15 August 2006The Roanoke TimesRobert F. Boyd*
Essays on global warming, due to the effects of atmospheric carbon dioxide (CO2), have lately appeared in this newspaper and others with increased frequency. Lest you have been marooned on an Arctic ice floe for the past few years, the cause of this increased CO2 is due to mankind's overuse of fossil fuels. Many in the public are unaware that besides CO2, other components in the atmosphere help control the Earth's temperature. One of those components is the gas methane.
Methane is a colorless, odorless gas that is released in a variety of ways. Cows and termites are major sources of methane. In both instances, the gas is produced as a result of the activity of microorganisms in the digestive tract. In termites, microorganisms in the gut decompose the cellulose found in wood and plant materials to produce methane. That methane is released into the atmosphere.
Although about 60 percent of atmospheric methane is due to the burning of fossil fuels, 11 percent comes from the digestive tracts of termites. It is estimated that another 2 percent result from the activity of microorganisms in the digestive tract of cows. They release the gas when they belch.
Scientists are becoming increasingly troubled at the increased rate at which methane is accumulating in the atmosphere -- an annual rate of 2 percent. The alarm bells are ringing because methane is capable of trapping heat at least 20 times more effectively than carbon dioxide and remains in the atmosphere from 15 to 20 years after it is released.
We already know that the destruction of tropical forests has resulted in the increase of dead plant material on the surface of the soil. This, in turn, has brought about an increase in termite populations and with it an increase in methane.
Another source of concern is the effect of global warming on the Arctic regions. Temperatures in the Arctic have increased by nearly 5 degrees Fahrenheit since the mid-1950s. Computer models predict that the Arctic Ocean's sea ice could disappear within 70 years. The Arctic permafrost (frozen subsoil) is also melting at a surprising rate. Massive amounts of methane have been trapped in the permafrost for millions of years and estimates go as high as 400 billion tons.
If global warming is not contained, we may reach a point where substantial amounts of methane could be released into the atmosphere. This worries many in the scientific community because it is believed that the extinction of more than 90 percent of marine species some 250 million years ago was the result of the release of massive amounts of methane into the atmosphere.
Unless all governments make a concerted effort to reduce deforestation and curb our gluttonous demands for fossil fuels, we as a civilization will not have to be concerned about a nuclear Armageddon. Nature will provide us with an apocalyptic surprise.
* Boyd, of Daleville, was a professor and science writer at Marquette University before his retirement.
