Posted by
KWG on Monday, June 02, 2008 3:22:43 PM
One of the most famous images in this debate is the graph of correlation of global temperature and amount of carbon dioxide in the atmosphere. While it’s true that there’s a large amount of correlation between CO2 and global temperatures, the relationship is often confused: CO2 levels have lagged behind global temperatures. It has been historically far easier to predict CO2 level changes using global temperature changes rather than the other way around.
The most popular anti- CO2-driven climate theory is the solar theory. When analyzing the data, a far closer and more predictive correlation can be found between solar activity (measured in amount of flares, sunspots, etc.) and global temperatures. And, contrary to the CO2 theory, this correlation works the right way around.
Both of these, unfortunately, confuse correlation with causation. The first thing that any basic statistics class will teach you is the fallacy of post hoc ergo propter hoc (roughly after this, therefore because of this). Just because one event follows another doesn’t mean that they are necessarily causing each other. With the incredibly confusing and complicated climate, it’s no surprise that this simple fact is often forgotten. Both of the theories make intuitive sense (carbon dioxide is hot, so more of it equals a warmer world… the sun is hot, so more solar activity might reflect upon the Earth), but stop at the level of correlation. And, of course, historical CO2-planetary temperature correlation has temperature as the independent variable with CO2 being dependent.
Predictions over what will happen in both the near and far future fluctuate almost as much as historical CO2 levels. Those estimates that have received the most press are often some of the scariest and least grounded in the statistical modular world. We’ve heard biblical end-of-days predictions of drought, famine, pestilence, and wars over scarce natural resources as well as measured-by-inches sea level rises and gently warming coasts. Obviously, the degree of severity with which our planet would warm greatly affects our decisions about what to do about it now. If our affect upon the planet approaches the world-ending calamity that some have predicted, we should obviously spare no expense in planning our survival. However, if the warming is more moderate, careful cost-benefit analyses are needed.
And this is where the global warming picture muddies almost beyond prediction. Predictive climate models are notoriously unreliable and border on random. It’s been much-publicized that, thirty years ago, scientists, the media, and climate models were predicting the same life-threatening global changes, but in terms of a cooling planet. Many counter this objection with the assertion that predictive knowledge and technology is better than the 1970s (true, obviously), and placate this objection with the notion that they’ve got it right this time. However, what we’ve learned over the past thirty years is simply that the climate is so complicated that it is impossible to predict with any authority or absolution. Climate models are at the mercy of an almost-unending string of variables due to the incredible complexity that defines our atmosphere. Changing one or two by the slightest amount often plunges the entire predicted future of our planet into chaos. A cliché holds true here: the only constant is change.