It's almost hard to believe, but new NASA-funded research confirms an old theory that plankton can indirectly create clouds that block some of the Sun's harmful rays. The study was conducted by Dierdre Toole of the Woods Hole Oceanographic Institution (WHOI) and David Siegel of the University of California, Santa Barbara (UCSB).
The study finds that in summer when the Sun beats down on the top layer of ocean where plankton live, harmful rays in the form of ultraviolet (UV) radiation bother the little plants. When they are bothered, or stressed, plankton try to protect themselves by producing a compound called dimethylsulfoniopropionate (DMSP). Though no one knows for sure, some scientists believe DMSP helps strengthen the plankton's cell walls. This chemical gets broken down in the water by bacteria, and it changes into another substance called dimethylsulfide (DMS).
DMS then filters from the ocean into the air, where it reacts with oxygen, to form different sulfur compounds. Sulfur in the DMS sticks together in the air and creates tiny dust-like particles. These particles are just the right size for water to condense on, which is the beginning of how clouds are formed. So, indirectly, plankton help create more clouds, and more clouds mean less direct light reaches the ocean surface. This relieves the stress put on plankton by the Sun's harmful UV rays.
For years now scientists have been studying related processes in the lab, but this is the first time scientists have shown how variations in light impact plankton in a natural environment. The research was done in the Sargasso Sea, off the coast of Bermuda.