Paul G. Falkowski is Board of Governors Professor in Environmental Biophysics and Molecular Ecology in the Institute of Marine and Coastal Sciences and the Department of Geological Sciences at Rutgers University. He has published numerous articles in "Science, Nature," and "Scientific American." John A. Raven is Boyd Baxter Professor of Biology at the University of Dundee, Scotland. His books include "Energetics and Transport in Aquatic Plants."