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new interpretation is based on Antarctic ice cores

Forscher des Alfred-Wegener-Instituts erweitern gängige Theorie zur Klimageschichte

Klimaforscher des Alfred-Wegener-Instituts für Polar- und Meeresforschung in der Helmholtz-Gemeinschaft (AWI) is a common theory extend to the formation of ice ages. In the current issue of the journal "Nature" will present three physicists from the AWI group "paleoclimate dynamics of the" new calculations on the relationship of natural solar radiation and long-term changes in global climate. Until now, the presumption, temperature fluctuations in the Antarctic, which are reconstructed for the last million years from ice cores, were caused by the erdumspannende effects of climate change on the northern hemisphere. The new study shows that significant portions of the temperature fluctuations as well by local climate changes in the Southern Hemisphere can be explained.

For the natural climate changes during the last million years, the variations in the Earth's orbit and the Erdneigung gave a decisive boost. At the beginning of the 20th Century, its influence on the seasonal distribution of solar radiation mathematician Milutin Milankovitch of the Serbian calculated and discussed since then as an astronomical theory of ice ages. Particularly given that the land surface are sensitive to changes in sunlight, the land masses on Earth, but uneven, with Milankovitch insolation changes wrote on the northern hemisphere generally a great importance for climate change by long periods of time. His idea became the standard working assumption in the current climate research, because many climate reconstructions from ice cores, ocean sediments and other climate archives, they seem to base.

The AWI scientist Thomas Laepple, Gerrit Lohmann, and Martin Werner have analyzed the temperature reconstructions from ice cores for the study now published again fundamental. They considered the first time that has in the recorded signal in Antarctic ice cores, the winter temperature has a stronger influence than the summer temperature. This effect is included in the model calculations can be reconstructed from ice cores, temperature fluctuations explain to local climate change in the southern hemisphere.

"Our results are also interesting because they lead us, perhaps from a scientific dead end," said Thomas Laepple, who with a grant from the Alexander staying von Humboldt Foundation is currently for research at the Harvard University, the importance of the new finding. For the question of whether and how the climate is linked to the northern and southern hemisphere with each other is currently the most exciting scientific questions for the understanding of climate change. So far, many researchers have tried to geological Climatic data from the Antarctic with the classical hypothesis to explain Milankovitch. "This hypothesis can be so far but not in all aspects of plausible reasons," said Laepple. "Now the game is up again, and we can try to understand the long-term physical mechanisms that determine the change of ice ages and warm periods to improve."

"We could also show that not only data from ice cores, but also Data from marine sediments have similar shifts in certain seasons. So put in the further interpretation of Paläoklimadaten still a lot of material for discussion, "adds Gerrit Lohmann. The AWI-physicist emphasize that one comes with a combination of high-quality data and models of climate change on the track. "findings on long past time to help us understand the dynamics of the climate the only way we know how the Earth's climate has changed, and how sensitive it reacts to changes. "

order to prevent confusion is the AWI scientists a final note is very important. The new study does not question that the currently observed climate change is largely human-caused. Cyclical changes as they have been investigated in the Nature publication oscillate in a cycle of tens of thousands or hundreds of thousands of years. The drastic Emissions of anthropogenic greenhouse gases within a few hundred years is added to the natural increase of greenhouse gases after the last ice age and is unique for the last million years. How the climate system will evolve in the long term, including the complex physical and biological feedbacks is the subject of current research at the Alfred Wegener Institute.

via Information Wissenschaft