAA/NCEI数据)。海洋长期变暖趋势在南大洋、中低纬度大西洋区域更强,地球系统模式的单个因子强迫实验证明,温室气体增加是主要的驱动因子;而年际尺度的海洋热含量变化主要受到厄尔尼诺-南方涛动模态调控。此外,本文给出了全球7个主要海域的海洋变暖测算,发现地中海、北大西洋、南大洋、北太平洋海区温度均创历史新高。最后,本文提出需要充分将全球和区域海洋变暖的影响纳入气候风险评估、气候变化影响和应对当中。