- Pink, red, purple, and green algae blooms are growing on glaciers all over the planet.
- Scientists who study snow and ice algae fear the blooms are a symptom of climate change.
- Algae blooms can induce ice melt, hastening the catastrophic disappearance of the world’s glaciers.
Glaciers around the world are turning beautiful but menacing shades of pink, red, purple, and green.
Eric Maréchal has seen it firsthand in the European Alps.
About 20 years ago, as he trekked through the mountains, he would occasionally run into other scientists who were giddy about finding rare “blood snow” — an overgrowth, or “bloom,” of red algae that stains the glacier’s surface.
Maréchal said the blood snow started becoming more common about 10 years ago. Now he sees bright pink and red algae blooms every year.
Much like soil, snow and ice are thriving with microorganisms.
Colorful blooms of microscopic algae have been documented on glaciers in nearly every continent. The “blood snow” algae has also been found in the Arctic, Antarctica, and mountains in both Americas.
Maréchal suspects snow and ice algae are on every glacier — vestige of a time when ice covered the planet, 20,000 years ago.
“It’s like the memory of the Ice Age, when the Earth was a snowball,” Maréchal, who studies algae at the French National Centre for Scientific Research, told Insider.
“We have the chance when they are blooming, that everybody who goes hiking can experience them. So it’s a wonder. At the same time, it’s a marker of environmental change, because when they are blooming, it means that there is a strong disturbance of the ecosystem.”
Algae may be accelerating the disappearance of Earth’s glaciers
Scientists like Maréchal think these algae blooms are getting larger and more frequent as rising global temperatures melt glaciers worldwide. This is still a hypothesis, as there is no historical data on glacier algae and scientists haven’t pinpointed exactly which nutrient or environmental condition is fueling the blooms.
But the researchers believe microalgae thrive in warmth and moisture.
“The moment you have melting, the algae just are happy,” Liane Benning, who leads a research project called Deep Purple, funded by the European Research Council, told Insider.
Her team is working to build a historical record of Greenland’s purple ice algae, including how much it bloomed before humans began changing the climate.
“They just need a little bit of water,” she added. “And they have a party. They go and bloom.”
It may be a party for the algae, but it’s a slow funeral for the glacier.
Instead of the blinding white that reflects sunlight away from a glacier, algae blooms create vast patches of pink, red, purple, or even green.
Studies in the Himalayas, Greenland, Alaska, and across the Arctic have found that these colorful blooms darken the surface of glaciers, causing them to absorb more sunlight and leading to new ice melt.
“It’s like a runaway effect,” Benning said. “You make more algae; they bloom more; they melt more. They melt more; there is more blooms.”
They’re still gathering data to prove it, but if that runaway loop hypothesis is real, it’s probably accelerating as Earth’s glaciers disappear.
Already, the catastrophic impacts of ice loss are creeping across the planet — like sea-level rise and the dwindling of water sources that are usually replenished by glaciers. Those dangers could worsen faster than scientists have predicted, since their models don’t account for microalgae.
Glacier algae seems to be booming, but scientists have a lot to learn
The first written record of snow algae appears in writings from Aristotle, the ancient Greek philosopher, who described seeing the red snow on Mount Olympus.
It was another two millennia before someone took a sample of glacier algae for scientific research, Maréchal said.
The algae species turning the Alps pink didn’t get a scientific name until 2019. Before that, it was mistaken for a different species.
“We are incredibly late. We are maybe 50 years behind the ocean sciences,” Maréchal said.
But in the last couple of decades, as the algae have seemed to boom, so has research on them. Ice algae and snow algae are different types of microorganisms, and different fields of study, but they both affect glaciers.
“Most people when they go on a glacier and they look at that, they think it’s just dirt,” Benning said. “Only when we looked at them under the microscope, we realized: ‘Wait a moment, this dirt is moving.'”
Scientists have learned that the algae take on their colorful pigments in order to protect themselves from UV damage from the brilliant glare of sunlight reflecting off white snow.
But there’s still much to learn about these vibrant microalgae.
“We still don’t know much about the fundamental ecology of snow algae,” Andrew Gray, who studies snow algae in Antarctica, told Insider in an email.
He added that the biggest snow algae mysteries include “where they are, why they are where they are, and how they’re likely to respond to warming.”
As glaciers disappear, so might this ancient algae
In May, Maréchal’s team hiked up to the glaciers to take samples of the snow while it was still white. They needed a baseline to compare against later in the summer, once the red algae started blooming.
But when they reached their sampling site, expecting blankets of pure white snow, they found it was already pink with algae. When they returned a week later, all they found was bare earth. The snow had already melted away.
The trend continued later in the year.
“This summer proved to be extremely difficult, because the snowpack and glacier proved to melt at an accelerated pace,” Maréchal said.
The disappearance of glaciers is a compounding global catastrophe, with dire implications for our climate, sea levels, and water supplies.
Beneath all of that, if you zoom in to microscopic levels, global ice melt could also spell the disappearance of these ancient algae, which are likely the foundation of an under-researched ice ecosystem.
Ice and snow are full of “bacteria, fungi, virus, cyanobacteria, algae,” and even insects, Gray said. Scientists don’t know enough about those ecosystems yet to understand what that loss could mean.
What if ice and snow microbes play a role in keeping glaciers stable, or pulling carbon from the atmosphere?
In some places, like one Italian ski resort, covering the glacier with reflective white material can slow its melt and counteract the snow’s color change. But that’s a Band-Aid solution.
“What can we do about these pesky algae? Everybody asks that question,” Benning said. “We should bloody stop changing the climate.”