Parts of the North Atlantic are witnessing an ‘exceptional’ marine heatwave

A marine heatwave described as “exceptional” is occurring in parts of the North Atlantic, particularly impacting the coasts of the United Kingdom and Ireland, where the highest sea-surface temperatures are being recorded.

According to the National Oceanic and Atmospheric Administration (NOAA), April and May of this year reported the highest ocean surface temperatures since records began in 1850.

Certain areas in the North Atlantic are experiencing a Category 4 marine heatwave, characterized as “extreme,” with water temperatures in some regions up to 5 degrees Celsius (9 degrees Fahrenheit) higher than usual.

The UK Met Office noted that sea-surface temperatures in the North Atlantic were approximately 1.25 degrees Celsius (2.25 degrees Fahrenheit) above average in May.

Stephen Belcher, the chief scientist at the Met Office, highlighted that the eastern Atlantic, from Iceland to the tropics, is significantly warmer than usual, while parts of northwestern Europe, including the UK, are experiencing some of the highest relative sea-surface temperatures.

Scientists have expressed concern about the potential adverse impacts of such a climatic event on marine life. Rising ocean temperatures have been linked to incidents such as mass fish deaths along the Gulf Coast in Texas, where warmer water holds less oxygen. In 2021, an extreme heatwave caused the death of approximately one billion shellfish on Canada’s West Coast.

Experts have described the spike in the Atlantic heatwave as “totally unprecedented” and expressed alarm at the rapid changes occurring in the ocean basin.

Several factors contribute to the increase in sea surface temperatures, with El Niño being a primary cause. El Niño refers to the abnormal warming of surface waters in the eastern Pacific Ocean and tends to have a global warming effect.

Other factors that may contribute to the temperature rise include reduced dust from the Sahara, which usually helps cool the region by reflecting sunlight. Weaker-than-average winds have also played a role, as strong westerly winds typically cool the ocean surface.