Protection of the Ozone Layer , Institute of Higher Studies (Santa Barbara, CA).

Stratospheric Pollution Due to Man-Made Chemicals , Agricultural Research Center, US Dept. of Agriculture (Beltsville, MD).

The Aerosol Threat to the Environment , Continuing Education Div., Santa Barbara City College (Santa Barbara, CA).

Química de la Estratósfera; Cinética Química Contemporánea: Teoría y Experimentos (Córdoba, Argentina).

Chemistry of the Atmosphere and Ozone Layer , National SACNAS Conference (El Paso, TX).

Chemistry of the Atmosphere , MBRS/MARC Program Seminar Series, University of Texas at San Antonio (San Antonio, TX).

The Changing Chemistry of the Global Atmosphere , Annual Meeting of the Caltech board of Trustees (Palm Springs, CA).

The Greenhouse Effect , Caltech Assoc./Faculty Dinner (Pasadena, CA).

Ozone Depletion at the Poles , XVIII Reunion de Física Estadística (Oaxtepec, Mexico).

Stratospheric Ozone Depletion , David French Lecture, Claremont College (Claremont, CA).

The Antarctic Ozone Hole , Featured Lecture, Celebration of the Sciences, Washington College, MD.

Our Endangered Atmosphere , Panelist, Earth Day, 1990: The Science Behind the Issues, Organized by the American Chemical Society and the University of Massachusetts, MA.

Protection of the Ozone Layer , Environment and Development, Rio Ciencia '92 (Rio de Janeiro, Brazil).

Ozone Destruction in the Antarctic Stratosphere , National Hispanic Heritage Month, National Science Foundation (Washington, DC).

Sources of Ozone Depletion , Center for Energy and Environmental Studies, Princeton University (Princeton, New Jersey).

The Antarctic Ozone Hole , Sigma-Xi Lectures: California, New Mexico, Connecticut, Massachusetts.

Stratospheric Ozone Depletion, The Greenhouse Effect and Other Changes in the Atmosphere, 13th International Conference on Chemical Education (San Juan, Puerto Rico).

La Investigación Química Frente a los Problemas Ambientales del Mundo , 30th Mexican Chemistry Congress (Cancún, Mexico).

Stratospheric Ozone: Recent Scientific Developments . Lecture presented at the Taipei International Conference on Ozone Protection (Taipei, Republic of China); and at the MIT-Agenda 21 International Conference on Sustainable Development and Environment (Beijing, China).

Global Warming and Ozone Depletion . Conference on Our Planet, Our Children, sponsored by Representative Ed Markey (Lexington, MA).

CFCs and the Ozone Layer-Disrupting a Delicate Balance . Panelist, ACS Satellite TV Seminar (Washington, DC).

Preserving the Global Environment: A Challenge for the 21st Century . Commencement address at the College of Chemistry, University of California, Berkeley (Berkeley, CA).

The Antarctic Ozone Hole , Opening Lecture of Complutense University Summer School (El Escorial, Spain).

Stratospheric Ozone and the Montreal Protocol . Keynote address at the 1996 International Day of the Ozone Layer Protection (Sao Paolo, Brazil).

Polar Ozone Depletion. Japan Association for Mathematical Sciences Seminar on Environment, Science and Technology (Onuma, Japan).

The Antarctic Ozone Hole . Keynote Address at the Annual Conference of the Society for Advancement of Chicanos and Native Americans in Science (Los Angeles, CA).

Stratospheric Ozone Depletion , Keynote address at the 1996 Hispanic Heritage Month Celebration at EPA (Washington, DC).

CFCs and Stratospheric Ozone , Ida Beam Distinguished Visiting Professor Lecture Series, University of Iowa (Iowa City, Iowa).

The Antarctic Ozone Hole , G.M. Kosolapoff Award Lecture, Auburn University (Auburn, Alabama)

Stratospheric Ozone Depletion: A Global Problem. H. Martin Friedman Lecture, Brooklyn College (Brooklyn, New York); 17 th Annual Fred Garland Memorial Lecture, Texas A & M University (Kingsville, Texas); Distinguished Scientist Lecture, Trinity University (San Antonio, Texas).

Stratospheric Ozone Chemistry , Plenary Lecture, Montreal Protocol 10 th Anniversary Colloquium (Montreal, Canada).

Science, Environment and News Media , Ten Nobels for the Future, Hypothesis (Milan, Italy)

Environmental Challenges for the 21 st Century , Bren Fellows Program 17 th Lecture, University of California at Irvine (Irvine, California).

Environmental Challenges for the 21 st Century: From Urban Pollution to Global Change , Keynote Address, Conference on Sustainable Development of a Commercial City, Central Policy Unit (Hong Kong Special Administrative Region).

