Thursday, May 18, 2006

Up one side -- scientific ignorance part 1

Ignorance of science, of the actual realities of the scientific method and scientific logic, and even of the factual knowledge generated by the scientific method, is endemic these days. I have come to expect that from my science phobic, religiously conservative students who fear learning any real science will damn them to an afterlife in hell fire. But what really gets me is when it shows up in people who actually claim the mantel of science.

Take Michael Crichton, graduate of Harvard Medical School, but best known as author of such blockbusters as The Andromeda Strain and Jurassic Park, and more recently State of Fear. The primary thesis of State of Fear (which reads more like a master's thesis than a compelling thriller) is that international discussion of global warming has far outstripped scientific knowledge and is primarily driven by political ambitions rather than by actual knowledge. One would be hard pressed to call it an "anti-environmentalist" tract since the overriding message of the book is that a lot more money should go into environmental research -- a conclusion with which it is hard to find fault.

What struck me about State of Fear however, is the lack of understanding of scientific reasoning demonstrated by Crichton. Although there were a number o f examples, one in particular has stayed with me for two years. This is the first novel I've ever read that has charts and diagrams in it with footnotes, and it is Crichton's interpretation of two of these charts that is problematic. One chart shows the steadily increasing (from the 1950's to the present) measurement of concentrations of CO2 in the atmosphere. [One of several sites where a cumulative graphic representation of CO2 concentrations similar to that used by Crichton can be found is]. The other show the more variable, but over all increase in world wide average temperature from 1880 to the present [if you've never seen this iconic graph check out the copy of it on the EPA's Global Warming (oops, sorry "climate change") page]. The graph of atmospheric CO2 concentrations shows a stead, uninterrupted, increase in concentration of the gas in the atmosphere over the past 60 years; the graph of average global temperatures, while showing an overall trend over the past 125 years of increasing temperature, shows significant year to year variations, and even a short period, centering around the 1960's during which the trend of global average temperatures went down slightly (before returning to an overall upward trend in the 1970's. Now here is Crichton's stunning piece of nonscientific logic from State of Fear: Because the two trends are not identical, year for year, the amount of carbon in the atmosphere can not possibly be a "cause" of the climatic temperature. Scientists, are you listening here -- unless you can show an exact, constant, never varying correlation, between your x variable and your y variable, you can never claim that x could be a cause of y. Unfortunately, this specious argument will sit quite well with the vast majority of scientifically illiterate Americans.

There is however, a simple, common sense way to demonstrate the flaw in Crichton's argument.
Ever since reading it two years ago, I have imagined having a conversation with Crichton, in front of an audience of undergraduate students, that would reveal to those students the scientific and logic flaws of Crichton's arguments. Since I am a lowly, unknown, community college faculty member in rural Kentucky, my chance to go head to head with Crichton are pretty slim. So I have decided to satisfy my urge by imagining how such a conversation might go.

Greer-Pitt: Dr. Crichton, as I understand your point, you contend that increasing CO2 concentrations could not be a cause of increases in global average temperatures, because, while CO2 concentrations have increased steadily, during the same time average global temperatures have risen, but not steadily, and global temperatures have even shown short periods of cooling before returning to an overall pattern of rise.

Crichton (in my imagination): Yes, Dr. Greer-Pitt, this is true. I point out in State of Fear, that for CO2 concentrations to have been the cause of the rise in temperature, that these concentrations also would have had to decline during those years of temperature decline.

Greer-Pitt: Dr. Crichton, like everyone else who lives in the northern Hemisphere, I'm sure that you have noticed, year after year, that the average temperatures in January are cooler than the average temperatures in June?

Crichton: Well, in California, we do some times have a warm sunny day in January, and a cool, foggy day in June.

Greer-Pitt: Indeed. But I'm talking about average temperatures. Would you not say that on the whole the average of temperatures (both highs and lows) in January are generally lower than the average of temperatures in June?

Crichton: Certainly. It is the difference between winter and summer.

Greer-Pitt: I'm so glad you brought up the issue of seasons, of winter and summer. What would you say is the primary cause of the passage of the season, the primary cause of cooler temperatures in winter (January) and warmer temperatures in summer (June).

