Do the maths on Global Warming

In yesterday's National Post, Lorne Gunter effectively puts the math of man made CO2 and global warming into layman's terms :

Think of the atmosphere as 100 cases of 24 one-litre bottles of water -- 2,400 litres in all.

According to the global warming theory, rising levels of human-produced carbon dioxide are trapping more of the sun's reflected heat in the atmosphere and dangerously warming the planet.

But 99 of our cases would be nitrogen (78%) and oxygen (21%), neither of which are greenhouse gases. Only one case -- just 24 bottles out of 2,400 -- would contain greenhouse gases.

Of the bottles in the greenhouse gas case, 23 would be water vapour.

Water vapour is the most abundant greenhouse gas, yet scientists will admit they understand very little about its impact on global warming. (It may actually help cool the planet: As the earth heats up, water vapour may form into more clouds and reflect solar radiation before it reaches the surface. Maybe. We don't know.)

The very last bottle in that very last case would be carbon dioxide, one bottle out of 2,400.

Carbon dioxide makes up just 0.04% of the entire atmosphere, and most of that -- at least 95% -- is naturally occurring (decaying plants, forest fires, volcanoes, releases from the oceans).

At most, 5% of the carbon dioxide in the air comes from human sources such as power plants, cars, oilsands, etc.

So in our single bottle of carbon dioxide, just 50 ml is man-made carbon dioxide. Out of our model atmosphere of 2,400 litres of water, just about a shot glassful is carbon dioxide put their by humans. And of that miniscule amount, Canada's contribution is just 2% --about 1 ml.