Cardiac fibrillation of the climate

In the current issue of the Scientific Journal Nature Geoscience a group of Norwegian, Swiss and German geoscientists prove that before the set-in of the Holocene very rapid climate changes already existed. The transition from the stable cold period took place about 12 150 to 11 700 years ago with very rapid fluctations up to the temperatur-threshold at which the Holocene began.

For this study, a group of scientists around J. Bakke, University of Bergen, examined sediments from Lake Kråkenes in Southwest Norway. These micro-layered lake deposits constitute a particularly suitable geological archive, with which scientists are able to analyse the climate volatility. The geochemical determination of titanium in sediments shows that during this phase significant short-term fluctuations in the titanium concentrations in the lake are detectable.

“We ascribe this to the short-term fluctuations in watermelt runoff from the inland glacier which feeds this lake”, explains Professor Gerald Haug from the DFG Leibniz Center for Earth Surface Process and Climate Studies at the University of Potsdam and the ETH Zürich, who carried out the analysis together with his colleague, Peter Dulkski, from the GFZ German Research Centre for Geosciences. “The fluctuating glacialmelt is a result of the intermittent advancement of the Gulf Stream and the resulting successive retreat of the sea-ice coverage.”

This process is closely linked with an equally high-frequence change in the westwind system and the therewith connected heat transport to Europe. This cardiac fibrillation of the climate is reflected again, as shown, in the fast-varying meltwater runoff into the examined lake, which at this point in time actually lay at the most climate-sensitive location of Europe, namely there where the Gulf Stream and the sea-ice coverage transformed.

* J. Bakke, Ø. Lie, E. Heegaard, T. Dokken, G. Haug, H. Birks, P. Dulski and T. Nilsen: (2009): Rapid oceanic and atmospheric changes during the Younger Dryas cold period, Nature Geoscience, Advance Online Publication, 15.02. 2009, 18:00 London time