Chlorophyll has long served as the chosen measure of phytoplankton biomass, but relating satellite chlorophyll data to ocean production requires an additional piece of information that has evaded detection from space, namely: physiological variability. Without this later term, it is unlikely that changes in ocean production will ever be reliably detected from satellite chlorophyll data. We have therefore abandoned chlorophyll altogether as a biomass index and instead derive phytoplankton carbon concentrations from satellite light scatter coefficients. In doing so, a physiological signal related to phytoplankton growth rates emerges that derives from variability in intracellular pigmentation and is detectable from space. Thus, it appears a path exists for retrieving both of the key terms in the productivity equation from space (biomass and growth rate), but following this path will require a major adjustment in our approach to quantifying algal biomass, as well as an evolution in future remote sensing measurements.Behrenfeld, M.J., E. Boss, D.A. Siegel, D.M. Shea, 2005. Phytoplankton Growth Rates and Carbon Biomass from Space.