Soil microbe GHG feedback ‘less dire than previously thought’

This is a visual representation of the model output. Credit: Christina Kaiser: IIASA/University of Vienna

From the International Institute for Applied Systems Analysis

The tiniest greenhouse gas emitters

Climate feedbacks from decomposition by soil microbes are one of the biggest uncertainties facing climate modelers. A new study from the International Institute for Applied Systems Analysis (IIASA) and the University of Vienna shows that these feedbacks may be less dire than previously thought.

The dynamics among soil microbes allow them to work more efficiently and flexibly as they break down organic matter – spewing less carbon dioxide into the atmosphere than previously thought, according to a new study published in the journal Ecology Letters.

 

“Previous climate models had simply looked at soil microbes as a black box,” says Christina Kaiser, lead author of the study who conducted the work as a post-doctoral researcher at IIASA. Kaiser, now an assistant professor at the University of Vienna, developed an innovative model that helps bring these microbial processes to light.

Microbes and the climate

“Soil microbes are responsible for one of the largest carbon dioxide emissions on the planet, about six times higher than from fossil fuel burning,” says IIASA researcher Oskar Franklin, one of the study co-authors. These microbes release greenhouse gases such as carbon dioxide and methane into the atmosphere as they decompose organic matter. At the same time, the Earth’s trees and other plants remove about the same amount of carbon dioxide from the atmosphere through photosynthesis.

As long as these two fluxes remain balanced, everything is fine.

But as the temperature warms, soil conditions change and decomposition may change. And previous models of soil decomposition suggest that nutrient imbalances such as nitrogen deficiency would lead to increased carbon emissions. “This is such a big flux that even small changes could have a large effect,” says Kaiser. “The potential feedback effects are considerably high and difficult to predict.”

Diversity does the trick

How exactly microorganisms in the soil and litter react to changing conditions, however, remains unclear. One reason is that soil microbes live in diverse, complex communities, where they interact with each other and rely on one another for breaking down organic matter.

“One microbe species by itself might not be able to break down a complex substrate like a dead leaf,” says Kaiser. “How this system reacts to changes in the environment doesn’t depend just on the individual microbes, but rather on the changes to the numbers and interactions of microbe species within the soil community.”

To understand these community processes, Kaiser and colleagues developed a computer model that can simulate complex soil dynamics. The model simulates the interactions between 10,000 individual microbes within a 1mm by 1mm square. It shows how nutrients, which influence microbial metabolism, affect these interactions, and change the soil community and thereby the decomposition process.

Previous models had viewed soil decomposition as a single process, and assumed that nutrient imbalances would lead to less efficient decomposition and hence greater greenhouse gas emissions. But the new study shows that, in fact, microbial communities reorganize themselves and continue operating efficiently – emitting far less carbon dioxide than previously predicted.

“Our analyses highlight how the systems thinking for which IIASA is renowned advances insights into key ecosystem services,” says study co-author and IIASA ecologist Ulf Dieckmann.

“This model is a huge step forward in our understanding of microbial decomposition, and provides us with a much clearer picture of the soil system,” says University of Vienna ecologist Andreas Richter, another study co-author.

###

Reference

Kaiser C, Franklin O, Dieckmann U, and Richter A. 2014. Microbial community dynamics alleviate stoichiometric constraints during litter decay. Ecology Letters. http://onlinelibrary.wiley.com/doi/10.1111/ele.12269/abstract

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30 thoughts on “Soil microbe GHG feedback ‘less dire than previously thought’

  1. ……… previous models….. assumed ….. .
    Says it all, really.
    But maybe it is encouraging that they have realized that they don’t know everything, or not yet anyway.

  2. So microbes alone produce 6X the CO2 from fossil fuels? Very nice factoid for whipping out in the next debate.

  3. Thanks for the bit of good news, Anthony. I hope it pans out. However, it is important to avoid reinforcing a common misconception here.

    “So microbes alone produce 6X the CO2 from fossil fuels? Very nice factoid for whipping out in the next debate.” is a version of the old “humans produce only 3% of all CO2 emissions” red herring. The important point to understand is that the CO2 produced from fossil fuels is new carbon as far as the biosphere is concerned, while atmosphere/ocean/land/biota exchanges are exchanges within what is effectively a closed system.

    (There are very slow leaks, of course – that’s how the fossil fuels get formed in the first place – but they are comparably very small.)

    Studies like this are still important, because it is important if the balance changes. For example, deforestation does not introduce new carbon, but increases the proportion of the already available carbon that is in the air and ocean.

