The influence of regional scale information on the global circulation has been investigated through the development and application of the so-called two-way nesting technique. The two-way nesting climate model system consists of a spectral atmospheric general circulation model and a grid point regional atmospheric model. Two simulations of 10 years each have been carried out with and without the feedback of the regional model to the global model. For the regional model domain the Maritime Continent covering the tropical area of the Indonesian islands has been selected as a key region influencing the global climate. The analysis of the global atmospheric temperature field shows a clear improvement through the regional model feedback; the systematic error with respect to re-analysis data can be reduced even in regions far away from the regional model domain.