Upper Ocean Temperatures Hit Record High in 2020 Advances in Atmospheric Sciences

The long-term warming of the ocean is a critical indicator of both the past and present state of the climate system. It also provides insights about the changes to come owing to the persistence of both decadal variations and secular trends, which the ocean records extremely well (Hansen et al., 2011; IPCC, 2013; Abram et al., 2019). It is well established that the emission of greenhouse gasses by human activities is mainly responsible for global warming since the industrial revolution (IPCC, 2013; Abram et al., 2019). The increased concentration of heat-trapping greenhouse gases in the atmosphere has interfered with natural energy flows, and currently there is an energy imbalance in the Earth’s climate system of almost 1 Wm-2 (Trenberth et al., 2014; von Schuckmann et al., 2016; Wijffels et al., 2016; Cheng et al., 2019; von Schuckmann et al., 2020a). Over 90% of this excess heat is absorbed by the oceans, leading to an increase of ocean heat content (OHC) and sea level rise, mainly through thermal expansion and melting of ice over land, providing a useful means to quantify climate change. Grant no. NA14NES4320003