Global Ocean Temperatures Reach Absolute Record High

The global average sea surface temperature reached an all time high of 21.1 degrees Celsius on August 22, according to the Copernicus Climate Change Service. This figure surpasses the previous record of 21.09 degrees Celsius set in March 2024. Scientists noted that ocean temperatures typically peak in March and April, making the August timing of this record particularly surprising. The data indicates that the oceans have been warming at a rapid pace since records began in 1979.

Experts attribute this record to a combination of long term anthropogenic climate change and a strong El Niño event currently developing in the tropical Pacific. Samantha Burgess of the ECMWF stated that El Niño is adding heat to a system already affected by decades of human caused warming. Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research added that the record is primarily a result of global heating caused by greenhouse gas emissions from the burning of oil, gas, and coal.

The consequences of this warming are already evident. The number of marine heatwave days globally has more than tripled since the early 1990s. Such warming increases the risk to marine ecosystems, including the widespread death of coral reefs, and threatens coastal communities through thermal expansion and rising sea levels. Additionally, warmer oceans transfer more heat and moisture to the atmosphere, which can intensify storms and precipitation. A warmer ocean also becomes less efficient at absorbing carbon dioxide, which weakens a critical natural buffer against climate change.