Many of today's most pressing environmental problems share one important characteristic: they are cross-boundary, i.e., they disregard political and geographical borders. Obviously, this is challenging for several reasons. One is that present legal and political institutionshave no effective reach beyond the nation-state. The same is the case with most political authority. Furthermore, the border crossing character of many environmental problems is also ethically challenging. What is a fair distribution of the burdens required to mitigate and adapt to e.g., climate change, chemical pollution andover use of marine resources and/or to make society less vulnerable to its' consequences? And perhaps even more difficult: Who has theresponsibility to take action - those causing the problems or those inrisk to suffer from the devastating effects? The papers in this section are discussing environmental problems from such points of view as authority, responsibility and distributive justice.