We have brought together a consortium of scientists and end-users from 10 countries to assess the direct and indirect effects of changes in the weather on the dynamics of lakes in northern, western and central Europe. Particular attention will be paid to water quality variables used as diagnostic elements in the water Framework Directive. The primary objective is to develop a suite of well as past changes in the weather. The models will be validated by historical data and perturbed by simulations of future variations in the weather. These simulations will be based on the output from an ensemble of Regional Climate Models and will be linked to socio-economic analyses of their costs and benefits of the predicted changes. One of the main outputs will be a Decision Support System that can be used to optimise the management of lakes in a warmer world.