For a while, I had always put pollution in the same category as greenhouse emissions, simply because to me, the cause and solution to both of these issues were the same. We’re addicted to driving, driving is a cause of pollution and driving causes greenhouse emissions. Some solutions to both of these problems are to reduce how much we drive, increase public transit and invest in hybrid vehicles. True, but after you dig a little deeper you’ll find that it’s not the whole story.
According to a wheels.ca article written by Gerry Malloy,
“The fact is, the auto industry has done more to address the smog issue over the past four decades than any other. The smog-forming gases in the exhaust from new cars and trucks have now been reduced by more than 99 per cent.
In some highly polluted areas, new vehicles are actually said to be air purifiers, in that the exhaust coming out the tailpipe is cleaner than the air going into the engine.
Cumulatively, new vehicles contribute less than a tenth of 1 per cent of Canada’s smog-forming gases annually – an inconsequential contribution.
Conversely, one 20-year-old vehicle, even if it is in top condition, produces as many smog-forming emissions as 37 new vehicles.”
Malloy points out that the problem with pollution and smog is a result of older cars. I can attest to this from visiting China, where it’s common to see very old cars on the road. The entire fleet of police cars in one city I visited was made up of HMC station wagons that appear to be from the 80′s; and trust me when I say that you can smell the pollution when an older car passes you in China. It reminds me of the old days when a black cloud of smoke would come out of the exhaust of a city bus and it would cause you to start choking.
Malloy’s suggestion is to penalize drivers who have old cars instead of penalizing all drivers and for the government to provide incentives for people to get new cars. But Malloy’s article should be taken with a grain of salt. I took David Suzuki’s advice and checked to see who’s paying Malloy, and of course, Mallow is a journalist with 25 years of consulting experience, with a clientele that included “most of the world’s major automakers”. (See his bio).
But Malloy still makes a good point nonetheless, that the majority of pollution and smog is caused by older cars. Smog and pollution is partially caused by Tailpipe emissions, broken down into 1) Hydrocarbons (Causes liver damage and lung cancer), 2) Nitrogen oxides (Causes smog and rain), and 3) Carbon monoxide (Dangerous for people with heart disease), as well as Evaporative emissions, caused by the evaporation of fuel, and Life Cycle emissions, caused by manufacturing, maintenance and disposal of automobiles. 
Global Warming is concerned with the carbon dioxide (CO2) emissions from cars. See this cool diagram that explains the carbon dioxide output of each different method of transportation (including driving, flying, trains and bus). The idea of fighting global warming is to address the issue of individual carbon dioxide output. The Kyoto protocol calls to reduce carbon dioxide emissions, but as we’ve seen Kyoto was unsuccessful since carbon dioxide emissions have increased since the Kyoto protocol was drafted.
Here’s a PDF that has some statistics about Canada’s energy consumption and projection for the future. Look specifically at page 24 (Describes Greenhouse Gas Emissions by Gas and by Sector) and page 30 that describes Greenhouse Gas Emissions by Province.
It’s going to take major lifestyle changes from all people in order to make an impact, and as Suzuki mentioned, now is an exciting time because even the most cynical people are starting to open their eyes.