The world's oceans are experiencing their highest-ever recorded temperatures, driven by the relentless impact of climate change, with severe implications for the planet's well-being.
According to the EU's climate change service Copernicus, the average daily global sea surface temperature recently surpassed the 2016 record, reaching a staggering 20.96°C (69.73°F), well above the usual levels for this time of the year.
The oceans serve as a critical climate regulator, absorbing heat, generating half of the Earth's oxygen, and shaping weather patterns. However, the warming waters are becoming less efficient at absorbing carbon dioxide, leading to an increase in the concentration of this planet-warming gas in the atmosphere. Moreover, this rising temperature can accelerate the melting of glaciers that flow into the ocean, exacerbating sea-level rise.
As the oceans and heatwaves grow hotter, marine species such as fish and whales are forced to migrate in search of cooler waters, disrupting the delicate balance of the food chain. Fisheries could also be affected, as some predatory species like sharks may become more aggressive due to confusion caused by warmer temperatures.
Dr. Kathryn Lesneski, monitoring a marine heatwave in the Gulf of Mexico for the National Oceanic and Atmospheric Administration, describes the water feeling like a warm bath, with widespread coral bleaching and coral death in Florida.
Adding to the stress on oceans is pollution and overfishing, further complicating the situation, warns Dr. Matt Frost from the Plymouth Marine Lab in the UK.
The timing of this unprecedented temperature record is concerning, as it occurred in August, while traditionally, March is when the oceans should be at their warmest globally, according to Dr. Samantha Burgess from the Copernicus Climate Change Service. The occurrence of this record raises fears of how much warmer the oceans may become before next March.
Scientists are diligently investigating the reasons behind the unusually high ocean temperatures. The primary driver remains climate change, as the seas absorb most of the heat from greenhouse gas emissions. The more fossil fuels are burned, the longer it will take to stabilize ocean temperatures.
This broken temperature record supersedes the previous one set in 2016 during the powerful El Niño climate fluctuation. Although another El Niño has started, it is still weak, indicating that ocean temperatures are likely to rise further above average in the upcoming months.
Throughout this year, a series of marine heatwaves have affected various regions, including the UK, the North Atlantic, the Mediterranean, and the Gulf of Mexico. These occurrences in unexpected locations underscore the severity of the situation, with temperatures in UK waters being 3 to 5 degrees Celsius higher than average in June, and sea surface temperatures reaching as high as 38.44°C (101°F) in Florida, way beyond the usual range.
The Intergovernmental Panel on Climate Change (IPCC) notes that marine heatwaves have doubled in frequency and become more intense and prolonged since the 1980s. While air temperatures have seen dramatic increases, ocean temperatures have taken longer to rise, despite absorbing 90% of the Earth's warming from greenhouse gas emissions. There are indications that the stored heat in ocean depths may now be surfacing, potentially linked to El Niño.
Scientists are still investigating the precise reasons behind this surge in ocean temperatures. While they expected sea surface warming due to greenhouse gas emissions, the extent of the recent escalation remains a subject of intense research. The urgency to address and mitigate climate change is greater than ever as the oceans face an unprecedented crisis that reverberates throughout our planet.