Pink Snow

Colorful patches of snow are a common find in alpine environments, and they hold a secret: they’re full of life. Researchers at Western Washington University are getting help from citizen scientists to find out more.

Kodner Lab researchers traveling to sample snow algae at Bagley Lake on Mount Baker in 2022. Photo courtesy of Claire Giordano.

Story by Sarah Archer

March 15, 2024

It’s the middle of summer, and watermelon-colored patches of snow litter the expansive snowfields of Mount Baker. Each pink patch is home to a tiny microbial ecosystem, each a world of small organisms surviving against all odds in the frozen climate.

A gloved hand reaches down and carefully scoops a capful of the snow into a small, plastic sample tube and tucks it away, ready to carry it home and mail it to the lab for analysis.

Snow algae in alpine environments are responsible for producing the natural phenomenon known as pink snow. Research concerning the algae is sparse, but data collection efforts have begun to gain momentum. Although the community of microbes is threatened by climate change, it also plays a small role in driving the continued warming of our planet. Researchers at Western Washington University and volunteers across the country are at the forefront of the work being done to demystify pink snow and determine how it impacts, and is impacted by, a changing climate. 

Algae are a diverse group of aquatic organisms that rely on photosynthesis to obtain the energy they need. Snow algae are a special subset of these organisms that have adapted to withstand the cold and solar radiation in melting snow. They form algal blooms– explosions of reproduction and population–that take shape as patches of pink snow. These blooms emerge and grow on the slushy surface of Mount Baker’s snowfields throughout the seasonal snowmelt of spring and summer. 

Snow algal blooms are normal and natural, but they’ve been getting larger and causing snow to melt faster, according to Ellie Ryan, a graduate student studying snow algae at Western.

Ryan is part of the university’s Remote Sensing and Aquatic Biogeochemistry Lab. One of the lab’s projects includes studying the effects of snow algae on albedo–the proportion of sunlight reflected off of a surface–in frozen environments.  

Snow algae can lead to a 20% reduction in albedo, according to a 2016 study published in the journal Nature Communications. This causes more heat from sunlight to be absorbed by the snow and may lead to the algae’s own demise in the future. Less snowpack due to melting means less habitat for snow algae in the long run. 

The algae alter albedo because of their color. These snow algae get their color from protective pigments within their bodies that they use to shield themselves from the harsh UV rays that shine down onto and reflect off of alpine environments. 

Large snow algal bloom on Mount Watson. Snow algae flourish in the slushy environment of melting ice and snow.

Photos courtesy of Clare Hanneman.

An orange trowll digs up pink snow in the sunlight. Every patch of pink contains a microbial ecosystem, a world of tiny organisms surviving in freezing conditions.

Snow algae flourish in the slushy environment of melting ice and snow. As more algae grow, more melting occurs, creating more of this habitat. This continuous melting and growing is what has the potential to destroy their frozen habitat.

“I think it’s kind of like humanity, we’re expanding and expanding and expanding and we’re going to reach a limit where we can’t anymore, and we run out of resources and the algae is doing a similar thing,” Ryan said. 

Up on Mount Baker, the snowpack undergoes continuous transformation as distinct winter layers of ice and snow give way to summer’s homogenous slush. As snow stops falling in the early spring, the surface of the snowpack consolidates and becomes peppered with sun cups, small craters in the snow whose shaded edges are home to snow algae.

Jason Martin is no stranger to the snow algae that dots Mount Baker. He is the executive director of the American Alpine Institute, a mountaineering school and guide service that offers guided climbs and training on Mount Baker. To him, patches of pink snow are a mountaintop standard. 

“It’s everywhere, it’s like grass,” Martin said.

Climate change has had major impacts on alpine and glacial environments. A projected 49% of the world’s glaciers are expected to be lost in the next century as the planet warms, according to a 2023 study published in the journal Science.

“The biggest issue that we see when it comes to mountaineering or any type of snow climbing, glacier climbing, is that we’re seeing some of the glaciated peaks either shut down or come close to shutting down,” Martin said. 

Global changes in snowpack and glacial mass heavily impact snow algae and mountaineers alike. Recreators have a huge stake in mitigating the impacts of climate change. The Living Snow Project is an organization making it possible for outdoor enthusiasts to get involved in conservation by collecting snow algae samples for analysis at Western. 

As a part of the Kodner Lab that studies algae at Western, the Living Snow Project is a volunteer-run research initiative. The lab, its researchers and volunteers aim to learn more about where and how pink snow impacts the environment.  

“We are just trying to get as much data as possible from as wide a span of places as possible,” Honu Pata, an undergraduate researcher working for the Living Snow Project, said.

Volunteers are able to collect sample kits from retail stores partnered with the project or are sent sample kits in the mail. The kits include sample tubes, gloves, a sticker and sampling instructions. Volunteers can use the kits to collect snow algae samples that they find hiking, skiing, or wherever they stumble upon them in nature. These samples are then mailed back to the Kodner Lab for imaging and analysis. 

Sample collection and analysis aid in the project’s main goal to spread awareness of pink snow. 

“I like to think that knowing more about the environment makes you care about it more. Everything that you learn about kind of connects you to it, and so being able to help make people care about the world around them is really meaningful,” Pata said.

The project also has an app, Living Snow Project, that anyone can use to record pink snow sightings. The project allows everyone, regardless of ability, to be involved in snow algae research.  

“It doesn’t have to be all in, like you’re going on a hike or you’re going back country skiing to a place,” Clare Hanneman, the program coordinator for the Living Snow Project, said. “I’d like to stress the accessibility of being a volunteer, it’s kind of what you make it.”

Clare Hanneman samples pink snow during a sunny day on Mount Watson.. // Photo courtesy of AG Camara.

Pink snow isn’t restricted to the slopes of Mount Baker. The Kodner Lab’s Living Snow Project has received volunteer-collected samples from Alaska to Montana. The Remote Sensing and Aquatic Biogeochemistry Lab is currently conducting field research on snow algae in the Antarctic. 

Data on snow algae is being collected at a rapid pace, but it could disappear just as quickly in the face of climate change.  

“The scary thing is it’s a new field, it’s emerging, but how is it going to be here?” Ryan said. “If there’s no snow, there’s no snow algae to study, and so it’s kind of already a disappearing field of study.”

Sarah Archer is a senior environmental science student striving to connect people to nature and conservation.