2023-05-26 17:32:56
Oxygen levels in the deep ocean near Antarctica have decreased as a result of a slowdown in the sinking of denser, oxygen-rich saltwater.
About 250 billion tons of this ahua sink near Antarctica each year. This is known as Antarctic Bottom Water (AABW). The sinking process drives a global network of currents. The newly formed AABW fills up to 40 percent of the total volume of the world’s oceans. Just like a lung pumps oxygen into our blood, AABW transports oxygen, as well as carbon and nutrients, to the depths of the Indian, Pacific, and Atlantic oceans.
But new study led by CSIRO researcher Dr Kathy Gunn reveals a disruption to this natural process. “Our observations show that the deep ocean circulation around Antarctica has slowed overall by 30 percent since the 1990s. This slowdown blocks decades of impacts,” Gunn said in a announcement.
Surface waters were less salty
This slowdown occurred because increased melting of Antarctic glaciers made surface waters less salty and therefore more buoyant. This means that there is less dense water that sinks from the surface to the depths. The disruption of a key process that replenishes the deep ocean with oxygen has effects far beyond the immediate sea..
The results of the study show that the deep ocean circulation is declining at a rate that models predicted would not happen until around 2050.
Professor Matthew England, co-author and deputy director of the Australian Center for Excellence in Antarctic Science, said recent modeling suggested that under the high emissions scenario of the IPCC, AABW flow would be reduced by more than 40% by 2050.
“But these latest observations suggest that the projected slowdown is already underway.”said Matthew. And as this circulation slows, the ocean floor begins to stagnate. “This would trap nutrients deep in the ocean, reducing the nutrients available to support marine life near the ocean surface,” he said.
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