Today the science academies for the G8+5 countries issued statements urging leaders worldwide to take action on two pressing global challenges. To mitigate and adapt to climate change, nations must begin a transition to being "low-carbon societies," a shift that will require energy-saving changes in all sectors -- from housing to transportation to industry -- and the development of a range of clean energy sources. Meeting global health challenges, such as infectious disease outbreaks and the rising incidence of lifestyle-linked diseases such as diabetes, will require stronger collaboration among nations, as well as the strengthening of their health systems and health work force.