Oceans heat up unusually quickly in a short time
Science is alarmed: the world’s oceans have suddenly heated up to an unusual extent in the past few weeks. The values are well above the record levels. Researchers are now trying to find out what this means and whether the development indicates an increase in global warming.
Some attribute the higher sea temperatures to a warming “El Niño” weather phenomenon brewing in potentially great magnitude, and a three-year rebound of its cooling counterpart “La Niña”. Both amplify the ongoing global warming that is heating the weather at greater depths. If correct, record ocean temperatures this month could be surpassed by many more.
According to the University of Maine’s renowned Climate Reanalyzer platform, the average surface temperature of the world’s oceans has risen by almost two-tenths of a degree Celsius since the beginning of March. That may not sound like much. But for the world’s oceans, which cover 71 percent of the Earth’s surface, the increase in the short space of time is “huge,” according to University of California climate scientist Kris Karnauskas Colorado says, “This is an incredible departure from an already warm state.”
Experts exchange information about the data with each other and on social media. Some, including Michael Mann of the University of Pennsylvania, don’t see too much cause for concern: they say it’s just an increasing “El Niño” effect combined with ongoing human-caused warming.
The sea has become warmer, especially off the coast of Peru and Ecuador, where most El Niño phenomena had started before the 1980s. The effect is the natural warming of parts of the equatorial Pacific, which is changing the weather around the world and causing temperatures to rise. For three years through March, the world was under the influence of the chilling antagonist “La Niña,” which was unusually strong and long-lasting, causing extreme weather events.
Other climate researchers, including Gregory C. Johnson of the US weather and oceanographic agency NOAA, are convinced that “El Niño” is not the sole reason for the warming of the oceans. Among other things, warming in the northern Pacific near Alaska and off the coast of Spain, the oceanographer explains.
Climate scientist Gabe Vecchi from Princeton University makes a similar statement. “It’s an unusual pattern,” he says. “This is an extreme event on a global scale” that cannot only be attributed to “El Niño”. “It’s a huge, huge signal.”
To first see where the sudden increase is greatest, expert Karnauskas subtracted the average temperature anomalies over the previous months from the anomalies in sea surface temperatures. The result: Much of the global warming was due to a long strip across the equator from South America to Africa, spanning both the Pacific and Indian oceans. That area warmed by four-tenths of a degree in just 10 to 14 days, which is highly unusual, Karnauskas says.
In parts of the area, a stronger “El Niño” is clearly on the way, which could be confirmed scientifically in the coming months, the researcher explains. But the region in the Indian Ocean is different: It could either be a coincidental, simultaneous, independent increase or it could be connected to a possible super “El Niño”. “We’re already starting at a greatly elevated level, a baseline of truly warm global ocean temperatures, including the tropical Pacific and Indian Oceans,” says Karnauskas. “And suddenly there’s an evolving El Niño, and now we have readings that kind of blow up our accounts.”
The last “El Niño” phenomenon was about seven years ago and it was massive. The world has warmed in these seven years, especially the oceans at greater depths. These absorb by far the most heat energy from greenhouse gases, as explained by oceanographer Sarah Purkey of the Scripps Institution of Oceanography. Temperatures reach new record highs every year, regardless of what happens on the surface.
In addition to deep-sea heating, the surface world has experienced three years of exceptional cooling as a result of La Niña. According to researchers, this worked like a lid on a warming pot – and now this lid is gone. As a result, March 2023 was the second highest global average surface temperature ever recorded in March, as NOAA marine scientist Mike McPhaden says, “What we’re seeing now is just the prelude to more records to come.”
