Sunday, May 3, 2009

Environmental Risk

Here’s an example of how knowledge can sometimes make life more difficult. In the morning, I am often confronted with the question of whether to empty the water out of the teapot and refill it with fresh water. It seems wasteful to dump the water in the pot down the drain, and furthermore that water has degassed its fluorine (although all fluorine probably degasses during boiling anyway). However, the water may have leached heavy metals from the pot while in contact with it for several days, or perhaps bacteria have begun to grow in the water. Also, I am impatient, and prefer to fill the pot with hot water so it takes less time to boil. So I dump the water out and then run the tap water for one minute before filling the pot because water standing in our pipes overnight may have leached metals from our pipes (this is unlikely to be a problem for us, though, because the practice is designed to avoid lead that leaches from solder that connects Copper pipes, and most of our pipes are galvanized steel). Is it better to save energy by using the water already heated in my hot water heater rather than heating cold water on my stove until it boils? Or is it better to save water by not running it until the water gets hot, which in my house takes roughly one minute? There are so many considerations that go into making such a simple decision, that complex decisions can seem overwhelming. Am I overanalyzing every situation? Wouldn’t life be simpler if I always did what was easiest, but perhaps at a slightly higher level of risk? Are the perceived dangers great enough to warrant my concern? Won’t I become unhappy if I have to assess a list of threats for every decision I make? Thinking about the world this way does make it seem to be a dangerous place.

The best approach to this problem of “too much information” is to only concern yourself with the greatest potential threats. The problem is that human perception of risk in the modern world is notoriously inaccurate. Stone Age humans faced essentially the same risks that their ancestors faced may thousands of years previously. Natural selection caused humans to evolve, preparing them to better deal with these risks and reducing their chances of succumbing to those risks. Also, they could pass on survival strategies orally from generation to generation. My guess is that Stone Age humans’ perception of risks in their environment was largely accurate. However, our society and environment is now changing so rapidly that evolution does not have time to prepare us for the many new risks we are faced with. Furthermore, the risks our generation faces are different from the risks faced by our parents, so the wisdom they impart to us is not sufficient, and we have to rely on other sources of information to adequately deal with these new risks. In this new world, how well do our new coping strategies prepare us for risk? Not very well. A famous study published in Science (*v. 236, 1987) examined the perception of risk by groups such as college students and The League of Women Voters. They were asked to rank risk associated with twenty different activities. Their rankings were then compared with the actual risks, defined as the mortality rate for that activity (number of deaths per year associated with that activity, probably normalized to the number of people participating in that activity *check). These two groups rated “nuclear power” as the highest risk, when in reality it was the lowest risk. Studies like this have led to several generalizations about risk perception:

1. We are genetically predisposed to worry about risks, because worrying about risk increases our chances of survival. However, it is possible to worry too much.

2. We tend to overestimate the risk associated with high-impact, low probability events (e.g., nuclear power plant disasters)

3. Man-made risks worry us more than natural ones (e.g., radiation from power lines & cell phones are less dangerous than radiation from the sun)

4. New (unfamiliar) risks worry us more than old risks.

A good example of point 2 is air travel. Many people are so afraid of traveling on airplanes that they refuse to fly. However, per mile traveled, the risk of dying in an automobile is much greater than in an airplane.

So what are the risks associated with global warming, peak oil, and water pollution? We will examine that question in the following chapters.

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