The biosphere is a complex coupled system and by coupled I mean that parts of it affects other parts which affect the first part back and so on. By complex I mean that the details are not or can not be known. Such system can be analyzed in their equilibrium configuration, basically one removes the time-dependent terms. That usually makes them simpler. For even more simplicity only dominant terms are considered. Also the equations can be linearized.

The interesting thing about dynamical systems is that they have various behaviors for various sets of parameters. Such systems may be remarkably robust over a large range of parameter space that is to say if we change the conditions, the system will not change much. If a critical point is reached, however, the system will change a lot.

Consider a piece of wood. It will be a piece of wood for many different temperatures, but at a certain point it will catch fire and be something totally different. The transition is usually fast (happens over a narrow temperature range).

The violent transition makes it difficult to estimate exactly when the transition will occur. This is because the transition as opposed to the linearized description is abrupt. Humans tend to have a very linearized view of things. If human vision/understanding/imagination was a Taylor expansion most people would be capable of 0th order perception and scientists would be capable first order perception using their mathematical/conceptual models. We do not really have good tools/brains to understand higher orders although they can be computationally simulated.

So suppose we have no concept of fire and we start heating the wood. One would think, well the piece is getting warmer, but it will remain a piece of wood, since that it has always been and if we keep heating it, we’ll merely get a hotter piece of wood. Why now the wood is smoking?! That’s probably some attribute of warm wood, nothing to worry about. If we keep heating all we’ll get is probably more smoke… and so on.

Similarly it is popular to note that humans are very smart, because humanity has solved all its problems in the past and thus it will be able to solve all its problems in the future — implicitly assuming that the humanity’s problems will never grow faster than human ingenuity. What if that is not the case?

Add to this the problem of unintended consequences. Suppose we have a field of corn with some undesired ‘elements’ like corn eating bugs. Now we eliminate the bugs using pesticide. However, some bugs grow resistant (unintended consequence) just like resistant bugs in your home become dominant as you remove their weaker competition with cleaning agents. In the field the sprayed bugs may be eaten by birds who die and thus stop eating bugs (another unintended consequence, this one is of second order). As a result, we now a system which is worse of than before but now depends on pesticide, since we changed it. The problem is the same with the human body, bacteria and antibiotics.

That is to say, if you take a self-adjusting system linearly away from its equilibrium, you usually have to keep adjusting, and your ‘adjustments’ will have to get bigger and bigger until you eventually fail.

The closer you are to the critical point the easier it is to fail. Once a variable approaches it’s critical point the reaction in some other part of the system will become violent. If the violent action can not be dampened, there is going to be trouble. Humans can try to dampen effects, but are they clever enough to dampen them forever?

If this is not convincing consider the economic system. This system was totally ‘written’ by humans and it is much simpler than nature, yet still, crashes (abrupt changes) occur and despite tons of regulations they can seemingly not be avoided. Another example of a human system is the Windows operation system. These are both cases, where humans have built something out of parts that are easy to understand in isolation, but where understanding of the emergent behavior of the complex system that obtains is apparently beyond us.

The worry here is that humans mayare building systems that have the potential to destroy us. The first such system was the mix of the nation-state and nuclear weaponry. The second such system is using fossil fuels both as a source of energy and as an indirect source of food.

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Originally posted 2009-05-29 08:48:33.