Dr. John P. Holdren, who served as President Obama’s Science Advisor and the Director of the White Office of Science and Technology Policy through both Obama terms, was responsible for interpreting, for the president, the state of climate-change science and its implications for policy. The analyses he provided played a major role in shaping the Administration’s climate-change policy, including the President’s June 2013 Climate Action Plan. In this talk, he will update his assessment of what the science is telling us about the urgency of increased ambition in addressing the climate-change challenge and will reflect on the gulf between Obama’s stance on this issue and Trump’s. Co-sponsored by the Institute at Brown for Environment and Society, the Watson Institute, and the Woods Hole Research Center. IBES 130, Carmichael Auditorium, 85 Waterman Street.