Poopy Clouds

Some of the clouds that waft across the Southern Ocean may have an icky source: penguin poop. Ammonia in the poo mixes with other chemicals in the air. That creates the “seeds” that form water droplets, which clump together to make clouds.

Water doesn’t form droplets on its own. It has to have something to glom on to—a grain of dust, a bit of pollen, or some other solid particle. Some of the particles are known as aerosols. They form when different chemicals link up in the air. And the clouds they create are brighter than other clouds, so they reflect more sunlight—helping control Earth’s temperature. And that’s what appears to be happening with the poop.

Researchers discovered the connection during the summer of 2023. They were studying the atmosphere from an island off the northernmost tip of Antarctica. That part of the continent has two large colonies of Adelie penguins—about 45,000 breeding pairs in all. When the winds blew across the island from the open ocean, the air contained almost no ammonia. But when the wind blew in from the continent, the amount of ammonia in the air increased by a factor of a thousand—picked up from the penguin poo. When the penguins moved to their winter grounds, the amount of ammonia dropped, but still remained high—carried from the leftover poo.

The ammonia mixed with sulfur produced by microscopic organisms in the ocean to produce aerosols—the “seeds” for clouds over the Southern Ocean.