How are clouds formed on Earth? If you didn't answer "tiny marine organisms floating in the sea, perhaps better known as one of the main foods consumed by blue whales," then you were wrong.
Boffins at the University of Washington (UoW) and the Pacific Northwest National Laboratory believe that microscopic organisms drifting in the sea "produce airborne gases and organic matter to seed cloud droplets, which lead to brighter clouds that reflect more sunlight."
The scientists said that the area they studied – the Southern Ocean covering latitudes between 35 and 55 degrees south – had revealed interesting findings about the Earth's climate.
Results suggested that, averaged over a year, the increased brightness reflected about 4 watts of solar energy per square metre, the UoW said.
Daniel McCoy, co-lead author of the US government-funded study and a doctoral student in atmospheric sciences at the university, said:
The clouds over the Southern Ocean reflect significantly more sunlight in the summertime than they would without these huge plankton blooms.
In the summer, we get about double the concentration of cloud droplets as we would if it were a biologically dead ocean.
The boffins chose to study the Southern Ocean because marine life in other parts of the globe are "swamped out by aerosols from forests or pollution." For this reason, it would be much harder for them to measure similar processes in the Northern Hemisphere.
They used NASA satellite data to measure cloud droplets in the skies.
"The dimethyl sulfide produced by the phytoplankton gets transported up into higher levels of the atmosphere and then gets chemically transformed and produces aerosols further downwind, and that tends to happen more in the northern part of the domain we studied," said Pacific Northwest National Lab scientist Susannah Burrows, co-lead author of the study.
"In the southern part of the domain there is more effect from the organics, because that’s where the big phytoplankton blooms happen."
The research was published in the open-access journal Science Advances on Friday.
It can be viewed here. ®