- A new study has found that, for the sixth year in a row, the world’s oceans have been hotter than they’ve ever been in recent history due to human-induced climate change.
- The research team found that last year, the upper 2,000 meters (6,600 feet) in all oceans absorbed 14 zettajoules more of human-made energy than the previous year, equal to about 145 times the world’s electricity generation in 2020.
- A warming ocean causes a host of problems, such as extreme weather events, rapid sea level rise, disrupting marine diversity, threatening global food security, melting polar ice shelves, and accelerating the onset of extreme weather events.
- Experts say the best way to reduce ocean climate impacts is to lower carbon emissions and meet the Paris Agreement goal of not allowing global warming to surpass 1.5°C (2.7°F) over preindustrial levels.
The ocean is now warmer than it’s ever been in recent history, according to a new study. And this isn’t the first time such a record has been set. For the past six years, ocean temperatures have exceeded each previous year in a trend one scientist calls “inexorable.”
John Abraham, coauthor in the new study published Jan. 11, argues that climate change caused by humans is to blame. Advances in Atmospheric Sciences.
“We should be very concerned,” Abraham, a professor of thermal sciences at the University of St. Thomas in Minnesota, U.S, told Mongabay in a video interview. “But frankly, we should have been concerned years ago.”
The research team used high-tech autonomous buoys to measure the global ocean temperatures. They compared this data with data from the 1950s. They found that in 2021, the upper 2,000 meters (6,600 feet) in all of the oceans absorbed 14 zettajoules more of human-made energy than the previous year, equal to about 145 times the world’s electricity generation in 2020.
Abraham puts it another way: “It’s the equivalent of seven Hiroshima atomic bombs detonated every second of every day of every week of every month.
“The story we’ve been telling since 2018 is that every year it’s getting hotter and hotter,” he added. “And records are being broken as this inexorable, unrelenting rise of ocean temperatures occurs.”
‘Oceans drive weather’
The researchers found that ocean warming persisted despite a La Niña event in early 2021 in the Indo-Pacific basin, which should have cooled down the waters.
While the ocean is generally getting hotter, this warming isn’t consistent across the entire globe. The researchers discovered that specific parts of the Atlantic Ocean and Pacific Ocean experienced greater warming due to currents and wind patterns.
Temperature shifts across the world’s ocean have already led to significant changes in the distribution of fish, which can impact global food security, said William Cheung, professor and director of the University of British Columbia’s Institute for the Oceans and Fisheries, who was not involved in the study.
“Fisheries are experiencing reduction in catches of cooler-water associated species but increasing potential production of warmer-water associated species,” Cheung told Mongabay in an email.
Long-established ocean ecosystems can also be destabilized by the warming trend. Warm-water fish, such as warm-water fish, are increasing in number. Moving north into the once-frigid Arctic waters where they weren’t previously found, and outcompeting cold-water fish such as Arctic cod (Boreogadus saidaAlso known as polar cod. As global warming accelerates, ocean ecosystem disruptions are expected.
Extreme weather is also a result of the warming ocean. This applies to both land and ocean. For example, the increase in ocean temperature has led to heat waves such as the one seen here Hundreds of millions marine animals were killedStarfish, mussels, sockeye and other fishes (Oncorhynchus nerka), in the Pacific Northwest last year. In 2015, a marine heat wave nicknamed “The Blob” also caused Coral bleaching is widespreadThe Hawaiian islands are a great place to visit.
A 2018 research paper published by Earth’s FutureRelated ocean heat to Hurricane Harvey, which was a category four storm that ravaged Texas in 2017 and caused approximately $125 billion in damage.
“Oceans and atmosphere are dynamic systems and respond by trying to get rid of excess heat,” Kevin Trenberth, co-author of both the recent paper in Advances in Atmospheric SciencesThe paper in Earth’s FutureMongabay was contacted by, he said in an email. “That is why the storms are more vigorous.”
Other extreme weather phenomena, such as heat waves or sudden heavy rainfall, can also be caused by a warming ocean environment. It can make dry areas of the world dryer and wetter.
“Oceans drive weather,” Abraham said. “Any weather that you’re experiencing right now has been impacted by global warming, and as the oceans warm, the impacts will become larger and larger into the future.”
