Pink snow isn’t a cute phenomenon – here’s why

The scientists used the device to record the albedo of the snow, a measure of how much of the sunlight shining downwards is reflected back up. Red snow means lower albedo, which means more sunlight is absorbed and the snow melts faster. Other factors also affect albedo, including dirt, dust and ash from wildfires. Sand from the Gobi Desert can blow all the way to the Pacific Northwest, while dust from the shrinking Great Salt Lake sometimes blankets the Wasatch Mountains. The team also measured the snow’s pigment concentration with a second spectroradiometer to find out how much of the red color spectrum, most likely from the snow algae, was present.

A bighorn sheep watched from a jagged cliff high above as the team worked through the rest of their routine: measuring the snow’s water content, collecting bags of snow samples, and taking a snow core that revealed two layers of algal blooms, including a obvious rusty band a few inches below the surface.

Later that day, in a lab at the University of Montana’s Flathead Lake Biological Station, Elser and Almela Gomez would use the samples to test which inputs help snow algae grow. They melt the snow, mix it together and add nutrients like nitrogen and phosphorus. Then, after five to 10 days under grow lights in a cold incubator, they measure the chlorophyll levels to see how much the algae grew.

The two types of nutrients come from different places. Previous work suggests the phosphorus is found in rocks ground up by glacial movement, while nitrogen is blown in from the chemical fertilizers and manure in agricultural areas. The researchers suspect that both types of nutrients stimulate algae growth, but they are particularly interested in nitrogen. They believe algal blooms are especially common in the Intermountain Rockies because of wind patterns, and they hope to learn more about the dynamics involved.

The team’s work is part of the small but growing field of snow algae research. The scientists hope to find out what allows snow algae to thrive and where they are likely to live. The Living Snow Project, a citizen science initiative by researchers at Western Washington University, asked skiers, climbers and hikers to collect pink snow samples. Scientists have also agreed on rising algal blooms in the French Alps.

Learning what influences snow algae growth is an important step in understanding a changing water supply. More algae means potentially more melting, and knowing where algae can accelerate snowmelt is especially crucial for the drought-prone western US. Gradual melting of the snow is good; it creates a more predictable water supply downstream for reservoirs and imbues streams with the cold water that fisheries and other aquatic life rely on during the hot summer months. However, rapid snowmelt brings a host of other problems.

Elser compared the role of snow to ice in a cocktail. “The ice is melting, but your drink is still nice and cold until that last piece of ice is gone,” he said. “Then it’s like, ‘What happened? My drink is warm.’” If snow algae melt the snow faster or melt all the snow quickly, streams can get warmer than normal and hold less water as the summer progresses. is a pretty big deal,” said Scott Hotaling, a member of the snow algae research team and an assistant professor at Utah State University who studies changing mountain ecosystems. “We’re talking about the entire West being in a drought, and if there’s a will be another factor that perpetuates earlier melting, that’s important.”

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