Global climate change is affecting our planet and mankind; climate science is thus instrumental in informing policy makers about its dangers, and in suggesting emission limits. Science also shows that staying within limits, while meeting the aspirations of a growing global population requires fundamental changes in energy conversion and storage. The majority of low-carbon technology innovation observed in the last decades, such as the 85% cost reduction in photovoltaic cell production since 2000, was driven by largely uncoordinated national policies. These included research incentives in Japan and the U.S., feed-in tariffs in Germany, and tax breaks in the U.S.