Crichton: As almost any American school child can tell you, seasonal change is caused by the tilt of the earth's axis. As the earth revolves around the sun, the north pole (since we live in the northern hemisphere) alternatively points towards the sun (during the summer) and away from the sun (during winter). This tilt in the axis affects the amount of time that sunlight shines on the northern hemisphere, and how directly that sunlight falls. We notice this in the changing length of days. Winter days are shorter (less sunlight) and summer days are longer (more sunlight).

Greer-Pitt: So you would say that the tilt of the earth's axis and the amount of sunlight falling on the surface (both in terms of the hours of the day and how directly the suns rays fall) are the root cause of the temperature differences that we in the northern hemisphere see between winter and summer?

Crichton: Certainly. But you know that weather and the actual temperature of any day, vary considerably due to a variety of factors such as the winds, cloud cover, and moisture content.

Greer-Pitt: Excellent point. In fact, as we trace the change in temperature from January to June, we don't always see a smooth upward rise in temperature do we?

Crichton: Certainly not. It is not at all unusual for a week or two in May to be cooler on average than the month of April.

Greer-Pitt: We in Kentucky call that common cold snap in May "Blackberry winter" because it seems that often we get a cold snap that coincides with the blooming of the blackberry vines.

Crichton: Weather is a very complex phenomenon, with many factors contributing to daily temperatures.

Greer-Pitt: Yet, you would still say that there is an overall rise in temperature from January to June?

Crichton: Certainly.

Greer-Pitt: And you would also say that this overall rise in temperature is caused by the tilt in the earth's axis and the amount of sunlight hitting the northern hemisphere?

Crichton: Yes.

Greer-Pitt: Would you say that the length of day (length of sunlight hours) and amount of sunlight increases in a regular, continuous manner from January to June 21 or 22 (the first day of summer)? There are no periods of fluctuation in which the earths axis changes its direction or that the day light hours decrease even slightly during that period?

Crichton: Well, cloud cover may limit our ability to see the sun on some days. But no the earths axis doesn't change direction.

Greer-Pitt: And the cloud cover doesn't change the overall increase in sunlight time and strength does it?

Crichton: No.

Greer-Pitt: So to summarize, you would say that the primary cause of the passage of the seasons, and the average increase in temperature from January to June in the Northern Hemisphere is the tilt of the earth's axis and its impact on the length of days and amount of sunlight hitting the northern Hemisphere.

Crichton: Yes.

Greer-Pitt: And you would say that this was so, even though the phenomenon of the axis tilt and amount of sunlight change in a consistent way, while the actual average temperatures of the weeks from January to June although on a general upward trend fluctuated considerably producing periods (from days to weeks ) in May and June that are cooler than February or March or April? You are saying that it is possible for there to be a cause that is constant and steady in its progress, while the consequence is less constant and more variable?

Crichton: Yes. Because observed weather, even if it has long term regularities like seasons (winter and summer), is a complex phenomenon, and the weather on any given day is the result of both the long term seasonal trend and factors such as wind, clouds, and moisture.

Greer-Pitt: And you would not argue that for axis tilt and amount of daylight to be considered the primary causes of seasonal change, they would have to vary exactly has the daily temperature varied? You would not discount axis tilt and day light hours as an overall cause of June being warmer than January just because the axis didn't wobble or the day light decline during "Blackberry winter"?

Crichton: Certainly not.

Greer-Pitt: Exactly. There is no requirement in science that there be a one to one correspondence between a causal factor and its consequence. As complex as weather is, climate is even more complex. But within that complexity we can identify basic causal factors. Increasing CO2 concentrations can be the cause of an overall increase in global average temperatures, even though it continued to rise during short periods of temperature decline. Just as we can say increased hours of sunshine are the cause of overall increase in seasonal temperatures, even though the hours of sunlight continue to rise during short periods of temperature decline (such as Blackberry Winter). While there may be other types of evidence that cause us to question the role of CO2 in global warming, one argument we can rule out is the lack of an exact one to one correspondence between the steady rise of CO2 and the more erratic, but still overall rise in global temperature.

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