Atmospheric Ozone: From Local to Global Pollution , presented at the symposium “Can Industry be Profitable Yet Environmentally Correct?” (Swedish Chamber of Commerce, New York)

Chemistry and the Environment: The Antarctic Ozone Hole , 1999 Dakin Memorial Lecture, Adelphi University (Garden City, New York).

Depletion of the Ozone Layer: Consequences for the Environment , A.R. Sanchez Distinguished Lecture, Texas A&M International University (Laredo, Texas)

The Antarctic Ozone Hole , J. Robert Oppenheimer Memorial Lecture, Los Alamos National Laboratory (Los Alamos, New Mexico).

The Science of Global Change , presented at the premier screening of “A Perfect Balance”, organized by Earth Communications Office and Union of Concerned Scientists (Santa Monica, California)

Air Pollution in Megacities: Mexico City Case Study , Third Rosenblith Lecture in Science and Technology, National Academy of Sciences (MIT, Cambridge, MA)

Chemistry of Stratospheric Ozone Depletion , Roberts Memorial Lecture, Colorado College (Colorado Springs, Colorado)

Major Environmental Challenges in the New Century , Global Ministerial Environment Forum, United Nations Environment Programme (Malmö, Sweden).

The Antarctic Ozone Hole , 16 th Annual Broberg Lecture, North Dakota State University (Fargo, ND); Natick Chapter of Sigma Xi (Natick, MA); Frontiers in Research Lecture, University of Ottawa (Ottawa, Canada).

Impactos de las Actividades Humanas en la Química de la Atmósfera , Keynote Address, XXIV Congreso Latinoamericano de Química, Federación Latinoamericana de Asociaciones Químicas (Lima, Peru)

The Antarctic Ozone Hole , The CFC-Ozone Puzzle: Environmental Science in the Global Arena (presented jointly with F.S. Rowland), Inaugural John H. Chafee Memorial Lecture on Science and the Environment, National Conference on Science, Policy and the Environment (National Academy of Sciences, Washington, D.C.)

Emissions Impossible, Panelist, World Economic Forum (Davos, Switzerland).

The Antarctic Ozone Hole (The Taplin Lecture); The Science and Politics of Climate Change ; Urban, Regional and Global Air Pollution , Inaugural Princeton Environmental Institute/ Princeton University Press Public Lecture Series (Princeton, New Jersey)

The Antarctic Ozone Hole and Chemistry on Ice Surfaces , The Danforth Lecture, Grinnell College (Grinnell, Iowa)

The Antarctic Ozone Hole , The Clifford Barger Hinto-Wright Lecture, Harvard Medical School (Boston, MA); Brdicka Lecture, Heyrovsky Insitute of Physcial Chemistry (Prague, Czech Republic).

Conservando el medio ambiente global: Un reto para el Siglo XXI . Commencement Address, Universidad de las Américas (Puebla, Mexico).

La Destruccion de la Capa de Ozono: un Problema Global , presented at the dedication of the Mario Molina Environmental Technology Laboratory, Universidad Tecnológica Nezahualcóyotl (State of Mexico, Mexico).

El Impacto de las Actividades Humanas en la Atmósfera, Casa de América/Foro Complutense, (Madrid, Spain); University of Costa Rica (San Jose, Costa Rica).

Preserving the Environment, Challenges for the 21 st Century , Commencement Address, University of Waterloo (Waterloo, Canada).

The Impact of Human Activities on the Atmosphere , Keynote Address, International Women's Forum (Mexico City, Mexico).

The Antarctic Ozone Hole: Global Environmental Consequences of Human Activity, Presidential Lecture, Florida International University (Miami, Florida).

The Antarctic Ozone Hole, Kukin Lecture, Yeshiva University (New York, NY); Daniel Fisher Dinner Lecture, Harvard College, Harvard University (Cambridge, MA); Distinguished Speaker Series: Nature and Society: Putting Knowledge to Work at the University of California, San Diego (San Diego, CA).

Los Cambios en las Ciencias y su Influencia en la Academia Universitaria , 1er Encuentro de la Academia Universitaria por el Desarrollo Sostenible, Instituto Centro Americano de Administración de Empresas (INCAE, San Jose, Costa Rica).

Global Environmental Change: Two Views of the Future (presented jointly with Bill McKibben), Cary Lecture Series (Lexington, MA).

Global Environmental Issues: The Impact of Human Activities on the Atmosphere, Ford/MIT Nobel Lecture, (Cambridge, MA).

Science and the Environment, Sesquicentennial Environmental Initiative Lecture, Washington University in St. Louis (St. Louis, MO).