Nobody’s melt model counted the penguins

A new study from the Antarctic Peninsula finds penguin droppings feed green snow algae, and green snow soaks up about 40% more sunlight than clean white snow.

Somebody had to go to Antarctica and study penguin poop. Alia Khan raised her hand.

Khan is a cryosphere biogeochemist at the University of Colorado Boulder, which is a long title for a person who chases dirty snow. Her team took a boat across the Drake Passage and worked down the coast of the West Antarctic Peninsula, collecting snow algae across five degrees of latitude. Some of their sites sat right beside penguin colonies. Others sat nowhere near one.

Green snow is fed snow

Snow algae are tiny plants that bloom on the surface in summer and stain the snow red or green. Back in the lab, the team counted cells under microscopes, pulled out the pigments and nutrients, and the colours told a pretty simple story about dinner. Green algae are the well-fed ones, stuffed with chlorophyll and growing fast. Red algae are getting by on scraps, so they make pigments that act like sunscreen and wait it out.

The green snow had far more phosphate in it. You can probably guess where the phosphate comes from.

The fertiliser has feet

Penguins eat fish, digest fish, leave what’s left of the fish on the snow, and then walk around in it. Khan’s own field report on her study subjects: “They’re just waddling around in their poop.” Every step spreads a little more fertiliser, and the algae throw a party.

Which would be a cute nature fact if snow didn’t care what colour it is. White snow throws most of the sunlight that hits it straight back. Stain it and it starts soaking that light up as heat. Red algae make snow absorb about 20% more sunlight than clean snow. Green algae push that to roughly 40%. Warmer snow melts faster, more bare ground opens up, and the melt feeds itself from there.

Somebody tell the models

The projections for how fast Antarctica melts pay close attention to the air, the ocean and the ice. The penguins were left off the guest list. Khan calls the link between wildlife, nutrients and snow algae “a critical missing component,” and her team’s read is that without it, we’re probably lowballing how fast coastal snow is going.

Before anyone starts a campaign against penguins, relax. They were living here long before anybody built a climate model, and the researchers themselves say the effect needs more study before it goes into the forecasts. Fair enough.

But next time someone shows you a slick projection of Antarctic ice, go ahead and ask the slightly ridiculous question. Did anybody count the penguins?