The article examines how producing biofuels on a large scale could affect global greenhouse gas emissions. The researchers used a model to predict the impacts of biofuel production on markets for energy, land, and other goods. They focused on the controversial issue of how using land for biofuel crops could lead to changes in forests and affect carbon levels. The study found that growing biofuels in the US and internationally could lead to changes in land use and emissions from forest carbon stocks.