Reducing the pressure of agriculture on forests is at the heart of debates over the future of biofuels and since 2009 it has been an explicit focus of negotiations on Reducing Emissions for Deforestation and Forest Degradation. One proposal, known as land sparing, aims to boost output on agricultural lands and/or steer agricultural expansion onto low carbon content lands to free land for forests and other productive uses. I present a framework to analyze land sparing and I highlight its promises and challenges using a simulation case study of Brazilian cattle ranching intensification. Under land sparing, agricultural yield increases cause a decrease in agricultural land relative to the area that would have existed without the yield increase. Because land sparing is market-mediated, the geography of land use and climate impacts from land sparing depends upon the geography of the markets for the products of the targeted agricultural systems. I illustrate this principle using a simulation depicting global land use and greenhouse gas emissions with and without policies targeting land sparing through the intensification of cattle ranching systems in Brazil. The simulation shows that global trade could offshore the land sparing from Brazilian cattle intensification. In the simulation, increases in low-cost Brazilian cattle reduce the area of profitable cattle around the globe and this delivers land sparing. Were this GHG mitigation offshoring to occur, it could deliver not only GHG benefits, but also political complications stemming from these trade effects. I conclude by exploring these politics, and also by discussing regulatory, political and behavioral assumptions to which these results are sensitive.