As the death toll from the extreme weather facing California this week rose to at least 17 and thousands in the state were displaced by mudslides and flooding, scientists from 16 international universities and institutes published a study Wednesday showing that a major driver of extreme weather—the heating of the world’s oceans—was worse than ever in 2022.
Experts from the Chinese Academy of Sciences, the National Center for Atmospheric Research, the National Oceanic and Atmospheric Administration, and other institutes found that the oceans had their hottest year on record last year. Record-keeping began in 1940 and the planet’s oceans have been heating steadily for more than six decades—with the trend accelerating particularly after 1990—but scientists believe the oceans are now the hottest they’ve been in 1,000 years.
“Measuring the oceans is the most accurate way of determining how out of balance our planet is,” John Abraham, a professor at the University of St. Thomas in Minnesota and one of 24 scientists who authored the study, toldThe Guardian. “We are getting more extreme weather because of the warming oceans and that has tremendous consequences all around the world.”
“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.”
The oceans absorb more than 90% of excess greenhouse gas emissions that enter the atmosphere largely as a result of fossil fuel extraction, and study co-author Michael Mann of the University of Pennsylvania warned that as long as humans continue extracting fossil fuels, record-breaking ocean heating will remain likely each year.
“The oceans are absorbing most of the heating from human carbon emissions,” Mann told France 24. “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. Better awareness and understanding of the oceans are a basis for the actions to combat climate change.”
The public can “thank your fossil fuel friends” for the “supercharged storms” and other devastating weather patterns that have been linked to warming oceans, said U.S. Sen. Sheldon Whitehouse (D-R.I.).
The scientists evaluated temperature data on the 2,000 meters (6,561 feet) of the oceans closest to the surface, where most heating occurs, and measured heating in zetta joules, finding that the oceans absorbed about 10 zetta joules more heat in 2022 than in 2021.
That amount of added heat is the equivalent of “every person on Earth running 40 hairdryers all day, every day,” The Guardian reported.
“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,” the researchers concluded.
The study also found that rising water temperatures combined with record-high salinity contribute to the “stratification” of oceans, in which water separates into layers. This process can lead to a loss of oxygen in the oceans because it alters “how heat, carbon, and oxygen are exchanged between the ocean and the atmosphere above it.”
“Deoxygenation itself is a nightmare for not only marine life and ecosystems but also for humans and our terrestrial ecosystems,” the researchers said in a statement. “Reducing oceanic diversity and displacing important species can wreak havoc on fishing-dependent communities and their economies, and this can have a ripple effect on the way most people are able to interact with their environment.”
The heating of the oceans can cause “shockwaves of disruption in the food chain [that] will lead to food shortages for many marine mammals,” said U.K.-based advocacy group Surfers Against Sewage. “For a thriving ocean we need a drastic reduction in CO2 emissions.”
