tl;dr: Global average sea surface temperature (excluding polar regions) hit a record 21.1°C on Saturday, per Copernicus data, surpassing the previous March 2024 peak—notable because ocean temps typically peak in March/April, not August. Scientists attribute this to human-caused climate change compounded by an intensifying El Niño, with further records likely as El Niño peaks. Consequences include stronger storms, rising sea levels, and stressed marine ecosystems, with regions like the western English Channel experiencing over three years of near-continuous marine heatwave conditions.