Climate change is causing global average sea-surface temperatures to rise, and global average ocean chlorophyll concentrations to fall.  Desertification is a reference to expanding regions of low ocean productivity, which result when biological activity causes nutrient loss from warm surface waters.  As with land deserts, the life forms that populate ocean deserts are adapted to extreme conditions. While the mechanisms behind ocean desertification are understood, the consequences are far from easy to predict because so little is known about most planktonic organisms and the ecological networks they form. Understanding these systems is important because of their importance to food webs, but especially because of the biological carbon pump, a process that removes large amounts of carbon from the atmosphere, sequestering it.  One approach to understanding ocean warming is to study sites where ocean surface temperatures fluctuate every year in seasonal cycles, causing rhythmic transitions between cool, productive, high chlorophyll periods and ultra-low nutrient conditions. A long-term study of the Western Sargasso Sea has shown annual oscillations between a productive community dominated by eukaryotic phytoplankton in the winter and spring, and a cyanobacteria-dominated community in the summer and fall. The study of microbial plankton in laboratories has revealed many extraordinary biochemical adaptions that enable cells to thrive during periods of extreme competition for nutrient resources.  Throughout seasonal succession microbial plankton form interacting networks, suggesting that plankton species interact in ways that have yet to be discovered and described.