Net ecosystem exchange of carbon greenhouse gases in high arctic ecoregions

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Human activities have elevated global atmospheric concentrations of the greenhouse gases (GHGs) carbon dioxide (CO2) and methane (CH4) to levels that have resulted in an unequivocal and unprecedented warming of the Earth's climate system. This is especially true in the high Arctic, where in the past century average annual temperatures have increased at almost twice the global rate. Current climate models predict that in certain regions of the Canadian Arctic, by 2100, autumn/winter temperatures will increase by up to 9 C, while annual precipitation will likely rise by 35%. Such warming and wetting is anticipated to result in permafrost degradation and glacial melt, increased surface runoff, pond formation and/or drying, and increased vegetation growth (i.e., primary productivity) on landscapes. In polar desert regions of the high Arctic, large amounts of CO2 could be sequestered from the atmosphere through primary production if tundra vegetation colonizes the desert ecosystem in response to increased warming and wetting. In contrast, in regions with large stores of organic carbon in soil, the increased soil activity that will result from permafrost degradation may cause increased decomposition and release of CO2 and CH4 into the atmosphere, positively feeding back on global climate warming. We are proposing to quantify the impacts of climate change on the net exchange of CO2 and CH4 from both terrestrial and aquatic landscapes in Quttinirpaaq National Park, Ellesmere Island. Such new and comprehensive measurements, at the most northerly landscape ever studied, are essential to determine if this region is currently in a phase of net primary productivity or net decomposition, whether future warming will result in positive or negative feedbacks of GHGs to the atmosphere, and what role Arctic ecosystems will play in future trajectories of climate change. From a socio-economic perspective, primary productivity provides energy for herbivorous animals like caribou, muskox, and numerous aquatic organisms including fish. Thus, understanding the net exchange of CO2 in high Arctic landscapes is important for predicting how abundances of certain organisms used as Inuit traditional foods may be altered due to climate change.