Friday, August 24, 2007

Northern Hemisphere forcing of the last 4 deglaciations

A study of the Fuji Dome and Vostok ice cores published in Nature shows that orbital-scale Antarctic climate change lags Northern Hemisphere insolation by a few thousand years since at least 360,000 years ago. Find the first paragraph of the article here.

Eocene bi-polar glaciation and the CCD

An article published in Nature by Edgar et al. discusses the link between the development of the cryosphere and the large changes in the CCD in the late Eocene. Find the link to the first paragraph here.

Tuesday, August 14, 2007

Microbes in 8 million year old ice from Beacon Valley

A team of molecular biologists and geologists claim they have found 8 million year old microbes embedded in buried glacier ice they collected in Beacon Valley, Dry Valleys, Antarctica. Bidle and others pulished their finding in the Proceedings of the National Academy of Sciences.
For more info see news article here ...
or the full open access article here...

Image: Bidle et al., PNAS.

Saturday, August 4, 2007

Antarctic circumpolar current developed in the Late Oligocene

In a recent issue of the journal Geology Lyle et al. present new sediment core data suggesting that deep flow in the South Atlantic ocean started as late as the late Oligocene. The Antarctic circumpolar current was thought to have thermally isolated Antarctica in the Eocene, so that an ice sheet could develop. Recent modeling studies, however, suggested that the story is more complex. Lyle et al. explain that shallow circulation may have existed earlier than the late Oligocene as indicated by Nd isotope studies, but that deep flow with vertical mixing was established by 23-25 Ma. These findings have consequences for studies of the evolutionary biology of the region as well. For more information read the abstract here

Image: NASA