Climate warming experiment finds unexpected results

From Phys.org
January 4, 2019 by Emily Pontecorvo, American Geophysical Union
Climate warming experiment finds unexpected results

Dried leaf samples are bagged and numbered before being returned to study sites in Puerto Rico’s El Yunque National Forest. Heaters warmed experimental plots to four degrees higher than the ambient temperature of the tropical forest. Credit: Stephanie Roe

Tropical forests store about a third of Earth’s carbon and about two-thirds of its above-ground biomass. Most climate change models predict that as the world warms, all of that biomass will decompose more quickly, which would send a lot more carbon dioxide into the atmosphere. But new research presented at the American Geophysical Union’s 2018 Fall Meeting contradicts that theory.

Stephanie Roe, an ecology Ph.D. student at the University of Virginia, measured the rate of decomposition in artificially warmed plots of forest in Puerto Rico. She found biomass in the warmed plots broke down more slowly than samples from a control site that wasn’t warmed.

Her results indicate that as the climate warms, forest litter could pile up on the ground, instead of breaking down into the soil. Less decomposition means less carbon dioxide released back into the atmosphere. But it also means less carbon taken up by the soil, where it’s needed to fuel microbial processes that help plants grow.

“These results could have significant implications on the carbon cycle in a warmer future,” Roe said.

Roe said there are few empirical studies of how tropical forests will respond to climate change. She set out to address this gap in June of 2017, when she and her research team travelled to El Yunque National Forest in Puerto Rico. They landed at a site called TRACE—the Tropical Responses to Altered Climate Experiment.

TRACE is the first-ever long-term warming experiment conducted in a tropical forest. It was established by the US Forest Service in 2016 for research like Roe’s. The site consists of three hexagonal plots of land enclosed by a ring of infrared heaters raised four meters above the ground, and three more plots enclosed by fake heaters that are used as the “control” forest.

Roe collected leaves from the plots, dried them out in the lab, and then returned them to the plots randomly. In addition to the native plants, she also included black and green tea, and popsicle sticks to represent woody biomass, to see how different materials would respond to the warming.

The heaters were programmed to continuously heat the plots to four degrees higher than the ambient temperature of the forest. The experiment was supposed to run for a full year, but at the beginning of October, Hurricane Maria swept across the island, destroying the TRACE sites.

Roe was back in Virginia when the storm struck. She had collected samples from the first few months of the experiment, and they were already showing signs of significant decomposition, so she decided to go ahead with the analysis based on what she had. And the results were not what she thought they would be.

“We would expect that microbes tend to work faster, like their metabolisms increase, with warmer temperatures,” Roe said. “So we would expect to see an increase of activity of microbes and other decomposers to decompose the litter.”

But instead of seeing faster rates of decomposition, Roe observed the warming produced a drying effect in the plots, which slowed decomposition. “What we found is actually it went the other way because moisture was impacted so much,” Roe said. Moisture in the litter from the treatment sites was reduced by an average of 38 percent.

Read more at: https://phys.org/news/2019-01-climate-unexpected-results.html#jCp

 

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91 thoughts on “Climate warming experiment finds unexpected results

  1. I keep my woodpile dry and elevated off the ground also for the same reason… reduces rot. Rotted wood … not good firewood.
    Also:
    “jerkey… sundried meat… last long time”, says Tonto.

    Funny how city-slicker scientists know so little about nature.

    • Too late she got smart” —— Stephanie Roe, an ecology Ph.D. student at the University of Virginia,

      But instead of seeing faster rates of decomposition, Roe observed the warming produced a drying effect in the plots, which slowed decomposition. “What we found is actually it went the other way because moisture was impacted so much,” Roe said. Moisture in the litter from the treatment sites was reduced by an average of 38 percent.

      The above wouldn’t have happened iffen Ph.D. student Stephanie Roe hadn’t been “brainwashed” into believing the “junk science” claim that the microbial decomposition of dead biomass during the Autumn and Winter in the Northern Hemisphere was/is responsible for the bi-yearly 7-8 ppm increase in atmospheric CO2 quantities, as per the Keeling Curve Graph.

