Tiny organisms that thrive in the vast stretches of the Southern Ocean have a crucial role in generating bright clouds ahead.
A new study by researchers from the Pacific Northwest National Laboratory and the University of Washington has shown that planktons, tiny organisms that drift in the sea, produce organic matter and airborne gases that seed cloud droplets, which produce brighter clouds that reflect more sunlight.
For the new study published in the journal Science Advances on July 17, Susannah Burrows, a climate scientist from the Department of Energy's Pacific Northwest National Laboratory, and colleagues combined computer modeling and satellite data over the vast sea surrounding Antarctica.
They found that natural particles produced by marine organisms, airborne droplets and aerosols, almost double the number of cloud droplets in the summers and this increases the amount of sunlight reflected back to space.
Marine life has two ways of affecting the clouds. One is by emitting gas such as dimethyl sulfide produced by the phytoplankton coccolithophores and Sulfitobacter bacteria, which produces the particles that seed marine cloud droplets. The other one is through organic matter on the surface of the water that forms a bubbly scum that gets launched into the air as tiny particles.
"Biogenic sources are estimated to increase the summertime mean reflected solar radiation in excess of 10 W m-2 over parts of the Southern Ocean, which is comparable to the annual mean increases expected from anthropogenic aerosols over heavily polluted regions of the Northern Hemisphere," Burrows and colleagues wrote in their study.
Although the oceans in the study are remote, they are considered an important region for the Earth's climate with the study showing that over a year, the increased brightness reflects around 4 watts of solar energy per square meter.
By having a better understanding of the amount of energy reflected by clouds, researchers may be able to better assess how climate models can capture the effect of marine particles on clouds.
"Phytoplankton in the oceans are a really important source for cloud-droplet-forming aerosols in remote marine air, and we can see the effect they have on clouds is big," Burrows said adding that given that clouds over the Southern Ocean play a large part in global climate, the findings could hopefully help them have a better sense of how sensitive out planet is to greenhouse gases.
