Sour milk for CO2: it really was oceanography of Antarctic isolation that cooled the Cenozoic – not CO2

A new 2021 Nature paper by Isabel Sauermilch and colleagues has told us what we always knew. From the asteroid-death of the dinosaurs till the present the earth has cooled a lot. From a declining hothouse to our current Pleistocene glaciation.

For decades the scientific understanding in geology and palaeo-climate was that a big part of this cooling was the stop-start tectonic isolation of the south polar continent of Antarctica and its final separation from Australia and South America. That southward currents from Africa which had hitherto warmed the Antarctic such that forests and rich faunal and floral ecosystems thrived there, to its present frigid state almost devoid of life other than marine and microbial. In two big steps – 32 and 16 million years ago, this disconnection was achieved and finalised by the establishment of the circum-polar current of the Southern Ocean flowing around the entire latitude and completing Antarctica’s ocean isolation. The only place on earth where a current latitudinally loops the globe. Profound cooling of the whole planet followed in its wake leading to the Pleistocene glaciation at both poles – which we are still in.

Until recently of course with the baleful politicisation of climate science and the tortuous reinterpretation of all past and present climate change as being only driven by carbon dioxide. An irresistible mandate to put the cart before the horse.

However real oceanographers were loathe to discard and betray their field so obediently. Thus Isabel Sauermilch and colleagues at the Universities of Tasmania, Australia and Utrecht, Netherlands, took a serious and detailed look at both the sediment proxy evidence and the tectonic ocean modelling of the Antarctic separation and its effect on meridional heat transport and global temperature. Their results are compelling and are published in Nature. Here’s the paper

The outcome of this excellent work is that we’re back where we started. Ocean current rearrangement linked to the isolation of Antarctica and establishment of the circum-polar current really did cool down the whole earth.

At the end is shown one of my favourite figures showing how crucially important Antarctica is to all the earth’s ocean basins – one could call it the “Grand Central Station” of the oceanic circulation system – also called the Thermo-Haline Circulation.

So in oceanography and climate the isolation of a part of the earth has a chilling effect on the whole planet’s climate. Something that western politicians would do well to understand in regard to their manic bordering-on-racist hostility and aggression toward the lands and people of Russia, Iran and China. Better to stay connected – if we don’t want an ice age.

Antarctica – the Grand Central Station of the world’s ocean circulation at all levels.

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