      ”DUH”, ….. Autumn time in the NH is “dry” time, and Winter time is “cold” time, …. and microbes pretty much refuse to “eat n’ pass gas” during those times.

      Those microbes also hate refrigerators and freezers, ….. ya know. 😊 😊

      • “Tropical forests store about a third of Earth’s carbon and about two-thirds of its above-ground biomass.”

        Carbon, C, a solid? Or carbon dioxide, CO2, a gas.

        ‘If you can’t say what you mean, you can’t mean what you say.”

    • Soon to be Dr. Roe apparently forgot, or never knew, that microbes and fungi need water, just like plants and animals.

  2. It was not a good experiment. They did not control for moisture. Heating the plots without adding water vapour, would have reduced the relative humidity at the sites.

    ALL computer models (yeah, yeah, I know), show that relative should stay the same, or increase, with warming.

    • Scientism today:

      “Let’s do an experiment where we change one variable ourselves and let a whole bunch of other variables do whatever the heck they like then look at the results and be surprised a lot”.

      ..”Now let’s put the word climate in our appraisal and apply for a grant “..

    • … or microbe populations have evolved to thrive within temperature and humidity ranges that are usually encountered, and would take months or years to adapt to the altered conditions used in the experiment.

      • Yes, exactly.

        Ideally, they would have set up multiple lines of investigation.

        – control plots at ambient conditions, in sun and shade
        – plots 4 deg warmer, but without added water vapour in both sun and shade
        – plots with added heat and water vapour, in both sun and shade

        Ideally, over multiple years.

        • This one didn’t even manage the full year! How can anyone make valid conclusions on samples from a few months? I hope this was only published online so no trees were harmed by producing it on paper.

        • …or since the lifespan of a typical soil microbe is only a few days, why not examine soil conditions, populations, and biochemistry during weather anomalies lasting several days and compare them?

    • ALL computer models (yeah, yeah, I know), show that relative (humidity) should stay the same, or increase, with warming.

      The preponderance of evidence is that relative humidity decreases as the climate warms. link

    • It was not a good experiment. They did not control for moisture. Heating the plots without adding water vapour, would have reduced the relative humidity at the sites.

      That was exactly my thought, Les J.

      Anybody who makes their own compost usually learns that you have to have adequate moisture in the pile, in order for proper decomposition to occur.

      Heating up a pile merely interferes with the moisture content. It’s NOT the heat alone retarding the growth; it’s the drying out that reduces the moisture.

      Add more heat, keep the moisture up, and then see what happens.

      • “Surprise” implies am expected result was not obtained. How many other surprises are in store for our valiant climate researchers! I expect some to be much bigger than discovering that warming the forest floor with infrared heaters dries out the leaf litter.

        One big shock will be that warming a fish tank of neons four degrees causes them to stop breeding. Surely that portends the end of civilisation?

        Heaven help us if they discover the stratosphere is cooling but “hasn’t changed much since 1995” according to NASA. Same as the terrestrial temperature, if you don’t accept NASA’s adjusted version of that data set. It is interesting that NASA claims the upper atmosphere is “not cooling anymore” but insists it is warming lower down, after adjustments. Perhaps those teams didn’t get the same message.

    • Nicholas

      This experiment didn’t even accomplish the predicted first order effect; that warming would produce enhanced decomposition. Think of all the times you have heard how melting the permafrost will accelerate the decomposition of biomass for a new loss, whereas growth will far overshadow decomposition.

      “The heaters were programmed to continuously heat the plots to four degrees higher than the ambient temperature of the forest.”

      Before I finished reading I had worked out that all they would observe was drying and reduced bacteria activity.

      Consider: what would the conclusion have been if the digestion increased instead of decreased – how would the conclusion have differed? By not a whit. The same conclusion would have resulted: warming is bad because…

      The error in the experimental design was to have warmed the forest floor without changing the bacteria that exist in the same area at a lower, warmer elevation. Climate change is so slow that the bacteria would have evolved or been replaced by types that can tolerate the new conditions.

      Typically when a forest is piling up undigested material such as pine needles, the solution is fungi. I guess she knew that, being so well advised and all.

