'Planetary boundaries'-exploring the challenges for global environmental governance
A range of studies from Earth system scientists argue that human activities drive multiple, interacting effects that cascade through the Earth system. Recent contributions state and quantify nine, interacting 'planetary boundaries' with possible threshold effects. This article provides an overview of the global governance challenges that follow from this notion of multiple, interacting and possibly non-linear 'planetary boundaries'. Here we discuss four interrelated global environmental governance challenges, as well as some possible ways to address them. The four identified challenges are related to, first, the interplay between Earth system science and global policies, and the implications of differences in risk perceptions in defining these boundaries; second, the capacity of international institutions to deal with individual 'planetary boundaries', as well as interactions between them; third, the role of international organizations in dealing with 'planetary boundaries' interactions; and fourth, the role of global governance in framing social-ecological innovations.