Red snow, snow or ice surfaces, usually overlying soil on mountains, that are coloured by algae such as Chlamydomonas or Raphidonema. During seasons when there is little sunlight and temperatures are below the freezing point, the algae are dormant. Red snow caused by Chlamydomonas nivalis.

When C. nivalis algae gather in high concentrations in the snow, this red pigment makes it appear pink. The red pigment also acts as a natural sunscreen, protecting the algae from damaging visible and ultraviolet radiation. And no, it’s definitely not edible – the algae are considered toxic to humans.

Watermelon snow, also called snow algae, pink snow, red snow, or blood snow, is a phenomenon caused by Chlamydomonas nivalis, a species of green algae containing a secondary red carotenoid pigment (astaxanthin) in addition to chlorophyll.

A bizarre bout of so-called “watermelon snow” in the Alps this year certainly looks picturesque. Unfortunately, the salmon-tinted landscape is actually a bad omen for Earth’s climate. Watermelon snow, which takes on a reddish-pink hue, is caused by snow algae. The algae is red because of its carotenoid pigment.

Pink snow, also called “watermelon snow,” has appeared at Northern Italy’s Presena glacier, according to Biagio Di Mauro of the Institute of Polar Sciences at Italy’s National Research Council.

Age: The sang de glacier or glacier blood phenomenon, in which alpine snow turns pink in the spring, has been observed for centuries. Aristotle believed it to be the work of “red and hairy worms” under the snow.

This phenomenon is especially common during the summer months in the Sierra Nevada of California where snow has lingered from winter storms, mainly at altitudes of 10,000 to 12,000 feet. Compressing the snow with your boot leaves a distinct footprint the color of watermelon pulp.

However, it is possible that snow algae might be contaminated by bacteria and toxic algae that are harmful to humans. Eating large quantities of watermelon snow has been known to cause digestive ailments, although the tolerance level of each person’s digestive system might be different.

A glacier in the Italian Alps is turning pink as algae eats away at its snow. Algae that changes the color of snow or ice causes it to melt faster, a process which drives glacier melt across the globe. Glacier-eating algae could be seen more frequently as global temperatures rise.

Glaciers and their immediate environs present many dangers for humans, such as crevasses and glacier mills into which one might fall, heavily crevassed ice falls, snow and ice avalanches from the side walls and, along the flanks, dumping of great boulders, ponding and floods from melt water.

Dirty Snow If you were to trek up the Italian Alps right now, you’d find your boots covered in bizarrely pink snow. While it’s a beautiful touch that turns the mountaintops into an alien landscape, Earther reports that the pink snow is actually a pretty bad sign. The pink color comes from blooming algae.

You may have heard of pink sand beaches, but what about “pink snow”? On Thursday, a local scientist discovered a glacier in the Italian Alps is covered in pink snow. The effect, also known as “watermelon snow,” is due to the presence of algae.

With regards to the sky when snow looks to move in, light bouncing off clouds and atmospheric particles is scattered, leaving longer wavelengths as the color we see. When snow is falling, that same light reflects off all the different snowflakes, giving a pink hue to the sky.

In a troubling sign for the future of the Italian Alps, the snow and ice in a glacier is turning pink due to the growth of snow-melting algae, according to scientists studying the pink ice phenomenon, as CNN reported. The algae will make the snow melt faster.

Pink snow has appeared at the Presena glacier in northern Italy, researcher Biagio Di Mauro, of the Institute of Polar Sciences at Italy’s National Research Council, told CNN Monday. While “watermelon snow,” as it is sometimes known, is fairly common in the Alps in spring and summer, it has been more marked this year.

Snow falls in the northern mountains of Italy from December to January every year, and occasionally it can snow in other major cities like Rome, Florence, and Milan. Snow is quite common between December and March in cities like Bologna, Milan, and Turin.

When summer hits the polar regions, the algae bloom, staining the snow and ice around it in blood-resembling red, as Live Science explains. The phenomenon was first noticed by Aristotle thousands of years ago and is often referred to as “watermelon snow” thanks to its subtly sweet scent and color.

Receding glaciers mean less water stored up to feed rivers, especially in times of summer drought. Also, rainwater drains away more quickly and is not stored in the Alps’ glaciers. Farmers and livestock pastoralists will find less grass in high meadows in summer to fatten up cows to produce milk for cheese.

Climate Change in the Alps | WWF. Global warming will impact mountain areas in a particularly severe way, posing a very serious threat to Alpine nature. Over the last century, global warming has caused all Alpine glaciers to recede. The European Alpine Programme coordinates WWF’s conservation work across the Alps.

Italian cities focus more on mitigation than adaptation. Currently, under the aegis of the Covenant of Mayors, about 3000 Italian towns and cities have submitted their Sustainable Energy Action Plans (SEAPs), pledging themselves to reduce their GHG emissions by at least 20% in 2020.