Tag Archives: biodiversity

Snow algae speeds up Arctic melting: Tiny creatures with a big impact

by Dr Stefanie Lutz

The enthusiastic skiers or snow hikers among you may have already experienced the red snow phenomenon, which is caused by tiny microorganisms – the snow algae. Often termed ‘watermelon snow’ because of its colour and scent, I would not recommend eating it though. All the algae need to thrive is sunlight and liquid water. That’s why they form massive blooms in the warm months in spring and summer. But too much sun is not good for them either. They produce their own ‘sunscreen’ in the form of red pigments (the so called carotenoids), that gives them their red colouration.

Greenland_Mittivakat glacier_Red snow_copyright LGB
Red snow algae sampled colelcted from the Mittivakat glacier in Greenland. Image copyright: Liane G. Benning

Red snow looks very pretty, but why should we care about these tiny organisms? Well, even the smallest organisms can have a large impact. The red coloration darkens snow and glacial surfaces. This decreases their so called albedo. The albedo determines how much sunlight is reflected back from a surface. White snow reflects more sunlight, whereas the darker red snow reflects less. Therefore more heat is retained, which causes more melting. It is the same effect that makes people choose white clothing in places with high sun exposure such as deserts. Black clothing would make the sun even more unbearable.

I was really lucky to work on this topic during my PhD at the University of Leeds. Together with my supervisor Liane G. Benning, we collected 40 samples from various places in the Arctic, ranging from Greenland to Iceland, Svalbard and Northern Sweden. We found that these algal communities are very similar in all studied places and over one melt season they reduce the albedo by an additional 13%. Calculating how much this equates in additional melting is not easy and will be addressed in our ongoing work.

A colony of red snow algae under the microscope. Image copyright: Stefanie Lutz

Our findings have been published in Nature Communications. Since the paper was published I have been approached by a many worried journalists who aske me what we should do against these dreadful algae. Well, we cannot and should not do anything against them. Snow algae are actually very important members of the natural food chain. Like plants, they do photosynthesis, and in doing so they fix atmospheric CO2 and transform it into organic carbon that can be used by other organisms. However, there is one thing that is worrying – and that is global warming, which may cause a ‘runaway effect’. Snow algae need liquid water to bloom, with rising temperatures more melting will increase the extent of the snow algae, which will further darken the glacial surfaces, causing more melting, and so on. So the only thing we can and should do is to reduce human-induced climate change.

We’ve just come back from gathering samples from the Greenland Ice Sheet, where a record-breaking ice melting enderway. As part of a big international, UK led team, we will further investigate the extent of these algae and their contribution to melting. At the moment climate models don’t consider the effect of algae on snow and ice melt, it is time to change that!

Dr Stefanie Lutz is a postdoctoral research associate at the GFZ Helholtz centre in Potsdam, Germany.

Our impact on the Earth

Here’s an impressive and rather scary visual of our impact on the earth, via the World Economic Forum.

2015 predicted to be disastrous for corals

The unique biodiversity within coral reefs support the livelihoods of over a billion people, but 2015 is predicted to be disastrous for corals.

“So long, and thanks for all the fish” … the end of coral reefs?

Leading scientist says that even ambitious greenhouse gas reduction targets will not be able to save the world’s coral reefs.

Professor Peter Sale from the University of Windsor, Canada claims that coral reefs, as they were 50 years ago, cannot be saved from climate change – even if the climate change talks in December this year (COP21) are “wildly successful”.

Professor Sale unveiled the depressing results today at the Goldschmidt conference, a gathering of the world’s top geochemists in Prague.

He said, “Even if Paris is wildly successful, and a treaty is struck, ocean warming and ocean acidification are going to continue beyond the end of this century. This is now serious; I find it very unlikely that coral reefs, as I knew them in the mid-1960s, will still be found anywhere on this planet by mid-century. Instead, we will have algal-dominated, rubble-strewn, slowly eroding limestone benches.”

A bleached coral. These events will become more common with global warming.
A bleached coral. These events will become more common with global warming.

Globally coral reefs are generally found in tropical waters. Not only are they some of the world’s most productive ecosystems they also deliver ecosystem services in tourism, fisheries and coastline protection. The global economic value of coral reefs has been estimated to be US $375 billion per year!

Loss of reefs will be a fatal blow for the animals and communities who rely on them

While the global policy debate has been about trying to limit global warming to 2 degrees by the end of the century, Professor Sale claims that this won’t be enough to save coral reefs.

“I see little hope for reefs unless we embark on a more aggressive emissions reduction plan. Aiming for CO2 at 350ppm, or a total warming of around 1°C is scientifically defendable, and would give reefs a good chance; a number of coral reef scientists have called for this.”

Sale summarised:

“Knowing what we are doing, do we have the ethical right to eliminate an entire ecosystem from this planet? It’s never been done before. But watching as our actions lead to the loss of all coral reefs on the planet is like removing all rainforests. I don’t believe we have that right”.