Ice sheets impact core elements of the Earth’s carbon cycle

University of Bristol

IMAGE: Leverett Glacier - SW Greenland Ice Sheet - vast volumes of meltwater and associated carbon and nutrient are exported from ice sheets every year during melt. Credit: Dr Stefan Hofer

IMAGE: Leverett Glacier – SW Greenland Ice Sheet – vast volumes of meltwater and associated carbon and nutrient are exported from ice sheets every year during melt. Credit: Dr Stefan Hofer

The Earth’s carbon cycle is crucial in controlling the greenhouse gas content of our atmosphere, and ultimately our climate.

Ice sheets which cover about 10 percent of our Earth’s land surface at present, were thought 20 years ago to be frozen wastelands, devoid of life and with supressed chemical weathering – irrelevant parts of the carbon cycle.

Now a world-leading international team, led by Professor Jemma Wadham from the University of Bristol’ School of Geographical Sciences and Cabot Institute for the Environment, have pulled together a wealth of evidence published over the last 20 years to demonstrate that ice sheets can no longer be regarded as frozen and passive parts of Earth’s carbon cycle.

Their findings are published today in the journal Nature Communications.

Professor Wadham said; “A unique set of conditions present beneath ice sheets make them important reactors in the Earth’s carbon cycle.

“Here, grinding of rock by moving ice is high, liquid water is abundant and microbes thrive in melt zones despite inhospitable conditions – the ice sheets erode their bedrock, cold-adapted microbes process the ground rock and boost nutrient release and glacial meltwaters export this nutrient to the oceans, also stimulating the upwelling of further nutrient from depth at glacier marine margins.

“All this nutrient supports fisheries and stimulates drawdown of carbon dioxide (CO2) from the atmosphere.”

Co-author Professor Rob Spencer from Florida State University added: “Ice sheets are also very effective at storing vast amounts of carbon as they grow over marine sediments, soils and vegetation.

“The Antarctic Ice Sheet alone potentially stores up to 20,000 billion tonnes of organic carbon – ten times more than that estimated for Northern Hemisphere permafrost.

“Some of this carbon is released in meltwaters and fuels marine food webs. The carbon that is left behind in deep parts of ice sheets is converted to methane gas by microbial and/or geothermal activity, which has the potential to be stored as solid methane hydrate under low temperatures and high pressure conditions.

“We have no idea how stable potential methane hydrate will be in a warming climate if ice sheets thin. There is evidence from past phases of ice sheet wastage in Europe that sub-ice sheet methane hydrate has existed and can be released rapidly if ice thins.”

The study also takes a walk back in time to the last transition from glacial (cold) to interglacial (warm) conditions of the present day, analysing ocean cores around Antarctica for clues which might link ice sheet nutrient (iron) export via Antarctic icebergs to the changing productivity of the Southern Ocean – an important global sink for carbon.

Co-author, Dr Jon Hawkings from Florida State University/GFZ-Potsdam, said: “One important way that the Southern Ocean takes carbon out of the atmosphere is by growth of phytoplankton in its surface waters.

“However, these tiny ocean dwelling plants are limited by availability of iron. We have long thought that atmospheric dust was important as a supplier of iron to these waters, but we now know that icebergs host iron-rich sediments which also fertilise the ocean waters as the bergs melt.”

Professor Karen Kohfeld, a palaeo-oceanographer and co-author from Simon Fraser University, added: “What you see in ocean cores from the sub-Antarctic is that as the climate warmed at the end of the last glacial period, iceberg sediment (and therefore, iron) supply to the sub-Antarctic Southern Ocean falls, as does marine productivity while CO2 rises.

“While there are many possible causes for the CO2 rise, the data tantalizingly suggests that falling iron supply to the Southern Ocean via icebergs could have been a contributing factor.”

What is important about this study is that is brings together the work of hundreds of scientists from all over the world published over three decades to show, via a landmark paper, that we can no longer ignore ice sheets in models of the carbon cycle and under scenarios of climate change.

