The world’s oceans experience the highest-ever recorded temperature. Recent data from the EU’s Copernicus climate change service reveals that the average daily global ocean temperature has surpassed all previous records, including one set in 2016, reaching 20.96°C (69.73°F).

Oceans absorb excess heat from the atmosphere. The surge in ocean temperatures impacts this capacity, leading to a rise in planet-warming carbon dioxide retention in the atmosphere.

Rising temperatures can accelerate the melting of glaciers that flow into the ocean, contributing to the already worrying issue of sea level rise. Low-lying coastal areas and island nations are at particular risk of flooding and extreme weather events.

Heatwaves and hot waters force marine life to seek cooler habitats. It disrupts their natural behaviour and migration patterns. This, in turn, can profoundly impact the food chain and fish stocks. This affects both marine ecosystems and the communities that depend on them for sustenance and livelihoods. Certain predatory animals like sharks may exhibit increased aggression due to confusion caused by changing environmental conditions.

Shallow reefs in Florida experienced widespread coral bleaching. This phenomenon occurs when corals expel algae living in their tissues, leaving them vulnerable and prone to mortality.

Climate change, pollution, overfishing, and other stressors push marine ecosystems to collapse. Pollution from plastics, agricultural runoff, and industrial waste degrade water quality, affect marine life, and have devastating consequences for the entire ecosystem.

Experts assert that the oceans are under more pressure now than ever before in history. Dr Samantha Burgess, from the Copernicus Climate Change Service, points out the unexpected timing of this record-breaking event. Traditionally, March is the month when oceans reach peak warmth globally. However, this year’s record in August raises concerns about how much hotter the oceans could become by the following March.

Dr Burgess explains that the continued burning of fossil fuels will perpetuate the time it takes for the oceans to stabilise and return to their previous state. Urgent action to reduce greenhouse gas emissions is crucial to halt the further escalation of ocean temperatures and mitigate the ensuing impacts on the planet.

The new average temperature record surpasses the one set during the 2016 El Niño. El Niño is a natural climate fluctuation characterised by ocean surface temperatures warming off the west coast of South America.

In June, UK waters experienced temperatures 3°C to 5°C higher than average.

Florida recently experienced a sea surface temperature of 38.44°C (101°F), exceeding the usual range of 23°C to 31°C, according to the National Oceanic and Atmospheric Administration (NOAA).

Between 1982 and 2016, the frequency of these heatwaves doubled, with intensification and longer durations observed since the 1980s.

Dr Karina von Schuckmann, at Mercator Ocean International, explains that a plausible explanation for the surge in ocean temperature is the release of stored heat from the deeper ocean layers. Over the years, much of the excess heat from greenhouse gas emissions has been absorbed and stored in the ocean’s vast depths.