{"id":1815,"date":"2025-01-09T15:11:53","date_gmt":"2025-01-09T12:11:53","guid":{"rendered":"https:\/\/planeta21vek.ru\/eng\/?p=1815"},"modified":"2025-11-20T12:38:09","modified_gmt":"2025-11-20T09:38:09","slug":"scientists-have-recorded-a-slowdown-and-change-in-ocean-currents","status":"publish","type":"post","link":"https:\/\/planeta21vek.ru\/eng\/2025\/01\/09\/scientists-have-recorded-a-slowdown-and-change-in-ocean-currents\/","title":{"rendered":"Scientists have recorded a slowdown and change in ocean currents"},"content":{"rendered":"

Antarctic currents, which supply 40% of the world\u2019s deep oceans with nutrients and oxygen, are slowing dramatically. Other models show the Gulf Stream is weakening and the AMOC could be close to collapse, with serious implications for climate. The Italian findings suggest that current modeling used to track the flow of sediment and pollutants in the deep sea and reconstruct ancient ocean conditions needs to be updated.<\/span><\/p>\n

<\/p>\n

Antarctic currents, which supply 40% of the world’s deep oceans with nutrients and oxygen, are slowing dramatically.<\/strong>\u00a0<\/span>These deep ocean tides supply nearly half the world’s oceans with vital nutrients and oxygen, but melting ice shelves are slowing them down.<\/span><\/p>\n

Deep-sea currents around Antarctica that are vital to marine life have slowed by 30% since the 1990s and could soon stop altogether, according to a new study.<\/span><\/p>\n

These currents, known as Antarctic Bottom Water, are fed by dense, cold water from Antarctica’s continental shelf that descends to depths below 10,000 feet (3,000 meters). The water then spreads north into the Pacific Ocean and eastern Indian Ocean, feeding a network of currents called the Global Meridional Overturning Circulation and supplying 40 percent of the world’s deep ocean with fresh nutrients and oxygen.<\/span><\/p>\n

However, global warming is releasing large volumes of less dense fresh water from Antarctic ice shelves, slowing this circulation.<\/span><\/p>\n

\u201cIf the oceans had lungs, this would be one of them,\u201d Matthew England, a professor of ocean dynamics and climate at the University of New South Wales in Sydney, Australia, who contributed to the study, said in a statement. Scientists from the U.K. and Australia collaborated on a study published in March in the journal Nature that predicted a 40% decline in the strength of Antarctic bottom waters by 2050.<\/span><\/p>\n

He also warned that the currents could eventually cease entirely. \u201cWe\u2019re talking about the potential long-term disappearance of an iconic water mass,\u201d England said.<\/span><\/p>\n

In a new study published May 25, 2024, in the journal Nature Climate Change, England and his colleagues say they have confirmed these predictions with real-world observations in the Australian Antarctic Basin, which spans the polar waters between Australia and Antarctica.<\/span><\/p>\n

\"\"
\nRising temperatures are increasing the flow of less dense meltwater and slowing deep-sea currents in Antarctica. UniversalImagesGroup<\/span><\/em><\/p>\n

Researchers looked at changes in the amount of bottom water entering the basin between 1994 and 2017 and found a 30% decrease in speed, suggesting these deep-sea, or abyssal, currents are starting to stagnate.<\/span><\/p>\n

Weakening circulation around Antarctica could slow the global network of deep currents and lead to a build-up of nutrients and oxygen in the deep ocean, which would have negative impacts on marine life.<\/span><\/p>\n

\u201cThe thing is, all the marine life that we have on the surface, when it dies, it sinks to the bottom of the ocean, so there\u2019s a lot of nutrient-rich water in the deep ocean,\u201d England said in a video produced by the Australian Academy of Science. \u201cIf we slow down the overturning circulation that brings that bottom water back to the surface, we cut off the pathway for nutrients to come back to the surface to restore marine life.\u201d<\/span><\/p>\n

According to a new study, about 276 trillion tons (250 trillion metric tons) of cold, salty, oxygen-rich water sinks around Antarctica each year. In a warming climate, fresh meltwater reduces the density of this sinking mass, meaning more of it remains in the upper ocean. \u201cThese regions supply deep water to the entire Pacific and East Indian basins, so the changes quantified here are likely to affect much of the global abyssal ocean,\u201d the researchers wrote.<\/span><\/p>\n

