Global oceans report warns of rapid warming and growing climate risks

Copernicus data shows that the pace of ocean warming has accelerated significantly. The eighth Ocean State Report found that the rate of ocean warming had almost doubled since 2005, while more recent observations show that global sea-surface temperatures have continued to reach record or near-record levels.

In August 2026, the average sea-surface temperature across the extra-polar oceans reached a record high for the month, while daily global sea-surface temperatures also reached an all-time record of about 21.1°C on 22 August. Copernicus said the continuing rise reflects long-term human-caused warming, with El Niño adding further heat to the climate system.

Scientists say warmer oceans can contribute to more frequent and severe marine heatwaves, damage sensitive ecosystems such as coral reefs and seagrass meadows, and disrupt fisheries and other industries that depend on marine environments.

Ocean warming also contributes to rising sea levels because warmer water expands. This increases risks for coastal communities and low-lying islands, while warmer oceans can influence atmospheric circulation, rainfall and tropical cyclone activity.

Another concern is the developing El Niño event in the tropical Pacific. Copernicus reports that El Niño conditions strengthened during 2026 and are expected to intensify further, potentially contributing to exceptionally high global temperatures during the remainder of the year and into 2027.

The effects are already visible in temperature records. July 2026 recorded the highest average sea-surface temperature for that month across the extra-polar oceans, while August also set a monthly record.

The findings highlight the role of human-caused greenhouse-gas emissions in the long-term warming of the ocean. The ocean absorbs the majority of the excess heat trapped in the Earth's climate system, making it a major indicator of the continuing accumulation of heat caused by global warming.

However, individual weather and climate events should not automatically be attributed entirely to climate change. El Niño is a natural climate phenomenon, although its effects are occurring against a background of long-term human-driven warming.

For now, scientists continue to monitor ocean temperatures, heat content, sea levels and marine ecosystems closely. The latest measurements show that the world's oceans remain under significant and increasing thermal pressure, with consequences extending well beyond the marine environment.