Rising Antarctic ice melt will dramatically slow global ocean flows - study

SINGAPORE (Reuters) - According to new study, the melting Antarctic ice is drastically slowing the movement of water through the world's seas. This could have a disastrous effect on the marine food chain, the global temperature, and even the security of ice shelves.

The flow of denser water toward the sea bottom, known as the "overturning circulation" of the seas, contributes to the global distribution of heat, carbon dioxide, oxygen, and essential minerals.

However, a research released on Wednesday in the journal Nature suggests that deep ocean water flows from the Antarctic may decrease by 40% by 2050.

Alan Mix, a paleoclimatologist at Oregon State University and co-author on the most recent IPCC assessments, who was not engaged in the research, said: "That's stunning to see that happen so quickly." "That's headline news, it seems to be starting up right now."

Freshwater from melting Antarctica ice penetrates the ocean as temps increase, lowering the salinity and density of the top water and decreasing the downhill flow to the sea floor.

Less study has been done on Antarctic bottom water circulation than on comparable overturning circulation in the North Atlantic, which is the process behind the apocalyptic scenario in which Europe would experience an Arctic blast as heat transfer fails.

Up until the middle of this century, scientists used about 35 million computing hours to run a variety of models and scenarios, and they discovered that deepwater circulation in the Antarctic may diminish at a pace that is twice as fast as that of the North Atlantic.

Oceanographer Matthew England, a co-author of the research and a professor at the University of New South Wales, said in a press conference, "They are massive volumes of water... and they are bits of the ocean that have been stable for a long time."


Although it has not yet been accounted for in the intricate models the IPCC uses to characterize various future climate change scenarios, the impact of meltwater on world ocean circulation will be significant, according to England.

According to Steve Rintoul, a second research co-author, ocean overturning enables nutrients to ascend up from the bottom, with the Southern Ocean sustaining roughly three-quarters of the world's phytoplankton output, the foundation of the food chain.

According to Rintoul, an associate at Australia's Commonwealth Scientific and Industrial Research Organization, "If we slow the sinking near Antarctica, we slow down the whole circulation and so we also reduce the amount of nutrients that get returned from the deep ocean back up to the surface." (CSIRO).

As the ocean's top strata become more stratified, the results of the research also imply that the ocean won't be able to take as much carbon dioxide, leading to more CO2 in the atmosphere.

The research predicted a rise in warm water incursions into the western Antarctic ice shelf, but it did not examine whether this might result in a feedback loop that causes further melting.

The catastrophe possibilities are not included, according to Mix. It is genuinely somewhat conservative in that respect.