An intense marine heat wave sets record ocean temperatures in the North Atlantic

It’s not just land that’s seeing record heat.

Ocean waters in the Northern Hemisphere have been unusually warm in recent weeks, with parts of the North Atlantic and North Pacific experiencing particularly intense marine heat waves.

Sea surface temperatures in these areas reached record levels this summer, said Dillon Amaya, a researcher at the National Oceanic and Atmospheric Administration’s Natural Sciences Laboratory in Boulder, Colorado. Parts of the Pacific and North Atlantic were anywhere from 2 degrees Celsius (3.6 degrees Fahrenheit) to 5 degrees Celsius (9 degrees Fahrenheit) warmer than average at times, conditions not seen since record-keeping began. since about six decades.

“They’ve been very extreme — some of the hottest temperatures we’ve seen in history — and have been for several months,” Amaya said.

The oceans naturally absorb and store heat, making these reservoirs good indicators of how much the planet is warming. Studies have shown that the oceans have absorbed more than 90% of the heat trapped on Earth by greenhouse gas emissions since 1970.

As climate change causes the rate of ocean warming to accelerate, scientists are concerned about the potential consequences for marine ecosystems, sea level rise and extreme weather events.

NOAA’s annual “State of the Climate” report, released Aug. 31, found that ocean heat, as measured from the surface to a depth of more than 6,000 feet, was the highest on record in 2021.

The increase in the ocean’s base temperature is worrisome, Amaya said, because it makes marine heat waves more likely to occur and persist for long periods of time.

“Each marine heat wave will be warmer than the last due to increases in greenhouse gases,” he said.

Researchers pay close attention to these temperatures because warmer oceans can intensify storms and increase the risks of extreme weather.

And globally, melting ice from warmer oceans can accelerate sea-level rise, posing significant threats to coastal communities and low-lying infrastructure. NOAA’s State of the Climate report found that global mean sea level in 2021 rose to new record highs for the 10th year in a row.

But the warmer-than-usual waters are also having an effect on the chemistry of the world’s oceans, with carbon dioxide absorbed from the atmosphere making ocean water more acidic. That acidification, combined with persistent heat in some bodies of water, can have a big impact on marine life, said Kathy Mills, a researcher at the Gulf of Maine Research Institute, a nonprofit organization.

Marine heat waves can, for example, change the migration patterns of some marine creatures, put new pressure on the area’s fish and invertebrates, or even cause invasive species to prevail, he said. Part of her research includes studying the effects of ocean warming on marine ecosystems and the subsequent effects on local economies.

Mills and her colleagues found that some species, such as northern shrimp and cod, have struggled with the warmer conditions, while the American lobster has fared better with the changing temperatures.

“We’re trying to understand how this will affect the biology of the organisms, the population-level effects on the species, and then what those changes will mean for fisheries in the area,” Mills said.

NOAA forecasts indicate that current marine heat waves in the North Pacific and North Atlantic oceans could persist for several more months. Amaya said it’s a worrying sign of what’s to come if global warming continues unabated.

“There’s definitely something going on right now,” he said. “This tells me that there is something persistent in the climate system that makes these marine heat waves persist for a very long time.”

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