Penguin droppings are speeding up snow melt in Antarctica by feeding green snow algae that absorbs far more solar energy than red algae, according to a study published in the Journal of Geophysical Research: Biogeosciences. Researchers traced the effect to guano spread across snowfields near penguin colonies on the West Antarctic Peninsula.
Snow algae are single-celled plants that make their home in some of the coldest places on Earth. When nutrients run scarce, the algae produces red pigments that shield it from the sun and slow its growth. When nutrients are plentiful, it proliferates and packs its cells with green chlorophyll to boost photosynthesis.
Why green snow melts faster than red
Snow containing green algae absorbs significantly more solar energy than snow containing red algae. That extra absorbed heat makes the green snow melt more quickly.
The color difference comes down to nutrients. Red algae is the stressed, protected state. Green algae is the fed, growing state. More food means more green cells, and more green cells means more melting.
How researchers connected penguin poo to the blooms
Alia Khan of the University of Colorado and her team set out to understand the impact of penguin guano on snow algae. They collected samples of red and green snow algae along the coast of the West Antarctic Peninsula, in areas both with and without penguin colonies.
Their results, published in the Journal of Geophysical Research: Biogeosciences, show that penguins track their guano across snowfields. The droppings inadvertently feed the algae, increasing green blooms and making the snow more likely to melt.
Did you know? The red pigment in snow algae works like a natural sunscreen, protecting the organism from intense solar radiation when nutrients are scarce.
Penguins moving south could widen the effect
As temperatures rise, penguins are waddling closer to the South Pole. That shift matters because it carries their guano into new snowfields that were previously untouched by this nutrient flow.
The phenomenon was previously unrecognised, and projections of Antarctic melting do not yet take it into account. If penguin colonies keep moving south, the green-bloom effect could spread across a wider area of the continent.
What the melting models still miss
Current projections of Antarctic ice loss leave out the guano-algae feedback entirely. How large that omission is remains an open question, because the research so far covers only the West Antarctic Peninsula coast.
What is not yet known is whether the effect will grow, shrink, or stay stable as colonies relocate and the climate continues to warm.
Questions readers ask about penguin guano and Antarctic melt
Alia Khan of the University of Colorado led the team that gathered the samples and published the results in the Journal of Geophysical Research: Biogeosciences.
Along the coast of the West Antarctic Peninsula, in snowfields both with penguin colonies and without them, so the researchers could compare the two conditions.
The study uses the term guano, the standard word for accumulated seabird and penguin excrement that acts as a nutrient source.
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