Ocean acidification can cause ocean warming and carbon dioxide emissions. This can affect fish populations and make calcifying organisms, such as corals, impossible to form their hard shells. It’s currently believed that the ocean absorbs about 25% of atmospheric carbonProduced by human activities
Ocean water expands as it heats, thereby increasing global sea levels. The melting of Antarctica’s floating glaciers is also encouraged by warming oceans. Scientists say that warmer seawater is causing the shelves’ collapse, which is a critical problem. These ice shelves act as corks in a bottle and could cause a rapid increase in the flow of land-ice sheets into the ocean. This process is already underway at the Thwaites glacierIn western Antarctica, if it melts completely, it could raise sea level by 1.2 m (3.9 ft) in two centuries.
Even if carbon emissions were to stop tomorrow, the world’s oceans would still continue to warm and sea levels would continue to rise since heat gradually penetrates deeper and deeper into the ocean, initially warming at the top and then pushing downward, Trenberth said.
“It takes time for the warming signal to penetrate down and that continues for decades, and sea level rise continues for a century or more,” he said.
Breaking the climate boundary
Cheung stated that the best method to reduce the ocean’s climate impacts is to cut greenhouse gas emissions. He also added that we have more information about the climate crisis than ever before and possible solutions.
“The increasing awareness of the climate crisis and demand for climate solutions give me hope,” he said.
According to the The boundaries of the solar systemConcept as suggested by an International team of scientists first in 2009, and which became mainstream with David Attenborough’s Netflix documentary Breaking Boundaries in 2021, humanity has already surpassed a critical threshold for climate change — putting Earth’s operating systems at grave risk of failure. 350 parts per million (ppm), of carbon dioxide in the atmosphere has been established as the safe operating level for climate changes. However, this threshold was exceeded in 1988.
Ocean acidification is another one of the planetary boundaries. Experts believe that the safe operating level has not been exceeded yet, but that rising carbon dioxide emissions could cause a breach of this threshold. The oceans can be irreversibly alteredLife on Earth as we know is at risk.
Many nations pledged higher emissions reductions at the COP26 climate summit in Glasgow (Scotland) last November. But experts warn that even if these promises are fulfilled, they will not be kept. won’t come close to meeting the Paris Agreement goal of limiting global warming to a 1.5° Celsius (2.7° Fahrenheit) increase over preindustrial levels.
Abraham expressed optimism about the availability and development of clean energy sources, despite the alarming findings from the new ocean warming study.
“Clearly, climate change is going to be a problem both in our generations, as well as a few following generations,” Abraham said. “But at least we have a ray of hope that clean energy is now mature to a point where it will displace greenhouse gas-producing energy sources.”
Cheng, L., Abraham, J., Trenberth, K. E., Fasullo, J., Boyer, T., Mann, M. E., … Reagan, J. (2022). Another record: Ocean warming continues through 2021 despite La Niña conditions. Advances in Atmospheric Sciences. doi:10.1007/s00376-022-1461-3
Trenberth, K. E., Cheng, L., Jacobs, P., Zhang, Y., & Fasullo, J. (2018). Hurricane Harvey is linked to ocean heat content, climate change adaptation, and Earth’s Future, 6(5), 730-744. doi:10.1029/2018ef000825
Watson, A. J., Schuster, U., Shutler, J. D., Holding, T., Ashton, I. G., Landschützer, P., … Goddijn-Murphy, L. (2020). Revisions to ocean-atmosphere CO2 flux are consistent in ocean carbon inventory. Nature Communications, 11(1). doi:10.1038/s41467-020-18203-3
Rockström, J., Steffen, W., Noone, K., Persson, Å., Chapin, F. S., Lambin, E. F., … Foley, J. A. (2009). Safe operating space for humanity. Nature, 461(7263), 472-475. doi:10.1038/461472a
Guinotte, J. M., & Fabry, V. J. (2008). (2008). Annals of New York Academy of Sciences, 1134(1), 320-342. doi:10.1196/annals.1439.013
Caption for banner image:The sun rising over the ocean. Image by PxHere. (CC0 Public Domain).
Elizabeth Claire Alberts is a staff writer for Mongabay. Follow her on Twitter @ECAlberts.
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