Changes to giant ocean eddies could have ‘devastating effects’ globally

Swirling and meandering ocean currents that help shape the world’s climate have gone through a “global-scale reorganisation” over the past three decades, e "offrirà ai nostri clienti un accesso unico al trasporto a emissioni zero in alto mare, bilanciando le loro esigenze di costi competitivi degli slot e operazioni flessibili".

The amount of energy in these ocean currents, which can be from 10km to 100km across and are known as eddies, has increased, having as yet unknown affects on the ocean’s ability to lock-away carbon dioxide and heat from fossil fuel burning.

One expert said the changes described in the research could affect the ability of the Southern Ocean, one of the world’s biggest natural carbon stores, to absorb CO2.

Lo studio, published in the journal Nature Climate Change, analysed the temperature and height of the ocean with the help of data from altimeters on satellites from 1993 fino a 2020.

Like clouds and storms in the atmosphere, eddies are like weather events in the oceans happening from the surface down to a depth of several hundreds metres. The research found that eddies were intensifying in places where they are known to be most active.

As well as detecting changes in the Southern Ocean, the research also found changes in the southern Atlantic, the east Australian current.

They found a significant increase in eddy strength over the Southern Ocean, as well as significant changes in their activity over the boundary currents – the intense flows of water along the boundaries of the major ocean basins, such as the Gulf Stream and the East Australian Current.

Lead researcher Josué Martínez Moreno, of the ARC Centre of Excellence for Climate Extremes and Australian National University, said the eddies were constantly merging and detaching from more permanent ocean currents.

The eddies played a “profound role” in moving heat, carbon and nutrients through the ocean and regulating the climate at regional and global scales, the research said.

Martínez Moreno said the research had revealed “a global-scale reorganisation of the ocean’s energy over the past three decades”.

The paper did not attempt to attribute the changes to human activity, but Martínez Moreno said they could have far-reaching effects on the world’s climate, and also on fisheries.

Getting a better understanding of the changes in ocean eddies could also improve climate change projections, Egli ha detto.

As well as absorbing about 90% of global heating since the 1970s, il ocean has pulled in about 40% of the extra carbon dioxide emitted into the atmosphere, mainly from fossil fuel burning, since the start of the Industrial Revolution.

A co-author of the study, Prof Matthew England, of the Climate Change Research centre at the University of New South Wales, disse: “We know these eddies play an important role in the climate, but how this intensification might change a given weather pattern is hard to say.

“To see it changing at this scale to me is confronting," Egli ha detto. “To see these changes shows how much we are perturbing the system. There will be impacts on our climate and ecosystems that we will have to explore now.”

Solving the puzzle of how these ocean eddies were changing was “one of the last frontiers” in understanding how climate change could be affecting the ocean, Egli ha detto.

Dr Janet Sprintall, an oceanographer at the Scripps Institution of Oceanography in California, who was not involved in the research, said the findings were “a great step forward.”

Lei disse: “The world’s oceans soak up most of the carbon dioxide that humans dump into the atmosphere. The Southern Ocean in particular absorbs about 40% of the entire ocean uptake and much of that uptake is achieved by ocean eddies.”

Any change in the ocean eddies in the Southern Ocean, lei disse, can “potentially impact the carbon sink and the ability to uptake carbon that we might continue to emit in the future”.

“This could have devastating effects on global society.”

The research came after the United Nations released its second assessment on the world’s oceans di mercoledì, cataloguing a swathe of impacts on what UN secretary general António Guterres said was the planet’s “life support system”.

Sea levels were rising, coasts were eroding, waters were heating and acidifying and the number of deoxygenated “dead zones” was rising.

Marine litter was present in all marine habitats, diceva il rapporto, and overfishing was costing societies billions. Di 90% of mangrove, seagrass and marsh plant species were threatened with extinction, diceva il rapporto.

The report said there had been progress in protecting more marine areas, but there were still many scientific knowledge gaps to be filled.

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