Ocean surface temperatures reach record high

The global ocean surface temperature reached 21.1°C (approximately 70°F) in early April, the highest recorded ocean surface temperature since records began. The recorded high beat the previous highest ocean surface temperature of 21.0°C, recorded in 2016.

The daily Sea Surface Temperature hit 21.1°C on April 1 and remained there through April 6, as recorded by the Climate Reanalyzer, a tool from the University of Maine’s Climate Change Institute.

“The current trajectory looks like it’s headed off the charts, smashing previous records,” Matthew England, a climate scientist at the University of New South Wales, told The Guardian.

While the previous few years, under La Niña conditions, saw slightly cooler sea surface temperatures, experts are now seeing heat rising up to the ocean surface. Global warming can further contribute to rising ocean temperatures, and globally, we are seeing an average of 0.32° F (0.18° C) warming per decade.

The record ocean surface temperatures could foreshadow El Niño conditions later in 2023. With these patterns, we could see more flooding around the Gulf Coast in the U.S. and in the southeastern part of the country. Warming ocean surface temperatures can also alter food webs and marine ecosystems.

In 2016, when the previous highest sea surface temperature was recorded, El Niño was occurring. This phenomenon typically happens when global temperatures are higher, and as The Washington Post reported, last month had a global average temperature about 0.92°F higher than the normal temperature recorded for 1991 to 2020.

With La Niña, the impacts of greenhouse gas emissions and global warming are often subdued, making surface temperatures cooler.

“The recent ‘triple dip’ La Niña has come to an end. This prolonged period of cold was tamping down global mean surface temperatures despite the rise of greenhouse gases in the atmosphere,” said Mike McPhaden, a senior research scientist at the National Oceanic and Atmospheric Administration, as reported by The Guardian. “Now that it’s over, we are likely seeing the climate change signal coming through loud and clear.”

Warmer ocean surface temperatures may also mean more marine heatwaves, and the conditions leading to ocean warming may also lead to increasing temperatures on land. Researchers are already recording an unusually high amount of extreme marine heatwaves occurring at once. Rising temperatures and increasing heatwaves can lead to several negative consequences, from melting ice and increasing sea level rise to more severe storms and risks to marine life, including coral bleaching events.