POTSDAM, GERMANY — A recent study published by scientists in Europe found that algae within Arctic snow is making the Arctic’s glaciers melt faster.
“Watermelon snow” is triggered by a type of green algae known as Chlamydomonas nivalis, which lies dormant during the winter under piles of snow.
When temperatures rise above freezing in the spring, the surface melts and the meltwater bring nutrients to the dormant algae cells, stimulating germination.
The cells then release green swimming cells with two flagella to propel them to the surface of the snow and daylight.
The algae propagate further as more snow is melted. In order to protect themselves from the increased UV light, the algae produce a red carotenoid pigment that changes their colors to pink and red.
“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.” Stefanie Lutz, lead author of the study and a geobiologist at GFZ German Research Center for Geosciences wrote to the New York Times in an email.
Ice and snow have a high reflectivity, or albedo, but the red algae darkens the snow and causes it to absorb more sunlight, reducing the albedo of snow by as much as 13 percent.
Scientists estimate that at least 50 percent of the snow surface in the Arctic will be covered by algal bloom during the summer. In addition to the Arctic, watermelon snow can also be found in places including Antarctica, the Himalayas and the Rocky Mountains.
