Asked by Marie
Glaciers began in Antarctica around 35 million years ago during a period of cooling climates. As the Antarctic continent drifted south, the Drake Passage opened, allowing the Antarctic Circumpolar Current to become established. This current effectively isolated Antarctica from heat transfer from further north, resulting in cooling. So, with its drift southwards to the South Pole, uplift of the Antarctic Peninsula mountains and the cooling effect of the circumpolar current, glaciers began to form on the mountains of Antarctica. See this article about Antarctic Peninsula Ice Sheet Evolution. The evidence for this mostly comes from offshore drilling programmes.
The Sirius Group provides evidence of ancient glaciation in Antarctica from long ago, up to 15 million years ago. Volcanoes in East Antarctica provide evidence of glaciation in the Miocene (12-15 million years ago).
Why do maps from the 1500’s show antarctica as a warm climate with animals? What happened between 1500 and 1800 to cause antarctica to ice over? Some one or something has to be in history somewhere?
Thank you for your question.
Between 1500 and 1800 a number of maps were produced depicting Antarctica as ‘ice-free’, including the ‘Piri Reis map, 1513′ and the ’18th century Buache Map’. Antarctica would have been ice-covered during these period. Thus it comes down to the approach taken by the cartographers. For the Piri Reis map, has been suggested to show Antarctica as it looked during the Neolithic period, a time without glacial ice. Whilst the Buache map example is said to show the subglacial topography of Antarctica, thus is also shown as ice free. I hope that helps!