Global Warming

[Thorne]

3) The release of volcanoes isn't that big of a deal since it's always been like this.

I have to disagree with you on this one. True, the volcanic activity may tend to average out over time, but one very large eruption can have devastating effects. When Mt. Pinatubo erupted several years ago it blew a massive hole in the ozone layer. Scientists were shocked by this, of course, since none of them had predicted it. But they really haven't been studying the ozone layer for all that long, so nobody knows how often this happens. According to the USGS at http://pubs.usgs.gov/of/1997/of97-262/of97-262.html -
"It injected a 20- million ton sulfur dioxide cloud into the stratosphere to an altitude of more than 20 miles. The climactic Pinatubo cloud was the largest sulfur dioxide cloud ever observed in the stratosphere since the beginning of such observations by satellites in 1978. It caused what is believed to be the largest aerosol disturbance of the stratosphere this century, although smaller than the estimated disturbances from the eruptions of Tambora in 1815 and Krakatau in 1883. Sulfate aerosol formed in the stratosphere from sulfur dioxide in the Pinatubo cloud increased the reflection of radiation from the Sun back into space. Consequently, the Earth's surface cooled in the three years following the eruption, by as much as 1.3 degrees ( Fahrenheit scale) at the height of the effect. The sulfate aerosols also accelerated chemical reactions that, together with increased stratospheric chlorine levels from man-made chlorofluorocarbon (CFC) pollution, destroyed ozone and led to the lowest ozone levels ever recorded to date in the stratosphere. Scientists now know that the "smoke" from volcanoes, once attributed by poets to be from Vulcan's forge, is actually volcanic gas, and an important agent of global change."

When Krakatoa exploded in 1883 it sent up such a large ash cloud that it circled the globe. From http://en.wikipedia.org/wiki/Krakatoa -
"In the year following the eruption, average global temperatures fell by as much as 1.2 degrees Celsius. Weather patterns continued to be chaotic for years, and temperatures did not return to normal until 1888. The eruption injected an unusually large amount of sulfur dioxide (SO2) gas high into the stratosphere which was subsequently transported by high-level winds all over the planet. This led to a global increase in sulfurous acid (H2SO3) concentration in high-level cirrus clouds. The resulting increase in cloud reflectivity (or albedo) would reflect more incoming light from the sun than usual, and cool the entire planet until the suspended sulfur fell to the ground as acid precipitation."

These kinds of major eruptions, though not as common as the normal eruptions happening every day, add significantly to global climate change.