[note: open access study, seems to be models all the way down]
New research finds that the average depth of the ocean, home to many commercial fishery species, will begin to lose oxygen at an unusual rate by 2021.
Federation of Geometry of the United States of America
By 2080, around 70% of the world’s oceans could suffocate from lack of oxygen due to climate change, potentially affecting marine ecosystems worldwide, according to a new study. a new study. New models find the mid-ocean depths that support many fisheries worldwide that have lost oxygen at an unusual rate and have crossed the threshold of severe oxygen loss by 2021.
The ocean carries dissolved oxygen in the form of a gas, and like land animals, aquatic animals need that oxygen to breathe. But as the oceans warm due to climate change, their water may contain less oxygen. Scientists have been monitoring the steady depletion of oxygen in the oceans for years, but the new study offers new urgent reasons for concern sooner rather than later.
The new research was the first to use climate models to predict how and when deoxygenation, i.e. a decrease in dissolved oxygen content in water, would occur across the world’s oceans outside the its natural variation.
It found that significant, potentially irreversible deoxygenation in the mean ocean depths, which support the majority of the world’s fisheries, begins to occur in 2021, likely to occur in 2021. impact on fisheries worldwide. New models predict that deoxygenation is expected to start affecting all areas of the ocean by 2080.
The results are published in the journal AGU . Geophysical research letterwhich publishes high-impact, short-format reports with immediate impact on all disciplines of Earth and space sciences.
New research finds that the mid-ocean depths (between about 200 and 1,000 metres), known as the mesosphere, will be the first to lose significant amounts of oxygen due to climate change. Globally, the Middle East is home to many of the world’s commercial fishery species, making this new find a potential sign of economic hardship, seafood shortages and environmental disruption.
Rising temperatures result in warmer water that can hold less dissolved oxygen, creating less circulation between the ocean’s layers. The middle layer of the ocean is particularly susceptible to deoxygenation because it is not as oxygen-enriched by the atmosphere and photosynthesis as the top layer, and algae decomposition – an oxygen consuming process – occurs most frequently in the upper layer. this.
“This area is really important to us because a lot of commercial fish live in this area,” said Yuntao Zhou, an oceanographer at Shanghai Jiaotong University and lead author of the study. “Deoxidation also affects other marine resources, but fisheries [are] may be most relevant to our daily lives”.
Matthew Long, an oceanographer at NCAR who was not involved in the study, said the new findings are deeply concerning and add to the urgency of meaningful engagement in climate change mitigation. .
“Humanity is currently changing the metabolic state of the largest ecosystem on the planet, with truly unknown consequences for marine ecosystems,” he said. “That could manifest in significant impacts on the ocean’s ability to sustain important fisheries.”
Vulnerability Assessment
The researchers identified the onset of deoxygenation in three regions of ocean depths – shallow, medium and deep – by modeling when the amount of oxygen lost from the water exceeded the natural fluctuations of the ocean. oxygen level. The study predicted when deoxygenation would occur in global ocean basins using data from two climate simulation models: one high-emissions scenario simulation and one representative low emission scenario.
In both simulations, the mesosphere loses oxygen at the fastest rate and over the largest area of the global oceans, although the process begins about 20 years later in the low-emissions scenario. This indicates that reducing emissions of carbon dioxide and other greenhouse gases could help delay the degradation of the global marine environment.
The researchers also found that oceans near the poles, such as the western and northern Pacific and southern oceans, are particularly susceptible to deoxygenation. They’re still not sure why, although rapid warming could be the culprit. According to Zhou, areas in the tropics known for low levels of dissolved oxygen, known as the oxygen minimum, also appear to be spreading.
“The oxygen minima is actually spreading into regions of high latitude, both north and south. That’s something we need to pay more attention to,” she said. Even if global warming were reversed, allowing dissolved oxygen levels to rise, “whether dissolved oxygen will return to pre-industrial levels remains unknown.”
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Newspaper headline:
“Emerging Global Ocean Deoxidation in the 21st Century”
Authors:
- Yuntao Zhou (corresponding authors) and Hongjing Gong, Faculty of Oceanography, Shanghai Jiaotong University, Shanghai, China
- Chao Li, Key Laboratory of Geographic Information Science (Ministry of Education), East China Normal University, Shanghai, China; School of Geosciences, East China Normal University, Shanghai, China
JOURNEYS
Geophysical research letter
DOI
ARTICLE TITLE
Emerging global ocean deoxidation in the 21st century
ARTICLE PUBLICATION DATE
November 19, 2021
Disclaimer: AAAS and Eurek
From EurekAlert!
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