Decomposition is Slower With Global Warming Which Means Less Future Warming

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.

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.

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.

The Work Has Not Analyzed Fire Risks

Slower decomposition can leave more dry biomass above ground, which could increase fire risks.

32 thoughts on “Decomposition is Slower With Global Warming Which Means Less Future Warming”

  1. From Oklahoma Terence? You read like ya Bama or some other place teachin ya fine understanding science thar. I be an evangelical admirn yur thinkn.

  2. It is an observational and interesting study on a small scale. You might replicate this with say a toaster and bread — does toasted bread grow mold as compared to bread in different conditions? You would probably find that heat, humidity and light affect the bread in different ways over time . If you go outside, leaves decompose like the bread and are affected by similar conditions. Maybe more studies will observe the same thing happening to the bread as the leaves. It might seem silly, but this silly stuff turns into that knowledge that builds empires based upon fact. Please don’t be so quick to judge things through comments. Instead replicate the study and share the results.

  3. To all the detractors, it pays to read the original article and get the full story.
    Roe is a PhD student, this is likely her thesis project, and “The results Roe shared are preliminary and not yet published.”

    This study was obviously done with a limited set of inputs (such as not including possible rainfall changes or humidity), she started with pre-dried leaves (in both the +4 degrees and control plots) and it was actually cut short not because the results were so clear but because a hurricane destroyed the test site so she had to work with what she had already gotten.

    I think this story has gotten attention not because of the level of science (pretty basic) or quality of the work, but because it appears to contradict a small aspect of global warming expectations, so some people will jump all over that, and elevate it above where it should be.

  4. This is one study done with a specific set of inputs. Roe, as it turns out, is a PhD student, this was a preliminary test, probably for her thesis. Take it for what it is, nothing more.

  5. This shows how you always need to look at what the study is looking at, test conditions, sometimes who funded it, etc. This has always been the case, nothing new. But when you take a new study that hasn’t yet been peer-reviewed and present it as fact, then 2 months later a different study with different conditions presents a different result, people will only remember the contradicting headlines and draw the false conclusion that scientists don’t know what they’re doing.

    This is good research for the narrow test conditions that they used. Obviously they need to consider current and future rainfall and humidity levels before jumping to conclusions. This may not be applicable in the real world, or maybe it will, or just for certain regions, we don’t know yet.

  6. Thanks for the article. You just proved my point but probably didn’t realize it. The article (it’s a meta study, mean of 20 models) says that at 1.5c warming, El Nino events will go from 4.5/100 years to 10.5/100 years (90% CI), ie frequency increases while intensity does not. However, El Nina events will not change in frequency or intensity (not even for RCP 8.5).

    The referenced models deployed for El Nino are flawed. They rely on pre-1950 guesses (>1950 is reliable, there are no temp records before this), and as you know ENSO modeling requires very long term accurate data (how else can you measure statistically accurately, something that happens every 25 years?). More importantly, and crucially, the models imply normal distribution (which is why they tested the 20 models with Students). However, it is known that ENSO variations are non-linear (ie non-parametric). The referenced models sloppily (or deliberately) do not take this into consideration. If they did, you will find no conclusion that says El Nino will INCREASE in frequency. See Hannachi 2002. And it makes sense – what is the process that increases the FREQUENCY of the entire Pacific oscillation because water temps increase? There is zero evidence to back this up. Intensity I can get, as water temps increase but even these flawed models say intensity won’t change. The ENSO/severe/scare is not supported by science.

  7. For people who are interested in arguments against man made global warming I suggest looking up these individuals on YouTube, Tim Ball, Don Easterbrook, Tony Heller, Hal Doiron, Leighton Steward, Jay Lehr, Fred Goldberg and Richard Keen.

  8. It does not need science to show that the biotic activity at the equator is far higher than temperate zones, so warmer will be faster. This article is misleading in is conclusions.

    However the topic of water cycle and the amount of water stored within our carbon sinks does not get enough air time .This maybe a more serious threat to the Earth than the CO2. Looking at the deforestation, fires and drying out of forests in Brazil and Indonesia we are well on the way to turning topics to desert by man’s Palm oil addiction.

  9. But what climate changes are we actually seeing? Objectively the global warming is still the 1 degree per century following the Little Ice Age. Storms and wildfires get amplifed media coverage but have actually decreased in some regions. But focusing on resilient building and infrastructure would be a winner for all.

  10. One of the biggest potential GW contributors is not the oxidation of soil carbon. Nope, it’s the release of methane trapped in permafrost. Read a couple of papers on that and it gives you the heebie jeebies.

