Antarctica’s ‘near tropical’ past

A drilling expedition off the coast of Antarctica has revealed the continent once boasted a warm “near tropical” climate.

Wellington Gardens: a window into ancient Antarctica? Credit: Sandra Passchier

In 2010, just hours before boarding the drilling ship JOIDES Resolution, Montclair State University Associate Professor Sandra Passchier took a photo of the Wellington Botanic Gardens and posted it on her blog, writing:

“This is what Antarctica was like more than 35 million years ago in the Eocene: no ice sheet and a vegetation of tree ferns, Nothofagus trees and shrubs. This is the image that emerges from previous Antarctic drill holes and samples that recovered pollen and spores from the Eocene. Our mission is to find out when and why it changed.”

Prof Passcheir was a member of the research team on Integrated Ocean Drilling Expedition 318 departing to Wilke’s Land in Antarctica to take sediment samples from the ocean floor.  New Zealander Robert MacKay from Victoria University Wellington was also on-board the ship. By analysing the pollen and biological materials in the different layers of sediment, researchers aimed do create a picture of what Antarctica’s climate was like over 30 million years ago.

Two and a half years later, the results of the expedition have been published in the prestigious  journal Nature. Environment Reporter Matt Stewart covered the story for the Dominion Post.

An excerpt (read in full here):

Southern climate once like Queensland

New Zealand once had a climate like Queensland, at a time when palm trees swayed in the balmy subtropical rainforests of Antarctica, new research shows.

A global team of scientists, who left from Wellington, analysed Antarctic pollen and spores, opening a window on the ancient climate of the continent about 52 million years ago, which showed humid weather similar to modern coastal Queensland.

Mean summer temperatures ranged between 20 and 27 degrees Celsius and frost-sensitive vegetation abounded, according to the study, which drilled sub-seabed rock samples from off the coast of what is now known as Wilkes Land, due south of Australia.

Even by the poles, scientists found the ‘Greenhouse’ Eocene epoch – 55 to 48 million years ago – was very warm, leading to the growth of “highly diverse, near-tropical forests”.

The research, published in the science journal Nature this week, confirmed what many scientists suspected – that Antarctica once boasted an enviable summer.

New Zealand’s climate would have been similar during the epoch and there may also have been land mammals, like possums, on Antarctica, said Dr Ian Raine, team researcher and a micro-paleontologist at GNS Science in Lower Hutt.

Apart from recurring ice ages, Dr Raine said, Antarctica had been frozen for just a fraction of its history – the latest freeze starting about 35 million years ago.

Continue reading…