A brief history of climate – the northern seas from the Last Glacial Maximum to global warming

Thursday, 18 December 2014
Bjørg Risebrobakken1, Tor Eldevik2, Anne E. Bjune1, Carin Andersson Dahl1, H. John B. Birks3, Trond M Dokken1, Helge Drange2, Mirjam S Glessmer2, Camille Li2, Jan Even Øie Nilsen4, Odd Helge Otterå1, Kristin Richter5 and Oeystein Skagseth6, (1)Uni Research Climate, and Bjerknes Centre for Climate Research, Bergen, Norway, (2)Geophysical Institute, University of Bergen and Bjerknes Centre for Climate Research, Bergen, Norway, (3)Department of Biology, University of Bergen, and Bjerknes Centre for Climate Research, Bergen, Norway, (4)Nansen Environmental and Remote Sensing Center, and Bjerknes Centre for Climate Reserch, Bergen, Norway, (5)Institute for Meteorology and Geophysics, University of Innsbruck, Innsbruck, Austria, (6)Insititute for Marine Research, and Bjerknes Centre for Climate Research, Bergen, Norway
The understanding of climate and climate change is fundamentally concerned with two things: a well-defined and sufficiently complete climate record to be explained, for example of observed temperature, and a relevant mechanistic framework for making closed and consistent inferences concerning cause-and-effect. This is the case for understanding observed climate, as it is the case for historical climate as reconstructed from proxy data and future climate as projected by models. The present study offers a holistic description of northern maritime climate – from the Last Glacial Maximum through to the projected global warming of the 21st century – in this context. It includes the compilation of the most complete temperature record for Norway and the Norwegian Sea to date based on the synthesis of available terrestrial and marine paleoclimate reconstructions into continuous times series, and their continuation into modern and future climate with the instrumental record and a model projection. The scientific literature on a variable northern climate is reviewed against this background, and with a particular emphasis on the role of the Norwegian Atlantic Current – the Gulf Stream’s extension towards the Arctic. This includes the introduction of an explicit and relatively simple diagnostic relation to quantify the change in ocean circulation consistent with reconstructed ocean temperatures. It is found that maritime climate and the strength of the Norwegian Atlantic Current are closely related throughout the record. The nature of the relation is however qualitatively different as one progresses from the past, through the present, and into the future.