"Climate Flicker" ended last ice age

Study: Rapid decadal climate change before the start of the warm period

Region around Kråkenes Lake in southwestern Norway © UIB / BCCR
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Before the onset of today's warm season, there were many very rapid climate changes. This has now been found out by an international team of scientists in a new study. Thereafter, the transition from the stable cold phase to very rapid fluctuations from about 12, 150 to 11, 700 years ago to a temperature threshold that established the current, warmer climate, the researchers said in the journal Nature Geoscience.

The scientists around Jostein Bakke from the University of Bergen examined sediments from the Kråkenes Lake in southwestern Norway. These very finely stratified lake deposits are particularly suitable geological archives with which scientists can analyze the instability of the climate.

Shocking advance of the Gulf Stream

In the geochemical determination of titanium in the sediment, it now turned out that there were very short-term fluctuations in the input of this element into the lake in this phase.

"We attribute this to very short-term fluctuations in the meltwater of the inland glaciers that feed this lake, " said Professor Gerald Haug of the DFG Leibniz Center for Earth Surface Process and Climate Studies at the University of Potsdam and ETH Zurich, together with his colleague Peter Dulski of the GFZ German Research Center for Geosciences conducted these analyzes. "The fluctuating glacier melt is caused by the intermittent advance of the Gulf Stream and the resulting gradual decline in sea ice cover off Norway."

Change of the west wind system

According to the researchers, this process is closely linked to an equally high-frequency change in the west wind system and the associated heat transport to Europe. This fibrillation of the climate is reflected, as shown, in the fast-varying supply of meltwater into the lake under investigation, which was at that time the most climate-sensitive point in Europe, namely, where Gulf Stream and sea ice cover changed. display

(idw - German Research Center for Geosciences GFZ / University of Bergen, 16.02.2009 - DLO)