Since the C02 leaving the tailpipes of so many cars is dispersed so quickly, you never even notice the gas. It is invisible and odorless, but it is there.
In the base atmosphere, dry air is about 78% nitrogen, 21% oxygen, 0.93% argon, 0.038% carbon dioxide, and trace amounts of other gases. Air also holds a variable amount of water vapor - about 1% on average.
That 0.038% C02 is in the air naturally from fires, volcanoes and the like. What people all over the planet are doing is jacking up that natural level. The natural level is now around 0.0387% (387 ppm) and rising.
Climate scientists tell us that anything over 350 ppm is bad. They also say that if it rises to 450 ppm, most of the ice in the natural world will melt. So, C02 rising is important, and the subject of the next animation shows how much volume the C02 gas takes up once it has dispersed to a level that causes damage.
The Gas Spreads Out
In the animation below, it is assumed that there is air in the barrels containing 387 ppm of C02, the air we now breathe. Then the car starts, and burns one gallon of gasoline. Again, that one gallon of gasoline makes twenty-three 55-gallon drums of pure C02 gas. However, this time when the gas is allowed to disperse, it spreads out enough to fill 51,136 55-gallon drums with the extra (63 ppm) of C02 need to push that 387 ppm air to the ice melting brink of 450 ppm.
This is enough gas to fill a small warehouse, as depicted in the drawing. So, the next time you hear of humans causing global warming, you know exactly how much: 1 car, 1 gallon, fills 1 big house.
Now that you have the local picture with humans causing global warming, what does this add up to globally? Right now people are putting a total of about 82 million tons worth of C02 into the air every day, about 30 billion tons per year. Interestingly, close to half of that comes from 2 countries, the USA and China.
Another half of the 30 billion tons is adsorbed back into the oceans, planet, or plants. There is after that a 15 billion ton excess of CO2 that just builds up year after year.
This number is just an average estimate and very approximate. There is no accounting for geography or winds, for example. However, It gives you an idea though that people are putting out enough C02 every year to cover the planet 100 meters or 300 feet deep!
One of the big tradeoffs for all of this driving is pollution. One of the bigger forms of that pollution is carbon dioxide, or CO2 for short. CO2 is produced when your car or truck burns gasoline (petrol) or diesel. The C02 is what is causing so called Global Warming. The way the data is presented can be hard to visualize. You will read on many sites that: 1 gallon of gasoline = 20 pounds of C02.
Most, if not all, carbon footprint calculators give your carbon footprint in tons of C02 per year. Except for dry ice, we have never seen a pound or a ton of C02.
If drivers are making all these pounds of C02, where are they? Where does 20 pounds of C02 go, and how does it contribute to humans causing global warming? Below are a couple of animations to show what happens when gasoline is burned in a car engine. (Diesel fuel is the same only it makes even more C02 than gasoline.)
Animations to help visualize CO2 in the real world
We have a few cartoons below to help you see how CO2 gas spreads out in the air. Skip the numbers if you want and focus on the fact that a little gasoline makes a lot of CO2 gas.
In the first (top) animation, the gas engine in the front of the car burns exactly one gallon of the blue colored gasoline in the trunk. As the gas gets burned, the gas goes down as the barrels fill up with PURE C02 gas. The drawing only shows 10 - 55 gallon drums. Actually, one gallon of gasoline will fill about twenty-three 55-gallon drums with pure C02 gas.
In real life, the C02 gas coming out of the tailpipe gets dispersed in the air pretty quickly. The gas is 1.5 times heavier than air and tends to settle, but it doesn't actually fill up a space as small as the 55 gallon drums. They are only for visualization of how much C02 1 gallon of gas makes. There are times when C02 concentrates naturally in low spots. When this happens, it pretty much smothers all plants, people and animals that get stuck in the gas.
In the case of the car, the fact that the gas does get dispersed so quickly makes it not noticeable. That's where the trouble starts with humans causing global warming.
First it should be noted that the warming trend continues. Study after study confirms continued warming, despite politicians and non-scientist hacks. Recent peer reviewed work led by Oregon State University paleoclimatologist Peter Clark confirms that high levels of CO2 provided the energy for the global thaw at the end of the last ice age. This means that in history at least, rising CO2 levels also drive warmer temperatures.
Next, take the term "humans causing global warming." It should be "humans causing global climate change" since it is actually climate change that is occurring. Some places are getting warmer, some colder, and some are about the same.
ON AVERAGE, however, the world is slowly getting warmer. Most people will not notice the difference year to year. It is the average that counts. The term should really be "average global warming" or "average climate change."
Why all of the warming anyway? People love to drive! Drive, drive, drive: some 3 trillion
miles of driving in the US alone in 2008. It's only 141 million miles to Mars.
Humans causing global warming: The term is at once illustrative of a hot planet and
confusing since it's not much warmer than last year in most places. We make it
clear why the term is confusing, and show what is really happening.
Since this is a site about transportation, we will mainly focus on just how gasoline
engines pollute the air with so called greenhouse gases. Industry and other sources actually produce more C02 gas to contribute to global warming.