Maryland-born Matthew Henson, the first explorer to reach the North Pole, achieved 90 degrees North latitude on April 6, 1909.

Credit: NSF slide

Welcoming remarks by James White, University of Colorado; followed by opening remarks by Ralph J. Cicerone, president of the National Academy of Sciences and Arden L. Bement, Jr., director of the National Science Foundation.

Credit: National Science Foundation/National Academy of Sciences

Richard Alley, Pennsylvania State University

Credit: National Science Foundation/National Academy of Sciences

Hajo Eicken, University of Alaska Fairbanks

Credit: National Science Foundation/National Academy of Sciences

David M. Holland, director of the Center for Atmosphere Ocean Science, New York University

Credit: National Science Foundation/National Academy of Sciences

Timothy Killeen, NSF's assistant director for geosciences

Credit: National Science Foundation/National Academy of Sciences

Stephanie Pfirman, Barnard College

Credit: National Science Foundation/National Academy of Sciences

Diana Wall, Colorado State University

Credit: National Science Foundation/National Academy of Sciences

Panelists respond to audience questions.

Credit: National Science Foundation/National Academy of Sciences