An integrated Modeling Approach to Assess the Impact of Climate Change Induced Extreme Events and Non-Stationarity on Lake Cyanobacteria Blooms

The multifaceted environmental impacts of anthropogenic activities and projected future climate variability/change are a major concern. The number of freshwater bodies with impaired water quality is increasing, with harmful algal blooms becoming more and more prominent, with numerous studies observing and anticipating worsening cyanobacteria blooms in response to climate change. Integrated modeling approaches offer a viable pathway for representing such complex systems due to their ability to portray the various interconnections. Regional modeling could be beneficial since usually at this scale mitigation policy actions and management practices may be tested. An integrated assessment model (IAM) of Lake Champlain’s transboundary Missisquoi Bay was employed to examine the response of cyanobacteria blooms to the projected climate scenarios of the period 2000-2100. The focus of this work is to investigate changes in higher-order moments of precipitation and temperature when assessing the effects of extreme events on blooms under climate change. More specifically, changes on the third moment (skewness) of extreme precipitation and temperature projections are assessed, in addition to traditional first and second moments, in the context of a non-stationarity framework, both at-site and regional scale. IAM simulations included a set of hydro-climatic extremes scenarios that were informed by the non-stationary frequency analysis. The importance of potentially new eco-hydrologic regimes emergence and their impacts on Missisquoi Bay’s water quality is highlighted.