Atmospheric scientists have reported a new and potentially important mechanism by which chemical emissions from ocean phytoplankton may influence the formation of clouds that reflect sunlight away from our planet.
Discovery of the new link between clouds and the biosphere grew out of efforts to explain increased cloud cover observed over an area of the Southern Ocean where a large bloom of phytoplankton was occurring. Based on satellite data, the researchers hypothesized that airborne particles produced by oxidation of the chemical isoprene which is emitted by the phytoplankton may have contributed to a doubling of cloud droplet concentrations seen over a large area of ocean off the eastern coast of South America.
Using complex numerical models, they estimated that the resulting increase in cloudiness reduced the absorption of sunlight by an amount comparable to what has been measured in highly polluted areas of the globe. If confirmed by field studies, this connection between clouds and biological activity could add a critical new component to global climate models. Many environmental scientists believe that increased cloud cover may be partially countering the effects of global warming by reducing the amount of energy the planet absorbs from the sun.
Researchers Athanasios Nenes of the Georgia Institute of Technology and Nicholas Meskhidze formerly at Georgia Tech but now at North Carolina State University reported their findings Nov. 2 in Science Express, the online advance publication of the journal Science. The research was sponsored by NASA, the National Science Foundation and a Blanchard-Milliken Young Faculty Fellowship.
"Studies like this one may help reshape the way we think about how the biosphere interacts with clouds and climate," said Nenes, an assistant professor in Georgia Tech's School of Earth and Atmospheric Sciences. "One of the largest uncertainties right now in climate models is the abilit
Contact: John Toon
Georgia Institute of Technology Research News