Overview
- The 10th Copernicus Ocean State Report, published Wednesday, Sept. 30, 2026, says the rate of ocean warming has doubled over the past 20 years and that sea surface temperatures set records in 2023, 2024 and 2026.
- The report found the oceans absorbed a record extra 23 zettajoules of heat last year and that global average sea level has risen about 3.8 millimetres per year since 1999 with acceleration since 2012.
- It documents ecosystem harm from rising heat and acidity, noting oceans are about 17% more acidic since 1985 and that 84% of coral reefs experienced bleaching-level heat stress between January 2023 and September 2025.
- Polar changes are extreme, with Arctic combined sea and ice-surface temperatures rising about 4.2°C since 1982 and Arctic sea ice shrinking by roughly half a million square kilometres per decade, threatening ice-dependent species like emperor penguins.
- The report calls for sustained, permanent ocean observation and capacity building so governments and communities can anticipate impacts to coastal infrastructure, fisheries and island economies.