Another Reason to Doubt the Global Climate Models

The study discussed in this article was performed in Puerto Rico’s El Yunque National Forest.

If you have been reading this blog for a while, you probably know that I am very skeptical of climate models that predict the consequences of rising carbon dioxide levels in the atmosphere. Initially, this was due to my own experience with large-scale computer models. In my early scientific research, I both wrote and used them, so I know how much their results are affected by the assumptions programmed into them. As time has gone on, my skepticism has increased, since it has been demonstrated over and over again that the climate models do not line up with the most relevant data.

Why do the climate models compare so poorly to the appropriate data? Mostly because they contain many assumptions that have not been tested. Typically, these assumptions neglect the idea that the earth has negative feedback mechanisms, which are the hallmark of nearly every well-designed system. As time has gone on, many such negative feedback mechanisms have been found, and they typically run counter to the assumptions programmed into the climate models (see here, here, and here, for example). It seems that a graduate student from the University of Virginia (Stephanie Roe) has found yet another of earth’s negative feedback mechanisms.

There is a lot of dead, decaying matter on the floors of the tropical forests of the world. As that dead matter decomposes, it releases carbon dioxide into the atmosphere. Well, decomposition is driven by chemical reactions, and chemical reactions speed up with increasing temperature. So, as the world warms, what should happen to the rate of carbon dioxide produced by decomposition? It should increase, right? That will release more carbon dioxide into the air, which will accelerate warming. This is an example of a positive feedback mechanism. In such a mechanism, a change promotes a process that amplifies the change. This particular positive feedback mechanism is programmed into the climate models that are being used to predict the consequences of increased carbon dioxide in the atmosphere.

While that assumption makes perfect sense, the real world often works differently from our simple assumptions. That’s one reason Stephanie Roe decided to test it. She went to Puerto Rico’s El Yunque National Forest, where the US Forest Service set up infrared heaters in different parts of the forest. Those heaters were programmed to keep their surroundings 4 degrees Celsius warmer than the rest of the forest. Those parts of the forest, then, should behave like the tropical forests will behave if the earth warms by an average of 4 degrees. In addition, there were parts of the forest where identical, non-working heaters were placed. They served as control areas – they stayed at the normal temperature of the forest, but they had the physical structures of the heaters present. Roe introduced various kinds of dead matter (both native and non-native) to the forest in both the warmed sections and the control sections. She then collected samples later to test the rate of decomposition in each.

What did she find? She found that the result was precisely opposite of what is programmed into the climate models. The warmed areas of the forests had slower rates of decomposition than the control areas. Why? According to her research, it is because the warmer parts of the forest were drier. The process of decomposition is accelerated strongly by moisture, so the loss of moisture slowed down the decomposition more than the higher temperature sped it up. Thus, according to her research, increased temperatures should reduce the amount of carbon dioxide produced by decomposition. This, of course, is an example of a negative feedback mechanism: a change promotes a process that decreases the rate of change. Once again, such mechanisms are the hallmark of designed systems, so it is not surprising that it exists here on earth.

The more we learn about climate, the less confidence I have in the predictions of the climate change doomsayers.


  1. John D says:

    Really neat study. I’m wondering how closely the heaters match what would actually happen in the event of large scale temperature rise? Do you think they neglect a certain amount of increased humidity from local ocean ?

    It seems that, over long periods of increased temperature rise, some jungles turn to desert and some just get more jungly. I’d be curious to see her do the test with some humidifiers just for fun!

    I’d definitely agree that all the feedback mechanisms seem to work hard on keeping earth balanced. It’s actually really cool the more you think about how nuanced this planet is.

    1. Jay Wile says:

      That’s a good point. The heaters only change the temperature, not the other things that are supposed to change with global warming. One thing she did mention was that there was a hurricane that destroyed the plots after she had collected her samples. She says that more hurricanes should actually increase the drying, because they would break down the taller trees, allowing more sunlight to hit the forest floor, which should dry it out even more.

      1. John D says:

        Wow I never even thought about that. Just what a forest needs after a soaking, a drying. Probably keeps it from becoming a bog too.

        I’m sure you’ve probably read up on all this, but I love the story of Mt. ST. Helens. A pocket gopher and an Alpine lupen get to work immediately rebuilding the forest! I don’t see how “slow change over time” evolutionary theory accounts for these excellent feedback mechanisms that happen after catastrophic events which occur quickly; and, in Mt. ST. Helens case, only once every couple hundred years.

        Good article here about how modern biologists were surprised by the sequence of events of the aftermath –

        1. Jay Wile says:

          Scientists who don’t understand that this world is the result of design are always amazed at how quickly things happen. Surtsey Island is another example.