    • Microbes that are tens to a couple hundred microns are not responding to an atmosphere 3 meters above ground. They are responding to micron scale climate including temperature. They are responding to the temperature in the air pockets between the leaves and the temperature of the leaves. There is nothing we measure that relates to forest microbe health. The best approximation would be soil temperature, not air temperature. Fundamentally, the student didn’t even know what to measure or that scale matters and how to measure at the right scale. Just measuring temperature on a 200 micron scale would have been the first actual challenge. What is the temperature profile across a microbe would have been the second challenge. No, we got bunkism instead.

  3. The alleged “facts” disagree with climate science accepted theory . Scrap ’em. As Nancy the Great has said, “I disagree with your facts”.

        • After listening to a few lawyers today, it appears that President Trump by law has the sole authority to determine what a national security crisis consists of, and there is even a specific law that gives the president the authority to do emergency construction using funds available, even though Congress has not allocated any funds for specific reasons.

          Of course, the president will be sued if he declares an emergency, but in America, anyone can sue anyone else, for good reason or no reason, so this action shouldn’t be a surprise, but I think the U.S. Supreme Court would take this issue up immediately, and from the discussion of the law as it stands today, the Court should rule in the president’s favor.

          This ought to be interesting. Trump wants to protect the nation, and the Democrats want to leave the nation unprotected, and are doing so for partisan political reasons. This will become more clear to the public as time goes by.

  4. “Tropical forests store about a third of Earth’s carbon”.

    I thought most of the Earth’s carbon was underground, in rocks, coal, oil, gas etc. It just shows how you can be wrong for years and it takes a young PhD student to put you right…..

  5. “Her results indicate that as the climate warms, forest litter could pile up on the ground, instead of breaking down into the soil.”

    More fuel for more fires?

  6. Roe collected leaves from the plots, dried them out in the lab, and then returned them to the plots randomly. … “What we found is actually it went the other way because moisture was impacted so much,” Roe said. Moisture in the litter from the treatment sites was reduced by an average of 38 percent

    Go figure, they took moist leaf litter from the site back to the lab and dried it, then returned it to the site and wonder why their test sites are drier than they should be. Naturally it is from the warming and not by the loss of moisture that was removed in the lab

    • I read that section three times, including at the linked article, and it just doesn’t make sense.

      She collected leaves, dried them out, then returned them to the site. So when, exactly, was the decomposition measured? She would have had to go back to get the samples a second time to measure decomposition compared to the first time. If that’s the case, why dry them out in the first place? If she had several months worth of samples, she must have been getting sub samples from the first dried out samples every month for several months. How, exactly, would you know that the litter you picked up today is the exact same dried out litter you returned to the plots several months before?

      If moisture was reduced 38% in the treatment sites, was this measured before she dried the samples out? That would make some sense. If after, it makes no sense. She would be measuring the ability of the sample to ABSORB moisture AFTER it had been dried out. Would the samples have shown the same behaviour if they hadn’t been dried out in the first place? I honestly don’t know, but that seems to me to be the better way to have constructed the experiment.

      Then there’s the popsicle sticks. Aren’t these made of birch? Does birch grow in tropical rain forests? No? So wouldn’t the native microbes have evolved for native wood? How microbes not evolved for birch react in a higher temperature with birch as a food source tells us what exactly about how they react when their food source is something they evolved for?

      Either the experiment is hopelessly flawed or the write up is hopelessly flawed or both?

      • OK, I see from the photo that the dried samples were in some kind of mesh envelope and numbered. So I suppose that they could be dropped off and then brought back later and would be the same sample.. But that just makes things go from completely doesn’t make sense to almost completely doesn’t make sense.

        See comment about local convection cell downthread, which makes it worse…

      • Another variable – does the leaf re-absorb water to the same extent that it had prior to being selected, dried, weighed, and the returned to the test plot? Some processes are not reversible. Aquifers, once depleted, do not refill to the same capacity when groundwater returns. If the leaf is drier, it will decompose more slowly, invalidating the experiment. We should submit a list of uncontrolled variables to the author.

