by Whit Gibbons

July 2, 2017

Opinions about global climate change are more polarized than those about whether to let your cat outdoors. I find the evidence for climate change convincing. Many talk radio hosts, some politicians, even a few scientists do not.

The earth's base temperature has fluctuated over the centuries and has trended upward during the last one. This is an accepted fact. The dispute begins with the question of whether temperatures have risen enough to cause noticeable environmental changes and rages on from there. Is the fundamental cause of climate change carbon emissions from industrialized countries. If so, should we do anything about it?

The United States’ decision to withdraw from the Paris Climate Agreement has led to arguments and ill will at state, national and international levels. Should controls be placed on fossil fuel use? Should we make a worldwide effort to mitigate what some view as a serious environmental problem? If so, how? Strong political and personal opinions surround the issue. A satisfactory resolution does not seem to be on the horizon.

I think global warming is a reality, and humans will learn firsthand about the consequences of melting polar ice caps, shorter winters and longer summers. But that outcome might be delayed by a natural event: the eruption of a major volcano. A volcanic eruption of a magnitude that affects the world's climates could temporarily mask all human influences.

Global cooling from a volcano occurs when airborne products from the eruptions shield the earth from the sun’s rays. Volcanic ash, most of which settles to earth within a few weeks, is not what blocks the sun's rays for a long period. Sun-shielding is caused instead by tiny droplets of sulfuric acid that can remain in the stratosphere for up to three years.

Volcanic activity at the planet’s surface has been around since the earth’s crust cooled and will continue for a few more billion years. The 1980 eruption of Mount St. Helens in the Cascade Range of the Pacific Northwest was the most memorable destructive volcanic eruption in the United States.

Volcanoes elsewhere have also made lasting impressions. Vesuvius resulted in lots of mummified bodies in Pompeii, Italy, nearly 2,000 years ago. In 1792 landslides and tsunamis following the eruption of Mount Unzen in Japan killed thousands of people. Mount Unzen came to life again in the early 1990s. The eruption of Mount Pinatubo in the Philippines in 1991 garnered worldwide attention not only because of the loss of life but also because of global cooling – some estimates are almost 1 degree Fahrenheit. Spectacular sunsets could be seen for months.

The effects of global cooling from momentous volcanic eruptions would confound interpretations of already controversial studies about whether human activities are a significant cause of global warming. The eruption of Krakatau in 1833 had a major influence on the environment.

When Krakatau blew its lid, an 18-square-mile volcanic island between Australia and Borneo disappeared. The sound of the eruption was reportedly heard more than 3,000 miles away. In Southeast Asia more than 36,000 people died. Rocks and ash were thrown 15 miles high. The ash cloud was so thick that villages 150 miles away were in darkness for days. A long solar eclipse. If something of that magnitude occurred today, news stories about human-caused atmospheric change would seem irrelevant.

In 1815, the eruption of the Indonesian volcano Tambora spewed enough ash and aerosols into the atmosphere to create a cold snap that led to Europe’s “year without a summer.” Another Krakatau or Tambora would lay all arguments about global climate change to rest for a while. We can certainly expect more environmental drama from volcanoes – but when and where?

The results of such eruptions would be spectacular and far-reaching. Because the earth's temperature would change dramatically, the finger-pointing about global warming would become completely irresolvable. Whatever else happens, a cooling of the rhetoric is something to look forward to.

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