Algal blooms turn glacier surfaces pink in Utah

The watermelon or blood snow is not uncommon in the high mountains or in the polar regions and has been known for centuries. It is a natural phenomenon that occurs in spring and summer, especially in mid-latitudes.

Algae responsible for discoloration of snow
So-called psychrophilic (cold, beware) snow algae are responsible for the discoloration of snow and glacier surfaces. They live in tiny fluid films – enclosed in ice and snow – and can also withstand freezing temperatures.

The single-celled algae are harmless to humans and animals. Their red pigmentation has absorbent and antioxidant properties and serves to protect them from the UV rays present on the snow surface. With the arrival of spring, they multiply very quickly – one speaks of the “algae bloom” – giving the white landscape a pink or red hue.

The melting of the ice is accelerated
However, the impressive natural spectacle also has a negative ecological effect: the color of the snow cover reflects more sunlight and thus absorbs more heat, causing ice and snow to melt faster. A circumstance that significantly accelerates the melting of ice in the polar regions, German and British researchers discovered in a study in 2016.

As more water vapor is produced when the water melts, more moisture and nutrients are released, causing algae to multiply more quickly. This in turn means that snow and ice are colored more pink or red, causing the white splendor to melt up to five times faster.