    • As pointed out earlier, the problem was that the heaters reduced the relative humidity. If the dewpoint was increased along with the temperature, the forest litter would have decomposed more quickly instead of more slowly.

      There is another matter: Back in the early 1970s, I was taught that in tropical rainforests, forest litter decomposes so rapidly that there is not much accumulation of it. This means making it decompose more rapidly than it already does won’t make much difference in the carbon cycle.

      • “Back in the early 1970s, I was taught that in tropical rainforests, forest litter decomposes so rapidly that there is not much accumulation of it.”

        WR: In the same time I learned the same. By the traditional practice of ‘slash and burn’ parts of the tropical wood became used for agriculture for only two or three years. After that two or three years, the used parcels of land became deprived of any plant food. Run off made disappear the remaining nutrients. After giving the land back to nature in some 20-30 years the process could be repeated. The new secondary wood improved the fertility of the soil and ‘slash and burn’ could start again.

        Coal seems to be formed under very wet circumstances. Marshes. The often cooler circumstances (because of evaporation) and the being deprived of sufficient oxygen below the water level caused sequestered carbon to remain. Land that dropped due to tectonic movements provided a good environment for thick layers of ‘coal’ to develop: new layers soon became inundated and became protected against decomposition.

        In the Dutch ‘polders’ (lying below sea level) the water level is controlled at the centimeter. Authorities don’t dare to lower water levels not even a centimeter below the level that is supposed to be safe: the often peaty soils (peaty by a lot of plant remnants from previous marshy circumstances) would lower down quickly because the plant remnants would decompose when they would become to dry. And our houses that are build on piles from tree trunks would soon sink into the bottom. The tree trunks are protected against decomposition below the water level, but not above.

        Last super dry and warm summer (2018) was decomposing part of our dikes. I photographed many cracks in roads on dikes and places where part of the dike was sinking. Serious enough to cause direct repair.

    • I live in a semi arid environment and I have a compost bin for my garden. If I don’t water it, the leaf matter will not decompose. How did this person get this research published? They take leaf matter, dry it out and wonder why it doesn’t decompose? And they draw conclusions from that? Science isn’t progressing, it’s regressing. Next we will be arguing about how many teeth a donkey has without actually counting them.
      Researchers caught in a stream of endless circular logic.

    • “Go figure, they took moist leaf litter from the site back to the lab and dried it, then returned it to the site and wonder why their test sites are drier than they should be.”

      Beat me to it! I had my quotes all ready and everything! 🙂

      I wonder why it was thought necessary to dry the leaves artificially in the first place?

  7. I cannot understand how Stephanie Roe thought she could determine anything using that methodology. Just removing and returning leaf debris, even if without intentionally drying it, would obviously make the leaf debris drier. Also, was the test patch heated using radiant heat or by forced air? Each method would cause a different amount of drying.

    I imagine any method of artificially raising the temperature of a patch of forest floor would induce unnatural conditions which would make the experiment invalid. I am amazed no one recognized this issue.

    Also, the methodology did not take into account probable variation in forest growth rate which would occur in warm years. In a naturally warmer year decomposition might proceed at a higher rate, and biomass of leaves falling to the floor might be higher. What would the resulting thickness of leaf debris be? A thicker layer might change things like moisture content and temperature. Perhaps the temperature might actually be lower within a thicker leaf mat produced during warmer years.

    Instead of arbitrarily altering conditions, the only reasonable way of conducting the test would be to simply monitor the forest floor for several years, Then, report the results. The paper should read something like: We measured X amount of decomposition in cool years and Y amount of decomposition during warm years. Therefore, our conclusion is Z. This concludes our research at this time. No additional monies need be sent until we think of another experiment.

    SR

        • Was heat applied only during the day to simulate the diurnal cycle, or continuously over 24 hours?
          Again, disrupting natural processes proves nothing. Observation without interference required to find out what happens naturally.

          • I believe it was continuous to maintain a simulated 4 deg. (C or F?) warmer environment throughout the term of the study period such that no matter what time of day, the test site was maintained as Ambient Temp +4 deg

    • Don’t blame the student. Blame the faculty/advisors. Thesis topics require approval before they are approved/funded. Maybe Hank Johnson, Occasional, Nancy and Chuck were on the committee.

