We know plankton as that ugly green film on the surface of the ocean, and as the primary food of whales, but most people probably aren’t aware of just how vital these creatures are to keeping the Earth cool.

These microscopic critters are apparently responsible for half of all the cloud droplets in the Southern Ocean during the summer, and this finding could help scientists gain more insight into climate change, according to a Live Science report.

The researchers found that marine phytoplankton, which survive off of light and spread in green globs in the ocean, can change the way clouds accumulate droplets of water, and the number of droplets appear to double in the summer over the Southern Ocean, and it’s because the plankton are the most abundant, the study found.

This stops a lot of solar radiation from making its way to the Earth’s surface, which has a cooling effect.

That’s because more than just blocking out the sun, the tiny water droplets in the clouds deflect the sunlight back out of the atmosphere, with the brightest clouds having the most water droplets.

That’s what marine life is so important, because it results in more water droplets which result in brighter clouds. They do this by emitting microscopic particles — aerosols — that float in the atmosphere and cause water droplets to gather and clump together into clouds.

By understanding this link between cloud droplet formation and the presence of plankton, scientists can more accurately make climate change predictions.

It’s also leading to some ideas for combating climate change: for example, could man-made aerosols be used artificially to create larger and brighter clouds, or is the amount already at its highest point? That’s something that may require more research.

Scientists want to know what the exact source of the aerosols is, but that’s tough to do because once aerosols depart from the surface, it’s tough to tie it to a source.