Astronomer at McDonald Observatory, University of Texas at Austin

Astronomy at McDonald Observatory, University of Texas at Austin

Professor, Arizona State University, School of Earth and Space Exploration in Phoenix, AZ

Member of the Board at Harvard Belfer Center for Science and International Affairs

Southeast Region Director at United States Geological Survey

Senior Vice President, Natural Climate Solutions at Conservation International

Senior Vice President of the Moore Center for Science at Conservation International

Associate Professor of Civil and Environmental Engineering at Princeton University

Environmental Science and Public Policy Lecturer, Harvard University in Cambridge, MA

Senior Climate Scientist, Director of Climate Science at Union of Concerned Scientists

Faculty Affiliate, Harvard Project on Climate Agreements at Harvard Belfer Center for Science and International Affairs

Chief Scientist at United States Geological Survey

Senior National Security Fellow at Center for Immigration Studies

Professor of Politics and International Affairs at Princeton University

Faculty Affiliate at U.S. Immigration Policy Center, UCSD

Professor of Political Science and Senior Fellow at the Freeman Spogli Institute for International Studies at Stanford, Department of Political Science

Professor Emeritus of the Pacific Rim at Claremont McKenna College

President, Inter-American Dialogue at Inter-American Dialogue