

For decades, climate scientists have been tracking troubling changes in glaciers around the world. These massive bodies of ice shift and flow under their own weight, but many glaciers are now shrinking. A new trend in the European Alps suggests glacial thawing could accelerate thanks to some unassuming pink algae

Glaciers are an important part of maintaining global temperatures because they reflect more light than other geological features — about 80 percent of solar radiation. As Earth’s ice sheets disappear, the planet absorbs more heat from the sun, contributing to higher global temperatures. And of course, higher temperatures also accelerate the melting. It turns out certain algae can make glaciers melt more quickly as well. 

Sometimes called Watermellon Snow, patches of algae-infused ice and snow are common on glaciers in the spring and summer. The pink-tinted ice in the Alps has researchers from Italy’s Italy’s National Research Council concerned. Biagio Di Mauro, who has studied changes in the Morteratsch glacier in Switzerland, says the algae itself isn’t dangerous. However, its increasing presence in glaciers could worsen climate change because it makes the ice darker. 

The pink algae darkens glaciers, making them less reflective and raising temperatures.

The algae, Ancylonema nordenskioeldii, is one of several species sometimes called ice algae.  Where the algae appears, it lowers the “albedo” of the ice, making it less reflective. The ice absorbs more solar radiation and therefore melts more quickly. This provides more water and air access to the algae, which expands and causes color changes in more areas of the glacier. 

Researchers are seeing much more of this Watermellon Snow in the Alps, but that’s not the only place it has appeared. We’re seeing the same pink ice in Greenland’s “dark zone,” which is also experiencing accelerated melting. There have also been reports of pink and red snow in Alaska and Antarctica. 

Scientists have not agreed on how impactful these algae blooms are to climate change. It’s possible we will need to adjust the current models to account for algae-induced melting. And that could mean we have even less time to make changes if we want to avert catastrophe.

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