Scientists have warned that the influx of freshwater into Antarctic waters is likely to continue and accelerate in the coming decades, meaning these vital currents could soon collapse. \u201cSuch profound changes in the oceanic cycling of heat, freshwater, oxygen, carbon and nutrients will have significant impacts on the oceans for centuries,\u201d England said.<\/span><\/p>\n

Atlantic currents slowed dramatically during the Younger Dryas. By reconstructing these ancient ocean conditions, scientists believe they can predict changes over the next century.<\/strong><\/span>\u00a0<\/span>Scientists have found that the Gulf Stream slowed dramatically at the end of the last ice age, with detrimental effects on organisms in the Atlantic. This discovery could help researchers predict how Atlantic currents will change in response to climate change today.<\/span><\/p>\n

The Gulf Stream is a warm ocean current that originates in the Florida Straits between Florida and Cuba, then flows around the east coast of the United States and Canada and across the North Atlantic to Europe. The heat it carries helps moderate conditions in Europe and, to some extent, North America. The current is part of the Atlantic Meridional Overturning Gyre (AMOC), which carries warm water from the Southern Hemisphere north and then back to Antarctica in a giant loop.<\/span><\/p>\n

Previous models have shown that the Gulf Stream is weakening and the AMOC may be close to collapse, which would have serious implications for the climate. Now, a new study published May 9, 2024, in the journal Science has found that the decline in the Gulf Stream could spell trouble for ocean creatures that rely on nutrients carried by the current from the tropics to the North Atlantic.<\/span><\/p>\n

\"\"
\nA NASA visualization showing the Gulf Stream as it unfolds from the Florida Straits across the North Atlantic Ocean. The current is colored based on sea surface temperature. Red is equivalent to about 90 degrees Fahrenheit (32 degrees Celsius), and green is equivalent to about 55 degrees Fahrenheit (13 degrees Celsius). NASA\/Goddard Space Flight Center Scientific Visualization Studio<\/span><\/em><\/p>\n

The authors based their findings on fossil and sedimentary records of a brief cold snap between 12,900 and 11,700 years ago, known as the Younger Dryas. The abrupt cooling temporarily reversed a period of global warming during the transition from the Pleistocene epoch to the modern Holocene epoch.<\/span><\/p>\n

\u201cThere is ample evidence that the AMOC weakened during the Younger Dryas cold period that marked the transition from the last glacial period,\u201d the researchers wrote in the study. \u201cWhile the details of the background climate and the timescale of the changes are different from today, this past climate event provides an opportunity to test mechanisms that have been implicated in climate models.\u201d<\/span><\/p>\n

To reconstruct the conditions that prevailed in the Gulf Stream during the Younger Dryas, the researchers studied the nutrient content of microscopic fossils and sediment cores from the Florida Straits. The team found that nutrient levels dropped during the Younger Dryas compared to the millennia immediately before and after. This starved the photosynthetic organisms in the North Atlantic that convert these nutrients and sunlight into organic matter. Their decline likely sent ripples up the food chain, affecting populations of fish and other marine creatures.<\/span><\/p>\n

\u201cIn this simulation, as the AMOC and nutrient flux weaken, upper North Atlantic nutrient content and primary productivity decline,\u201d the researchers wrote in the study. The decline in nutrient content at the base of the Gulf Stream was associated with stagnation of currents in the Southern Hemisphere, where the AMOC typically picks up nutrient-rich water and pushes it north.<\/span><\/p>\n

\u201cIn this simulation, as the AMOC and nutrient flux weaken, upper North Atlantic nutrient loads and primary productivity decline,\u201d the researchers wrote in the study. The decline in nutrient loads at the base of the Gulf Stream was associated with stagnation of currents in the Southern Hemisphere, where the AMOC typically picks up nutrient-rich waters and pushes them north. This snapshot of the Younger Dryas supports current climate models, which predict that nutrient transport to the North Atlantic will drop sharply if the AMOC and Gulf Stream continue to slow, according to the study. The resulting decline in primary productivity will impact critical North Atlantic fisheries and may also limit the amount of CO2 the oceans can absorb, the researchers wrote.<\/span><\/p>\n

The speed and direction of deep-sea currents off the coast of Mozambique are more variable than previously thought.<\/strong><\/span>\u00a0<\/span>Currents on the seafloor were previously thought to be constant and flow from south to north in the region off the coast of Mozambique that the authors studied. However, the results of the study show that deep-sea currents are much more dynamic than previously thought. The results suggest that current modeling used to track the flow of sediment and pollutants in the deep sea and reconstruct ancient ocean conditions needs to be updated.<\/span><\/p>\n

