deoxygenation

Rivers And Climate Change | Earth Wise

October 11, 2023 By EarthWise Leave a Comment

Our planet is heating up. Scientists have concluded that the changing climate is primarily the result of increased greenhouse gas emissions from human activities. Some of the effects of global climate change include thawing permafrost, rising seas, intensifying storms and wildfires, and warming oceans.

According to a new study led by researchers from Penn State University, rivers are warming and losing oxygen even faster than oceans. The study, which was recently published in the journal Nature Climate Change, found that warming occurred in 87% and oxygen loss occurred in 70% of the nearly 800 rivers studied.

The research team projects that within the next 70 years some river systems, especially those in the American South, will experience such low oxygen levels that the rivers could “induce acute death” for some fish species and threaten the aquatic diversity of river ecosystems.

The research team used artificial intelligence and deep learning to analyze water quality data from nearly 800 rivers across the U.S. and central Europe. The researchers found that rivers are warming up and deoxygenating faster than oceans, which could have serious implications for both aquatic life and humans.

While climate change has led to warming and oxygen loss in oceans and lakes around the world, the researchers did not expect to find warming and deoxygenation in shallower, flowing rivers. Since life in water depends on temperature and dissolved oxygen, the researchers hope this study serves as a wake up call. Warming and deoxygenating rivers have significant implications for water quality and the health of aquatic ecosystems worldwide.

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Rivers are rapidly warming, losing oxygen; aquatic life at risk

Photo, posted June 2, 2017, courtesy of Francisco Anzola via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Ocean-based Climate Intervention And Deep-sea Ecosystems | Earth Wise

May 2, 2023 By EarthWise Leave a Comment

Deep-sea ecosystems cover more than 40% of the Earth. These regions are some of the least well-known and understood areas of our planet but are home to numerous ecosystems. The deep seas are already directly exposed to the effects of human-induced climate change but could potentially be greatly threatened by efforts to artificially counteract climate change.

A class of geoengineering solutions called ocean-based climate interventions are increasingly being claimed as promising ways to mitigate climate change. Such interventions would remove carbon dioxide from the atmosphere and sequester it in the deep sea. There is very little known about the impact of such efforts on ocean biogeochemistry and the biodiversity of ocean ecosystems.

One approach is direct CO₂injection into the deep ocean, which would sequester large amounts of it and reduce the concentration in the atmosphere. However, too much carbon dioxide in the water is called hypercapnia, which can have serious consequences on marine life.

Other approaches include ocean fertilization – which is enhancing phytoplankton production at the surface, leading to their eventual deposition on the deep-sea floor – and crop waste deposition – which is deep-sea disposal of terrestrial crop waste.

A multinational study led by the Scripps Institution of Oceanography warns that there needs to be much more research and governance before any such interventions ever take place. The deep sea faces unprecedented threats from industrial fisheries, pollution, warming, deoxygenation, acidification, and other climate-related problems. Ocean-based climate intervention represents yet another serious threat to the functioning of these essential ecosystems.

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HKU Marine Scientist contributes to research assessing the potential risks of ocean-based climate intervention technologies on deep-sea ecosystems

Photo, posted January 6, 2010, courtesy of Emrys Roberts via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Climate Change And The World’s Fisheries | Earth Wise

March 10, 2022 By EarthWise Leave a Comment

According to a new study, approximately 70% of the world’s oceans could be suffocating from a lack of oxygen by 2080 as a consequence of climate change. This has the potential to impact marine ecosystems all around the world.

The study, which was recently published in the journal Geophysical Research Letters, is the first to use climate models to predict how and when deoxygenation will occur throughout the world’s oceans outside of its natural variability.

According to the findings, significant and potentially irreversible deoxygenation of the ocean’s middle depths began occurring last year. The models predict that deoxygenation will begin affecting all zones of the ocean by 2080.

According to the study’s models, mid-ocean depths are already losing oxygen at unnatural rates. Globally, the ocean’s middle depth – known as the mesopelagic zone – is home to many of the world’s commercially fished species. This makes these new findings a potential harbinger of economic hardship, seafood shortages, and environmental disruption.

Just like land animals, aquatic animals need oxygen to breathe. As climate change warms the oceans, the water holds less oxygen and is more buoyant than cooler water. This leads to less mixing of oxygenated water near the surface with deeper waters, which naturally contain less oxygen. Warmer water also raises oxygen demand among living organisms, resulting in less availability for marine life.

The researchers also found that oceans closer to both the North Pole and the South Pole are particularly vulnerable to deoxygenation. While they are not yet sure why, accelerated climate warming could be the culprit.

These findings should add new urgency to climate change mitigation efforts.

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Climate change has likely begun to suffocate the world’s fisheries

Photo, posted January 28, 2019, courtesy of Joseph Gage via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.