Castle Lake Limnological Research Station

Atmospheric scientists have predicted that large-scale climatic changes will result from increasing levels of tropospheric CO2. We have investigated the potential effects of climate change on the primary productivity of Castle Lake, a mountain lake in Northern California. Annual algal productivity was modeled empirically using 25 years of limnological data in order to establish predictive relationships between productivity and the climatic variables of accumulated snow depth and precipitation. The outputs of monthly temperature and precipitation from three general circulation models (GCMs) of doubled atmospheric CO2 were then used in the regression model to predict annual algal productivity. In all cases, the GCM senarios predicted increased algal productivity for Castle Lake under conditions of doubled atmospheric CO2. The primary cause of enhanced productivity was the increased length of the growing season resulting from earlier spring ice-out.