Climate change has likely started to suffocate world’s fisheries

A new study has shown that 70% of the world’s oceans could become suffocating due to a lack oxygen. This could potentially have an impact on marine ecosystems worldwide. The new models reveal that the mid-ocean depths supporting many fisheries worldwide are already losing oxygen in unnatural ways and have passed a critical threshold of oxygen losses in 2021.

The oceans contain dissolved oxygen, which is a gas. Aquatic animals also require this oxygen to breathe, just as land animals. However, as the oceans become warmer due to global warming Climate ChangeTheir water can hold less oxygen. For years scientists have been monitoring the oceans’ constant decline in oxygen. But the new study gives new and urgent reasons to be concerned sooner than usual.

The new study is the first to be used climate modelsIt is possible to predict when and where deoxygenation will occur, which is the reduction or elimination of dissolved oxygen in water, outside of the natural variability of the oceans.

It found that significant, potentially irreversible, deoxygenation in the ocean’s middle deeps, which support many of the world’s fished animals, began in 2021. This likely affected fisheries around the globe. The new models predict that the ocean’s middle depths will be affected by deoxygenation by 2080.

The results were published in AGU journal Geophysical Research LettersPublishes short-format, high-impact reports with immediate implications that span all Earth and Space sciences.

The new study shows that the ocean’s mesopelagic zone, which is located between 200 and 1,000 meters below the surface, will be the first areas to experience significant oxygen losses due to climate changes. The mesopelagic zones are home to many of the commercially fished species in the world. This new finding could be a sign of economic hardship, shortages of seafood, and environmental disruption.

Rising temperatures can lead to warmer waters, which can hold less dissolved oxygen. This results in less circulation between the ocean layers. The middle layer of the ocean is particularly vulnerable to deoxygenation because it is not enriched with oxygen by the atmosphere and photosynthesis like the top layer, and the most decomposition of algae—a process that consumes oxygen—occurs in this layer.

“This area is very important to us as it has a lot of commercial opportunities. Fish“Live in this area,” says Yuntao Zohou, an oceanographer from Shanghai Jiao Tong University who is also the principal study author. “Deoxygenation can also affect other marine resources, but fisheries will not be affected,” Yuntao Zhou, an oceanographer at Shanghai Jiao Tong University and lead author of the study. [are]Perhaps our daily lives are the most affected by this.”

Matthew Long, an Oceanographer at NCAR who wasn’t involved in the study, says the new findings are very concerning.

“Humanity is changing the metabolic state the largest ecosystem on Earth, with very unknown consequences. marine ecosystemsHe stated that he agreed. “This could have significant impacts on the ocean’s ability to sustain key fisheries.”

Evaluating vulnerability

The researchers identified the beginning of the deoxygenation process in three ocean depth zones—shallow, middle and deep—by modeling when the loss of oxygen from the water exceeds natural fluctuations in oxygen levels. The study used data from two climate models to predict when global ocean basins would experience deoxygenation. One simulation represented a high-emission scenario, while the other represented a low-emission scenario.

Both simulations showed that the mesopelagic area lost oxygen at the fastest pace and over the largest area of global oceans. However, this process starts about 20 years later in low emission scenario. This shows that reducing carbon dioxide and other greenhouse gas emission could help slow down the degradation of global marine ecosystems.

Researchers also found that oceans near the poles like the west and north Pacific as well as the southern oceans are especially vulnerable to deoxygenation. They don’t know why but accelerated warming may be the reason. Zhou says that Zhou is also seeing an increase in oxygen minimum zones (areas in the tropics with low levels of dissolved oxygen), which are known for spreading.

“The oxygen minimum zones are actually spreading into high latitude regions, both to the north as well as the south. This is something that we need to be more attentive to,” she said. “Whether dissolved oxygen would return back to pre-industrial levels is unknown even if global warming reverses,” she says.