Influence of Phytoplankton on Climate

Phytoplankton pigments, by absorbing solar radiation, may affect mixed-layer dynamics, currents, air-sea interactions, and climate. Numerical experiments with a 3-dimensional general ocean circulation model, OPYC, and satellite-derived pigment concentration reveal a general increase in the amplitude of the annual cycle of sea surface temperature (SST), by typically 0.5 to 1 K. The SST anomalies produced by OPYC are introduced into a climate model, CCM-3, to quantify effects on tropospheric temperature and precipitation. The globally and annually averaged surface temperature increases by about 0.2 K. Some regions exhibit larger surface temperature changes on an annual scale. For example, a 1 to 1.5 K temperature decrease is obtained in Central Europe at the 95% confidence level. Convective precipitation is significantly increased in Central America and decreased in the Eastern Equatorial Pacific, by about 2 mm/day on average. Solar radiation absorption by phytoplankton pigments should be taken into account in the numerical modeling and analysis of climate change.