From cells to biomes: the impacts of recent climate change on northern ecosystems

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Climate change is leading to broad scale impacts on global ecosystems through changing temperature and precipitation patterns. For example, climate change is altering disturbance regimes, changing the seasonal patterns of precipitation, altering the frequency of extreme weather events, and changing species distributions and phenological patterns. In northern regions, the impacts of climate change are heightened due to Arctic amplification which has caused the Arctic to warm nearly 2X faster than mid-latitude regions. *** The rapid warming in the Arctic is leading to changes to physical and biological components of high-latitude ecosystems. For example, within the field of***dendroclimatology, recent studies have noted that since the 1970-80s, there has been an increasing off-set between tree-ring temperature reconstructions and measured***temperatures at some high-latitude sites. This offset between actual temperatures and those reconstructed from tree ring studies is known as the "Divergence Problem".***Divergence is potentially an ecosystem response to recent climate change and challenges the assumption that tree ring chronologies can be used as a reliable***predictor of past climate. In addition, the spatial extent of the Divergence Problem is largely unexplored.*** My research will further our understanding of climate and environmental change in northern Canada using highly-resolved proxy data sources (tree ring records). I will address the Divergence issue in tree ring research in Canada, especially the spatial occurrence of divergence across northern Canada and the potential factors leading to divergence. The main geographic areas that will be investigated are Inuvik and Norman Wells in northwest Canada;Yellowknife near the central Canadian treeline; and Churchill, MB near treeline on the coast of Hudson Bay. The specific objectives of this research project are:***1: Determine the spatial signature of the Divergence Problem across treeline in north-central Canada.***2: Determine the cause(s) of the Divergence Problem.***3: Develop long, highly resolved quantitative records of past climate for the three study regions using multiple sources of tree ring data that do not display diverging climate-growth relations. Few annually-resolved millennial length records of climate exist for Arctic/subArctic regions of Canada. I will explore the possibility***of developing supra-long tree ring chronologies for northern Canada by recovering submerged logs from the bottom of lakes.***4: Explore the utility of wood anatomical features (lumen area, cell wall thickness) as proxies for reconstructing past climatic conditions at treeline sites.*** My research program will provide insights useful in a number of fields of study within the natural sciences (climate and ecosystem modellers, ecologists, policy analysts) and advance our knowledge of climate change and its impacts in the Arctic.