  8. If you want to store carbon in plants, the best way is to make coal or peat.
    Swampy, low lying, acidic habitat that stop decomposition.

    • Plant fast growing trees (like Poplar), harvest and replant every 10 years, stack the cut logs and their associated leaf trimmings in an old coal pit mine and gradually flood them over the top as you go

    • I believe it was 4d above otherwise ambient temperature but F or C? So if daytime temp reached 100f, test site temp was 104f or if C 38 and 42 respectively

      • I would suspect +4 degrees C.

        But, it isn’t clear: And if the “press release” which is quoted were “translated” to “Americanese” degrees +4F for US distribution, I would be wrong.

        So, baked dried wood NOT touching the moist ground and leaf cover, allowed to be dried further by separating it with a metal screen around the wood and leaves, and then disturbed regularly by digging up adjacent metal packages, does not decay as quickly as wet wood and leaves kept buried.

        Yepppers, I’d agree with that. No “surprise” at all.

  9. The site consists of three hexagonal plots of land enclosed by a ring of infrared heaters raised four meters above the ground

    Yeah, that wouldn’t create a local convection cell, would it? That would in turn dry out the ground cover?

    Nothing about this experiment makes any sense….

    • According to CO2 global warming theory the tropics will not warm much, only the poles.
      As mentioned above the bacteria live in the microclimate on the forest floor.
      Nowhere near the calculation of GASTA.
      The forest itself adjusts its own temperature through transpiration and cloud formation,
      http://ec.europa.eu/environment/forests/pdf/EU_Forests_annex1.pdf
      2 executive summary.
      So it turns off the heaters from the sun by reflection.
      Not sure of the relevance of this experiment.

      • the Poles have jumped off of the bandwagon and are not attempting to mitigate any warming.

        So if they will probably welcome any extra warming.

    • F=MA is a model. So is E=Mc^2. Difference is those are good models that have been validated. Every time a Climate Science model is invalidated it seems they either blame the data (leading to more adjustments) or they adjust the model while saying it is still valid. But Climate Science is never wrong.

  10. Kudos to them for at least trying to do an actual experiment and get some actual data, even if it was too simplistic and poorly designed. The results wouldn’t have really said anything useful about “climate change” even if the experiment had not been destroyed.

    No points, however, for trying to draw conclusions from just a couple months worth of results.

    “there are few empirical studies of how tropical forests will respond to climate change.”
    Even though “the science is settled.”
    But it seems like whenever they do run an experiment or collect some actual data they get “surprised” by the results.

    • TDBraun: “Kudos to them for at least trying to do an actual experiment and get some actual data”

      WR: Agree. Too few experiments are done, it is all theorizing on assumptions. This experiment showed that humidity had a higher influence on decomposition than temperature. And raised many questions which is better than to use ‘a model’ and say that you discovered ‘answers’.

      Experiments are needed. Are there any experiments done on the effect of back-radiation? Could be as interesting as the above experiment but with a wider impact. What is the effect of back radiation on sea surface temperatures? Does it cause a temperature rise of the oceans? Or does it cause a higher evaporation = cooling of the surface?

  11. You have to give her points for including the fake heaters on the control plots. She probably had way more grant money than she needed for the actual experiment. lol

  12. If you are trying to compost leaves in a garden compost heap the leaves need to be moist.
    If the leaves are too dry then they don’t break down.
    Maybe if there had been a misting unit as well as the heaters the results might have been different

  13. So what, it’s a moot point. Besides, CO2 levels are largely insensitive to how fast biomass decomposes as a function of temperature. It’s the steady state that matters and all biomass that arises in a forest will eventually decompose. What matters is how much biomass there is and the more biomass there is, the higher the ambient CO2 levels must be in response, as is so clearly demonstrated by the lag in the ice cores.

    For some reason the steady state where goes into’s are equal to goes out of’s is a foreign concept to many alarmists. They treat energy entering the atmosphere the same way and require far more coming out than is going in so they can support their insanely large ECS. It’s almost like they think that when surface energy is stored (captured) by the atmosphere and returned to the surface, the Joules stay in the atmosphere!

