I like.

Umbra,

Do you know how much carbon a tree would 'offset?'

As a hot air balloonist, I am very aware of the "weight" of air.  After all, we fly by filling a balloon with heated air, which weighs less than (but NOT zero) the surrounding air, and therefore floats.  Same principle as a boat--it may weigh a lot, but it's lighter than the equivalent volume of water, so it floats to the top.

Another reason I am aware of the mass  (to use the Science word)of the air is this:  if you ever stand in front of the seemingly weightless balloon as it floats a foot or two off the surface, and it is moving toward you, get out of the way!  It will mow you down like a semi.  The balloon and basket and the people in it have some weight/mass, but the big item is the air inside the balloon--about 3 tons of air!!

If you have ever seen a hot air balloon, here's a way to visualize the "weight" of CO2:  Balloons come in a range of sizes, but I'll use the typical sport balloon her for example, a "size 7."  This balloon contains 77,000 cubic feet of air.  At sea level, 77,000 cubic feet of air weighs 6237 pounds!  CO2 is actually a bit heavier than air, so if I filled my balloon with pure CO2 (at sea level, standard temperature, blah, blah, the gas inside would weigh/mass 9562 pounds, or nearly 5 tons.

Of course, the CO2 in the atmosphere is mixed in with all the other gases.

So there you have it--if you want a visual image, 5 tons of CO2 is just about an (unheated) hot-air balloon full.

The combustion of one gallon of LPG or propane produces 12.64 pounds of CO2 gas.

You might ask why if a galon of propane weighs 4.22 pounds, how can that be. It's because it combines with the oxigen provided by the air.

That is the fuel I displace most when I install solar heaters. A commercial pool 25 x 12.5 meters can produce well over 100 tons of CO2 a year in mild climates.

Out of sight/out of mind?
Here's another way to look at it - a "medium sized" power plant that produces 300 MW a year also produces close to 2 million tons of carbon dioxide a year, which would take a "square" balloon that was over half a mile on each side to hold it.

385 doesn't sound like a whole lot. But when reported in Billions of tons, it does.

It's all smoke and mirrors. It seems probable that generating as much CO2 as we do isn't such a good idea. We probably should reduce that.

Is it an "emergency"? For environmentalists everything is an emergency. Their natural global outlook is negative.

I have profound pity for you. Every freaking question you have been asked recently would probably make a MIT graduate flinch for the calculations you have to explain to us lay people.

Grist should give you a pay raise, medal and vacation for having to answer all of those damn math questions. Bless you!

Solar Greg makes a point similar to my thought here. Let's see-- I fill the gas tank in my car that gets 28 mpg, I drive 28 miles and... HEY, a gallon of gas is missing! Where the heck did it go? Oh that's right-- it went into the air! And it weighed something, didn't it? Solar Greg refines this startling observation to point out that the burning can make my original gallon weigh more than it did as a liquid. But start with the weight of the fuel because it all goes into the air.

Gas is "weightless" only in the simple sense that a kid's balloon doesn't seem to have weight. But this is similar to a water balloon having no weight when you drop it in a swimming pool. The atmosphere is pressing down on the earth just as the oceans do, because of the gravitational attraction between the earth and these fluids. Add more gas to a pressurized tank, and the tank's weight increases. All molecules have mass, and therefore weight.

As a scientist, I'm quite fond of the first paragraph. ;)

Well done on the explanation Umbra, keep it up. :)

"So what is a mole, you badger? If I tried to describe it, all the actual scientists who are still reading this would fall down laughing, so I leave that to you and your own research, dear readers."

A mole is a very simple thing. It is just 6.02 x 10^23 atoms or molecules of anything. It has no units because it is a counting number, like a dozen.

Imagine a dozen carbon dioxide molecules. Then imagine 5.01 x 10^22 of those dozens. That is a mole of carbon dioxide molecules.

Well done, Umbra.  I relish the rodent references.

I also appreciate the equation  CH4 + 2O2 => CO2 + 2H20

CH4 is a hydrocarbon.  We buy the hydrocarbons, which are mostly carbon (75 to 90%) because hydrogen is light.  But CO2 is only 27% carbon by weight.  

So for each pound of fuel you buy, you make about 3 pounds of CO2!  Save a little hydrocarbon, save a lot of greenhouse gas.  

It helps me to think of a gas in terms of gallons. A mole of any gas is 22.4 liters (at "standard temperature and pressure," as scientists say).  According to my calculations, one pound of carbon dioxide equals about 61 gallons.

I've read that burning one gallon of gasoline results in emission of about 19 pounds of carbon dioxide.

This means that burning one gallon of gasoline results in emission of about 1,200 gallons of carbon dioxide.

Something to think about each time you fill up your gas tank.