Our scouting trip to find a pass over a ridge between two sets of lakes was unsuccessful, but we encountered some gorgeous scenery on the almost 8 mile hike around Saddlebag Lake on the Tioga pass road over the Sierras of California.
Yes, it really is pink snow, colored not by leaching minerals but by the growth of the green alga (yes, it really is green under the microscope), Chlamydomonas nivalus. If there is one thing we have learned about life on earth, it’s that microbes can thrive just about anywhere, and here’s proof of life on the ice.
The algae are actually in a metabolically quiescent state, awaiting appropriate conditions, like lake water, to begin growing. But to protect themselves (and their chlorophyll) from the damage of intense radiation at high altitude, they synthesize a protective sunscreen of carotenoid pigments (yes, the same ones that make Cardinals a bright cheery red).
And so, these green, but appearing red due to carotenoids, algae slide down the snow banks toward fresh water to begin a new cycle of growth.