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As Temperatures Rise, The World’s Oceans are Losing Oxygen


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Scientists have warned that the world’s oceans are being asphyxiated as they are losing oxygen at an alarming rate. The situation is made worse by the current climate crisis, according to a new study issued at the annual global climate talks in Madrid.

The largest study of its kind which unites the research of 67 scientists from 17 different countries was released by the International Union for Conservation of Nature (IUCN). They discovered that because of intense farming practices and climate change, vital ecosystems were in danger of collapse due to a proliferation of certain areas known as “dead zones” in the waters.

The paper states, It has been known for some decades that nutrient run-off from agriculture causes oxygen-depleted zones to form in the sea, as life-giving oxygen is used up in the water column and on the sea floor. This phenomenon is called ‘ocean deoxygenation’.”

One of the consequences of ocean deoxygenation is that the seawater becomes increasingly acidic and can severely damage marine life dissolving the shells of mollusks such as clams and mussels and killing off entire schools of fish.

With this report, the scale of damage climate change is wreaking upon the ocean comes into stark focus. As the warming ocean loses oxygen, the delicate balance of marine life is thrown into disarray.

Dr Grethel Aguilar, Acting Director General, The IUCN

In order to survive, all fish species require dissolved oxygen in the water, however, larger fish species are those most at risk as they require more to sustain their lives. Fish, including sharks, marlin, and tuna, become vulnerable to over-fishing as they move towards the surface for a better oxygen supply. What’s more is that the so-called dead zones –  areas almost completely depleted of oxygen – have increased up to four times in extent over the last half-century. Scientists also believe that there are at least 700 areas where the amount of oxygen present in the water is critically low: a statistic up from just 45 when research was initiated back in the 1960s.

With an ever-increasing global population and the increase of human activity across the world, enormous stress is put on the planet’s ecosystems. In particular, the oceans are affected because we warm, deoxygenate, and acidify waters through our release of carbon dioxide (CO2 ) and other greenhouse gases into the atmosphere.

The acidity of today’s oceans is now 26% more than the seas of the pre-industrial period because the excess carbon dioxide in the atmosphere is absorbed into the seawater, according to the Intergovernmental Panel on Climate Change.

Yet, the consequences stretch beyond a reduction of marine life and more acidic waters as warming of global temperatures is also associated with ocean deoxygenation. As the waters become warmer and oxygen levels reduce on a large scale there is a lesser chance of oxygen-poor waters mixing with oxygen-rich waters, leading to a process called ocean stratification. The result of this process is rapid climatic warming on a global scale which could, in effect, disrupt ecosystems on terrestrial land as well in the oceans.

The oceans are the focus of the 2019 UN climate conference, known as COP25, for the first time in the history of the delegation which hosts over 25,000 representatives from 200 countries. The focus was chosen due to the fact that Chile – first selected to be the location of the conference – is a country with over 4,000 km of coastline and a heavy reliance on the marine economy. However, due to political unrest in Santiago, it was decided that the conference would be moved over 10,000 km to Madrid, Spain.

Scientists leading the recent study believe that by rapidly addressing these issues seriously by protecting marine life would help sustain the oxygen balance of the oceans as waters with thriving marine life would soak up excessive amounts of carbon.

A healthy ocean with abundant wildlife is capable of slowing the rate of climate breakdown substantially.

Dr Monica Verbeek, Executive Director, Seas at Risk

Moreover, a study presented by Greenpeace International at COP25 also states that resilient oceanic ecosystems decrease CO2 pollution and have a considerable role to play when it comes to tackling the climate emergency.

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David J. Cross

Written by

David J. Cross

David is an academic researcher and interdisciplinary artist. David's current research explores how science and technology, particularly the internet and artificial intelligence, can be put into practice to influence a new shift towards utopianism and the reemergent theory of the commons.


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