Professor Wadham added: “Ice sheets are highly sensitive parts of our planet – we change temperatures in the air and ocean waters around them and thinning and retreat are inevitable.

“The evidence we present here suggests that ice sheets may have important feedbacks to the carbon cycle which require further study as the uncertainty is still huge.

“Gaining access to some of the most inaccessible and challenging parts of ice sheet beds, for example via deep drilling, alongside building numerical models which can represent biogeochemical processes in ice sheets will be key to future progress in this field.”

###

This research is a collaborative venture between the University of Bristol (UK), University of Leeds (UK), Florida State University and University of California, Riverside (USA), German Research Centre for Geosciences at Potsdam (GFZ) and Geomar, Kiel (Germany), Memorial University and Simon Fraser University (Canada).

From EurekAlert!

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56 thoughts on “Ice sheets impact core elements of the Earth’s carbon cycle

  1. Structures covering 10% of the Earth actually play a part in global chemical cycles. Wow! Who’d have thunk it?
    “as the climate warmed at the end of the last glacial period, iceberg sediment (and therefore, iron) supply to the sub-Antarctic Southern Ocean falls”. How does that work? More melting on a vast scale creates less sediment run-off to the oceans? Hmmm

    • I too found that relationship between iron and glacial melt to be incongruous without further explanation, and contradicted by the test of the article itself..

      “However, these tiny ocean dwelling plants are limited by availability of iron. We have long thought that atmospheric dust was important as a supplier of iron to these waters, but we now know that icebergs host iron-rich sediments which also fertilise the ocean waters as the bergs melt.”
      …and:
      “What you see in ocean cores from the sub-Antarctic is that as the climate warmed at the end of the last glacial period, iceberg sediment (and therefore, iron) supply to the sub-Antarctic Southern Ocean falls, as does marine productivity while CO2 rises.”

      So does the melt water increase of decrease iron content? Are the authors assuming that melting ice sheets creates less ice bergs as they get smaller?
      Maybe the sediment layers contain less iron from the ice berg melt because it is being taken up in the food chain? …scrambling for some logical explanation of the incongruity

    • EurekAlert!</
      Noun, an often elaborate, occasionally logically-consistent but always mythical story, or “narrative”, based on a false premise.

      The Earth’s carbon cycle is crucial in controlling the greenhouse gas content of our atmosphere, and ultimately our climate.

  2. Speaking of the carbon cycle, I have been pouring over the leading mainstream paper on this issue, Le Quere et al 2018 on the Global Carbon Budget.
    This paper appears annually and seems to be a major underpinning of the U.N. IPCC Reports.
    My reading is that overall the 78 co-authors have an aggregate 32% uncertainty/68% certainty rating on the various contributors of CO2 and greenhouse gases to and from the atmosphere.
    And the ocean with its enormous contribution factor is well assessed ?
    Any comments on this.

      • Hans Erren,

        You make a false assumption when you write,
        “50% of fossil combusted co2 leaves the atmosphere,”

        NO! In reality, the annual rise of atmospheric CO2 concentration is approximately equal to half the anthropogenic emission of CO2.

        And you attempt to justify your false assumption by providing an unjustifiable assertion; viz.
        “there is simply no budget for additional net sources.”

        NO! In reality, there is insufficient data on sources and sinks for an audit capable of providing an accurate “budget”. Indeed, this thread is about a claimed discovery of yet another unquantified CO2 source.

        Richard

  3. The second to last paragraph reads, ““The evidence we present here suggests that ice sheets may have important feedbacks to the carbon cycle which require further study as the uncertainty is still huge.”

    Yup, in other words, they want to go on taxpayer handouts for the rest of their working lives.

    Regards,
    Bob

    • And there is:
      Gaining access to some of the most inaccessible and challenging parts of ice sheet beds, for example via deep drilling, alongside building numerical models which can represent biogeochemical processes in ice sheets will be key to future progress in this field.”

      The only beneficiary of this ‘future progress’ will be the gravy train.

