Microfossils Give New Insight into Climate Shift 30 Million Years Ago
16.12.2009 - Water & Oceans, Flora & Fauna
Microfossils found in ocean sediment cores have allowed scientists from the University of Southampton's School of Ocean and Earth Science (SEOS) to reconstruct past environmental conditions in the North Atlantic during a critical period of Earth's climate history.
Some 55 million years ago, at the beginning of the Eocene, the Poles were most likely ice free; yet at the beginning of the early Oligocene some 25 million years later, Antarctica was already covered in an ice sheet and continental ice had developed on Greenland. The climate shift is believed to have occurred after a strong decrease in greenhouse gas concentrations and a change in the Earth's orbit, although altered ocean currents may have influenced local temperatures at the Poles as well.
Thanks to the sediment fossils, the scientists were able to provide a detailed overview of the evolution of the climate over the Vøring Plateau in the North Atlantic. While mainly consisting of species living in fresh or salt water in the earlier periods studied, samples from the late Eocene only featured marine plankton. The Vøring Plateau had by then subsided, opening the way for marine connections to be made between the various Nordic sea basins. These connections would then have caused increased productivity, drawing carbon dioxide from the atmosphere and leading to a decline in temperatures and the development of continental ice on Greenland.
