Executive summary: Due to continental drift, the formation of the Antarctic Circumpolar Current blocked intrusions of warm tropical waters that warmed Antarctic and initiated the Antarctic Refrigerator Effect. Cold polar regions are a natural result of inadequate solar radiation. Reduced forcing from diminished levels of CO2 is not required to explain global cooling. The resulting formation of Antarctic sea ice expelled colder, salty waters that filled the abyss and began cooling the deep oceans. After 30+ million years of cooling, 2 to 3 million years ago, colder ocean waters eventually upwelled in the mid latitudes along the west coasts of major continents as well as along the equator. The resulting global cooling, allowed the growth of Arctic ice caps, glaciers and sea ice. The Antarctic Circumpolar Current also increased global upwelling and the efficiency of the biological pump. Decreases in atmospheric CO2 are associated with reductions in populations of CO2 producing coccolithophorids along with increasing populations of diatoms that pumped CO2 to depth. If the Antarctic Refrigeration Effect can account for the changes in global temperatures, it suggests the global sensitivity to varying levels of CO2 is relatively insignificant.
Guest essay by Jim Steele
Reference link: Déformation professionnelle
Director emeritus Sierra Nevada Field Campus, San Francisco State University and author of Landscapes & Cycles: An Environmentalist’s Journey to Climate Skepticism
For the past 55 million years the global surface temperature has declined by more than 10°C from a “hot house” condition into an “ice house” with increasing temperature variability as depicted in Figure 1 (Mya = millions of years ago). During the Cretaceous and Early Cenozoic, glaciers and ice caps were absent from both Antarctica and Greenland. Antarctica was covered in para-tropical vegetation and Greenland was home to crocodiles. More importantly for millions of years the oceans had been storing enormous amounts of heat. In contrast to near freezing temperatures today, Antarctic bottom waters averaged about 11°C, suggesting Antarctic coastal temperatures never dropped below 11°C even during the long polar nights. Amazingly the equator to pole surface temperature difference…
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