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What is Watermelon Snow?

Definitely NOT a cool treat to beat summer heat

Watermelon_snow_streaks_3_Will Beback
© Will Beback

If you’ve seen the environmental news cycle lately, you may have seen a deluge of new stories discussing patches of red-colored snow surfacing on Galindez Island, located off the coast of the Antarctic’s northernmost peninsula. And while this is certainly shocking, this isn’t the first time we’ve seen reports of this visually striking phenomenon. There have been sightings all over the world including the Arctic, Himalayas, Rockies and in Yosemite National Park just last summer.

Images showcase the variety in the snow’s color ranging from a picturesque icy, pink wonderland to something eerily reminiscent of a deleted scene from The Shining. Known by various names like “pink snow”, “red snow” or “blood snow”, the fan-favorite and most commonly used name has been “watermelon snow.” Reportedly, the snow even smells somewhat sweet and fruit-like, but experts do not recommend eating it (although not harmful in small amounts, it’s considered a laxative and can cause digestive ailments).

We’ve known about watermelon snow for a long time, with recorded accounts dating back to 300 B.C. in notes made by Aristotle. The colored snow puzzled explorers and scientists for years until the 19th century when a Scottish botanist named Robert Brown found that the coloration was caused by a species of ice-loving algae, Chlamydomonas nivalis.

800px-Chlamydomonas_nivalis_Ökologix
© Ökologix

When you observe C. nivalis under a microscope, they are green in color but contain a secondary red pigment called a carotenoid. It lays dormant during winter months but during warmer summer months, the algae “activate” their carotenoid as a protective barrier, or sunscreen, against the sun’s damaging UV radiation, and become red.

The addition of color to the translucent snow causes it to absorb more heat rather than reflect, which ultimately leads to faster melting rates. This can be especially problematic in areas like the Arctic and Antarctic where algae are found in glaciers, contributing to critical issues like sea level rise. Without more study, it’s difficult to determine just how much this will have an effect.

A study from the GFZ German Research Center for Geosciences examines summer snow microbes (like C. nivalis) and found that the algae are so global, that the algae’s effect on melting snow and ice needs to be included in climate models. Many suggest that future climate simulations should account for the effects of algae when making predictions about the rate of melting ice and contributions to climate change.

Learn more about what Ocean Conservancy is doing to address the climate crisis.

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