4th Swiss Geoscience Meeting, Bern 2006 Holocene climate swings – An attempt to understand global dynamics

• Main Author: Heinz Wanner
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Antarctic; Arctic; Greenland; Ross Sea; Antarc*; Antarctica; Greenland ice core; ice core; North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.528.1940; http://geoscience-meeting.scnatweb.ch/sgm2006/SGM06_abstracts/06_Holocene/Wanner_Heinz_talk.pdf

Greenland ice core records show that, prior to the 20th century, temperatures during the Holocene in the Northern Hemisphere mid and high latitudes were only higher during the so-called “Holocene Climate Optimum”. Pollen analysis has demonstrated that this warmer period, also called “Atlantikum”, occurred in the Canadian Arctic, North Atlantic and Europe between approximately 8000 and 4500 cal yr BP. Glaciological evidence reveals that, during the mid-Holocene, the glaciers strongly retreated in the European Alps, the Canadian Rockies, in the Arctic and other regions of the northern hemisphere. Macrofossils bring evidences that the northern tree line moved north and was located at the Arctic coast over most of Russia. Antarctic ice cores show a widespread Holocene warm period between 11,500 and 9000 cal yr BP and secondary warmer phases in the Ross Sea sector (8000 – 6000 cal yr BP) and eastern Antarctica (6000 – 3000 cal yr BP). There is a lively debate whether the Holocene climate was cyclic or even periodic not only during the last glacials, but also during the Holocene. This debate was strongly triggered by the discussion around the most recent transition from the Medieval Warm Period to the Little Ice Age. Based on the fluctuations of Alpine glaciers Holzhauser et al. (2005) as well as Jörin et al. (2006) have also demonstrated that two examples of a transition from warmer to colder periods during the late Holocene