Ocean Heat Reach Record Highs in May 2023

The European Union’s climate monitoring unit has reported that global oceans were warmer in May 2023 than any other May in records dating back to the 19th century. The Copernicus Climate Change Service (C3S) reported that sea temperatures were a quarter of a degree Celsius higher than ice-free oceans in May when compared to the period between 1991 and 2020. The increase is caused by year-round, long-term trends that have added 0.6C to the ocean’s surface waters in 40 years, according to Samantha Burgess, C3S deputy director. She noted that April had also seen a new record for heat. Burgess warned that ocean temperatures could rise further in the coming months due to the emergence of the El Nino signal in the equatorial Pacific. El Nino is a periodic shift in ocean winds that enhances warming globally.

Impact of Global Warming on Oceans

Oceans cover 70 percent of Earth’s surface and have kept the planet liveable as global warming caused by human activity accelerates. The surface of the planet is, on average, 1.2C hotter than pre-industrial levels, which has already unleashed devastating climate impacts. Oceans absorb a quarter of the CO2 humans spew into the atmosphere and 90 percent of the excess heat generated by climate change. However, this ability comes at a price. Widespread marine heatwaves are destroying coral reefs and the ecosystems dependent on them, including over half-a-billion people. The accelerated disintegration from below of giant ice sheets could lift oceans by a dozen meters. Ocean acidification is disrupting life cycles and food chains from the tropics to the poles. Oceans, forests, and soil, which soak up an even larger percentage of human-generated greenhouse gases, are showing signs of battle fatigue, and their capacity to soak up CO2 could diminish.

In addition to the rising ocean temperatures, Copernicus reported that temperatures in several parts of the world were higher than normal, including Canada, where wildfires have destroyed over three million hectares (8 million acres) in recent weeks. There are 413 wildfires burning across the country from Pacific to Atlantic, including 249 deemed “out of control.”

Earlier this month, the World Meteorological Organization (WMO) said there’s a 60 percent chance that an El Nino will form before the end of July and an 80 percent change by the end of November. Most of the warmest years on record have occurred during El Ninos, and scientists are concerned that this summer and next could see record temperatures on land and in the sea.

In Antarctica, sea ice extent reached a monthly record low for the third time this year, with satellite data showing it was 17 percent below average in May.

The Copernicus report is based on computer-generated models that draw on billions of measurements from satellites, ships, aircraft, and weather stations worldwide.