    • High on my list of reading that should be compulsory for policy makers and concerned citizens is Why Greatness Cannot be Planned. In it, the authors show why it is that scientific breakthroughs can’t be produced on demand. In fact, trying to manage the process more or less guarantees that it won’t happen.

      A good example of the above is battery science. We have had wonderful incremental increases in battery capacity but not the kind of breakthrough that would make renewable energy viable.

      We also have a tiger by the tail. The reason Malthus was wrong is that we find ways to use resources more efficiently or to substitute different resources when necessary. That means we have to keep innovating. If that process stops, Malthus will probably become right.

      Based on the above, we have to keep subsidizing curiosity based research. If it looks like welfare for a bunch of curious geeks, so be it. We also have to put up with the fact that the vast majority of scientists never produce worthwhile breakthroughs. That doesn’t actually matter because the profit society gets from the real breakthroughs is so immense that it dwarfs the cost of subsidizing all the scientists who won’t succeed in producing a breakthrough.

      So, yes, scientists are looking for life long handouts. In the big picture, that’s just fine.

      • Good comment that makes me reflect on research in higher education.

        Today, university science departments or organizations under which they fall are loaded with “communications” specialists whose jobs basically involve marketing and promotion. One can’t produce research results on demand as you say, but English majors can spin and craft stories in all kinds of imaginative ways.

        • “One can’t produce research results on demand”

          If you’ve had much involvement with academic publishing, you might not say that. Combining research designs and statistical analyses which are both substandard, plus the huge selection of available publishing outlets, means that people who simply not very competent can produce a lot of papers on demand.

          Our department started paying faculty “bonuses” for publications in outlets that were at least not completely ridiculous. Guess what, the publishing output increased, which had the desired impact on the next accreditation cycle.

          • Actual scientific breakthroughs can’t be produced on demand. Research results, on the other hand, can. No matter how crazy your opinion, you can always find an expert to support it, for a small fee or research grant. It reminds me of a joke.

            An engineer, a physicist, and a lawyer were being interviewed for a position as chief executive officer of a large corporation.

            The engineer was interviewed first, and was asked a long list of questions, ending with “How much is two plus two?” The engineer excused himself, and made a series of measurements and calculations before returning to the board room and announcing, “Four.”

            The physicist was next interviewed, and was asked the same questions. Before answering the last question, he excused himself, made for the library, and did a great deal of research. After a consultation with the United States Bureau of Standards and many calculations, he also announced “Four.”

            The lawyer was interviewed last, and was asked the same questions. At the end of his interview, before answering the last question, he drew all the shades in the room, looked outside the door to see if anyone was there, checked the telephone for listening devices, and asked “How much do you want it to be?” link

        • Indeed!
          Reading the above Press Release I was struck repeatedly by the bombastic claims, pompous alleged findings and absurdities.

          e.g.

          “Ice sheets which cover about 10 percent of our Earth’s land surface at present, were thought 20 years ago to be frozen wastelands, devoid of life and with supressed{sic} chemical weathering – irrelevant parts of the carbon cycle.”

          Over ten years ago, scientists discussed “Blood Falls” caused by microbes using iron and sulfates for their energy. Large meltwater lakes were discovered under the glaciers giving credence that life lives and survives extreme conditions.

          Before that, algae, microbes and other life were discovered to live within the ice.

          e.g. 2:

          ““Here, grinding of rock by moving ice is high, liquid water is abundant and microbes thrive in melt zones despite inhospitable conditions – the ice sheets erode their bedrock, cold-adapted microbes process the ground rock and boost nutrient release and glacial meltwaters export this nutrient to the oceans, also stimulating the upwelling of further nutrient from depth at glacier marine margins.”

          Of a certainty, those conditions are not inhospitable to the life forms living there! Why call it inhospitable when talking about the ice and the life growing there?

          I began to wonder, is Jemma Wadhams related to Peter Wadhams; who is well known for extreme language and outrageous claims when discussing the Arctic?

