One of the most common pieces of evidence for global warming is the fact that the size of mountain glaciers has been decreasing. A well-publicized example is Glacier National Park in Montana, where glaciers are now hard to see from the main roadway, and where all remaining glaciers are projected to disappear within a few decades, given current trends.

However, there are two aspects of de-glaciation that do not jibe with human-induced global warming.

Data from the World Glacier Monitoring Institute, compiled into graph form by the National Oceanic and Atmospheric Administration (NOAA, see www.ncdc.noaa.gov/img/climate/globalwarming/ipcc18.gif ) indicate that rapid worldwide de-glaciation began in the mid 1800s, decades before any significant contribution to greenhouse gasses due to industrialization.

Furthermore, the data indicate that a number of glaciers have actually rebounded in size since about 1975, at least in the widely distant locales of Europe and New Zealand. Other glaciers have shown a less precipitous decline in the last quarter century, despite the fact that greenhouse gas production has risen considerably.

Do the data on glaciers actually counter arguments for human-induced global warming? That's hard to answer. Glaciation heavily depends on precipitation, a variable that is largely independent from temperature. If global warming results in higher precipitation rates in some regions, then we could--at least temporarily--see a growth of some glaciers.

But because rapid de-glaciation began before mass industrialization, it's justified to imagine that the causes for it may be mostly non-human. Indeed, recent high-profile books on the topic of climate change, such as "The Revenge of Gaia," replete with other intriguing and disturbing information, do not address the anomalies of glaciers, perhaps because they are difficult to reconcile.

On the other hand, because the main trend for glaciers is still downward, and because loss of glaciers should contribute doubly to global warming (since white-colored glaciers reflect solar radiation away from the earth), we should definitely be concerned.

My personal conclusion from all this is that it is important to always question theories. One of the foremost problems of modern civilization is the tendency to jump on cultural bandwagons, one way or another. Such bandwagons unfortunately often tempt us toward rather unrealistic and impractical directions, usually to the profit of various marketers, who are generally the sponsors of the band (in other words, the controllers of the mass media).