Here's the short version:
New research has shed light on a sudden cooling event 34 million years ago, which contributed to formation of the Antarctic ice sheets.
High-resolution simulations of ocean circulations show that the tectonic opening of Southern Ocean seaways caused a fundamental reorganisation of ocean currents, heat transport and initiated a strong Antarctic surface water cooling of up to 5°C....
“A 600m change in the depth of an ocean gateway can cause a dramatic drop in coastal temperatures and, therefore, the fate of the Antarctic ice sheet.”
The last land bridges connecting Antarctica with its surrounding continents, Australia, and South America, broke off about 34 million years ago. This tectonic event did not only leave the polar continent isolated by other land masses; it also led to a major reorganisation of ocean currents in the Southern Ocean.
A circumpolar current started to flow, preventing subpolar gyres from transporting warm surface waters to the Antarctic coast. At the same time, ice sheets started to build on Antarctica and the Earth underwent one of its most fundamental climate change events, transitioning from warm Greenhouse to cold Icehouse conditions.
The role of the opening seaways in the formation of Antarctic ice sheets versus decreasing amounts of greenhouse gases in the atmosphere, has always been strongly debated by scientists.
And here's the long version, in Nature Communications (open access).
1 comment:
Mostly this is all bullshit, although the reasoning is not THAT bad. But its just a feature of the current science mafia that they will not consider that the North and South Poles aren't stationary. They don't move all that often but they do move. Their last move was definitely within the last 13000 years or so and may have been a great deal more recent. The prior position was far more long-standing.
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