      • A geographer from Bristol isn’t going to have any breakrhroughs and the rest of the climate weevils have perfected the static state of NOT looking for breakthroughs and are simply 100% pure cost.

        A commenter on a thread the other day linked to Arhenius’s 1896 paper on CO2 and warming, and the formulae in it and the magnitude estimated by a doubling have simply been lifted out of that paper by the climate weevils and repeated ad nausseam to the tune of hundreds of billions with politicians spending trillions more to mitigate nothing. The immense pay-off of a number of breakthroughs has already been squandered.

        Arhenius was enough of a real scientist to opine the most likely outcome of a considerable benefit to follow from added CO2 instead of the the less likely one of net harm to serve left political purposes and personal enrichment.

      • By quoting Malthus you raise a very significant point: never cry “Crisis” for a forecast event in 2100 based on present day technological and scientific knowledge and capability to manage such a crisis, even if such a crisis will occur! Better still, never throw £billions of tax payers money today for any such crisis that could occur in 2100!
        Malthus was wrong when he predicted that, because labour was leaving the land for the new industrial cities for a better life and that the UK’ population was rising, we would soon be unable to feed ourselves. He failed to consider the massive increase in agricultural productivity created by the Industrial/Agricultural Revolution which, through free market driven pressures, created innovative labour saving machines such as horse drawn harvesters. No longer were whole villages needed to bring in the harvest!

        • “By quoting Malthus you raise a very significant point: never cry “Crisis” for a forecast event in 2100 based on present day technological and scientific knowledge and capability to manage such a crisis, even if such a crisis will occur! Better still, never throw £billions of tax payers money today for any such crisis that could occur in 2100!”

          The billions of tax payer’s money won’t be thrown in 2100, instead it will be thrown today. If one is on the receiving end of these thrown billions of today then he will benefit today. If he is proven wrong then it’s no big deal (at least for him) because the year 2100 is eighty years away from today.

      • commieBob, in response to:

        “So, yes, scientists are looking for life long handouts. In the big picture, that’s just fine.”

        In defense of “scientists,” most are trying to make a living and support families. The work projects come from above and in many cases, are based on what governments want to fund. Blaming the scientists is analogues to blaming the bank workers for offering credit cards that transfer wealth from the poor to the rich or blaming the auto salesman, bartender, etc. when their product can be fatal.

        I was a government contractor scientist/engineer in my early career and thought I was doing important work with nuclear waste research – only to realize much later in life that a portion of that work went unused and in some cases was counter productive.

        • “The work projects come from above and in many cases, are based on what governments want to fund.”

          Here’s a good example of what you are talking about …

          https://en.wikipedia.org/wiki/NASA#/media/File:NASA-Budget-Federal.svg

          The funding for NASA boomed from its inception in 1958 (thanks to the Sputnik launch by the Soviet Union) and then funding peaked in 1966, from there on funding went downhill.

          Many (most?) students who were sucked in to going into Aerospace in the early part of the Sixties were shaken out of Aerospace in later part of the Seventies.

          • I was one of the lucky ones – planned to go into aerospace engineering and took a one-year sidetrack into Chem E because of a scholarship – which led to a career in Ch E/environmental consulting.

  4. Correction: The Earth’s water cycle is crucial in controlling the content of our atmosphere, and ultimately our climate.

    • Phillip Bratby:
      TOTALLY agree. The steam engineers know this; but are ignored by the scientists obsessed with CO2, radiation and statistics.
      The water cycle provides the basic global thermostat through the mechanism of the Rankine Cycle in the atmosphere, where energy is driven upwards for dissipation to space oblivious of CO2. It has a strong net NEGATIVE feedback to the Greenhouse Effect.

    • You beat me to it.

      We are still talking about the assumption that CO2 is a significant driver of climate, but climate science, without any confirmation of this assumption, has simply declared it as a given truth. Perhaps this is what Joe Biden meant when he said: “We choose truth over facts!”

