Pink Algae Bloom in Italian Alps Sparks Climate Concerns

The algae darkens the snow, causing faster melting

Many skiers in the western United States are familiar with the phenomenon of “watermelon snow,” a pink algae bloom appearing at high altitudes in the summer months. But the appearance of pink algae in Italy, where it was previously uncommon, sparked concerns this week over glacial melt.

These algae decrease the albedo on the snow surface—the amount of light energy reflected by the snow—and thereby absorb more heat. Glacier ice normally reflects 80 percent of the sun’s energy. But the darker the color on the snow surface, the more quickly they increase in temperature and melt.

The discovery of the algae on the Presena Glacier caused a stir among scientists because Italian glaciers are already receding at an alarming rate. Known by its Latin name, Ancylonema nordenskioeldii, the algae thrives in a positive feedback loop of melting snow. The more the snow melts, the more water feeds them, and the farther they can spread.

The algae, first recorded in the notes of Aristotle, has been a driver of melt for centuries. Combined with anthropogenic climate change, the acceleration of glacier melt could prove devastating to the Italian alpine environment, economy, and culture.

Scientist Biagio Di Mauro of Italy’s National Research Council said to The Guardian that while humans are accelerating climate change, natural phenomena such as the algae contribute as well. But human-algae interaction increases this process. Compressing the snow with boots and skis deepens the color, further decreasing the snow’s albedo.

The Presena glacier has lost more than one third of its volume since 1993. The melt-out has gotten so bad that locals have taken to covering the glacier in white tarpaulin. With scientists predicting a 70 percent reduction in snowfall by the end of the century, it is clear that the time to solve this crisis is running out.

Sound off in the comments below!

Join the conversation