    But the three per cent transfer from mineral deposits to active near-surface processes is not directly comparable to the fluxes within the active processes. It’s analogous to the difference between economic exchanges of goods and services for money on the one hand, and minting new currency on the other.

    Now, you can come up with a thousand reasons why the analogy is imperfect, but perfection isn’t the point of an analogy.

  4. And that’s why cow belches make no difference. If it’s not microbes in the three stomachs it’s microbes in the soil that dispose of the plants.

  5. Oh crap! I carried on reading though.

    To understand these community processes, Kaiser and colleagues developed a computer model that can simulate complex soil dynamics. The model simulates the interactions between 10,000 individual microbes within a 1mm by 1mm square. It shows how nutrients, which influence microbial metabolism, affect these interactions, and change the soil community and thereby the decomposition process.

  6. It sure would be nice to validate the model with some actual experiments. You know, some soil, some microbes, a closed, controllable environment. But experiments are hard, code is easy.

    Still, it is good to see they didn’t just code the model to ramp up CO2 no matter what other parameters they tweaked.

  7. Rosanne: “Its these tiny tiny microbes that belch out the terrible CO2 and we’re all gonna die.”
    Male Anchor: “Now Rosanne Rosannadanna you do realize that if it is the tiny microbes then man has nothing to do with it don’t you?”
    Rosanne: “Oh……..Nevermind.”

  8. And of course the microbes and plants have little to do with the present Earth atmosphere. /sarc. if needed.
    The wizards need to go and get a real education in Geology and the physical sciences. Perhaps these wizards would do well in a Methane and Ammonia atmosphere.

  9. The understanding of how microbes affect soil and plants is being advanced in biological farming. http://ezinearticles.com/?Biological-Farming:-How-Natural-Farming-Works&id=7434280

    “All of this biological activity also increases soil carbon. Soil carbon benefits microbial communities, traps CO2 from the air, and helps clean water as it moves to the water table. Plant material and sugars fed to microbes are two ways carbon is easily stored in the soil under biological farming. This can effectively remove carbon from the atmosphere and offset the use of mechanical equipment on the farm.”

    Article Source: http://EzineArticles.com/7434280

  10. So, the climate models try to account for all sources of GHG – which means they need to accurately model volcanic processes and ALL biologic processes, including soil microbes, – in other words they need to model the entire world. And they claim they do this accurately for decades/centuries out.

    Right. And I believe in pixies.

  11. Is there anything about Global Warming/Climate Change/Climate Disruption/ that isn’t less dire than they think it is?

  12. “Soil microbes are responsible for one of the largest carbon dioxide emissions on the planet, about six times higher than from fossil fuel burning,”
    ======
    Need help with the math here…

    Man 4%…..how much of that is from fossil fuel burning?

    and 6 times that is what?

    and what percentage of temperature increase can be attributed to that?
    ….oh wait….nevermind

  13. LadyLifeGrows says:
    April 8, 2014 at 12:48 pm
    “Another MODEL? Can we get some science in here?”

    ckb says:
    April 8, 2014 at 1:07 pm
    “It sure would be nice to validate the model with some actual experiments.”
    ========================
    I caution to be careful when you see the word “model” and having the same visceral reaction as when we skeptics hear/read about GCMs. In many areas of science and engineering, models are critical to understanding. I use models in my job all the time. I help design and build some of the very satellites and science instruments, trying to characterize climate and measure weather, which we read about here. Models are fine in furthering the science as long as the outputs of the models are correlated to actual observations and measurements. If they don’t correlate and are falsified, they need to be discarded or updated (which doesn’t seem to be happening with GCMs in a way that actually improves the outputs). A correlated model can then be used to study sensitivities to changes in variables and to study new scenarios (which of course then also need to be subsequently validated with real life). The problems with GCMs seem to be their simplicity in trying to describe an incredibly complex system (with non-linearities, chaos, etc.) and their omitted/misunderstood feedbacks.

    I may have missed it but I didn’t see enough detail in here to understand how well or if the model of the microbe process was validated against observation. This modeling may have indeed been carefully validated and could be why this work has thus furthered our understanding. I’d be careful not to throw out invectives just because of the word “model”.

  14. ha ha “six times higher than from fossil fuel burning” plus or minus ten times or 5 times or ten times higher than from fossil fuel burning? show me the numbers and data the numbers are based on or STFU.

    What they don’t tell you is just how uncertain their 6 times estimate actually is and it could be as much as orders of magnitude. They just don’t have much data nor understanding to make such estimates anything like accurate.

    It’s certainly possible that changes in land use are entirely responsible for the changes observed in atmospheric CO2 concentrations and they would not know.

