Artist's rendering of NASA's Orbiting Carbon Observatory (OCO)-2, one of five new NASA Earth science missions set to launch in 2014, and one of three managed by JPL. With atmospheric carbon dioxide now at its highest concentration in recorded history, the need to make precise, global, space-based measurements of this key greenhouse gas has never been more urgent. As carbon dioxide levels have increased, so too have uncertainties about them -- we don't yet have a clear picture of how these emissions are partitioned between Earth's ocean, land and atmosphere, or how Earth's forests, plants and ocean will respond to increasing levels of carbon dioxide in the future. OCO-2 will address these critical questions to help us better assess the health of our warming planet.