Global Sea Surface Temperature Reaches Record High of 21.1°C Amid Strengthening El Nino

The daily global average sea surface temperature (SST) has surged to a record, reaching 21.1°C on August 22, according to a report by the Copernicus Climate Change Service (C3S), implemented by the European Centre for Medium-Range Weather Forecasts (ECMWF). This figure exceeds the previous record of 21.09°C set in March 2024.

This reading is unusually late for this time of year. Normally, the warmest global ocean temperatures occur in March and April, following the austral summer. The latest figure also beats the previous highest August value, which was reached in 2023 at 20.98°C. The new daily record follows a series of monthly sea surface temperature records and near-records observed across the extra-polar ocean (60°S to 60°N) throughout 2026, pointing to persistent warmth across the global ocean.

The tropical Pacific is rapidly warming, and a powerful drought-bearing El Nino is taking shape, adding to the long-term warming driven by climate change. The World Meteorological Organization (WMO) has stated that El Nino is likely to strengthen in the coming months, with the C3S seasonal forecasting system indicating the event could reach levels not seen for several decades.

Samantha Burgess, Strategic Lead for Climate at ECMWF, noted that the record is a clear signal of an ocean under growing stress. She stated that while El Nino is adding heat to the system, it builds upon decades of human-driven warming. As ocean temperatures rise, the risks to marine ecosystems and coastal communities increase. The report noted that the number of marine heatwave days globally has more than tripled since the early 1990s.

The steady increase in ocean warming carries major implications for communities and ecosystems. Warmer oceans cause sea levels to rise through thermal expansion, threatening coastal communities and low-lying island nations. Higher temperatures also increase the likelihood and intensity of marine heatwaves, which can devastate key ecosystems like coral reefs and seagrass meadows, disrupting marine food webs and industries such as fisheries and aquaculture.

Additionally, warmer oceans take in more heat and moisture, which can lead to heavier rains and stronger storm systems. The report also highlights that a warmer ocean loses some of its ability to absorb carbon dioxide from the atmosphere, potentially undercutting a vital natural buffer against climate change.

"The continuous rise in global sea surface temperatures presents significant long-term implications for global supply chains, coastal infrastructure, and key industries like fisheries and agriculture. As climate patterns shift and extreme weather risks increase, businesses across sectors will need to factor environmental volatility and climate resilience into their operational and risk management planning." — Dr. Shishir Gupta, Founder & CEO, StartupLanes