Climate and Lakes

This theme investigates how lakes regulate climatic processes and how, in turn, climate influences lakes and society. Our prairie LTER program reveals that climate warming since 1990 has increased lake pH by 1.5 units and stimulated CO2 capture by lakes to rates equivalent to 50% of provincial agricultural emissions. Further, we show that influx of energy (E) increases spatial synchrony of lake properties, whereas the influx of mass (m) reduces temporal coherence, particularly that of aquatic food webs. Our whole-lake experiments, surveys, and stable isotope analyses reveal that variation in jet stream position, and consequently winter precipitation, is the main climatic mechanism structuring central Canadian lakes, despite chemical and food-web effects of E exchange during summer. Finally, we are developing a series of paleo-climate reconstructions to forecast the risks of droughts on the Canadian Prairies. These conditional probability analyses estimate that the risk of severe (1930s) droughts is as high as 45% by 2030 AD, with expected losses of $650 billion. This information is being used by crop insurance, agricultural and hydroelectric corporations in all Prairie Provinces to evaluate their susceptibility to climate extremes.