Abstract
Environmental problems that cross national borders are attracting increasing public and political attention; regulating them involves coordinating the goals and activities of various governments, which often presupposes simplifying and standardizing complex knowledge, and finding ways to manage uncertainty. This article explores how transboundary environmental problems are dealt with to render complex issues governable. By discussing oil pollution in the Baltic Sea and the gas pipeline between Russia and Germany, we elucidate how boundaries are negotiated to make issues governable. Three processes are found to be particularly relevant to how involved actors render complex issues governable: complexity reduction, construction of a spatial identity for an issue, and ascription of capabilities to new or old actor constellations. We conclude that such regulation is always provisional, implying that existing regulation is always open for negotiation and criticism.