Prof. David Archer of the University of Chicago, an expert on ocean biogeochemical cycles and climate change, will present two seminars in the Department of Earth, Atmospheric and Planetary Sciences as a part of the annual Houghton Lectures. On February 24 his topic will be the Longevity of Climate Change; on February 25 he will speak about Methane Hydrates. (Prof. Archer's website; more about the speaker.)