Global sea level rose slower than in the previous year. Sea surface temperatures
globally and Australia broke new records. The Great Barrier Reef experienced the fifth bleaching event since 2016.
Oceans absorb 93% of excess heat from climate change. Global ocean heat content increased by 3.6% compared to the previous year, in line with a steady increase in ocean heat over the last three decades. The global mean sea level at the end of 2024 was 1.6 mm higher than at the end of the previous year, when there was a rapid increase. Sea level has increased by 88 mm since 2000 and 108 mm since 1993.
Mean sea surface temperature in 2024 was the highest on record, both globally and around Australia. Ocean temperature was 0.79 °C higher than the 1961–1990 average globally, and 0.89 °C higher in the Australian region. Ocean warming is in line with an unambiguous and steady increase in temperatures since around 1970. The Great Barrier Reef (GBR) experienced above-average sea temperatures. After being hit by tropical cyclone Jasper in December 2023, the Central GBR was affected again by cyclone Kirrily in January 2024. Temperatures peaked in March, triggering the fifth mass coral bleaching event since 2016. Crown-of-thorns starfish outbreaks persisted on some Southern GBR reefs. Although hard coral cover increased across the reef, regional levels remain similar to those in 2022 and 2023, with most surveys conducted before the full impact of bleaching and cyclone damage was clear.
In December 2024, a marine heatwave reached Ningaloo Reef in Western Australia and started a coral bleaching event there
