Penguin poo is making the Antarctic snow melt faster, a study shows. As temperatures rise, penguins are waddling closer to the south pole, with potential for this previously unrecognised phenomenon to affect a wider area.

Snow algae are tiny single-celled plants that make a home in some of the coldest places on Earth. When nutrients are scarce, the algae produces red pigments to protect itself from the sun and slow growth.

And when nutrients are abundant, it proliferates, packing its cells with green chlorophyll to boost photosynthesis and grow. Snow containing green algae absorbs significantly more solar energy than snow containing red algae, making it melt more quickly.

Alia Khan from the University of Colorado and her team wanted to understand the impact of penguin poo on snow algae. They held their noses and gathered samples of red and green snow algae along the coast of the West Antarctic peninsula, in areas with and without penguin colonies.

Their results, published in Journal of Geophysical Research: Biogeosciences, showthat penguins track their poo, or guano, across snowfields, inadvertently feeding the algae and increasing green blooms, making the snow more likely to melt.

Projections of Antarctic melting do not yet take this phenomenon into account, but it could be significant, particularly as penguins move south.