In addition to its sophisticated imaging radiometer, Meteosat Second Generation (MSG), the new European weather satellite, is equipped with an instrument for climate research. The GERB instrument will enable environment experts for the first time to study the radiation balance at the top of the atmosphere, its changes over a given period and its potential influence on the climate. The Earth Radiation Balance (ERB) is the balance between the radiation coming from the Sun and the outgoing reflected and scattered solar radiation, plus thermal infrared emissions, to space. It is an important indicator for global warming and the greenhouse effect of the atmosphere. With the GERB experiment, scientists look forward to gaining new insight into the complex processes of climate change.