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Ocean temperatures hit a record high this week with the worst heat still to come

The world’s ocean surface temperatures have surged to an all-time high, and scientists warn that they’re set to climb even further. 

According to data from the Copernicus climate modeling service, the global average daily sea surface temperature (SST) reached a blistering 20.96C this week, marginally surpassing the previous record of 20.95C set in 2016.

Peak ocean temperatures

Dr. Samantha Burgess, a researcher from Copernicus, voiced her apprehension about the development. “The fact that we’ve seen the record now makes me nervous about how much warmer the ocean may get between now and next March,” said Dr. Burgess. 

Interestingly, the peak ocean temperatures typically occur in March, not August. This suggests that we could indeed break the current record.

El Niño impact

El Niño is the recurrent climate pattern involving changes in the temperature of waters in the central and eastern tropical Pacific Ocean. Researchers have implicated it as a factor driving these unprecedented temperatures.

Coincidentally, 2016 was also an El Niño year. However, we cannot overlook the incendiary effects of burning fossil fuels.

“The more we burn fossil fuels, the more excess heat will be taken out by the oceans, which means the longer it will take to stabilize them and get them back to where they were,” said Dr. Burgess.

Political actions on ocean temperatures

The timing of this news appears to be in stark contrast with recent political actions. This week, British Prime Minister Rishi Sunak announced plans to grant over 100 new oil and gas licenses in the North Sea, a move that diverges from the recommendations of climate experts.

Ocean and climate

Oceans play a fundamental role in regulating Earth’s climate. They absorb heat, influence weather patterns, serve as carbon sinks, and offer respite by emanating cool air that mitigates hot terrestrial temperatures. But as ocean temperatures rise, these beneficial functions are undermined. 

Warmer waters also absorb less carbon dioxide, which consequently leads to an increased concentration of this greenhouse gas in our atmosphere. The net effect is a vicious cycle that further aggravates climate change.

Warming trend

Sea surface temperature measurements, dating back over 150 years, are among the most enduring instrumental records aiding our understanding of the climate. Leveraging this wealth of data, scientists have found that the global mean sea surface temperature has risen by close to 0.9C over the entire period of the records. The rise over the past four decades alone is approximately 0.6C.

Regions such as parts of the Arctic Ocean, the Baltic Sea, the Black Sea, and areas of the extra-tropical Pacific are experiencing the brunt of this warming trend. They’ve been hit with multiple marine heatwaves this year, with the waters off Florida reaching a staggering 38C last week. Earlier this summer, the weather also affected the UK and Ireland.

Increasingly frequent heatwaves 

A 2019 study found that these marine heatwaves are becoming alarmingly frequent, with the number of heatwave days having tripled in recent years. Much like the way wildfires devastate large forest areas, these heatwaves inflict extensive damage on marine life. 

The impacts for humans are far-reaching as well. We depend on the oceans for oxygen, food, storm protection, and for the removal of carbon dioxide from the atmosphere. 

Ocean-climate interactions 

In ways critical to life on Earth, the oceans and the climate share an intimate interconnection. Here are some of the key ways in which they interact:

Heat regulation

Oceans act as the planet’s primary heat regulator. They absorb about 90% of the excess heat trapped by greenhouse gases. Without the oceans, the land would heat much more quickly and dramatically.

Carbon dioxide absorption

Oceans are a major “carbon sink,” meaning they absorb large amounts of carbon dioxide from the atmosphere. This helps to mitigate the impact of human-induced carbon emissions. However, as the water temperature increases, its capacity to absorb carbon dioxide decreases, leading to higher concentrations of CO2 in the atmosphere.

Weather and climate patterns

Oceans influence weather and climate patterns around the world. They help to distribute heat around the planet via currents, which influence weather systems and climate zones. Warm water from the equator is transported towards the poles, while cold water from the poles is transported towards the equator.

Sea level rise from from ocean temperatures

Warmer temperatures cause seawater to expand, and ice (such as glaciers and ice sheets) to melt, both of which contribute to sea level rise. Rising sea levels pose a significant threat to coastal communities and ecosystems.

Ocean acidification

When oceans absorb carbon dioxide, it reacts with seawater to form carbonic acid, leading to ocean acidification. This negatively affects many marine organisms, particularly those with calcium carbonate shells or skeletons, including oysters, clams, sea urchins, shallow water corals, deep sea corals, and calcareous plankton.

El Niño and La Niña 

These refer to fluctuations in the temperature of the surface waters in the Pacific Ocean, which have major impacts on global weather patterns. El Niño leads to warmer waters (and consequently, a rise in global temperatures), while La Niña leads to cooler waters.

The intensifying cycle of ocean warming, ice melt, and sea level rise are among the most concerning aspects of climate change. Scientists around the world are closely monitoring these developments to better understand future impacts and devise mitigation strategies.


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