more nonlinearities

The Wall Street Journal today published a long story on Malthusian predictions. It is quite an interesting read and it got me thinking again about nonlinear behaviors. Even though such behaviors are all around us, many people find the concept difficult to visualize, and even more find it difficult to be concerned about. Yet all natural systems display significant nonlinearities. And there is one particular form of nonlinear behavior that we should be very worried about. And that is one where you cross an invisible threshold and things become self-sustaining. Let me give an example.

Anyone familiar with medicine knows that certain conditions are caused by toxins and that removing the toxins is essential to curing the condition. But they also know that there is often a point where this simple solution is no longer effective. Even though the toxins are removed, and the patient is no longer exposed, the damage keeps going and eventually leads to organ destruction and death. Such events are relatively rare, but they frighten both doctors and patients. More so because the point of no return is situated somewhere along the path of exposure but nobody knows exactly where or when. Such a phenomenon occurred in a small number of people as a result of a very promising anti-diabetes drug developed by Warner-Lambert, now Pfizer. That drug was subsequently withdrawn. The affected patients required a liver-transplant and many died.

A similar scenario worries climate scientists. We pollute the environment and we assume that, at all times, we will be able to stop and even reverse the damage by some technological means. You could argue that we have done so successfully in the past. There have been times where pollution in big cities was extensive and was remedied effectively by new rules and regulations. Cities like London have better air today than they did at many time periods in the past. The same has happened in Los Angeles and other metropolitan areas. So far so good. At some levels pollution is really a linear phenomenon.

The idea that we can reverse damage when we want to seems like a logical assumption to make. It is a good reason why people feel things will be alright in the end. If pollution really becomes a problem we will have a fix for it. And even if we don't, we can always do something about it then and there. But that may not always be the case. So far the episodes we had to deal with were all pretty confined and local. And the pollution had few secondary effects. It consisted of noxious gases and particles that eventually dispersed or dropped to earth. It wasn't the type of slow accumulation in the atmosphere of gases that had other significant impacts such as trapping heat.

When it comes to greenhouse gas pollution, we are dealing with extensive secondary effects and a global situation. Climate change is a global event. There are fewer remedies available for global effects. There is no place the gases can go. We can think of technological ways of trapping gas, but projects of such magnitude are very difficult to implement. The best we can hope for is to trap greenhouse gases where they are produced. Removing gases from the atmosphere in large quantities is a bit more involved. And it may not help. Once the climate changes significantly, other things happen. These in turn may sustain further warming, even if we should manage to remove all the excess CO2.

We could find ourselves in a situation where we do not know what is driving further changes. And if matters accelerate we may not be able to find a good solution quickly. Or we may run out of time trying to implement it. Such scenarios may sound far fetched, but in effect very little global change is needed to jeopardize our long term survival. You may think we are pretty robust and we are very adaptable, but you better think again. There are good indications that humans are quite fragile and that adaptations take a long time to develop. It may be far easier to change behaviors now. And more effective too.