The term “glacier blood” or “blood snow” sounds like something you would read in a supernatural horror novel. But it is actually a purple phenomenon, a colorful sign of blooming life produced by tiny organisms that inhabit snow-covered mountain habitats. The eerie biological dye has many names – watermelon snow or red snow, for example – and is found on glaciers on mountain peaks all over the world, from the Sierra Nevada to the Himalayas to the Greenland ice sheet, prompting speculation among climbers, naturalists and polar explorers for centuries.
In recent weeks, snow on Ukraine’s Vernadsky Research Base, off the coast of Antarctica’s northernmost peninsula, has taken on a red hue thanks to the algae that thrive in icy weather. Green algae, as their name suggests, produce red carotenoid pigments, a kind of sunscreen, like warm weather. When algae get lots of sun, they produce a natural sunscreen that colors snow in pink and red tones.
In recent years, alpine habitats around the world have seen an increase in snow algae blooms, with dramatic hues and clusters of invisible creatures. The phenomenon is not well understood, but new research in the journal Frontiers in Plant Science could help uncover the story behind these blooms and their potential effects. Alpine habitats around the world are experiencing a “reverse” snow algae bloom which the New York Times reported. In 2020, researchers published a study in the journal Nature that presented initial estimates of the distribution of the biomass of green snow algae on the Antarctic peninsula.
Recently, Antarctica experienced record temperatures, causing the southernmost continent’s ice cap to melt at an unprecedented rate. As a result, Eagle Island, a small island on the northwest tip of Antarctica, experienced a peak of melting brown rock that appeared as ice, and several ponds of melted water gathered in the middle. A team of scientists scaled the Alps to study blood snow, recording mountain ranges stretching across parts of the mountain.
In the southern hemisphere, the algae turn red in the middle of summer. At record temperatures, algae thrive in ice-cold water dormant under the snow and ice of the continents, and cover the Antarctic peninsula in full bloom with blood-red flower spores. In the same family as green algae, this strain produces flower-like pink and blood-red hues.
This eerie scene is not the result of a failed seal hunt; it is the red-pigmented microscopic alga Chlamydomonas nivalis that thrives in freezing water, while the ice melts in record-breaking warm summers in Antarctica. Watermelon snow (also known as Snow Algae, Pink Snow, Red Snow or Blood Snow) is a phenomenon caused by Chlamysdomona nivali, a type of green algae that contains a secondary red carotenoid pigment, astaxanthin, in addition to chlorophyll. Red-colored algae strains produce the same carotenoid pigments that turn carrots and pumpkins orange and turnips purple.
Unlike most freshwater algae species, Chlamydomonas nivalis, a green algae species that contains a secondary red carotenoid pigment astaxanthin in addition to chlorophyll, appears to be crypophilic (warm-loving) and thrives in freezing water. This type of snow is most common in summer in alpine, coastal and polar regions such as the Sierra Nevada in California.
At altitudes between 3,000 and 3,600 m, the temperatures can be very cold, and in some years, the snow remains dormant long after the winter storms. Grey or black snow is not good, as it suggests that chemicals in the air still pollute snowflakes when they fall. If you walk on watermelon snow, you will get bright red soles and pink trouser cuffs. If you compress the snow and step on it, so that snowballs are created, it looks red. Snow algae dominate the glacier biomass, and their pigmentation darkens the surface of the glacier with the onset of melting.
The ancient Greek philosopher Aristotle discovered snow covered with red stripes in the third century BC. Experts add that unusual snowfalls are likely to become more common due to climate change. It’s summer in Antarctica, which means record temperatures and glacial melt, but there’s another symbol of our changing climate – a bit of blood-red snow splashing the Antarctic peninsula. You may have been warned about yellow snow by scientists, but it’s the red snow that keeps you on your toes at night.
The colorful snow consists of clusters of algae that thrive in liquid water in sub-zero temperatures, leading to an algae bloom. Blood congestion – what researchers call the “blood group” – is the red pigment of an algae called Chlamydomonas chlamy domonas nivalis, which hides in snowfields and mountains. It is sometimes referred to as “blood snow” because it occurs in California’s Yosemite National Park.
Watermelon snow smells sweet and is not unlike the fruit after which it is named, Smithsonian Magazine reported. Due to the red raspberry color, the snow reflects less sunlight and melts faster. According to Ukrainian scientists, the red color of the algae absorbs more sunlight, causing the snow to melt faster and create a feedback loop.