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https://theconversation.com/antarctic-alarm-bells-observations-reveal-deep-ocean-currents-are-slowing-earlier-than-predicted-206289>
"Antarctica sets the stage for the world’s greatest waterfall. The action takes
place beneath the surface of the ocean. Here, trillions of tonnes of cold,
dense, oxygen-rich water cascade off the continental shelf and sink to great
depths. This Antarctic “bottom water” then spreads north along the sea floor in
deep ocean currents, before slowly rising, thousands of kilometres away.
In this way, Antarctica drives a global network of ocean currents called the
“overturning circulation” that redistributes heat, carbon and nutrients around
the globe. The overturning is crucial to keeping Earth’s climate stable. It’s
also the main way oxygen reaches the deep ocean.
But there are signs this circulation is slowing down and it’s happening decades
earlier than predicted. This slowdown has the potential to disrupt the
connection between the Antarctic coasts and the deep ocean, with profound
consequences for Earth’s climate, sea level and marine life.
Our new research, published today in the journal
Nature Climate Change, uses
real-world observations to decipher how and why the deep ocean around
Antarctica has changed over the past three decades. Our measurements show the
overturning circulation has slowed by almost a third (30%) and deep ocean
oxygen levels are declining. This is happening even earlier than climate models
predicted.
We found melting of Antarctic ice is disrupting the formation of Antarctic
bottom water. The meltwater makes Antarctic surface waters fresher, less dense,
and therefore less likely to sink. This puts the brakes on the overturning
circulation."
Cheers,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
