A press release from the National Science Foundation – remote Siberian lake has clues on climate change at the Poles. A preliminary analysis of a very long sediment core from a lake in NE Russia, not too far from the Bering Strait, has produced the longest record of changing temperature in the northern hemisphere – going further back than the Greenland ice cores, a mere 110,000 years in comparison to 4 million years. Well, it must be preliminary as that is a very long core – but according to the journal Science, who are publishing the paper, the core shows a succession of warming and coolings – assumed to represent the various interglacial periods (see also http://wattsupwiththat.com/2012/06/22/claim-fates-of-polar-ice-sheets-ap….
The lake was formed nearly 4 million years ago on the geochronology time-scale, after a meteorite slammed into the Earth and created a large crater – which subsequently filled with water and formed a lake eleven miles wide. It has been collecting sediment ever since. However, the lake has never been covered by glaciers, it is alleged, so the build-up of sediment is uninterrupted -which is why it was chosen. The sediments are said to match the glacial/interglacial pattern of the Ice Ages – but some warm periods were very warm. The same article abstract can be seen from a German perspecitive at http://notrickszone.com/2012/06/22/new-2-8-million-year-reconstruction-t… where the authors of the study find warming periods greater than today, without co2 as a driver. It seems a lot is being read into what is an abstract. How did they divide the sediment into periods – what is it based on, and what assumptions are at the heart of the reconstruction etc.