  14. A crappy experiment but, one solid piece of take-away:

    means less carbon taken up by the soil, where it’s needed to fuel microbial processes that help plants grow

    Please everyone, do try do remember that next time you’re ploughing, cultivating, draining (wet patches), throwing nitrogen fertiliser around and ESPECIALLY, burning anything biomass
    (One of those plants needing microbial process might even be Hordeum Vulgare – then where would you be? Is January still dry 4U?)

    Those activities are all the same thing really = burning. The Original Sin against all life on Earth if not absolutely everywhere.

  15. Oh no! If biomass doesn’t break down as quickly, that means we’ll all be knee-deep in sticks & leaves!

    Ya just can’t win…..

  16. As if tropical forests could possibly warm four degrees even under 600 ppm of plant food in the air.

    IPCC’s central fake figure of three degrees C at 570 ppm means less than that in the tropics, about that much in temperate zones and more at high latitudes.

  17. What about the worms?

    [The warned warmed worms were warned not to eat the warmed, non-wormed woods by the warmed worms metal screening devices. .mod]

  18. The microbes might not be working faster, but insect life might be doing more work with greater depth of cover. It sounds like a limited and disrupted experiment anyway–not exactly replicated.

  19. The concept of confounding variables seems to have escaped this PhD level student. Would that be as a result of decades of drumming it into people’s minds that the world’s climate is allegedly a univariate system whose state is supposedly determined by a trace gas?

  20. “Moisture in the litter from the treatment sites was reduced by an average of 38 percent.” Never occurred to them that increased heat may dry out things rather than increase decomposition and release of more CO2. These advocates are pre-conditioned to interpret any of their studies as replicating natural conditions of global warming. Even to the point that they are continually surprised when their assumptions don’t pan out. They are trying their best to force nature to abide by their rules. They never stop to think that their basic premise is wrong, hence all the wrong assumptions.

  21. Why on Earth are the control areas surrounded by fake heaters? Does this fool the forest into thinking it’s a double blind study?

  22. If you cut off a frog’s legs one at a time, it loses its hearing with each limb lost, as measured by how far it can jump. And when you cut off its last leg, it also loses its sense of touch. You can scream at it and poke it with a stick and it still won’t jump.

  23. Once again we find that it is more difficult to get a passing grade on a middle school science fair project than it is to pass through the peer review process in the field of climate change. The scientific standards for 11-year-olds are far higher than for Phd students.

    Then again, I haven’t judged a middle school science fair in about 15-20 years. Back then, teaching the scientific method was still the focus of the science fair. Today, it may be 50% on presentation, 50% on promoting social justice, and a 20% bonus for demonstrating high self-esteem!

  24. “Roe collected leaves from the plots, dried them out in the lab, and then returned them to the plots randomly. In addition to the native plants, she also included black and green tea, and popsicle sticks to represent woody biomass, to see how different materials would respond to the warming.”

    paraphrase … “Roe collected leaves, sterilized them somewhat in the lab, returned them to the plots, reduced the humidity of the plots relative to natural conditions, and was surprised that the leaves did not break down as fast as untouched (natural condition) forest debris.”

    When my doorbell rings, my dog runs to the front door (even though the chime is in the hallway above the bathroom door). If Roe lived in a house like mine, it is likely that she would be repeatedly surprised when, answering at the bathroom door, and nobody was there.

  25. The site consists of three hexagonal plots of land enclosed by a ring of infrared heaters raised four meters above the ground, and three more plots enclosed by fake heaters that are used as the “control” forest
    Enclosed by fake heaters? Placebo?

  26. When I was a kid living in Ecuador, we visited Panamá for several weeks for a vacation. I was struck by how the closets all had incandescent bulbs inside – that stayed on all the time. It was explained to me that the heat helped reduce moisture, keeping thing drier so mold wouldn’t grow and things would not decompose which they otherwise would in the dark in the damp warm climate.

    And I didn’t even get a grant or a PhD for that wisdom which I have retained to this day.

    “The secret to mold control is moisture control” – Abraham Lincoln, via the internets

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