Phytoplankton (image) University of Pennsylvania Share Print E-Mail Caption Phytoplankton, the single-celled plants that perform half of the world's photosynthetic activity, are sensitive to climate change. New research is shedding light on how their populations will rise, fall and shift as the Earth warms. Credit NOAA Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.