Large-scale currents are the ocean\u2019s conveyor belts, transporting water and nutrients and controlling Earth\u2019s climate. Surface currents are relatively easy to measure and track. But deep ocean currents remain largely a mystery. A new study published in Nature Geoscience has unveiled the largest data set to date on the speed and direction of currents flowing near the seafloor, and it\u2019s not what scientists expected.<\/span><\/p>\n

Scientists can measure deep-sea currents using sensors called acoustic Doppler current profilers (ADCPs) anchored to the seafloor. But deploying and managing these moorings is difficult and expensive, so many studies have used them sparingly for short periods of time.<\/span><\/p>\n

In a stroke of luck, Italian oil and gas company Eni deployed an unprecedented array of 34 ADCPs for industrial purposes over an area of \u200b\u200babout 2,500 square kilometers (965 square miles) in the Mozambique Channel, just off the coast. The company shared the data, giving scientists a unique and detailed view of the seafloor. The instruments measured the speed and direction of currents every 10 minutes for four years.<\/span><\/p>\n

\"\"
\nThe researchers used 34 acoustic Doppler current profilers, like the one pictured here, to measure deep-sea currents near Mozambique. Mike Clare<\/span><\/em><\/p>\n

When Lewis Bailey, a geologist now at the University of Calgary, began analyzing the mountains of ADCP data, the results looked so different from the expected trend of constant northward currents that he wondered if he had made a mistake. \u201cThe first thing I thought was, \u2018This can\u2019t be true,\u2019\u201d he said.<\/span><\/p>\n

But after crunching the numbers, the researchers found that the currents on the seafloor often sped up, slowed down, and even changed direction. \u201cWe were really surprised to see how variable all the currents were, even between the jetties, which were pretty close together,\u201d Bailey said.<\/span><\/p>\n

The researchers studied what might be causing the changes. \u201cIt was almost like detective work,\u201d Bailey said. The currents varied with the seasons and tidal cycles. ADCP and patterns in the eroded seafloor showed that currents on exposed seafloor slopes flow north on average. But in submarine canyons, which are oriented roughly east to west, the currents often reverse direction, flowing up or down their lengths.<\/span><\/p>\n

Scientists suggest that the nature of the currents is largely determined by the tides and the topography of the seabed.<\/span><\/p>\n

Scientists also rely on ocean current modeling and limited seafloor core samples to study the transport and deposition of sediment and pollutants such as microplastics and how they might affect deep-sea ecosystems. They also use similar techniques to reconstruct ancient ocean conditions.<\/span><\/p>\n

The authors of the new study suggested that these simulations may be oversimplified.<\/span><\/p>\n

The researchers acknowledged that the study was only conducted in one area of \u200b\u200bthe world’s oceans, and additional data from other areas would be invaluable in creating better models.<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

Antarctic currents, which supply 40% of the world\u2019s deep oceans with nutrients and oxygen, are slowing dramatically. Other models show the Gulf Stream is weakening and the AMOC could be close to collapse, with serious implications for climate. The Italian findings suggest that current modeling used to track the flow of sediment and pollutants in the deep sea and reconstruct ancient ocean conditions needs to be updated.<\/p>\n","protected":false},"author":1,"featured_media":1816,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[19,23,777,539],"tags":[858,856,857],"class_list":{"0":"post-1815","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-antarctic-currents","12":"tag-gulf-stream","13":"tag-mozambique"},"_links":{"self":[{"href":"https:\/\/planeta21vek.ru\/eng\/wp-json\/wp\/v2\/posts\/1815","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=1815"}],"version-history":[{"count":1,"href":"https:\/\/planeta21vek.ru\/eng\/wp-json\/wp\/v2\/posts\/1815\/revisions"}],"predecessor-version":[{"id":1817,"href":"https:\/\/planeta21vek.ru\/eng\/wp-json\/wp\/v2\/posts\/1815\/revisions\/1817"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/planeta21vek.ru\/eng\/wp-json\/wp\/v2\/media\/1816"}],"wp:attachment":[{"href":"https:\/\/planeta21vek.ru\/eng\/wp-json\/wp\/v2\/media?parent=1815"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/planeta21vek.ru\/eng\/wp-json\/wp\/v2\/categories?post=1815"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/planeta21vek.ru\/eng\/wp-json\/wp\/v2\/tags?post=1815"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}