  11. ‘The El Niño event of 2015-16 was one of the strongest on record, bringing flooding to much of South America, southern US and East Africa, and severe drought to Australia and southeast Asia.
    Now a new study, published in Nature Climate Change, suggests that similar “extreme” El Niño events could become more frequent as global temperatures rise.
    If global warming reaches 1.5C above pre-industrial levels – the aspirational limit of the Paris Agreement – extreme El Niño events could happen twice as often, the researchers find.
    That means seeing an extreme El Niño on average every 10 years, rather every 20 years.’

  12. You’re right, of course. If I’d written a report this amateurish in high school science, I’d have gotten an F.

  13. Google’s news editors are sinking lower and lower…posting terribly written “science” articles and crap about Kim Kardashian. Do they think we’re all as stupid as Trump?

  14. I’m no scientist; never even played one on TV – but I feel this way. There seems to be no middle ground on this issue – man either has or has no impact on climate. Only one side is correct. So why not plan for the best (scenerio – no effect by man), BUT prepare for the worst (scenario – we are indeed affecting the climate)? Life goes on and everybody’s happy.

  15. What do you want to remedy? Solutions exist, and have for some time. LFTR power gen and HVDC lines that power EVs will, more or less, eliminate manmade Co2. Easy peasy. But who will pay for it? Especially in places that has nowhere the money to pay for it but are the future sources of Co2 (e.g., India/Nigeria)?

    The global warming debate is still about the science, e.g., will we see 8c warming, 1.5c or none? Where, and what effect? Humans are awful at making long term predictions. Who knows, maybe we do nothing and in 20 years some awesome tech comes along and we are all saved. Sometimes it’s better and cheaper to wait.

    Bottom line, the prescription is there. But no one is willing to ask voters to open their wallets – especially if the money goes elsewhere. There is no global village. The main reason the IPCC has repeatedly said it is not about “fixing” global warming, it is about income redistribution and a “new world order”.

  16. All of these explanations though do not address the climate changes we are experiencing now…I understand scientific understandings change as data and observations increase and not final word can be given on causes. Why doesn’t the conversation focus on remedies to the current situations and dispense with the political naratives, which do nothing but prevent solution thinking.

  17. What this article shows is that the “Experts” haven’t got a clue how the earth will behave. Maybe some honest debate is in order instead of religious dogma when it comes to “climate change” and its “deniers” !

  18. Unfortunately, this article shows just how redicuridi and political “science” is becoming, and they wonder why after years of promoting doomsday climate studies, most people are not buying into it.

  19. No guarantee that higher temperature would lead to drier conditions everywhere. Higher temp generally means higher evaporation of the oceans and other water, which means more moisture in the air, which has to go somewhere. There could easily form areas with higher temp and higher humidity at the same time. That could have a different effect on decomposition rates.

  20. What an idiotic (unpublished/reviewed) study. Put space heaters in the forest and heat up leaves and popsicle sticks (no joke!) 4c higher than the surroundings. OMG – the stuff dries out and doesn’t decomp. Ergo global warming will dry the planet and not release Co2. Who woulda thunk? This “science” should be filed under “satire”.

  21. Uh, no. One article refers to ENSO, a naturally occurring event. There is no evidence that I know of at least that AGW makes ENSO effects more or less pronounced – statistically significant.

    The other article is from 2009 and is a meta reference with the sort of humble conclusion “Our review also identifies key information gaps and scientific uncertainties that currently hinder our ability to predict tree mortality in response to climate change and emphasizes the need for a globally coordinated observation system.” They also admit the ENSO effect.

    yes, burning of forest sucks, but the palm business is nothing, more like a rounding error, compared to the amount of wood people use to cook and heat in places like Africa. Additional, global tree cover has INCREASED in the past 40 years, not decreased. This finding (Song, Hansen, Nature 2016) is directly contradicting FAO’s report and the reason is clear. FAO doesn’t count forest replanting. It is also a myth that rainforests are better carbon sinks – grasslands are.

    I agree that burning down millions of acres of the Amazon to grow food is a problem. I doubt it though. Currently, 90% of brazilian palm is built on former pasturelands. So much easier than clearing thick rainforest.

  22. Here’s a couple suggesting that’s possible. It might not have to though – the new Bolsonaro government’s first move was to open up the Amazon to exploitation. If the conversion of rainforest to palm oil plantations in Borneo is any guide, this will mean greatly increased fires, and a huge rise in CO2 outgassing from deep peat soils drying out. We could kill the Amazon without any help from global warming.

  23. Please post a link showing that climate change (i.e. global warming) will likely kill the Amazon forest.

  24. But climate change is also likely to Kill the Amazon forest so there are point to here and to there… Our geoengineering activities should be very delicate like pumping Nitrogen to forests to fertilize tree growth.

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