Does Antarctica have snow?

Green and red snow : Algal blooms in the Antarctic intensify snowmelt

In some regions of Antarctica, the snow turns blood red or green in summer. Snow algae are responsible, which can occur in large numbers in polar regions in summer and discolor the snow.

Since the colored surface absorbs much more solar radiation than white snow, the phenomenon intensifies the thawing of snow. Green algae in particular could significantly accelerate the melting of snow on the Antarctic Peninsula, researchers write in the journal "The Cryosphere".

Tagesspiegel Background Energy & Climate

Coal phase-out, climate change, sector coupling: the briefing for the energy and climate sector. For decision-makers and experts from business, politics, associations, science and NGOs.

Free test now!

[If you want the latest news from Berlin, Germany and the world live on your mobile phone, we recommend our app, which you can download here for Apple and Android devices.]

Reduced reflection

"We see how such algal blooms spread along large coastal areas", first author Alia Khan from the University of Colorado in Boulder is quoted in a message from the US "Snow and Ice Data Center".

"These blooms can be so intense and dark that they warm the surface and increase melting." Climate change is likely to enlarge the affected area and extend the season for algal blooms.

The algae appear on the Antarctic Peninsula in the summer there, but have also been documented in the Arctic and in high mountain regions. In January 2018, Khan's team examined three coastal regions with algal blooms on Nelson Island and King George Island and near Palmer Station on Anvers Island. In these places, the excrement of seals, penguins and other birds provide nutrients that the snow algae depend on.

Compared to white snow, red algae reduced the reflection of the incident light by around 20 percent, the team reports. In the case of green algae, the albedo even fell by around 40 percent. The reason for this is the higher chlorophyll content of the green algae, the researchers write.

This increases the average amount of energy absorbed in summer, the so-called radiative forcing, per day and square meter for red algae by 13 watts and for green algae by 26 watts. This is comparable to the consequences of dust deposits on snow in mid-latitudes, for example in the Rocky Mountains. The team calculates that algal blooms on the Antarctic Peninsula lead to the additional melting of more than 3700 cubic meters of snow each year.

In any case, the Antarctic Peninsula, which stretches far north towards South America, has been warming particularly quickly for decades. On February 6, 2020, the record temperature of 18.4 degrees Celsius was measured at the Esperanza research station. (dpa)

Now new: We give you 4 weeks of Tagesspiegel Plus! To home page