EARTHSS 15 Lecture Notes - Lecture 15: Antarctic Circumpolar Current, James Croll, Antarctica
8 Nov 2016
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Document Summary
Deep past, ice ages, the global carbon cycle. Continents bunched up at south pole about 500 million years ago. Huge ice sheets left deposits and erosion across southern hemisphere. Late paleozoic (~300 ma: most continents bunched up near south pole ( gondwanaland, evidence of ice sheets in africa, south america, and australia. Arctic: co2 was 400% to 600% of present concentration. Cenezoic climates ( since the dinosaurs, 65 ma) Gradual separation of australia, south america, and antartica: antartica moved into polar position, south america and australia moved north. Opening of drake passage initiated circumpolar current in the southern ocean. Ocean surface anf bottom temperatures cooled by 10 c. Cool temperate forest in antarctica ~20 ma gave way to ice, reached current volume ~ 5 ma. Northern hemisphere ice sheets appeared about 3 ma. Antarctic circumpolar current isolated south polar region. Northern ice sheets grow and collapse in a cycle of ice ages. Europeams have been living with glaciers for millennia.
