It’s not an open loop system

In control systems and electronic amplifiers engineers design things to be self correcting. Think of the simple control system for the heating system in your home. You set the thermostat to a particular temperature and it will turn the heat on it if gets too cool and off when it reaches the desired temperature. This is a closed loop system. There is a sensor which provides information about the current status of the system and this information is used to control the heat source and keep the temperature within acceptable limits. The system has a feedback loop from the output (the room temperature) back to the input (the heat supply).

Without such a feedback loop it would be very difficult to maintain a system at a stable temperature. When the outside temperature changed the inside temperature would change too. If someone left a window open the interior temperature would change.

I have often thought our planet must have one or more feedback loops to maintain it’s temperature at something very close to the same (averaged the entire surface over the entire year) temperature. I knew one feedback loop, which the climate change people seldom, if ever, mention, was that plants are CO2 starved. At our current concentration of about 400 ppm of CO2 in the atmosphere it’s not easy for the plants to absorb and then pull the carbon apart from the oxygen to build plant matter. In fact, at current atmospheric pressures, photosynthesis shuts down at between 150 ppm and 200 ppm. As atmospheric CO2 increases plants grow faster. Faster growing plants mean more energy is absorbed from the sun, reducing atmospheric heating, and more CO2 is absorbed from the air. Hence the green house effect, atmospheric warming, from increased CO2 is counteracted, at least in part, by the feedback mechanism of increased plant growth.

There are other feedback systems as well. One of which only very recently was discovered:

According to a study by the Institute of Catalysis and Environment in Lyon (IRCELYON, CNRS / University Lyon 1) and the Leibniz Institute for Tropospheric Research (TROPOS), the oceans are producing unexpectedly large quantities of isoprene – a volatile organic compound (VOC) – which is known to have a cooling effect on climate.

Our planet temperature is not an open loop system. If it were then the global warming/cooling climate change people would be right to be concerned. But it is, almost, obviously not. Closed loop systems are much more difficult to upset and are much more stable. We have a closed loop system with many feedback loops. These loops make the system extremely difficult to model but don’t tell me climate is changing until you can explain to me how the inputs to the system have the potential to break the feedback loops which stabilize the temperature.


9 thoughts on “It’s not an open loop system

  1. The question is, how sensitive are the various feedback mechanisms? We know the world has been both warmer and cooler than it is currently. So there’s some range of variation that is not corrected. It’s plausible that the excess greenhouse gas emissions produced by humans have nudged that thermostat up a few degrees.

    Not that I think the solution is massive government intervention, but that we should take increased global temperature and its likely consequences into account in our own planning.

    • There is always an error term in the feedback loop equation. In this context the error is the difference between the set point and the actual output (the temperature you set the thermostat to versus the actual temperature). So, yes, I completely agree with, “there’s some range of variation that is not corrected.” But, at least in the statements via the MSM, I never here mention of a feedback system at all. I suspect these feedback mechanisms may account for the inability of the people making the models have much success. In the 1970’s they were predicting cooling. Then warming, then when the warming stopped they just said, “Change”.

      Also keep in mind that even single loop controls systems are easy to make unstable. In fact that is how you make an oscillator–with feedback. The system may oscillate without any input from humans. Look at all the ice-ages and the great range of atmospheric CO2 even before the industrial age. Until they understand the entire system much better it is very difficult to correctly claim humans are creating climate change above the noise level of what the system does on it’s own. And even we were, before demanding we undo any change we are making, they need to demonstrate that change is adverse to human interests. Preventing another ice age and 100 foot glaciers over most of Canada and part of the U.S. would seem to be good thing, if that is what is coming, instead of most glaciers melting off.

  2. The concepts discussed are far too complicated for the typical leftist who
    buys into the “AGW” con game. These are the same people who believe
    that it is possible for the government to ‘spend us out of debt’.

  3. How about links to your sources of information on the various “feedback loops” mentioned. I would like to see your source material.

    BTW, I was planting Spring bulbs here in northern MN during the 3rd week of December. In unfrozen ground. No one around here over 40 questions that our weather is a lot warmer on average (and less predictable) than it used to be.

    “Climate is what you expect, weather is what you get”

    • I second this recommendation. I particularly like his investigations into tropical cloud formation as a nearly instant feedback mechanism.

      Short version: Dark ocean water absorbs the sun’s heat efficiently (they have a low albedo). Clouds are shiny and reflect the suns heat efficiently (high albedo). When tropical water warms up enough, you get increased evaporation and convection, resulting in clouds reflecting away more incoming heat, effectively capping tropical warming. Hence the “traditional” afternoon thunder-clouds. When events (such as volcanic eruptions) decrease warming rates because of arasols and particulates, thundercloud formation happens later in the day, giving the sun’s rays more time to heat the ocean.

      That is one of many basic things that current global climate model do not even attempt to include. That’s right: the models don’t include a near-instantaneous negative feedback mechanism.

  4. My undergrad concentration and the one semester I spent working on an MS were both in feedback control systems. Whether you’re talking about the earth or the movement of an aileron actuator, feedback loops are feedback loops. There are certain fundamentals that apply to the overall general behavior of the system.

    First and foremost among these is that if the net sum of the feedback loops is positive, the system will in general trend towards instability. The problem in climate modeliing is that they all assume the net sum of the loops is positive. That’s why their models consistently overpredict temperatures even at CO2 concentrations that are lower than observed. They’ve engineered models from the ground up to be wildly unstable in their outputs.

    Empirically we know this in incorrect for a number of reasons. First is there have been periods of history where CO2 concentrations were higher but temperatures were not higher to the relative magnitudes they predict. Secondly is their simple inability to make accurate predictions. Whenever we designed a model, we would tune it to match observed behaviors, perform test runs of both the modelee and the model and compare. The gold standard was to predict the behavior of the modelee beforehand. If you didn’t meet that standard your model was wrong.

  5. One more thing. Nature trends towards stability by and large. There are very few natural processes that are fundamentally unstable with positive feedback loops. One that everyone is probably aware of, along with it’s results, is nuclear fission…..

    • Nuclear fission — in some settings, yes. But I think not so, in some reactor types — doesn’t the fission rate have a negative temperature coefficient?
      Anyway, I’d apply the anthropic principle here: it’s obvious that the overall climate feedback system is stable — because if it were unstable, temperatures wouldn’t be consistent enough to support life.

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