Ocean Temperatures Surge Faster Than Expected, Copernicus Warns of Accelerating Change

According to the Copernicus marine service, surface waters across the globe have warmed to above 21 °C by late September, a rise of about 0.7 °C compared with the 1991-2020 baseline. In its tenth annual ocean report, the program warns that the pace of warming has accelerated, doubling in the last twenty years. This thermal expansion, combined with melting continental ice, is driving sea-level rise at an estimated 4.2 mm per year between 2012 and 2025, up from 2.6 mm in the preceding two decades.

The report also documents a 17 % increase in ocean acidity since 1985, a shift that hampers the formation of shells and other calcium-carbonate structures. Researchers attribute these changes to ongoing greenhouse-gas emissions and a likely unprecedented El Niño developing in the Pacific. The findings underscore deepening transformations in marine ecosystems and heightened climate risks.