Lakes at risk under climate change: Climate variability matters

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The project will enhance the understanding of lake ecosystems’ responsiveness to global warming, particularly to the variability in climate and weather conditions. The focal question is in what ways the detailed seasonal pattern of observed and projected climate warming affects the physical and biological structure of lakes. The rationale of this approach is that mean temperature changes (averaged over years or seasons) are inadequate measures of the changes that ecosystems experience, especially since the same average temperature change can derive from a multitude of warming patterns from sub-daily to decadal temporal scales. We thus challenge the supposition that the risk of critical ecosystem change increases quasi-linearly with rising mean temperature. For a suite of different lakes in Central Europe and beyond, the project will systematically analyse effects of different degrees of local and global warming upon key lake properties such as stratification events and plankton population dynamics. Using multi-decadal observational time series, already observed climate changes will be grouped according to their average annual and seasonal warming rates, followed by analysis of the ecological variability within these groups as imposed by short-term variability in the weather. Analogously, ecological impacts and risks of change under a range of future scenarios that explicitly cover a large range of possible realisations of seasonal weather evolution will be explored by use of statistical and mechanistic models and a probability-based analytical framework. The project is expected to contribute substantially to the understanding of climate change impacts upon the temporal variability of ecosystems.