{"id":1881,"date":"2025-05-06T11:44:56","date_gmt":"2025-05-06T08:44:56","guid":{"rendered":"https:\/\/planeta21vek.ru\/eng\/?p=1881"},"modified":"2025-11-20T12:37:53","modified_gmt":"2025-11-20T09:37:53","slug":"acid-zone-could-make-up-half-of-the-worlds-oceans-by-the-end-of-the-century","status":"publish","type":"post","link":"https:\/\/planeta21vek.ru\/eng\/2025\/05\/06\/acid-zone-could-make-up-half-of-the-worlds-oceans-by-the-end-of-the-century\/","title":{"rendered":"Acid zone could make up half of the world’s oceans by the end of the century"},"content":{"rendered":"

At 13,000 feet below the ocean\u2019s surface is an acidic zone, and it\u2019s growing. The carbonate compensation depth\u2014the zone where high pressure and low temperatures create conditions so acidic that they dissolve shells and skeletons\u2014could comprise half the world\u2019s oceans by the end of the century. At the same time, declining oxygen levels in the water pose a critical threat to nature and society on Earth.<\/p>\n

<\/p>\n

In the deepest parts of the ocean, below 13,100 feet (4,000 meters), a combination of high pressure and cold temperatures creates conditions that dissolve calcium carbonate, the material marine animals use to build their shells<\/strong><\/span>,<\/span> Livescience reports.<\/p>\n

This zone is known as the carbonate compensation depth \u2013 and it is expanding. This contrasts with the much-discussed acidification of ocean surface waters due to the ocean’s absorption of carbon dioxide produced by the burning of fossil fuels.<\/p>\n

But these two phenomena are interconnected: due to the increase in the concentration of carbon dioxide in the ocean, its pH decreases (becomes more acidic), and the deep-water zone in which calcium carbonate dissolves increases, starting from the sea floor.<\/p>\n

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\nThese maps show changes in the area of \u200b\u200bocean exposed to caustic bottom waters in 17 different regions. The pre-industrial CCD is dark blue, and areas above the lysocline are light blue. Map A shows the present, while Map B shows a 300-metre rise in the lysocline. Mark John Costello, Peter Townsend Harris, CC BY-SA<\/em><\/p>\n

The transition zone where calcium carbonate becomes increasingly chemically unstable and begins to dissolve is called the lysocline. Because the ocean floor is relatively flat, even a few meters of elevation in the lysocline can quickly result in large undersaturated (acidic) areas.<\/p>\n

Research has shown that this zone has already risen nearly 100 metres since pre-industrial times and is likely to rise another several hundred metres this century.<\/p>\n

Millions of square kilometers of ocean floor could potentially undergo rapid change, causing limestone deposits to become chemically unstable and dissolve.<\/p>\n

The upper limit of the lysocline transition zone is known as the calcite saturation depth, above which sediments are rich in calcium carbonate and ocean water is supersaturated with it. The calcite compensation depth is its lower limit, below which sediments contain little or no carbonate minerals.<\/p>\n

The area below the calcite compensation depth varies greatly across the oceans. It already occupies about 41% of the world’s oceans. Since the Industrial Revolution, this zone has risen for all parts of the ocean, ranging from almost zero rise in the western Indian Ocean to more than 980 feet (300 m) in the northwest Atlantic Ocean.<\/p>\n

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\nThe carbonate content of the sediments decreases within the lysocline, reaching zero below the carbonate compensation depth (CCD). Above the lysocline is the calcite saturation depth (CSD), where the sediments are rich in calcium carbonate. Mark John Costello, Peter Townsend Harris, CC BY-SA<\/em><\/p>\n

If the calcite compensation depth were to increase by another 980 feet, the area of \u200b\u200bthe seafloor beneath it would increase by 10%, to 51% of the world’s oceans.<\/p>\n

For the first time, a recent study has shown that the calcite compensation depth is a biological boundary with different habitats above and below it. In the northeastern Pacific Ocean, the most common seafloor organisms above the calcite compensation depth are soft corals, brittle stars, mussels, sea snails, chitons, and bryozoans, all of which have calcified shells or skeletons.<\/p>\n

Below the calcite compensation depth, however, anemones, sea cucumbers, and octopuses are more abundant. This undersaturated (more acidic) habitat already limits life to 54.4 million square miles (141 million square kilometers) of ocean and could expand to another 13.5 million square miles (35 million square kilometers) if the calcite compensation depth rises to 980 feet.<\/p>\n

In addition to the expansion of calcite compensation depth, low-latitude parts of the ocean are losing species as the water becomes too warm and oxygen levels decline, also driven by climate change.<\/p>\n

Thus, the most suitable habitat for marine species is reduced both from below (increasing calcite compensation depth) and from above (warming).<\/p>\n

Some countries’ exclusive economic zones will suffer more than others. Generally, oceanic and island countries will lose more, while countries with large continental shelves will lose proportionally less.<\/p>\n

Bermuda’s EEZ is projected to be most affected by an increase in calcite compensation depth of 980 feet above current levels, with 68% of that country’s seafloor submerged below the lysocline. In contrast, only 6% of the US EEZ and 0.39% of Russia’s EEZ are projected to be affected.<\/p>\n

From a global perspective, it is remarkable that already 41% of the deep sea is effectively acidic, and half could become so by the end of the century, and that the first study showing the impact of this on marine life was only published last year.<\/p>\n

Decreasing oxygen levels in water threaten all life.<\/strong><\/span>\u00a0<\/span>Decreasing oxygen levels in water pose a critical threat to nature and society on Earth, an international team of scientists said in an article for the journal Nature Ecology & Evolution.<\/p>\n