  15. “So microbes alone produce 6X the CO2 from fossil fuels? Very nice factoid for whipping out in the next debate.” is a version of the old “humans produce only 3% of all CO2 emissions” red herring.
    When people say things like this, I imagine their veiw of reality must include unseen magical beings like Faries, Nymphs, Sprites, Elves and other fairefolk all busy sorting the “good” natural CO2 from the “evil” anthropogenic CO2. Perhaps anthropogenic CO2 is subtiley different and as such either unrespirable by plants. This has to be it, because how else would one type of CO2 be so much more damning than another?

  16. To understand these community processes, Kaiser and colleagues developed a computer model that can simulate complex soil dynamics. The model simulates the interactions between 10,000 individual microbes within a 1mm by 1mm square. It shows how nutrients, which influence microbial metabolism, affect these interactions, and change the soil community and thereby the decomposition process.

    Yes, but did they validate their shiny new model? No mention of how well model results agree with observations.

    “Our analyses highlight how the systems thinking for which IIASA is renowned advances insights into key ecosystem services,” says study co-author and IIASA ecologist Ulf Dieckmann.

    In other words, “IIASA is great. Give us more grants!”

  17. “…are one of the biggest uncertainties facing climate modelers.”

    I wish they would just replace “uncertainties” with “unknowns” and be done with it.

  18. The dynamics among soil microbes allow them to work more efficiently and flexibly as they break down organic matter – spewing less carbon dioxide into the atmosphere than previously thought, according to a new study published in the journal Ecology Letters.

    Whew!!!
    I’ve been unable to sleep, just thinking about all of those billions and billions and billions (ghost of Carl Sagan) of microbes spewing, yes spewing, CO2! Thanks for the no-disaster-pending-any-time-soon news, University of Vienna and IIASA!
    I’ll sleep well tonight – you betcha!
    Mac

  19. “Soil microbes are responsible for one of the largest carbon dioxide emissions on the planet, about six times higher than from fossil fuel burning,”
    ==============
    So why are Gore and Hansen not moving to tax these pesky microbes? Surely the EPA should be regulating soil microbes and the amount of CO2 they produce.

    After all, the EPA has ruled that CO2 is a pollutant. Since microbes are producing 6x the pollution as fossil fuels, the EPA needs to regulate these microbes and stop the pollution.

    Or could it be that the EPA cannot do this because they are POWERLESS to stop simple microbes from polluting the environment whenever they want? That while the EPA seeks to prevent human access to fossil fuels under the guise of preventing pollution, they are completely powerless to stop a much larger source of pollution.

    How can it be that the EPA says that CO2 is a pollutant, yet they do nothing to stop one of the largest sources of pollution in the world? A much larger source of pollution that fossil fuels.

  20. Unlike ocean creatures, where aquaria may not reflect the ecosystem, various soils and litters are relatively self contained. They could have literally have been put in controlled condition boxes with temperature, ambient CO2, moisture, whatever systematically varied to get real data. But no, build a computer model instead. Dirt is too dirty? A lab less fun than a computer keyboard and screen?
    What about verifying the model with real dirt? Maybe even throw in some composting nematodes, earthworms, and insects, a vital part of organic recycling beyond microorganisms?
    Even though this model is good news, it is still just models.

  21. One cringes to imagine the instrumentation grid that would be required to validate their model. Based on assumptions they have coded, increased air temperature above did not make their virtual compost heap go anaerobic?

  22. “As long as these two fluxes remain balanced, everything is fine.”

    Economists frequently make the same mistake, assuming a current, pre-existing, or future, equilibrium. Living organisms, and hence their products, are never, evah, in equilibrium.

    A chemists’ joke states that “Old chemists never die. They just reach equilibrium.”

  23. A simple exercise in back of the envelope calculation:

    1)Total area of the earth: approx. 510 million square kilometers
    shifting to scientific notation from now on, total area ~ 5.1 x 10^8 km^2
    2)Total area of the seas/oceans (~72% of the earth surface is water): ~ 3.6 x 10^8 km^2
    3)Total land area: ~ 1.5 x 10^8 km^2
    4)”The model simulates the interactions between 10,000 individual microbes within a 1mm by 1mm square”
    5)Number of 1mm by 1mm squares required to cover total earth land area: ~ 1.5 x 10^20
    (it takes 10^12 1mm by 1mm squares to cover one square 1km by 1km)

    >>>These folks have extrapolated their model by 20 orders of magnitude!!!!

    That has to be the most ridiculous, pseudo-scientific paper I have heard about this year!
    Who were these Ecology Letters peer-reviewers who allowed this garbage to get through?
    /sarc Makes the infamous hockey stick look like robust, honest science!

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