  5. Ice sheets are melting, more real estate becomes available for all kind of uses.
    President Trump was a real estate mogul long before entering politics, but his latest target may be unusual and ambitious but if the GW proceeds according to the IPCC projections it may prove to be a profitable one.
    Is Donald Trump considering buying Greenland ?
    If he does, Dr. Svalgaard would be ideal for position of a governor, Dr. S speaks lingo and has spent some time living there.
    https://edition.cnn.com/2019/08/15/politics/trump-buy-greenland-wall-street-journal/index.html

  6. Some of this research is legitimate but the reasons given for it are bogus, as is the climate spin given to it. What a shame. Professor Wadham (no relation to Peter Wadhams) seems in most respects to be a good scientist.

    • “Some of this research is legitimate but reasons given for it are bogus.”

      One uses what works. If the reason results in funding then one prospers. If the reason does not result in funding then one starves.

      If the funding pool was infinite in size then the reasons wouldn’t matter. But the funding pool is not infinite in size thus the reasons do matter.

      Again, one uses what works.

  7. “We have no idea how stable potential methane hydrate will be in a warming climate if ice sheets thin.”

    Translation: We need more funding (aka money) in order to find out.

    “The evidence we present here suggests that ice sheets may have important feedbacks to the carbon cycle which require further study as the uncertainty is still huge.”

    Note: “furthur study” = funding.

    • “alongside building numerical models which can represent biogeochemical processes in ice sheets will be key to future progress in this field.”

      Based on the fiascos of chloroflurocarbons and CO2, undoubtedly the UN will commiserate with climate scientists in the future, on some other man made chemical that the models will demonstrate; will cause the “destruction” of humanity.

  8. ““While there are many possible causes for the CO2 rise, the data tantalizingly suggests that falling iron supply to the Southern Ocean via icebergs could have been a contributing factor.”

    Clearly, the retreat from ‘ it’s AGW wot dun it!” is slowly, even glacially, happening.

    • “. . . suggests that falling iron supply to the Southern Ocean via icebergs could have been a contributing factor.”

      As opposed to glacial ice melt runoff from land or at the ice/sea interface that would distribute much more iron (compounds) via ocean water circulation currents?

  9. “as the climate warmed at the end of the last glacial period, iceberg sediment (and therefore, iron) supply to the sub-Antarctic Southern Ocean falls” … “falling iron supply to the Southern Ocean via icebergs could have been a contributing factor” … “Ice sheets are highly sensitive parts of our planet – we change temperatures in the air and ocean waters around them and thinning and retreat are inevitable”.

    As I read it (have I understood it correctly?) they are saying that more sea ice => more iron which is good, but the sea ice around Antarctica will inevitably thin and retreat so that is bad. There is one massive problem with this argument.m: The sea ice around Antarctica has been growing, not shrinking. That’s presumably because the Southern Ocean has been cooling, not following the climate alarmists’ script. https://wattsupwiththat.com/2019/04/10/the-curious-case-of-the-southern-ocean-and-the-peer-reviewed-journal/ Shouldn’t they have mentioned that????

  10. So there you have it.. a fleet of ships running the Southern Oceans spreading iron into the water and CAGW is history.

  11. “Some of this carbon is released in meltwaters and fuels marine food webs”

    Acknowledging that Carbon is a necessary component of Life’s food chain. More specifically, CO2 is a necessary component of Life’s food chain.

    But, if we are to accept EPA’s proclamation that [ Carbon = Pollution ], then it must follow that:

    Pollution is a necessary component of Life’s Food Chain.

    If the definition of ‘pollution’ is to be harmful to Life, then how can that be anything other than a contradiction? Of course, once a contradiction has been introduced into a syllogism, any conclusion can be derived

  12. “However, these tiny ocean dwelling plants are limited by availability of iron. We have long thought that atmospheric dust was important as a supplier of iron to these waters, but we now know that icebergs host iron-rich sediments which also fertilize the ocean waters as the bergs melt.”

