The dire consequences of the world's 'relentless' warming oceans

Ocean life.
Ocean life. Illustrated | Gettyimages

New research has found that oceans hit record temperatures in 2022, making this the fourth record-breaking year in a row. The "relentless warming" could have dire ecological consequences. Here's everything you need to know:

How are the oceans doing?

Not great. "The state of our oceans can measure the world's health, and judging by the updated oceanic observations … we need a doctor," wrote the researchers of a recent study on oceanic warming, published in the journal Advances in Atmospheric Sciences. 

Ocean temperatures are of high interest to scientists because they are a better indicator than other environmental indicators of the state of climate change due to the fact that, unlike the air and atmosphere, oceans are less susceptible to weather and seasonal changes, CNN explains.

Why are oceans warming?

The oceans are warming as a direct result of man-made climate change. In fact, the planet's seas have absorbed more than 90 percent of the excess heat trapped by greenhouse gases since the 1970s, explains The Guardian.

"Oceans contain an enormous amount of water, and compared to other substances, it takes a lot of heat to change the temperature of water," Linda Rasmussen, a retired researcher at the Scripps Institution of Oceanography, told The Washington Post. But "the Earth's energy and water cycles have been profoundly altered due to the emission of greenhouse gases by human activities, driving pervasive changes in Earth's climate system," said the scientists who worked on the new analysis. One of the report's authors, Michael Mann, a professor at the University of Pennsylvania, added that "until we reach net zero emissions, that heating will continue, and we'll continue to break ocean heat content records."

What does a warmer ocean mean for marine life?

Warmer oceans can lead to cascading problems, ranging from extinction events to infrastructure damage. Notably, warmer water has a lower oxygen content, which is harmful to the marine ecosystem and the fishing community. Warming can also cause some ocean regions to have more salt than others: When the warm water evaporates, it leaves more salt, and when it rains in other regions, that water becomes fresher. The study calls this phenomenon the "salty gets saltier — fresh gets fresher" pattern.

"Great power brings great responsibility," Curtis Deutsch, a professor of geosciences at Princeton University, told The New York Times after publishing his own research on the link between climate change and marine life in 2022. "And we're learning about our power, but not about our responsibility — to future generations of people, but also to all the other life that we've shared the planet with for millions of years."

What's more, "some of the most productive and biodiverse marine ecosystems, like coral reefs and kelp forests, are very sensitive to temperature," explains Rasmussen. Coral reefs in particular can become "bleached," meaning that the "corals will expel the algae (zooxanthellae) living in their tissues causing the coral to turn completely white," according to the National Ocean Service. Corals can survive bleaching but with the current warming trend, it is harder for the coral to adapt.

What does a warmer ocean mean for humans?

Another consequence of warmer oceans is rising sea levels, which threaten coastal towns and islands. This is due to heat causing water particles to move further apart, resulting in expansion. Certain towns in Florida have already been pinpointed as at-risk areas for becoming over-flooded in the coming years.

Ocean surface warmth also exacerbates storms and extreme weather, meaning that as the water temperatures increase, the planet can anticipate more intense storms. This can lead to "greater and more rapid intensification of hurricanes ... since the winds no longer churn up cold sub-surface water that would otherwise dampen intensification," Mann says.

"Until we reach net zero emissions, that heating will continue, and we'll continue to break ocean heat content records, as we did this year," Mann explains. The consequences will only get worse as the temperatures rise, however, scientists say the heating "probably is irreversible through 2100."

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