It’s caused by a red algae, and it’s bad news for the Arctic.
The appearance of the so-called pink snow, which Arctic explorers have observed for centuries, is the result of a red algae that likes to bloom in the frozen water. In a study published Wednesday in the journal Nature Communications, researchers found that those algal blooms are causing the ice to melt faster, and the algae is likely to grow more rapidly as climate change melts even more of the Arctic into the liquid water that feeds them.
The presence of red algae, the study found, lowers the snow’s albedo, or its ability to reflect light instead of absorbing it as heat (similarly to how a white T-shirt keeps you cooler in the sun than a black or colorful one does). Over a 100-day period during the melting season, the study found that snow affected by the red algae had a 13 percent lower albedo than white snow.
This is not an instance of the unprecedented melt in the Arctic occurring naturally and without manmade global warming. On the contrary, the study authors say, it’s an example of how human-caused climate change functions on a positive feedback loop with other things in nature.
“As we infer from our data, melting is one major driver for snow algal growth,” the study notes. “Extreme melt events like that in 2012, when 97% of the entire Greenland Ice Sheet was affected by surface melting, are likely to re-occur with increasing frequency in the near future as a consequence of global warming. Moreover, such extreme melting events are likely to even further intensify the effect of snow algae on surface albedo, and in turn melting rates.”
That’s because the glacier melt, which is disproportionately driven by the rise in global temperatures, is effectively watering the red algae, lead study author Steffi Lutz of the University of Leeds explained to Gizmodo.
“The algae need liquid water in order to bloom,” she said. “Therefore the melting of snow and ice surfaces controls the abundance of the algae. The more melting, the more algae. With temperatures rising globally, the snow algae phenomenon will likely also increase leading to an even higher bio-albedo effect.”