    Note the importance of iron again. I suppose you all might have suspected I’d chime in here about this, but we can completely control the rise in atmospheric CO2, restore the oceans, and feed hundreds of millions of people by adding just a little bit of iron. RussGeorge.net

  13. Wikipedia:
    “In 2012, Wadham’s team at the University of Bristol used computer models to predict the amount of trapped methane under ice sheets and discovered 400 billion metric tons of carbon beneath.”

    Ah, yes, computer models do whatever you tell them to do, regretfully my family seldom does.

  14. “Earth’s carbon cycle is crucial in controlling the greenhouse gas content of our atmosphere”
    More Green propaganda job creation trolling. Without seeing the “EurekAlert!” in the heading I could tell where t was from.

  15. If that’s the case, I’m going to use a computer model to find a few tons of gold under my property. It has to be there. The computer model discovered it.

  16. “Ice sheets are also very effective at storing vast amounts of carbon as they grow over marine sediments, soils and vegetation”

    If this is true they must also be remarkably good at getting rid of it unnoticeably, for if you study the areas that were ice-covered during the last glaciation, they are almost completely devoid of any organic materials older than the current interglacial. Yes, there must have been lots of organic sediments there at the end of the previous interglacial, but almost none of them have survived, so ice-sheets are actually very good at destroying vast amount of organic carbon.

    ““However, these tiny ocean dwelling plants are limited by availability of iron. We have long thought that atmospheric dust was important as a supplier of iron to these waters, but we now know that icebergs host iron-rich sediments which also fertilise the ocean waters as the bergs melt.”

    The trouble with this mechanism is that it works the wrong way. It should cause CO2 to rise during early glacial periods, when ice accumulation is larger than calving and to decrease during intervals when calving is greater than accumulation. It is actually the other way around.

  17. “We have no idea how stable potential methane hydrate will be in a warming climate if ice sheets thin. There is evidence from past phases of ice sheet wastage in Europe that sub-ice sheet methane hydrate has existed and can be released rapidly if ice thins.”

    The evidence shows that it was not large enough to be considered a problem today. Convenient how ignorance comes upon them only at convenient times.

    But, as the philosopher Skeletor once said, “I could write a book about what you don’t know”

    • “We have no idea how stable potential methane hydrate will be in a warming climate if ice sheets thin. ”

      So in in order to find out we will need to be allocated a huge amount of money for research.

  18. If the ice sheets on Antarctica are grinding over rocks which contain organic deposits, this would mean that sometime in the distant past Antarctica had a warmer climate which could support plant growth, which was NOT due to human emissions of CO2 from fossil fuels. This would mean that there was a warming climate that was due to natural, not human, causes.

    Also, if iron is transported into the ocean by icebergs, a warming climate would cause increased calving of ice at the edge of the ice sheet. If the edge of the ice sheet was over the ocean, the calved ice would float off as icebergs. The flow of iron would only decrease if the ice sheet retreated so that its edge was over land, and calved ice would melt over land.

  19. ”Professor Karen Kohfeld, a palaeo-oceanographer and co-author from Simon Fraser University, added:

    “What you see in ocean cores from the sub-Antarctic is that as the climate warmed at the end of the last glacial period, iceberg sediment (and therefore, iron) supply to the sub-Antarctic Southern Ocean falls, as does marine productivity while CO2 rises.

    “While there are many possible causes for the CO2 rise, the data tantalizingly suggests that falling iron supply to the Southern Ocean via icebergs could have been a contributing factor.”
    __________________________________________________________

    We DO know why “climate warmed at the end of the last glacial period, [ … ] CO2 rises.”: Because CO2 gets outgassed from warming ocean waters.

    And we DO know why “climate warmed at the end of the last glacial period, iceberg sediment (and therefore, iron) supply to the sub-Antarctic Southern Ocean falls,

    as does marine productivity while CO2 rises.”

    – Because the warm-blooded population rises due to the more benign environmental conditions, these warm-blooded creatures multiply rapidly – and claim available iron sediments to formation of red blood cells for oxygen transport in their bodies.

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