Penguin guano is fertilizing snow algae blooms along the Antarctic Peninsula, creating dense green patches that absorb more sunlight and accelerate snowmelt. Researchers warn that this biological darkening effect is missing from current climate projections, potentially underestimating how fast coastal snowpacks and ice-free terrain will expand.
Antarctica is often imagined as a pristine white wilderness, but along the coasts of the West Antarctic Peninsula, the snow is turning distinct shades of red and green. A new study published in the Journal of Geophysical Research: Biogeosciences (authored by Elise L. Ryan and Alia L. Khan under DOI: 10.1029/2026JG009918) demonstrates that penguin guano is driving these color changes by feeding dense patches of snow algae. These tiny organisms thrive during the harsh Antarctic summer, altering the reflectivity of the snow and compounding local warming trends.
How Penguin Guano Fuels Color-Changing Antarctic Algae
The life cycle of Antarctic snow algae depends heavily on nutrient availability. When nutrients run low, the algae protect themselves from intense sunlight by producing sunscreen-like red pigments, which can visually look similar to the guano itself. Red snow absorbs about 20 percent more solar energy than clean, white snow, which accelerates the melt rate. However, when nutrients are abundant, the algae shift strategy, packing their cells with green chlorophyll pigments to maximize photosynthesis and growth during the short summer.
Green snow is even more effective at trapping solar energy, absorbing 40 percent more radiation than clean snow and doubling the overall melt effect. While penguins spend their time at sea feasting on marine life, they return to the coastal landmasses and deposit nutrient-rich droppings across the ground. Laboratory analyses confirmed that these green algal blooms correlate directly with elevated phosphate concentrations found in bird guano, proving that the droppings act as a direct fertilizer and link the marine food chain directly with snow ecological systems.
Sampling Along the West Antarctic Peninsula
Collecting the data required researchers to navigate the rough waters of the Drake Passage by boat and gather samples across five degrees of latitude along the West Antarctic Peninsula, visiting areas both with and without established penguin colonies. Fieldwork near penguin colonies involved gathering algae-tinted snow into bags using ceramic spoons amidst strong odors.
“It’s very stinky working near penguins. They’re just waddling around in their poop and tracking it all over the snow.”
Alia Khan, via Techexplorist
In the laboratory, lead author Elise Ryan and other members of the research team examined the samples under a microscope to count algae cells and extract pigments and nutrients. This microscopic examination verified that samples dominated by green pigments contained significantly higher levels of phosphate than those dominated by red pigments.
Missing Elements in Regional Climate Projections
The study provides the first direct documentation linking penguin guano cycles to the different life stages of Antarctic snow algae. Researchers emphasize that this biological feedback loop is currently absent from established predictive models of Antarctic ice loss.
Khan noted that the research began while she was at Western Washington University before continuing at the University of Colorado Boulder. Without accounting for these biological darkening factors, scientific models likely underestimate how rapidly coastal snowpacks are melting and how fast ice-free terrain will expand. As environmental conditions shift, penguins are moving their ranges southward, raising the possibility that guano-fertilized algae blooms could broaden their melt-enhancing footprint across more of the continent. Further field data must be collected before this wildlife-driven greening can be formally integrated into future regional snowmelt projections.