Abstract: We document differences in the elasticity of agricultural output with respect to land in temperate and tropical regions. We estimate this elasticity from the relationship of rural labor/land ratios and agro-climatic constraints using global district-level data. We find the elasticity in temperate areas (0.285) is higher than the tropics (0.126), and this is not an artifact of the level of development. The land elasticity influences the degree of decreasing returns to labor and capital in agriculture, and thus how sensitive living standards are to shocks in productivity and population. Evidence from the post-war mortality transition supports this prediction.