We live in a world that is more interconnected - and more vulnerable - than ever before. The fallout from the banking crisis was worldwide. Concerns about infectious diseases have risen and fallen in the public's consciousness, and while no catastrophic pandemic has yet hit us, it is clear that preventive measures require global monitoring and cooperation. There has also been a stronger focus on crises that are less immediate but deeply disquieting: the pressures on energy and resources caused by a larger and more empowered population, and aggravated by anthropogenic climate change. This is the first century when one species, ours, risks irreversibly degrading the entire planet's environment. (Editorial)