Of all the CO2 that humans are emitting into the atmosphere, about half is being absorbed by the land and the oceans. To better understand the processes that control carbon emission and carbon uptake, NASA is working to develop realistic models that describe how carbon moves between the atmosphere, land and oceans. We combine a wealth of satellite data with a description of physical processes that control the carbon cycle. A whole lot of math and computer power in order to better understand how carbon is changing both today and in the future.