The Australian, Weekend Review, August 13-14, p. 4
Was surprised to read that according to Jane “when Mt Pinatubo erupted in the Philippines in 1991 it threw out more greenhouse gas into the atmosphere than the entire human race had emitted in its entire time on earth”. Googled this phrase and its part of a climate denying email going around.
Do volcanos emit more CO2 than human induced causes? No. “Human activities, responsible for a projected 35 billion metric tons (gigatons) of CO2 emissions in 2010 (Friedlingstein et al., 2010), release an amount of CO2 that dwarfs the annual CO2 emissions of all the world’s degassing subaerial and submarine volcanoes (Gerlach, 2011).” http://volcanoes.usgs.gov/hazards/gas/climate.php
Pinatubo did have a measurable effect on global climate temperatures through SO2 emissions. “The 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 in the twentieth century, though probably smaller than the disturbances from eruptions of Krakatau in 1883 and Tambora in 1815. Consequently, it was a standout in its climate impact and cooled the Earth’s surface for three years following the eruption, by as much as 1.3 degrees at the height of the impact. ” http://volcanoes.usgs.gov/hazards/gas/climate.php
In effect Pinatubo did cause a dip in the overall trend for increasing global temperatures. Regrettably, volcanic eruptions with SO2 emissions of the size of Pinatubo are not common.
see also article here http://www.agu.org/pubs/pdf/2011EO240001.pdf
You can see a longer analysis of Jane Fraser’s piece here http://scienceblogs.com/deltoid/2011/08/the_australians_war_on_science_71.php
Friedlingstein, P., Houghton, R. A., Marland, G., Hackler, J., Boden, T. A., Conway, T. J., Canadell, J. G., Raupach, M. R., Ciais, P., and Le Quéré, C., 2010, Update on CO2 emissions, Nat. Geosci., v. 3, n. 12, p. 811–812, doi:10.1038/ngeo1022.
Gerlach, T.M., 2011, Volcanic versus anthropogenic carbon dioxide: Eos Trans. AGU, v. 92, n. 24, p. 201-202. (http://www.agu.org/pubs/pdf/2011EO240001.pdf)
…”You are entitled to your own opinions — but not your own facts”