Pink Ice in the Alps: How Threatening to Glaciers Can It Be?

Italy's Placerna Glaciers are turning pink, and scientists are investigating its mysterious appearance. Studies reveal that the algae cause the change of color, Ancylonema nordenskioeldii, and its presence could contribute to the increase in the glacial melt.

The colored ice is known as "watermelon snow" and is caused by algae, Ancylonema nordenskioeldii, which is common on the ice sheet in southwest Greenland, Biagio Di Mauro of Italy's National Research Council said.

It is unclear how the algae found its way to the Alps from Greenland, but Di Mauro said he would not be surprised to find it on other glaciers in the Alps.

During winter, these algae are dormant. But in spring and summer, the algae proliferate. Scientists believe that the increased light and nutrient, an abundance of meltwater, and an increase in temperature, are ideal conditions for these algae to bloom.

When exposed to sunlight, these algae turn red or pink. Exposure to sunlight also prompts the algae to produce a naturally protective red carotene layer, which protects it from the harmful ultraviolet radiation.

But the algae do not only come in shades of red. It can also come in brown, violet, yellow, or green. A recent survey in Antarctica showed that the glaciers are turning green from the algal bloom. Increased temperature, exposure to light, and excrement of marine animals and birds prompted its bloom.

No matter what color the algae is, however, it still contributes to the thawing of already melting glaciers. Glaciers exude that bright, white surface. These features enable the glacier to reflect around 80 percent of the sun's radiation into the atmosphere. But in cases of algal bloom, the algae darkens the ice as it spreads over the glacier's surface. The colored ice absorbs more solar radiation, heating the glacier and melting it at a faster rate.

Matthias Huss, a glaciology professor at ETH Zurich, said that although the algae contribute to the reduction of the ice's albedo, the pink algae will not affect the "glacier retreat significantly.' According to Huss, pink algae's algal bloom lasts for a relatively short time and are not widespread in the Alps.

The main culprit of glacial melt, however, remains to be climate change, he said. He cited a study in 2019 that was published by the European Geosciences Union (EGU) the revealed that if nothing is done to curb global carbon dioxide emissions, the Alps will be ice-free by 2100. Only 5 percent or less of the present-day ice volume will remain, which are likely the isolated ice patches at high elevation.

The study, in which Huss was a co-author, used computer models to analyze the ice flow and melt processes. The study revealed that the glaciers in the Alps are expected to lose about 50 percent of their total volume in the middle of this century, despite what happens with emissions. Algae growth was not among the factors in their projections.

According to one of the study's co-authors, Harry Zekollari, "approximately one-third of the present-day [glacial] volume by the end of the century," may still be saved if the world cuts the carbon dioxide following the 2015 Paris climate agreement.