by Whit Gibbons

February 17, 2008

Opinions about global climate change are as polarized as those about whether people should talk on cell phones while driving, be allowed to smoke in privately owned restaurants, or let their pet cats outdoors.

The earth's base temperature has fluctuated over eons or even centuries. That is a verified fact. The dispute arises over whether temperatures are significantly warmer now than they were a couple of centuries ago—warm enough to cause noticeable environmental changes. I find the evidence for climate change convincing. Some talk radio hosts and even some scientists do not. The next arguable point, and there is argument aplenty, is whether the fundamental cause of climate change is carbon emissions from the industrialized countries and whether, if that is true, we should do anything about it.

Arguments at the international level abound. Should countries place controls on fossil fuel use? Should we make a global effort to ameliorate what some view as a serious environmental problem? If so, how should we set about this task? Because of the strong political and personal opinions surrounding this issue, including many self-serving ones on both sides, a satisfactory resolution does not seem to be on the near horizon.

Believing as I do that global warming is a reality, I think we will find out what the consequences of melting polar ice caps and shorter winters really are. But that outcome might be delayed by a natural event: a volcanic eruption of a magnitude that actually affects the world's climate.

All human influences on global warming could be masked temporarily by the eruption of a major volcano. Global cooling from a volcano can occur as a result of sun-shielding by airborne products from the eruptions. The ash, most of which settles to earth within a few weeks, is not the volcanic product that blocks the sun's rays for a long period. Sun-shielding is caused by tiny droplets of sulfuric acid that can remain in the stratosphere for up to three years.

Volcanic activity at the earth's surface has been around since the crust cooled, and it will continue for several billion years. Many people remember the eruption of Mount Saint Helens in 1980, the most destructive volcanic eruption to date in the United States. Other volcanoes have also made lasting impressions, such as Vesuvius, which resulted in lots of mummified bodies in the town of Pompeii. Unzen in Japan and Mount Pinatubo in the Philippines became revitalized in the early 1990s and garnered worldwide attention.

Mount Pinatubo is calculated to have spewed out more than 20 million tons of sulfur dioxide that reached the stratosphere. Global cooling effects from major volcanic eruptions of that magnitude have the potential to confound interpretations of already controversial studies to determine if global warming from human activities is a phenomenon to be apprehensive about.

When Krakatau (sometimes called Krakatoa) erupted in 1833 it had a major influence on the environment. If something of that magnitude occurred today, most news stories about human-caused atmospheric change would seem trivial. Because the earth's temperature would change dramatically, the finger-pointing about global warming would become completely irresolvable.

When Krakatau blew its lid, an eighteen-square-mile volcanic island located between Australia and Borneo disappeared. The sound of the Krakatau eruption was reportedly heard more than 3,000 miles away. Tidal waves were created in southeast Asia, and at least 36,000 people perished in coastal cities. Rocks and ash were reportedly thrown more than 15 miles high. The ash cloud was so thick that villages 150 miles away were in total darkness for days.

Though not as famous as Krakatau's performance, Tamburo's eruption produced even more dramatic environmental results. In 1815 that Indonesian volcano spewed enough ash and aerosols into the atmosphere to create a cold snap. In Europe, 1815 became known as "the year without summer."

A volcanic eruption the magnitude of Krakatau's or Tamburo's would lay all arguments about global climate change to rest for awhile. And we can certainly expect more environmental drama from volcanoes in the future, although no one knows when and where. The results of such an eruption would be spectacular and far reaching. I kind of look forward to it.

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