( redict how clouds would respond to chan...)Researchers link ocean organisms with increased cloud cover and potential climate change

Researchers had previously theorized that dimethyl sulfide (DMS) ?which is also emitted by phytoplankton ?affects the formation of clouds by increasing the number of sulfate particles, which can absorb moisture and form cloud droplets. When oxidized, isoprene may enhance the effect of DMS by increasing the number and size of the particles while helping them to chemically attract more moisture. The impact of isoprene on atmospheric particulate matter was previously thought to be important only for terrestrial plants, Nenes said.

The researchers stumbled upon the phytoplankton-cloud connection quite accidentally. "While looking at the satellite pictures, I noticed that cloud properties over large phytoplankton blooms were significantly different from those that occurred away from the blooms," recalled Meskhidze, now an assistant professor in NC State's College of Physical and Mathematical Sciences.

The Southern Ocean normally has relatively few particles around which cloud droplets can form. The isoprene mechanism could therefore have a significant effect on the development of clouds there ?and may account for most of variation in the area's cloud cover.

"If a lot of particles form because of isoprene oxidation, you suddenly have a lot more droplets in clouds, which tends to make them brighter," Nenes explained. "In addition to becoming brighter, the clouds can also have less frequent precipitation, so you might have a build-up of clouds. Overall, this makes the atmosphere cloudier and reflects more sunlight back into space."

In their paper, the researchers estimated that the isoprene emissions reduced energy absorption in the area by about 15 watts per square meter. "This is a huge signa
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Source:Georgia Institute of Technology Research News