Steve Pacala, Ph.D., is an ecologist and environmental biologist who designs and tests mathematical models to investigate interactions between greenhouse gases, climate, and the biosphere, and to predict their effects on local and global ecosystems. He is the co-author of the climate stabilization “wedge” approach, which argued over 15 years ago that climate change could be solved using science, technologies and industries already within humanity’s grasp. He is the Frederick D. Petrie Professor in the Department of Ecology and Evolutionary Biology at Princeton University.