This paper concerns the way in which the scientific debate on climate change and new risks is being adopted as a basis for political decision making. How does the crucial risk issue 'diffuse' into policy, which in turn has to give the public account of the risks of climate change? In discussing the science –policy interface, reference is made to the debate on blurring boundaries between science and policy making. Here, hetero-geneous and often competing discourses come into play. This makes discourse analysis an appropriate and well-accepted tool in both conceptual and theoretical aspect. However, which of the competing discourses wins the day can hardly be explained in a dis-course analytical way, due to its constructivist bias. Case studies provide some evidence that complex understanding can be obtained when discourse analysis is framed by a more realistic approach, such as Kingdon's policy window approach. Two cases are presented. Although representing overlapping policy domains, the risk management differs considerably. In both the state proves to be the pivotal actor. In the first case, on coastal protection in northern Germany, the administrative officers in charge try to transform and to curtail the risk issue and its emphasis on uncertainty in a way that makes it compatible with their own safety discourse, thus generating a scientific – admin-istrative hybrid. The second case, a newly enacted political strategy on riparian flood pro-tection, draws explicitly on uncertainty and risk, thus transferring and integrating the issue firsthand into the political – administrative system. Taking a governance perspective, the explanation refers to different steering contexts in terms of institutional settings, actor constellations, political framings and natural extreme events.