Undersea Heat Wave Worries Scientists

According to the World Meteorological Organization, June and the first days of July were the hottest days on record.

Residents of the southern United States and southern Europe have endured warmer temperatures, numerous heat advisories, wildfires and severe declines in air quality. However, records have been broken not only on land, but also in water.

The Global sea surface temperatures were higher Especially with more North Atlantic satellite measurements than any other June on record, according to a report by the Copernicus Climate Change Service.

Last month was set by the National Oceanic and Atmospheric Administration (NOAA) for the largest difference between expected and actual temperatures.

Water temperatures around Florida were particularly warm.

Researchers are also tracking a large oceanic heat wave underway off the west coast of the United States and Canada that formed in May.

According to the science NGO Mercator Ocean International, the heat wave has slowed in the northeast Atlantic. Another appears to be intensifying in the western MediterraneanEspecially around the Strait of Gibraltar.

Extreme sea temperatures are also observed in areas near Ireland, the United Kingdom and the Baltic Sea, as well as New Zealand and Australia. More recently, scientists have suspected a possible heat wave South of GreenlandIn the Labrador Sea.

“There are these huge ocean heat waves in different parts of the ocean that form unexpectedly early in the year, very strong and in large areas,” says oceanographer Karina von Schuckmann of Mercator Ocean.

Carlo Buontempo, director of the European Union’s Copernicus Climate Change Service, says scientists Expect large temperature variations in the Pacific OceanAssociated with the El Niño weather pattern, a phase of global warming is just beginning, although NOAA is tracking a major heat wave in the Gulf of Alaska that has been in the ocean since 2022.

But what we see now in the North Atlantic is true “unprecedented”Buontempo says.

Scientists are still trying to unravel all the reasons.

Short-term changes in regional oceanic and atmospheric circulation patterns can provide periods of extreme ocean heat for weeks, months, and even years.

But still Long term increase Rising ocean temperatures driven by increases in greenhouse gas emissions have been a major factor in recent heat waves.

near 90% more heat Anthropogenic climate change stored in the seaAnd the rate of heat accumulation in the Earth’s climate system has doubled over the past two decades.

A 2021 report by the Intergovernmental Panel on Climate Change (IPCC) found that ocean heat waves doubled in frequency between 1982 and 2016 and returned. The most intense and long since the 1980s.

Another possible contributing factor is the amount of aerosols in the atmosphere, which have a small cooling effect. But this seems to have subsided as a result of efforts to clean up the shipping sector.

Recently, an unusual situation has occurred Saharan dust scarcityIt usually produces chills.

Even today’s ocean heat waves can get worse. Although experts do not believe El Niño is the driving factor in the North Atlantic, the WMO expects it to contribute to the warming of the oceans in general.

Experts have expressed concern that ocean heat waves may be affected Life in the oceans, fisheries and weather patterns.

The summer of 2010/2011 was the hottest temperature ever recorded on the west coast of Australia. “Catastrophic” fish mortality And destroyed kelp forests, And fundamentally changed the coastal ecosystem.

Years later, an unprecedented ocean heat wave caused by climate change and amplified by a strong El Niño led to the worst. Coral bleaching Spotted on the Great Barrier Reef in 2016.

Ocean heat waves can trigger coral bleaching events and add to the stress corals are already under. Reef ecosystems All over the world.

High temperatures cause coral polyps to expel the zooxanthellae that live in their tissues, turning them white and more vulnerable to disease and other threats.

In the Mediterranean Sea, exceptional temperatures between 2015 and 2019 caused repeated mass die-offs of key species such as corals and algae. A recent study described these types of ocean heat waves as “widespread stressors for global marine ecosystems.”

Ocean heat waves also facilitate proliferation Invasive creature. For example, Japanese kelp flourished in New Zealand when the 2017-2018 ocean heat wave in the Tasman Sea wiped out the area’s native kelp.

Dan Smale, a marine ecologist at the UK Society of Marine Biology and a member of the International Working Group on Ocean Heat Waves, says: “Short and quick feet” They don’t give species time to redistribute, and those within the range their bodies can support are particularly at risk.

But around the British coast, it is not considered an extreme environment and scientists expect ecosystems to change gradually, which could be dangerous if the ocean heatwave continues throughout the summer.

However, there is much more to learn about the impact of ocean heat waves compared to land-based heat waves because they are more difficult to monitor and lack long-term records, says Small.

“The information that satellites have been giving us since the early 1980s has been fantastic…the problem is when we try to go further,” he says.

A significant decline in numbers Phytoplankton This has already been seen in the North Atlantic, with the Mercator Ocean responsible for recent heat waves.

The spring bloom is particularly important because it provides much of the energy needed to sustain the marine food chain in the area and is a significant contributor to global CO2 absorption from the oceans.

The economy of Regional fisheries can also be affected.

A heat wave in the Northwest Atlantic in 2012 changed when and how many species could catch warm water north and migrate early.

The North Atlantic is also a major driver of extreme weather.

leading to higher sea surface temperatures hurricane, It remains to be seen whether an El Nino event will amplify or moderate this effect next year.

On the other hand, the warming of the North Atlantic water is the most important factor behind the alternating circulation between sDrought and abundant rain in Central Africa.

Overall, experts say, the recent ocean heat waves are a worrying sign of how climate change is playing out with heat waves on land, freezing ice in the Himalayas and loss of sea ice.

Even if humans stop pumping CO2 into the air tomorrow, Von Schuckmann says. Oceans will continue to warm for years to come.

“I worry as a climate scientist that we are further along than we thought.”

By Isabella Kaminsky

BBC News World

BBC World