"Watermelon Snow" Is Causing Arctic Glaciers To Melt Even Faster


Robin Andrews

Science & Policy Writer

Watermelon snow, in all its pinky-red glory. Liane G. Benning/GFZ

The Arctic really has everything going against it. If we burn all our fossil fuel reserves it will warm by up to 20°C (36°F) – twice the rate the rest of the planet is warming, on average. Ocean currents are preferentially taking the warmest water directly towards it, and a process known as Arctic Amplification is causing sea ice, snow and ice caps to melt there at truly unprecedented rates, and earlier than ever before.

A new study in Nature Communications, sadly, has yet more bad news for the northern reaches of our planet. All across the world, there are certain species of algae that thrive in snow, from the icy realms of Greenland and the Antarctic to the tops of the European and Japanese Alps. These green algae actually take on a red hue, as does the snow they're residing in. This may look quite beautiful, but it actually dramatically reduces the reflectivity – or “albedo” – of the snow or ice.


The lower the albedo of the snow, the more heat they’ll absorb, and the faster the snow will melt. So in effect, the presence of this algae is causing a so-called “bio-albedo feedback” that is accelerating the disintegration of ice cover around the world. As this study’s huge analysis of 21 glaciers in the European Arctic points out, this “watermelon snow effect” is getting increasingly more potent as time goes by.content-1466679793-snow-algae.jpg

These algae lay dormant in the winter, and wait for the ice to begin thawing and the environment to begin warming before they blossom and replicate and grow into their surroundings. Unfortunately, record early glacier melts are almost certainly causing them to blossom earlier, which means that they are reducing the albedo of the snow and ice earlier than ever before.

It’s a remarkably effective feedback cycle – the red algae can reduce the surrounding snow’s albedo by up to 13 percent. These algae are not restricted to certain small regions of the snow cover either; even the most conservative estimates suggest that 50 percent of the snow surface of glaciers in this region contain red algae by the time melting has wound down.

“Our results point out that the “bio-albedo” effect is important and has to be considered in future climate models,” lead author Stefanie Lutz, postdoc at the German Research Centre for Geosciences GFZ and at the University of Leeds, said in a statement.


The study’s authors stop short of saying quite how much of the melting is directly down to the algae’s presence, but it’s clear that they are a clear and present threat to the Arctic. Between them and the horrific extent of climatic warming brought on by man-made climate change, it seems that the Arctic has never been in such a bad place as it is today.

Image in text: Snow algae under the microscope. Stefanie Lutz/GFZ


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  • watermelon snow