Carbon dioxide: the stuff of life.  The stuff plants are made of and animals who eat the plants and animals who eat the animals who eat the plants that eat the... like that.  Carbon dioxide is responsible for 3.5% of the greenhouse effect.  Humans are responsible for 3.7% of the carbon dioxide.  Canada is responsible for 1.6% of the human amount.  Ya, save you the math: we could all stop moving and die and you wouldn't be able to measure it in terms of carbon dioxide.  Other pollutants sure, but who cares about other pollutants now?  It's all the Axis of Carbon now, War on Carbon anyone?