In Antarctica, white snow suddenly begins to turn green near penguin colonies — and melts noticeably faster. A new study reveals an unexpected link between bird droppings and the rate at which snow cover disappears on the Antarctic Peninsula.
Scientists from the University of Colorado Boulder analyzed 111 snow samples from nine areas along the western coast. In places where penguins nest nearby, the concentration of phosphates in the green snow turned out to be ten times higher than in red or clean snow. Bird guano serves as a natural fertilizer, supplying the nutrients that microscopic algae need.
When algae receive enough phosphates, they multiply actively and saturate their cells with chlorophyll. Green snow absorbs roughly 40 percent more solar energy compared with white snow, and red snow absorbs 20 percent more. The extra heat accelerates melting, and warming, in turn, expands the algae's habitats.
The study, published in the Journal of Geophysical Research: Biogeosciences, shows that this process creates a feedback loop. Penguins carry nutrients from the sea to the land, intensifying local darkening of the surface. However, the authors emphasize that the birds merely amplify the effect caused by overall climate warming.
Climate models still rarely take into account the influence of wild animals on snow albedo. Meanwhile, the link between the marine food chain and the ecology of snow cover may prove to be an important missing piece for forecasts of the expansion of ice-free territories.
Understanding such natural mechanisms helps to assess more accurately how quickly Antarctica is changing under the influence of global changes.
