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Pink snow: A visual delight or environmental concern?

Cold-adapted algae and bacteria could unlock questions behind Alpine glacier melting

An algae that provides snow banks a pink hue has piqued the curiosity of drivers and hikers traversing Guardsman Pass on Wednesday, June 28, 2023, near Park City, Utah. The so-called “watermelon snow” comes from algae that swim to the surface and change colors to protect themselves from ultraviolet rays. (AP Photo/Rick Bowmer) (Rick Bowmer, Copyright 2023 The Associated Press. All rights reserved)

If you see yellow snow, it’s likely you know what happened, and not to eat it, but what if the snow is pink? It might sound wild, but it happens.

According to the experts at the United States Geological Survey, this phenomenon isn’t as rare as you might think. It pops up in mountainous regions all around the globe. Some even call it watermelon snow.

Now, despite its vibrant hues, this colorful snow wasn’t dyed or delivered by a unicorn. Nope, it’s actually the work of green algae thriving in cold, snowy environments.

Jana Brough walks across pink-hued snow at Tony Grove Lake on Wednesday, June 28, 2023, near Logan, Utah. The snow's color has piqued the curiosities of hikers and campers throughout Utah this summer (AP Photo/Rick Bowmer) (Copyright 2023 The Associated Press. All rights reserved)

Turns out, the specific algae responsible for jazzing up the snow is called Chlamydomonas nivalis. But get this — algae species living on ice and snow can paint the frozen landscape in a whole spectrum of colors — purple, green and even orange!

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Scientists have been curious about these cold-loving critters. Why? It turns out, not much was known about what makes them tick, especially when it comes to those colorful blooms they create.

Picture this: nutrients like phosphorus, nitrogen and carbon are basically the buffet for these little guys, but why do they decide to throw a party in one place and not the other? And why do their parties vary in intensity from year to year? It’s like trying to figure out why your neighbor’s yard always looks better than yours!

An algae that provides snow banks a pink hue has piqued the curiosity of drivers and hikers traversing Guardsman Pass on Wednesday, June 28, 2023, near Park City, Utah. The so-called “watermelon snow” comes from algae that swim to the surface and change colors to protect themselves from ultraviolet rays. (AP Photo/Rick Bowmer) (Copyright 2023 The Associated Press. All rights reserved)

Now, here’s where it gets really interesting. These algae and cyanobacteria pigments are darker than the regular plain white snow, so they soak up way more sun. Kind of like how dark clothes make you sweat in the summer. With temperatures on the rise, glaciers are melting faster than ice cream in July. And guess what? These dark snow patches are speeding up the process even more. Scientists are trying to understand what the driving factor behind the cold-adapted algae and cyanobacteria blooms are, in hopes that it will provide more information to understand the effects of the blooms on the melting snow and ice. Sounds like a lot doesn’t it?

But wait, there’s more! Scientists are also wondering if these cold-loving creatures had the time of their lives during the last Ice Age. Imagine Earth as a big pink planet instead of an icy white one during those chilly times. Scientists are looking into whether or not the Earth was completely inhospitable or if the cold-adapted algae and cyanobacteria covered our planet in patches of pink.

So, next time you’re hitting the slopes and you spot some colorful snow, you’ll know it’s not just your ski goggles playing tricks on you. Oh, and you probably shouldn’t eat that snow either.

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