North Atlantic is much too hot for the time of year: “The oceans are under constant pressure”

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Never before have the oceans been as hot at this time of year as they are now. The average temperature on June 11 was 20.9 degrees Celsius, according to data from the University of Maine. This is 0.2 degrees above the last record from 2022. The previous maximum temperatures for this year were already reached on April 1 with 21.1 degrees.

That is unfortunately not surprising. Nicolas Gruber, professor of environmental physics at ETH Zurich, explains when asked: “The abnormal temperatures of the sea surface have been increasing for months.” And there is no sign of the situation easing. It’s an alarming development – researchers around the world agree.

But why are our seas getting so warm now? Thomas Frölicher, a climate physicist at the University of Bern, explains: “Human-induced climate change is primarily responsible for the current heat wave.” But not only – there are also natural climate fluctuations.

The water temperature also affects the land

As abstract as the current situation sounds, the effects are real. “When the water gets warmer, it expands, which causes sea levels to rise,” says Frölicher. “In addition, the ice caps are melting faster, which also leads to higher sea levels.”

And that’s not all: “Such extreme temperature fluctuations also affect the organisms in the sea.” In particular, warm water corals – with the Great Barrier Reef as the best-known example –, fish and algal forests are particularly at risk. In a nutshell: “The oceans are under constant pressure.”

Rising temperatures in the sea also have consequences on land, Frölicher explains. “This increases the chance of heat waves and dry periods, but also of heavy precipitation.”

More hurricanes due to ocean heat wave?

The changes in the North Atlantic are particularly strong. Temperatures in the North Atlantic tend to rise in summer, peaking in late August or early September. On March 5, the average temperature reached 19.9 degrees, surpassing the previous record set in 2020 by 0.1 degrees. Rising trend.

This is a particular concern for the Americas, where hurricane season officially began on June 1. The North Atlantic is considered a breeding ground for hurricanes, as American meteorologist Ben Noll points out Twitter writes. “The region has an average temperature of 28 degrees, beating the previous record from 2005.” According to him, 2005 was one of the most active hurricane seasons of all time.

The blob that boiled the Pacific

The fact that there are heat waves in the world’s oceans is not new. As ETH climate researcher Nicolas Gruber recalls, there was a similar — albeit much longer-lasting — phenomenon in the Pacific Ocean eight years ago. In 2015, the North Pacific experienced the largest marine heat wave ever recorded, which came to be known as the “Blob”. At its peak in 2015, the blob covered about 4 million square miles of ocean, stretching from Alaska to Baja California.

“The blob had a huge impact on marine ecosystems, forcing fish and other organisms to migrate in search of cooler habitats,” says Gruber. Extensive blooms of harmful algae have also had a devastating effect on clam and crab fisheries, in turn leading to the mass extinction of seabirds, seals and sea lions, Gruber points out in an article for Carbon Brief.

Gruber describes the blob back then as “truly exceptional” – on the one hand because of its size and duration, after all this heat it lasted for several years. Whether the current record temperature in the North Atlantic could develop into a kind of “Blob 2.0” is still in the stars. “It’s definitely not comparable,” says Gruber.

Source: Blick