Environment

Pink Snow Is Sending a Message and Scientists Are Reacting

Snow is turning pink throughout the Arctic at an alarming rate, a study published Wednesday in Nature Communications reported. And it has many scientists worried.

The pink snow — sometimes termed "red snow" or "watermelon snow" — may look pretty, but it actually causes glaciers to melt faster and contributes to global climate change.

What makes snow pink?

The pink snow is caused by the Chlamydomonas nivalis species of snow algae, Scientific American explained. These algae lie below the surface year-round and turn snow from a white shade to a pink shade during spring and summer blooms.

"Such snow algal blooms can substantially darken the surface of glaciers because of their red pigmentation (secondary carotenoids) which the algae produce as a protection mechanism (for example, from high levels of irradiation)," the study authors explained.

What does it mean?

These pink algal blooms decrease snow and ice albedo — how they reflect heat. It's essentially a viscous cycle: when albedo is decreased, snow and ice melt into water more quickly, which causes even more algae to bloom.

“The algae need liquid water in order to bloom,” lead study author Steffi Lutz told Gizmodo. “Therefore the melting of snow and ice surfaces controls the abundance of the algae. The more melting, the more algae. With temperatures rising globally, the snow algae phenomenon will likely also increase leading to an even higher bio-albedo effect.”

The albedo effect

Albedo is "the ratio of the light reflected by a body to the light received by it," NASA explains. "Albedo values range from 0 (pitch black) to 1 (perfect reflector)."

Glaciers help lower the planet's temperature by reflecting sunlight. When albedo is low, glaciers melt and sunlight is absorbed instead of reflected, which makes the planet hotter.

"We estimated that the overall decrease in snow albedo by red pigmented snow algal blooms over the course of one melt season can be 13 percent," the study authors reported.

It's well known that carbon gas emissions contribute to global warming, but the study suggests that algae also play a major role.

Previously, "bio-albedo has been a niche topic," biologist Daniel Remias told Science Daily. Remias explained that the study was the first to delve into "the large-scale effect of microorganisms on the melting of snow and ice [on] the Arctic."

The study authors argue that future studies and climate models should include the role of bio-albedo.

On an unrelated note, the pink snow is also an unwise snack choice — it has a laxative effect.

[h/t Gizmodo]