Pink snow: Here's how this 'cute' phenomenon threatens water supplies in the US

Pink snow isn't as cute as it sounds.
Nergis Firtina
Pink snow
Pink snow.

Wikimedia Commons 

Researchers from the U.S. are currently trying to find out what triggers the algae that gives snow its pink color. Also known as "watermelon snow," it could be a threat for water supplies, researchers say.

Snow algae, a group of freshwater microalgae, gives snow its pink color. These algae have been observed in a variety of colors that are related to the unique species, stages of life, or geography. Snow algae have also been discovered to travel long distances when transported by wind. More importantly, pink snow means lower albedo, which means more absorbed sunlight and faster snowmelt. Albedo is also influenced by other variables, such as dirt, dust, and wildfire ash.

According to High Country News, Jim Elser, an ecologist at the University of Montana and the director of the Flathead Lake Biological Station, and his team have been scanning the snowfields clinging to the lower slopes of Clements Mountain in Montana's Glacier National Park.

In the research, a device was used to measure the snow's albedo, which is a measurement of how much of the sun's rays are reflected back upward. The scientists also used a spectroradiometer to assess the pigment.

Pink snow: Here's how this 'cute' phenomenon threatens water supplies in the US
Watermelon snow pits.

What about the water?

The crew carried out the other steps in their routine, including measuring the snow's water content, gathering bags of snow samples, and extracting a snow core. This revealed two layers of algal blooms, including a prominent rusty band a few inches below the surface.

These kinds of nutrients come from various sources. According to earlier research, phosphorus is found in rocks that have been eroded by glaciers, whereas nitrogen is blown in from agricultural areas' chemical fertilizers and manure. Although both types of nutrients are thought to promote algal growth by researchers, nitrogen is of special importance to them. The researchers think wind patterns may make algal blooms more frequent in the Intermountain Rockies, and are interested in discovering more about the dynamics at play.

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Understanding the factors that affect snow algal growth is a crucial first step in comprehending a changing water source. Knowing where algae might hasten snowmelt is especially important for the Western U.S., which is prone to dryness. 

More algae might potentially imply more melting snow. Snowmelt that occurs gradually is beneficial because it provides reservoirs with a more stable water supply and fills streams with the chilly water that fisheries and other aquatic life need to survive the hot summer months. However, rapid snowmelt creates a number of additional issues.

"The ice is melting, but your drink is still nice and cold until that last piece of ice goes away," Elser said to High Country News. "Then it's like, 'What happened? My drink is warm.'" If snow algae hastens snowmelt or melts all the snow quickly, streams may end up warmer than usual and have less water as the summer advances.

"It's a pretty big deal," also added Scott Hotaling, a member of the snow algae research team and an assistant professor at Utah State University who studies changing mountain ecosystems. "We talk about the whole West being in a drought, and if there's going to be another factor that perpetuates earlier melt, that's important." 

How often does pink snow appear?

This kind of snow is frequent in the summer in arctic and alpine regions, including the Sierra Nevada in California. The weather is frigid year-round here at an elevation of 10,000 to 12,000 feet (3,000-3,600 m). Thus, the snow from winter storms has stayed. Snow turns scarlet when it is stepped on or compressed into snowballs. You frequently end up with bright crimson soles and pink trouser cuffs after walking in watermelon snow.

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