Already the Day After Tomorrow?

Abstract
The thermohaline circulation of the ocean is a process that generates a giant flow pattern in which water moves around the planet. Recently, dire predictions and Hollywood movies have raised public consciousness of the impact of ocean flows on climate change. In their Perspective, Hansen et al. discuss recent observations and suggest that although the circulation may be weakening, which might lead to climate cooling in northern Europe, compensating effects make the picture richer and more complex and difficult to predict than previously thought.