#1. The Intergovernmental Panel on Climate Change (IPCC)

This network of thousands of international scientists has been around since the late 1980s, but it was in 2007 that the IPCC — charged with forging a scientific consensus on climate change — really made its mark. In its fourth assessment report on climate change, which comprised a series of reports released throughout the year, the IPCC made the final case that global warming is real, and that humans are the main cause. The IPCC also detailed the potential consequences of unchecked warming, and produced a road map for the kind of economic and technological changes needed to avoid the worst-case scenarios. Climate change is a momentous challenge, but the IPCC — which shared the Nobel Peace Prize with Al Gore this year — has shown us the way.