Polar Climate Stability Network The Polar Climate Stability Network is funded by the Canadian Foundation for Climate and Atmospheric Science. The Network will be closely involved in International Polar Year (IPY 2007-08). The work of the Polar Climate Stability Network (PCSN) will focus on the problem of climate change at high northern latitudes, the region of Earth that we expect will be most strongly affected by greenhouse gas induced global warming. Since the Canadian landmass and adjacent shelves of the Arctic Ocean constitute a major portion of this region, the issue of the stability of northern ecosystems to the expected, indeed already clearly evident, climate change is an important national concern. The scientific efforts of the PCSN group involve investigations under four primary themes, respectively connected with the issues of: Theme I: Mechanisms of Rapid Climate Change: Oceanographic and Terrestrial Theme II: Polar Cryospheric Stability: Land Ice and Sea Ice      Theme III: The Arctic/North Atlantic Oscillation and the role of the Arctic Ocean  in the Climate System:  Paleoclimatological Perspectives   Theme IV: Low Latitude - High Latitude Teleconnections: Paleoceanographic Perspectives And Atmospheric Dynamical Interactions The scientific program involves both an observational component and a theoretical modelling component in the work under each of the four themes. The observational aspects of the program involve the use of deep sea sedimentary cores, ice cores from the ice caps in the eastern Canadian Arctic archipelago and in the high mountains such as Mt. Logan in the west, as well as pollen based records from high latitude lakes and records of temperature change with depth in deep boreholes in surface bedrock. The theoretical modelling aspects of the program involve the use of high performance supercomputers to simulate various aspects of the Earth System Climate. The computer models used in the program vary over a wide range of physical complexity and simulate physical and dynamical processes such as glacier advance/retreat and the global scale evolution of the atmosphere-land surface-ocean-sea ice system. Currently the network is focusing upon the following scientific foci: Polar Climate Stability Network: Current Scientific Foci Central to Network Integration 1) The Labrador Sea Issue: Andrew Weaver to act as lead This integrative project is focused upon understanding the impact of the formation of Labrador Sea Water (LSW) upon the response of the Atlantic Thermohaline Circulation (THC) to meltwater pulses released during deglaciation. This problem has significant implications for understanding post-glacial climate variations in the North Atlantic (e.g. the 8.2 ka BP event). It also has potential implications for understanding synoptic scale atmospheric variability in the North Atlantic sector of the climate system (e.g. storm tracks). 2) Low-Latitude High-Latitude Teleconnections: Tom Pedersen to act as lead This focus of the collaborative activity within the Network will involve investigation of the causal relationships in climate variability between changes that occur in the Polar Region and the Tropics. The activity will address the important issue of the timing and response of changes which occur synchronously or quasi-synchronously between the Polar Regions and the Tropics with special focus upon both the last degalciation and the Holocene. The group is not only interested in teleconnections from the tropics to high latitudes but also the reverse. 3) Mass Balance of the Polar Cryosphere: Garry Clarke to act as lead This critical focus of activity will focus upon investigation of both the modern and the historical mass balance of the high northern latitude regions of the globe with special emphasis on Canadian high latitudes and Greenland. It is expected that the new data sets being provided by the GRACE satellite system will play an extremely important role in this activity. 4) Oxygen Isotopes as a Tracer of Climate Processes: Claude Hillaire-Marcel to act as lead One of the most useful new archives that is enabling us to trace the mechanisms involved in the control of high latitude climate variability concerns the use of oxygen isotopic measurements. Such stable isotopic measurements will enable the group to comment usefully upon:       i)          atmosphere-cryosphere interactions, past and present       ii)         ocean circulation, past and present 5) Polar Amplification of Climate Change: Andrew Bush to act as lead Given the collective expertise within the Network, it will be possible for the group to develop a uniquely Canadian perspective upon those characteristics of the climate system that have a significant impact on the strength of the amplification of the climate change signal that all models suggest to be characteristic of the Arctic. The operative mechanisms include sea ice and permafrost feedbacks, snow cover changes at high latitudes, as well as tree-line advance and soil moisture effects.