How does risk or uncertainty in the productivity of research affect the growth rate of the economy? To answer this question, a model of endogenous technological change is used where sustained growth stems from intentional investments in R&D from profit-maximizing firms. The uncertainty arises...

I examine GHG emission policy in a world with a fixed number of regions. In each region, labor and emissions are complementary in production, total world-wide emissions decrease welfare, and total factor productivity can be improved by R&D. A subset of regions can establish an "abatement...