13 March 2007

What Causes Global Warming?

Did You Know?

For every pound of gasoline your car burns, about three pounds of CO2 come out the tailpipe. So if your car gets 20 miles per gallon, you are emitting about a pound of CO2 per mile.

(For every kilo of petrol your car burns, about three kilos of CO2 come out the tailpipe. So if your car gets 8.5 km per liter, you are emitting about a quarter of a kilogram per kilometer.)

How can the amount of CO2 that comes out be three times the amount of gas that goes in? It's because of the oxygen. Your car uses a lot of O2 to burn that pound of gasoline, and some of that oxygen becomes part of the CO2 emitted. You can review the math here.

So that trip to the store to buy a loaf of bread, bag of dog food, quart of milk or bottle of wine probably put a pound or more of CO2 into the atmosphere. That is likely as much as all the CO2 emitted by all the processes involved in growing, manufacturing and packaging that product, and transporting it to your local store.

That is what causes global warming.

David Wheat's Science In Action site has articles about science and math in the real world, weird science, science news, unexpected connections, and other cool science stuff. There is an index of the articles by topic here.

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1 comment:

CC said...

It would be much more accurate to say that those things contribute to what is called the greenhouse effect. There may be reason to believe that CO2 is not the only reason that we're in a stretch of climate change in which the average temperature is rising. It may be a case of correlation not equalling causation. For instance, there are some suggestions that changes in the sun's activity is indirectly causing fewer clouds, which is a factor in warming the earth. More clouds would act as a wall against the heating of the sun (such as when volcanic clouds lower the temperature for a while), fewer clouds lead to a warmer earth. We don't know the degree of influence of the various components of climate, so it's a bit misleading to say it the way you have.