posted on Dec, 22 2009 @ 08:42 PM
Philippines Volcano - Global Impacts? Dr. Greg Forbes, Severe Weather Expert
As I write this on Tuesday December 22, a volcano in the Philippines -- Mount Mayon -- is threatening to erupt. It has triggered more than 2000 small
earthquakes as the lava works its way through cracks in the rocks to the Earth's surface, and sulfur dioxide emissions are running about 12 times
normal. Both of these are signs of an imminent eruption. It has had some small lava flows and puffs of smoke in recent days, another sign of an
imminent large eruption. The Mayon volcano poses tremendous hazards in its immediate
vicinity, of several potential types. Past eruptions have been in various forms, some with flowing lava. Some eruptions have been explosive and shot
rocks into the air and down at distances away from the volcano. Some have resulted in destructive mudflows (lahars). And there has even been a nuee
ardente - a destructively fast flow of deadly superheated air filled with a dense concentration of choking dust. Evacuation orders are in effect.
Volcanoes in the Hawaiian Islands, by contrast, are predominantly of the flowing lava type due to a different chemical composition of the magma. Mount
St. Helens in Washington was of the explosive type.
Which form, and how intense, the imminent Mayon eruption takes is not known. But at its extreme it could have global environmental ramifications. If
the explosion is upward and intense enough to send dust and sulfur dioxide particles (aerosols) into the stratosphere (roughly above 50,000 feet), it
could have effects that last for several years.
An explosive eruption of Mount Pinatubo in the Philippines in 1991 was of that type. It resulted in a warming in the stratosphere, and a near-surface
cooling of about a half degree Fahrenheit globally (a fraction more in the Northern Hemisphere) for about two years. The near-surface cooling results
from reflection of sunlight off the dust and sulfate aerosols, so less sunshine to warm the ground and air nearby. Thus, explosive volcanoes are one
way that the Earth can offset global warming.
Those aerosol and dust particles result in some spectacular red sunsets around the globe. But the sulfates in the stratosphere are one of the agents
that can result in accelerated destruction of the ozone layer. A bit more ultraviolet radiation gets through, with its risks of sunburn and skin
So we all have a reason to be interested in the nature of the eruption of a volcano half way around the world! And let's hope for the best for the
Philippines. They have suffered terribly this year from flooding from several typhoons. They don't need another disaster!
Posted at 4:45 pm ET