        2. John D says:

          Whoa! That Surtsey island article is awesome! Thanks.

  2. Doug Lindauer says:

    I have to ask a question about her research and conclusions. (Since the paper is preliminary, maybe she’ll address it in her final paper.) So if global temps increase, won’t the water content in the air also increase because the world is covered by oceans? Will the relative humidity reach the same level it had at the lower temps? I suppose this is a question for a meteorologist. It would seem pretty pertinent.

    Maybe the only thing that can really be said is that it demonstrates that people can (and do) make a lot of unverified assumptions in support of their pet causes. These come about because time and again scientists (so-called) make glib statements based on VERY partial knowledge! Examples of what I mean were the pronouncements that most of our DNA is junk (soundly debunked by the ENCODE project) and the charge that the human eye is poorly designed (also soundly and thoroughly debunked by numerous people yet still touted by the likes of Richard Dawkins.)

    But don’t get me started. 🙂

    1. Jay Wile says:

      I don’t think that’s right, Doug, but I am not an expert. Yes, rainfall might increase, but rain drains off the forest floor quickly, so the real issue is the staying power of moisture, and that definitely goes down with increasing temperature.

      1. Doug Lindauer says:

        I understand your objection but in a way you buttressed my main point. I.e. that even educated guesses are still guesses based on partial knowledge and perhaps intuition. You say you’re not an expert. What you’re implying is that you haven’t done thorough research of the issue of what happens to the relative humidity in a rain forest if global temps go up (and other environmental factors stay the same.)

        I’ll bet that nobody has rigorously done that. I speculate that maybe relative humidity would return to the same level. You don’t think so. I can see your thinking and maybe you’re right. Maybe your guess is better than mine. Good chance of that, I’ll agree. But we’re both just guessing and there ARE an awful lot of interrelated factors that might make us both wrong somehow. 🙂

  3. Doug Lindauer says:

    Here’s a second comment on your article Dr. Wile. The argument that there is a positive feedback mechanism because of decaying material in rain forests would seem to me to be faulty to begin with. I can definitely see that increasing the decay rate would TEMPORARILY increase CO2 in the atmosphere. BUT, there is only a certain amount of that plant material on any forest floor. If the decay rate increased it would necessarily burn through the old material. Eventually it would reach equilibrium, wouldn’t it? And then the decay rate would just match the amount of falling leaves and branches or whatever.

    So there MIGHT be a burst of increased CO2, but then things would return to normal. Also I would think that the increase in temperatures and CO2 would spur the growth of new plants. Since plants convert CO2 back to O2 I have to think that there really is no positive feedback mechanism at all.

    Just my two cents.

    1. Jay Wile says:

      There is already a lot of evidence that increased CO2 has accelerated plant growth. Of course, with more plants, there is also more plant death and therefore more biomass to decompose. It’s hard to know all the long-term effects, but we do know that there is a certain amount of CO2 “locked up” in dead matter lying around. If the decay accelerates, it will add to the amount of CO2 in the atmosphere. As you point out, however, what is there now can only add a finite amount.

      1. Doug Lindauer says:

        Exactly! An actual positive feedback mechanism (in the context of alarmism global warming) would imply a continually accelerating effect which won’t lead to an equilibrium. Seems to me that the amount of plant and animal life will always lead to an equilibrium state, not runaway global warming.

        Will increased plant growth add ANY percentage of CO2 to the atmosphere? I don’t think so (ok, I’m no expert but …) because then the plants USE more CO2. But I suppose I’m arguing from a position of ignorance because I think there are too many variables to make glib statements. I guess it would require differential equations and careful computer simulations.

        Maybe it’s just better to enjoy the warmth and not worry about it. 🙂 Today my average temp at home is around 19 degrees F. Where’s global warming when you need it!

  4. Sandra Bundgaard says:

    Have you considered the difficulty in keeping a closed environment such as an aquarium or terrium in equilibrium? A forest is not a closed environment. Earth is not a closed environment. Also, what about human effects, e.g. burning of fossil fuels releasing carbon dioxide into the atmosphere in such quantities as to increase the green house effect of earth’s atmospheric blanket? Also, what about the stripping the earth of much of its forested areas, where carbon dioxide would be used by plant life?
    There are far too many unknows in this experiment to come to any acceptable conclusion about climate change. Just as you’ve said about conclusions drawn by most of the world’s scientists, I find it to be conjecture based on limited data.

    1. Jay Wile says:

      You are correct that no firm conclusions can be drawn. However, this experiment at least shows that the assumption used in most climate models of a positive feedback when it comes to decomposing matter is definitely not justified.

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