Glacial Ice Tea

April 30, 2014

Dr. Marek Stibal, who was part of the Dark Snow Team last year, as well as today, talks about his line of research – the little discussed feedback effect of biological communities on the Greenland Ice Sheet.

Dr. Marek Stibal at

What do glacial surfaces and tea have in common? The obvious answer to a glaciologist… ‘a glaciologist – standing on the surface of a glacier, drinking tea’. While this is, of course, correct, here’s another that is more interesting and of high relevance to the Dark Snow Project; the surface’s colour. Or – more precisely – its pigmentation.

The Dark Snow Project is interested in all things dark on the surface of glaciers and ice sheets. Joe Cook summarizes the ways microbes can contribute to the darkening of glacial surfaces. I’ll focus on a specific process that may be the key biotic factor for albedo reduction of the Greenland ice sheet.

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There are three species of algae that grow on glacier surfaces worldwide – Cylindrocystis brébissoniiMesotaenium berggrenii, and Ancylonema nordenskiöldii. I’ll call them ‘ice algae’. Each belongs in a single group of green algae called Zygnematophyceae, also calledconjugating algae due to their inventive and esthetic way of having sex. It is still a mystery why only these few species reside on ice, and from only one group, but we begin to understand how: it’s to do with tea!

Imagine the environment of the surface of the Greenland ice sheet… It’s of course cold, around freezing all the time, and it can be very bright, further amplified by ice crystals reflecting the incoming light in all directions and multiple bounces between clouds and the surface increases the glare. If you’re an alga, then you too are cold and you’re dazzled much of the time. You get most of your food from the atmosphere as carbon dioxide, but you still need some other nutrients such as nitrogen and phosphorus, and there is not much of that around. And you may even need to protect yourself from large predators that stalk these vast white planes. Ok, not large for humans. Microscopical predators. But still scary.

It seems that ice algae have solved these problems in one fell swoop by producing a special pigment stored small vesicles (called vacuoles) inside the cells, and its colour has been described (see Yallop et al. 2012). Now, depending on the observers’ state of colour-blindness and/or gender, the pigment is seen as purple brown (Yallop et al. 2012), brownish (Remias et al. 2012), and dark brown (Uetake et al. 2010). I am going to call it ‘dark’. Until recently, the chemical nature of this dark pigment was unknown. But then Daniel Remias and his colleagues from Innsbruck University decided to look at one of the ice algae – M. berggreniifrom an Alpine glacier – more closely (Remias et al. 2012). They managed to resolve the structure of the main compound responsible for the dark colour and gave it a beautiful name:purpurogallin carboxylic acid-6-O-b-D-glucopyranoside.

What can purpurogallin carboxylic acid-6-O-b-D-glucopyranoside do? Well, it’s dark, so of course it absorbs sunlight, mostly in the ultraviolet and visible parts of the spectrum. In other words, it is a sunscreen, a protection against the harmful UV radiation and also excessive visible radiation which can inhibit photosynthesis in the cells. But that’s not all. The pigment may also represent a sink for surplus energy that cannot be invested in cells due to limitations in temperature or nutrient availability, and may even act as a chemical defense against grazers as, for example, phenolic compounds in marine kelp. So, given the nuisances you have to put up with as an alga living on the surface of an ice sheet, it seems like a very useful thing to have.

Absorption spectra of purpurogallin carboxylic acid-6-O-b-D-glucopyranoside (c) and its likely precursor (b) isolated from Mesotaenium berggrenii. From Remias et al. 2012

And strangely, purpurogallin carboxylic acid-6-O-b-D-glucopyranoside is a pigment that has only been detected in higher plants, such as fermented plant tissue… leaves, more specifically… fermented leaves of Camellia sinensis, even more specifically. Also known as black tea.

So here we are, glaciologists standing on the melting surface of the Greenland ice sheet, sipping tea that is black precisely for the same reason why the ice surface is getting dark – a simple pigment produced by a living organism.

We promise we won’t spill much of the tea.



Uetake J, Naganuma T, Hebsgaard MB, Kanda H, Kohshima S (2010) Communities of algae and cyanobacteria on glaciers in west Greenland. Polar Science 4: 71–80

Remias D, Schwaiger S, Aigner S, Leya T, Stuppner H, Lütz C (2012) Characterization of an UV- and VIS-absorbing, purpurogallin-derived secondary pigment new to algae and highly abundant in Mesotaenium berggrenii (Zygnematophyceae, Chlorophyta), an extremophyte living on glaciers. FEMS Microbiology Ecology 79: 638–648

Yallop ML, Anesio AM, Perkins RG, Cook J, Telling J, Fagan D, MacFarlane J, Stibal M, Barker G, Bellas C, Hodson A, Tranter M, Wadham J, Roberts N (2012) Photophysiology and albedo-changing potential of the ice algae community on the surface of Greenland Ice Sheet. ISME Journal 6: 2302–2313



15 Responses to “Glacial Ice Tea”

  1. dumboldguy Says:

    Who says scientists don’t have fun? This piece will bring a smile to the face of anyone who ever struggled with compound names in organic chemistry or enjoyed the rather poetic names given to organisms.

    purpurogallin carboxylic acid-6-O-b-D-glucopyranoside?

    Cylindrocystis brébissonii, Mesotaenium berggrenii, and Ancylonema nordenskiöldii.?

    And some sex thrown in also with the conjugation link? I wonder if there’s any “algae porn” avaiable on the web?

    Excellent stuff—-lively writing, and another reminder of how complicated this world is that we are so intent on destroying in our arrogance and ignorance.

  2. Well, THAT’s cool! I want to do this kind of stuff!! Do they have room for a lurker?

    Although I’m not sure about the poetic nature of organic compound nomenclature. Bacteria naming? Yes. 6-O-b-D? Nope, not poetic at all….

