A great lecture aimed towards the general public by Dr. James ("Jim") Hansen. He gives a clear and engaged description of the science and the challenges that lies ahead. One of the best talks I've seen.
The talk was recorded at James Hansen's New Zealand tour in spring 2011 at the University of Otago, NZ.
The lecture draws much from the paper "The Case for Young People and Nature: A Path to a Healthy, Natural, Prosperous Future" by James Hansen, Pushker Kharecha, Makiko Sato, Paul Epstein, Paul J. Hearty, Ove Hoegh-Guldberg, Camille Parmesan, Stefan Rahmstorf, Johan Rockstrom, Eelco J.Rohling, Jeffrey Sachs, Peter Smith, Konrad Steffen, Karina von Schuckmann, James C. Zachos. The paper can be downloaded from James Hansen's homepage : columbia.edu/~jeh1/mailings/ (under 2011)
Dr James E. Hansen is the director of the NASA Goddard Institute for Space Studies (GISS) in New York City. He is also an adjunct professor in the Department of Earth and Environmental Sciences at Columbia University.