Carbon-climate interactions in hard-water lakes

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It is now widely accepted that lakes are important nodes of carbon processing and play a major role in the global carbon budget. A better understanding of the patterns and underlying causes of variability in CO2 among lakes is needed to improve predictions of how lakes will both contribute and respond to future climate change. Research conducted in soft-water, boreal ecosystems has shown that most projections of climate change will result in positive feedback loops with increasing CO2 emissions from these lakes. For example, boreal lakes are predicted to experience elevated respiratory-derived CO2 concentrations as the atmospheric temperature increases and organic carbon loadings from the watershed are elevated with increasing frequency of flooding events. In contrast, much less is known about the climate and carbon dynamics in hard-water systems, which comprise over half of the volume of inland waters worldwide. Work to date suggests that hard-water lakes are more strongly regulated by inorganic carbon loading from the catchment, and that negative feedback mechanisms, whereby CO2 uptake increases as the climate warms, are more prevalent. The work proposed in this NSERC DG seeks to establish a mechanistic understanding of how climate change affects lake carbon processing across many different types of lakes through variations in the climate parameters of Energy flux (e.g. temperature) and mass flux (e.g. precipitation). Understanding the interplay between carbon and climate in inland waters is critical in projecting the future of climate change in Canada and across the globe. I propose to establish the relationships between carbon and climate in hard-water lakes in the Canadian prairies by 1) developing accurate annual CO2 budgets for hard-water and saline lakes by measuring concentrations of CO2 at daily and seasonal time scales; 2) determining local (in-lake) chief regulators of CO2 along a spatial gradient of varying productivity and salinity; and 3) examining how regional Energy and mass flux variability (via storms, drought and pluvial periods) affect lake CO2. The research proposed here will lead to a predictive and quantifiable framework that can be modified and adapted to other systems to develop more accurate CO2 estimates across the continuum of lake types (low-high productivity, low-high alkalinity) worldwide. Together, these objectives will allow for the evaluation of how ecosystem and landscape level processes both contribute and respond to atmospheric greenhouse gas concentrations.