Climate-change mitigation will require the development and diffusion of a large number and variety of new technologies. Will patent protection accelerate orimpede this critical process? A new paper published by the National Bureau of Economic Research reviews the evidence on the role of patents for innovation and international technology transfer. The literature suggests that patent protection in a host countryencourages technology transfer to that country but that its impact oninnovation and development is much more ambiguous. The NBER analysisdiscusses the implications of these findings and othertechnology-specific evidence for the diffusion of climate change-related technologies, concluding that the presence of both environmental andknowledge externalities suggests that patent protection may not be theoptimal instrument for encouraging innovation in this area, especiallygiven the range and variety of green technologies as well as the need for local adaptation of technologies.