    • dumboldguy Says:

      You have to run it together and “sing it” to see the “poetics”.

      Not “six”—“O”—“B”—“D”, but “sixohbeedee”.

      (and that always reminds me of other “poetics” like “garnetiferous mica schist”, which is pretty to look at as well as say).

  3. rayduray Says:

    Dark Snow and the Colorado River Basin

    Dark snow is implicated in causing snow to melt three weeks earlier than a century ago in the Rocky Mountains above the Colorado River headwaters. The darkening matter is a combination of Colorado Plateau dust and soot. Both are largely man-made problems. The first, the dust, arises from plowed ground, gravel roads and ATV trails as well as the occasional pedestrian breaking the fragile crust over much of the plateau. The soot comes from across the West. The locals blame the Chinese and the Gobi Desert. They’re living in a state of denial.

    The early snow melt means more evapo-transpiration of the water in the snow pack. Some calculating scientists estimate that as much as a million acre feet of water that used to drain into the reservoirs no longer even gets into the river. This is sort of a positive feedback to the drought.

  4. redskylite Says:

    Given access (thanks to University of Chicago) to the data from 7000+ global temperature monitoring stations, I compared the decadal trend 1980 – 2010 of warming of Greenland with New Zealand. Some interesting results:-

    Region Latitude # Stations Trend °C /Decade
    Antarctic 60.2S – 75.5S 16 .17°C
    New Zealand 35.1 S- 46.9S 7 .16°C
    S Aus&America 35.1 S- 46.9S 29 .16°C
    Tropics South 10S – 20S 76 .16°C
    Equator 10N – 10S 144 .23°C
    Tropics North 10N – 20N 168 .21°C
    mid-lats north 1 20N – 30N 100 .30°C
    mid-lats north 2 30N – 40N 174 .30°C
    Mid -latitudes Nrth 40N – 50N 103 .32°C
    High mid- lats North 50N – 60N 208 .39°C
    Arctic Circle 60N – 70N 111 .42°C
    Greenland 60.1 N – 68.7N 4 .86°C

    Only 4 stations in Greenland but remarkable differences in trend:

    Greenland Temperature Trend, °C / Decade Averages
    Time Range: – 1980 – 2010

    Egedesminde (68.7N) 1.01°C
    Godthab Nuuk (64.2N) 0.98°C
    Angmagssalik (65.6N) 0.79°C
    Prins Christi (60.1N) 0.66°C

    Greenland is the place to watch for sure:

    The results suggest that the decadal warming upward trend is much stronger in the Northern Hemisphere (between 2x and 5x higher) and trends increase at higher northern latitudes, it is markedly noticeable in the Arctic, especially around Greenland. The trend is significantly smaller in the Southern Hemisphere, which could explain the general unconcern in local opinion polls and lack of media attention.

  5. […] a recent Dark Snow posting, Dr. Stibal noted that organisms on the ice produce dark pigments to shield themselves from intense […]

  6. […] may be darkening the ice sheet. More on this in upcoming videos, but if you have not yet read Dr. Stibal’s post here, do so […]

  7. […] point man this year is on our Biologist, Dr. Marek Stibal, who was up here in june to set up several experimental patches on the ice, that will be enriched […]

  8. I am trying to find out the forcing factor of CH4 over C02 in time frames that matter, specifically the life time of the methane.
    This is the question my friend Kevin posed to someone the other day, his explanation is way better than I could manage.
    As you might understand from the question, this is quite a relevant topic to bring up, what with near term human extinction being the result.
    Thanks for your time
    Sincerely Robert

    Dear XXX
    I am not involved in research now but do have an Honors Degree in Chemistry from a UK university, and specialized in spectroscopy.

    For more than a year I have been very troubled by the way the relative warming effect of methane compared to carbon dioxide is calculated, the UNIPCC initially assigning a value of 23 times CO2 over 100 years and 72 times CO2 over 20 years, which were subsequently increased to 34 times CO2 over 100 years and 86 times CO2 over 20 years.

    I have searched, with no success, for the instantaneous absorption-re radiation value of CH4 versus CO2, and many months ago telephoned (and emailed) Paul Beckwith at the University of Ottawa to discuss the matter; at the time he said he thought it was about 250, but has not confirmed this figure. The decay curves I have seen suggest an instantaneous value for methane of the order of 300 times that of carbon dioxide, and I have seen an unreferenced article by Malcolm Light suggesting a value between 1,000 and 300 times CO2 for times scales that matter.

    It seems to me there is something very suspect in the manner in which the IPCC calculates the effect of methane in the atmosphere, in that it treats methane as though it decays to carbon dioxide (which we know it does) and assigns and average value over time for the decay. Yet the concentration of methane in the atmosphere does not decline because every molecule of methane that gets oxidized by the OH ion or OH radical mechanism is replaced by another. Indeed, the rate of release of methane molecules into the atmosphere clearly far exceeds the rate of oxidation, so the concentration and actual mass of atmospheric methane both increase, as you are well aware, and have been highlighting.

    The inability (unwillingness?) of scientists in the Anglo-American sphere to resolve the methane question led me to comment recently that ‘it will probably be the Russians who find the answer to the methane question (I am writing from New Zealand, by the way).

    Clearly you will not be able to answer my question immediately, but I would appreciate it if you could give the matter some thought and discuss it with anyone who knows the answer or is in a position to do the research necessary to discover the answer.

    Kind regards


  9. […] immediately ran into microbiologist Marek Stibal, who is already here camping not far away, taking sediment samples to flesh out the picture of […]

  10. […] immediately ran into microbiologist Marek Stibal, who is already here camping not far away, taking sediment samples to flesh out the picture of […]

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