The Peril Of Major Volcanoes

I realize that we have enough to worry about already. The latest climate report about global warming is the most alarming one yet.

But there is another great peril to civilization that doesn't get much attention. It is the possibility of a major volcano eruption.

There were two great such eruptions in the Nineteenth Century, Tambora in 1815 and Krakatoa in 1883. Both volcanoes were located in what is now Indonesia. In recent memory there has been the eruptions of Mount St. Helens and Mount Pinatubo, but neither of these came close to having the global effects of Tambora or Krakatoa.

The eruption of Tambora threw so much debris into the upper atmosphere, which scattered around the world, that the following year, 1816, is known as "The Year Without A Summer" because the debris blocked so much sunlight.

The colder summer temperatures caused by the reduced sunlight caused devastating harvest failures across the world. The year 1817 became known in northern Europe as "The Year Of The Beggar". The change in climate, accompanied by vivid red skies and spectacular sunsets, lasted about three years until the dust released by the volcano settled to earth.

This scenario was repeated, late in the Nineteenth Century, with the eruption of Krakatoa which was almost as powerful as Tambora. The global temperatures were lowered until the dust released by the volcano settled back to earth. The eruption of Krakatoa, in 1883, is especially known for the shockwaves that it produced, which were felt thousands of km away.

Great tsunamis were produced by the eruption of Krakatoa, which echoed across the world. As with Tambora the eruption reddened the sky and produced brilliant sunsets, which caused many false alarms of forest fires in New York State. The sky is usually blue because only small particles of dust can stay aloft, which reflect the short-wavelength blue light. But a massive volcano eruption puts larger dust particles in the atmosphere which, until they settle back to earth, reflect the longer-wavelength red light.

Disastrous harvest failures caused by great volcanic eruptions have taken place throughout recorded history. Around the year 1600 Russia is believed to have lost about a third of it's population because of a volcanic eruption in far-distant Peru.

There is, of course, absolutely nothing that humans can do about a pending volcanic eruption. But, like the great solar storm known as the Carrington Event in 1859 which would fry the sensitive electronics that we are utterly dependent on across the world if it occurred today, no eruption on this scale has occurred since Krakatoa in 1883.

Volcanoes vent heat that is trapped inside the earth. There is still heat from when the earth was formed, which would have long since radiated away if it was at the surface. Radioactive elements release energy upon decay and this is always going on inside the earth and the energy stored up as heat. 

The moon was once volcanic but being smaller than the earth means that it has a much greater surface-to-volume ratio than the earth. This allowed the moon's internal heat to radiate away into space and the moon is believed to be now volcanically dormant.

There are well-established volcanic zones around the world, but that does not preclude an eruption in an unexpected place. There is a vast reserve of magma, molten rock, beneath the western U.S., which provides the heat for the hot geyser, known as Old Faithful, in Yellowstone National Park.

But, as we can see in the examples of Tambora and Krakatoa and the earlier volcano in Peru, it doesn't really matter where the volcano is located for it to have a devastating effect on global agriculture, because the dust that it throws into the upper atmosphere and which blocks the sunlight gets scattered around the world.

The one advantage of such a major volcanic eruption world be, of course, at least a temporary reversal of global warming.