Shifting Climate States of the Polar Regions

A major challenge of modeling past climate change - and predicting the possible future patterns of the current climate warming - is that the data sets we have on Holocene climate changes in the polar regions are few and that existing ones are often hampered by noise, making comparisons between the two hemispheres difficult. New datasets are urgently needed in order to provide a firmer basis for modeling and understanding dynamic interactions between important components such as polar ice, atmospheric circulation patterns, sea-surface temperatures, sea-ice, and also for predicting potential consequences associated with regional climate changes. Without acquiring a better knowledge of the true natural climate variability of the Polar regions, it will be extremely difficult to assess the future importance of such underlying trends. The SHIFTS project have addressed these major limitations through an extensive research program that have collected and produced data on glacier variability throughout the last 10 000 years, a research effort that has be carried out in the polar regions of the World. Alpine glaciers represent natural systems that are particular sensitive to climate change (this we know from modern observations) and the sites chose for this purpose are also located in areas that are witnessing rapid ongoing change including Spitsbergen and Sennalandet in Arctic Norway (northern hemisphere) as well as South Georgia and Kerguelen (southern hemisphere). The comparable datasets on glacier variability produced by the SHIFTS project provide new high-quality proxy-data on spatial, temporal, and scalar climate change through the Holocene. We are now able to construct accurate reconstructions of past shifts and trends in the major polar atmospheric circulation systems, as these are intimately linked to the physical activity of alpine glaciers. Changes in glacial activity depend on the balance between summer melting and winter accumulation. Glacial activity can be detected and quantified through sediment changes in distal glacier-fed lakes. The sediment-cores from each lake characterized by invoking multi-proxy analyses, including rock magnetic properties (palaeomagnetism), physical properties, grain-size distribution, and geochemical variations detected by XRF and X-ray analyses. Age control of the sedimentary sequences are provided by a suite of dating methods, integrating cosmogenic analyses, radiocarbon dating, advanced radiocarbon dating (gas-hydration), tephra chronology, and geomagnetic palaeointensity. Geomorphological mapping of moraines in lake catchments and control of lake sedimentary infill by seismic investigations have been applied. Further we are for instance now able to assess the importance of the observed polar amplification in a historical context because the polar regions have already experienced two major warming periods during the current interglacial, one rapid and one slow. Not only have we gathered important data on Holocene climate change, but we have also focused on integrating new types of datasets to test conflicting hypotheses about key dynamic interrelationships between bi-polar land and sea-ice fluctuations, and their potential impacts on regional climate variations. The new and improved reconstructions of high-resolution glacial-based palaeoclimatic variations are beyond the current state-of-the-art and provide significantly enhanced and robust documentation of multi-decadal climate changes during the Holocene (<11 700 years).

This cross-disciplinary proposal will collect and produce data on glacier variability throughout the last 10 000 years, a research effort that will be carried out in the polar regions of the World. Alpine glaciers represent natural systems that are partic ular sensitive to climate change and the sites chosen for this purpose are also located in areas that are witnessing rapid ongoing change including Spitsbergen and Sennalandet in Arctic Norway (northern hemisphere) as well as South Georgia and Kerguelen ( southern hemisphere). Comparable datasets on glacier variability will provide new high-quality proxy-data on spatial, temporal, and scalar climate change through the Holocene. By doing so we will be able to construct accurate reconstructions of past shift s and trends in the major polar atmospheric circulation systems, as these are intimately linked to the physical activity of glaciers. This timely project will for instance be able to assess the importance of the observed polar amplification in a historica l context because the polar regions have already experienced two major warming periods during the current interglacial, one rapid and one slow. SHIFTS will produce a new type of datasets that will be of sufficient quality to test conflicting hypotheses ab out key dynamic interrelationships between bi-polar land and sea-ice fluctuations, and their potential impacts on regional climate variations. Glacial activity can be detected and quantified through sediment changes in distal glacier-fed lakes. The sedime nt-cores from each lake will be characterized by invoking multi-proxy analyses, including rock magnetic properties, physical properties and geochemical variations. Age control of the sedimentary sequences will be provided by a suite of dating methods, int egrating cosmogenic analyses, lichenometry, radiocarbon dating, tephra chronology, and geomagnetic palaeointensity. Finally, the interpretations of the.multi-proxy data will be validated against recent climate data.