Winter carbon losses in wetland ecosystem under current and future climates

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High latitude cold regions, including Arctic and northern areas of Canada, are warming more than twice as fast as the rest of the planet, with the greatest warming occurring during the winter. Given that a major process responsible for carbon dioxide (CO2) emissions, microbial respiration, increases with warming even at sub-zero temperatures, winter is a critical period for carbon cycling. Consequently, CO2 emissions during the non-growing season (NGS; fall, winter, spring) are expected to increase as the climate warms. However, there is large uncertainty in estimates of current NGS CO2 emissions from cold region ecosystems. Canada's temperate to subarctic wetlands and permafrost peatlands hold large stores of carbon which are susceptible to loss under future climate warming scenarios. Therefore, understanding the factors which regulate the processes controlling greenhouse gas emissions during the NGS is critical for predicting the fate of these vulnerable carbon stocks and for creating climate adaptation and mitigation strategies. With a focus on these critical ecosystems, we bring together Canadian leaders from multiple disciplines from across universities with federal government scientists and policy makers to determine the drivers of NGS carbon cycling, develop process-based environmental models, and estimate CO2 emissions. In doing so, we will address the knowledge gaps on NGS emissions to provide data and tools to evaluate the impact of winter warming mitigation in controlling carbon losses from pan-Canadian wetland ecosystems. Through a combination of historical data synthesis, laboratory experiments and modelling, the proposed research will focus on 1) determining the hydrological and climatic factors driving microbial NGS carbon cycling; and 2) integrating the information and data gained into models describing the underlying processes controlling NGS emissions for incorporation into the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS). This will advance our ability to track and predict carbon fluxes in cold regions wetland ecosystems and make improved, evidence-based recommendations to estimate winter carbon losses and evaluate mitigation strategies.