Carbon
The major gas of the six greenhouse gases covered by the Kyoto protocol. It?s so fundamental to measuring total greenhouse pollution that the other 5 gases are referred to as CO2-e, carbon dioxide-equivalent. Before the industrial revolution, CO2 levels were around 280 parts per million in the air; they are now at 385 ppm and climbing every year by a few ppm. Some scientists, including NASA?s Jim Hansen, argue we should not just be slowing CO2 growth, to avoid a climate catastrophe we should be returning it to around 350 ppm. www.csiro.gov.au/science/Climate-Change.html; www.columbia.edu/~jeh1/