Don’t blame volcanoes

Re: “Quit picking on the oilsands,” Letter, Aug. 18.

The U. S. Geological Survey estimates that humans emit 135 times more CO2 than all volcanic activity. As well, the net effect of all volcanic activity is short- term cooling. This can be seen in the aftermath of Tambora, Krakatoa, El Chichon and Pinatubo. Jack Dale, Calgary