As RIA Novosti reports, scientists believe that the oxygen level in water has turned out to be one of the so-called planetary boundaries \u2013 global ecological indicators that determine the Earth\u2019s ability to support human existence. The observed deoxygenation of freshwater and marine ecosystems is another process that is critical for the Earth\u2019s ecological and social systems. Rapid and constant deoxygenation of the Earth\u2019s aquatic environments indicates that the oxygen content is approaching a critical threshold.<\/p>\n

According to researchers from the American University of Santa Cruz, since 1980, the Earth’s lakes and reservoirs have lost 5 and 18% of oxygen, respectively. The seas, in turn, have lost 2% of oxygen since 1960. The enormous volume of the World Ocean makes such a small loss seem large in absolute terms.<\/p>\n

A thin, cool surface skin enhances ocean carbon uptake.<\/strong><\/span>\u00a0A new study, partly funded by the European Space Agency, shows that a cool \u201cocean skin\u201d allows the oceans to absorb more atmospheric carbon dioxide than previously thought. The findings could improve global carbon estimates, shaping more effective policies to reduce emissions.<\/p>\n

The world’s oceans absorb about a quarter of human-caused carbon emissions, which is critical to slowing climate change. On the other hand, however, this benefit comes at a price: as the oceans absorb more carbon, their waters become more acidic, threatening the health of marine ecosystems.<\/p>\n

Improving our understanding of the complex processes that control carbon flows between sea and air, and refining estimates of how much carbon the global ocean absorbs, are critical to accurately assessing the carbon budget and informing climate action.<\/p>\n

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\nResearch vessel RSS Discovery. ESA<\/em><\/p>\n

Scientists thought the ocean slick – a layer of surface water 0.01mm thick, thinner than a human hair, that is typically slightly cooler than the water below it – should increase the amount of carbon dioxide absorbed from the atmosphere.<\/p>\n

This is because colder water absorbs carbon dioxide more efficiently. The concentration of the gas between this thin top layer and the water at a depth of about 2 mm is what controls the exchange of gas between the atmosphere and the ocean.<\/p>\n

However, such large-scale measurements at sea have not been carried out before. In a study partly funded by the ESA, scientists from the University of Exeter (UK), Plymouth Marine Laboratory and the University of Southampton assessed the results of in-situ measurements taken from ships as they crossed the Atlantic Ocean.<\/p>\n

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\nAn array of sensors on board the ESA research ship RSS Discovery<\/em><\/p>\n

The measurements were made using flow systems that detected minute differences in the carbon dioxide content of the air moving to and from the ocean surface, as well as precise readings of the temperature of the extremely thin ocean film.<\/p>\n

New results published in the journal Nature Geoscience based on these measurements confirm that ocean surface temperatures enhance carbon uptake.<\/p>\n

The results show that the ocean absorbs about 7% more carbon dioxide each year than previously thought, due to its cool surface. This may not sound like much, but when integrated across all oceans, this extra carbon uptake is equivalent to one and a half times the carbon captured by a year\u2019s forest growth in the Amazon rainforest.<\/p>\n

Currently, global estimates of carbon dioxide fluxes between the atmosphere and the ocean generally ignore the importance of surface temperature differences.<\/p>\n

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\nScientists brave rough seas for science. ESA<\/em><\/p>\n

Craig Donlon from ESA said: \u201cMeasuring the cool ocean surface and precise fluxes between the atmosphere and the ocean simultaneously on board a ship is an incredibly challenging task. The implications of these results are huge for carbon accounting, which currently pays little attention to the role of the ocean surface. With climate change now more urgent than ever, these results will help us better understand, appreciate and take action on the complex role of the oceans in regulating climate.\u201d<\/p>\n

The research was funded by ESA’s Science for Society initiative, Horizon Europe and the UK’s Natural Environment Research Council. The cruises on the ship were part of the Atlantic Meridional Transect project, led by Plymouth Marine Laboratory.<\/p>\n","protected":false},"excerpt":{"rendered":"

At 13,000 feet below the ocean\u2019s surface is an acidic zone, and it\u2019s growing. The carbonate compensation depth\u2014the zone where high pressure and low temperatures create conditions so acidic that they dissolve shells and skeletons\u2014could comprise half the world\u2019s oceans by the end of the century. At the same time, declining oxygen levels in the water pose a critical threat to nature and society on Earth.<\/p>\n","protected":false},"author":1,"featured_media":1883,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[19,23,777,539],"tags":[879,402,372],"class_list":{"0":"post-1881","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-news","8":"category-klimat","9":"category-climatechange","10":"category-hydrosphere","11":"tag-acid","12":"tag-ocean","13":"tag-oxygen"},"_links":{"self":[{"href":"https:\/\/planeta21vek.ru\/eng\/wp-json\/wp\/v2\/posts\/1881","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/planeta21vek.ru\/eng\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/planeta21vek.ru\/eng\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/planeta21vek.ru\/eng\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/planeta21vek.ru\/eng\/wp-json\/wp\/v2\/comments?post=1881"}],"version-history":[{"count":2,"href":"https:\/\/planeta21vek.ru\/eng\/wp-json\/wp\/v2\/posts\/1881\/revisions"}],"predecessor-version":[{"id":1884,"href":"https:\/\/planeta21vek.ru\/eng\/wp-json\/wp\/v2\/posts\/1881\/revisions\/1884"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/planeta21vek.ru\/eng\/wp-json\/wp\/v2\/media\/1883"}],"wp:attachment":[{"href":"https:\/\/planeta21vek.ru\/eng\/wp-json\/wp\/v2\/media?parent=1881"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/planeta21vek.ru\/eng\/wp-json\/wp\/v2\/categories?post=1881"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/planeta21vek.ru\/eng\/wp-json\/wp\/v2\/tags?post=1881"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}