Pink Snow in the Arctic

Chlamydomonas nivalis pink snow

Pink snow is commonly seen during the spring and summer seasons.

As lovely as anything of this color may be, no one expects to see pink snow at the North Pole. Scientists wondered why nature would create such an incredibly colored snow, and the phenomenon unfortunately related to a more serious issue: climate change.

The emergence of pink snow seems to be caused by an alga that blooms under the warm sun and, in return, creates a deficit in snow’s reflection.

While the glaciers covered by algae populations are no more white but pinky-red, the sun rays are no longer reflected by the surface and are absorbed more quickly. Pink snow is an invitation to sunlight and its thermal power, and more heat creates more ice melting.

“Imagine wearing black instead of a white T-shirt in the sun. It feels much hotter. It is the same for the snow: More heat means more melting,” patiently explained Stefanie Lutz, one of the authors of the study.

Snow and ice areas were considered to lack any type of life. Until now, scientists only paid attention to a type of bacteria that lived in cryoconite holes. The new study focuses on snow algal blooms and tries to connect them to ice melting in the Arctic.

The snow algal blooms dominate the spring and the summer, and they form the main vegetal mass after the melting. The alga commonly associates with other bacteria and archaea.

The study involved the analysis of 40 pink snow areas from 16 glaciers.

A surprising fact was that the bacteria was clearly separated geographically, even if their small size would have permitted them to spread quickly and thus be found in more compact masses. Moreover, their population was very diverse.

On the contrary, the pink algae were found to have similar characteristics despite the vast distances between populations. Scientists also noticed that modifications in the local environment can affect bacteria, but not algae.

The extreme melting events registered in the last decades could, in fact, have maximized the population of pink algae, which thrive in warmer waters.

The scientists calculated that the overall decrease in reflection due to the pink snow effect can be up to 13% during the melt season, which adds up to a higher percentage of ice melting during the Arctic spring and summer.

The study’s findings can be correlated with other factors that influence the reflection capacity of the snow, such as the black colored carbon released by forest fires that is carried away by winds in the atmosphere. Dirty snow, either black or pink, can have powerful negative effects on the North Pole glaciers.

Image Source: Wikipedia

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