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Study: Tiny plankton play a big role in keeping the earth cool

Obsession
The Sea
Obsession
The Sea

In the middle of the world’s southern ocean, there’s a mighty force that’s helping keep the sun’s rays at bay. The force is made up of many tiny things invisible to the naked eye: phytoplankton.

Phytoplankton live in the shallow depths of the ocean around the world. Recently, scientists from the University of Washington and the Pacific Northwest National Lab found that phytoplankton help reflect some of the sun’s rays back into space by changing the composition of certain clouds.

“If you were to turn off clouds altogether in the southern ocean in January, you can estimate…that clouds change the reflected shortwave by about 125 Watts per square meter,” Daniel McCoy, a graduate student at the University of Washington and co-author of the paper, tells Quartz. The research showed that the presence of aerosols produced by plankton increases the amount of sunlight reflected to back to space by 10 Watts per square meter.

In other words, microscopic plants are helping to keep temperatures around the southern ocean a lot cooler.

In the ocean, phytoplankton produce organic chemicals that make their way up into the atmosphere through sea spray. Susannah Burrows, an atmospheric scientist at the Pacific Northwest National Lab and co-author of the study, explained that it’s a similar phenomenon to the way salt gets all over our bodies at the beach.

The researchers explained that in order for clouds to form, individual cloud droplets need to have a particle to surround. The organic aerosols from plankton are the perfect size. Assuming the cloud size and the amount of water vapor in them are the same, clouds formed with aerosols from plankton will have many more droplets, which explains their additional reflective properties.

Humans and other plants in forests emit aerosols all the time, but the resulting clouds aren’t as reflective as the ones formed with plankton aerosols. The more reflective clouds are, the less the sun’s energy reaches our planet to warm temperatures.

Burrows explained that although this research doesn’t definitively indicate that phytoplankton are fighting global warming, it does give scientists clues about how humans are affecting cloud formation. “We need a good representation of the good natural background aerosol,” she tells Quartz. Burrows thinks this research will help scientists understand how human activity has been changing the atmosphere.

The photograph above was shared by Flickr user NOAA Photo Library under a Creative Commons license. It has been cropped.

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