Lost in all the talk about global warming, is some simple math that can help you understand the carbon dioxide (CO2) problem more intuitively. The executive summary of this post is as follows:
- Every gallon of gasoline used produces about 20 pounds of CO2.
- A car could produce 20 tonnes or more of CO2 per year.
- The world’s 500,000,000 vehicles could produce about 10,000,000,000 tonnes (10 gigatonnes) of CO2 per year.
- When you factor in all the other uses of fossil fuels, the estimate of global CO2 emissions of 27 gigatonnes per year seems reasonable.
- The entire atmosphere weighs approx 5,000,000 gigatonnes and it is currently about 390 parts per million (ppm) CO2, which would be around 2,000 to 3,000 gigatonnes CO2.
- 27 gigatonnes of human-created CO2 will actually affect the composition of the atmosphere, possibly causing the level to rise by about 1%/year.
- The pre-industrial CO2 concentration is estimated at around 270ppm, we are currently at about 390ppm, almost a 50% increase in 200 years.
- It has been known for 150 years that CO2 acts as a greenhouse gas, in the concentration currently found in the atmosphere. Anyone who says it’s a trace gas or a naturally-occurring by-product of life is misleading you, either deliberately lying or because of their own ignorance.
So far, you don’t need to be a scientist to comprehend the numbers, but the shock comes when you look at the number that scientists are starting to agree on that CO2 needs to stabilize at: 350ppm.
The worst part is that it’s mostly only in the US and Canada that acceptance of these numbers is split largely on political boundaries. Conservative leaders in both countries are absolutely willing to lie to the public to maintain the status quo, and regular people don’t have the ability to do the calculations for themselves. Now ask yourself why they’ve been lying to you – the answer is the same as it was for tobacco: money, politics and “free markets”.
Before the lying, astroturfing trolls get here and accuse me of incorrect science, let me say that I’m just a home dad who put this together in an afternoon of Google research. I’m sure I’ve made mistakes and it’s much more complicated than I’ve shown, but I think you’ll agree that we’re dumping CO2 at a scale that is actually capable of changing the atmosphere. Given that CO2 is a greenhouse gas, even at the current “minute” level, you can see that increasing it without boundaries could have potentially catastrophic consequences.
If you haven’t seen the numbers presented this way, verify them for yourself, learn about the subject and you’ll begin to see how blatantly the misinformation has been propagated. To me, there is no other conclusion but that the people who’ve made this a political issue have miscalculated and our children and grand-children will be paying the price for decades of obstruction. This is not something I’m willing to forgive and I hold you partly responsible (assuming you are what I call a “denier” and I am what you might call an “alarmist”).
I’ll even go so far as to issue a challenge to the despicable, lying, Astroturfing frauds, similar to the one at Greenfyre’s, show me evidence that I’m substantially wrong about any of these basic numbers:
- 20 pounds of CO2 per gallon of gas
- up to 20 tonnes or more of CO2 yearly for a single vehicle, or perhaps 10 gigatonnes for 500,000,000 vehicles.
- total global CO2 emissions of about 27 gigatonnes a year
- total CO2 in the atmosphere about 3,000 gigatonnes
- explain a natural mechanism that accounts for measured increases in atmospheric CO2 since 1959 while somehow excluding the substantial amount of man-made CO2
- provide evidence that CO2 does not act as a greenhouse gas at current levels, and that doubling it (or more) will make no difference to melting ice caps and glaciers, sea level rise, climate patterns, etc.
I don’t want politics (“the lefties just want socialism”), anything about Al Gore (because I hate to tell you this, but regardless of how you feel about his politics, he has the facts on his side and all you have are lies), economics (“it’s too expensive”) or propaganda (“just a bunch of alarmists”), I want evidence, backed by scientific research, not just something that you read on someone’s blog.
However, if you don’t have any evidence, but you still just don’t see the possibility that it’s a problem we’re creating and that we have to get under control, take a stand for your position. Comment below for the rest of us to laugh at your stupidity. Who knows, maybe in 20 years I’ll be eating my words.
“Back of the envelope” calculations:
Generally, the gasoline your car uses is about 90% “octane” (that’s what the octane rating indicates, it’s more complicated than this, but for these calculations, it’s close enough) and 10% “heptane”.
The molecular formula for octane is C8H18, meaning it’s composed of 8 carbon atoms and 18 hydrogen atoms, while heptane is C7H16.
Octane combustion is given by this equation:
2C8H18 + 25O2= 16CO2 + 18H2O
which means that 2 octane molecules and 25 oxygen molecules from the atmosphere combine to produce 16 CO2 molecules and 18 water (H2O) molecules. The result of the reaction is energy released that is used to move the car.
Now, if you look at the “Periodic Table of the Elements“, you can find the atomic weights of hydrogen, carbon and oxygen, which I will round off to 1, 12 and 16, respectively. You can use these numbers to compare the relative mass of the inputs and the outputs:
Octane: 8 C atoms x atomic mass of 12 + 18 H atoms x atomic mass of 1 = 8 x 12 + 18 x 1 = 114
O2 (an oxygen molecule in the atmosphere): 2 O atoms x 16 = 32
CO2: 1 C atom x 12 + 2 O atoms x 16 = 44
H2O: 2 H x 1 + 1 O x 16 = 18
You can verify that the equation balances:
2 x 114 + 25 x 32 = 16 x 44 + 18 x 18
1028 = 1028
This is conservation of mass, and this is the key part that doesn’t seem intuitively obvious to us. We tend to think we put gas in, it’s burned up and “disappears” because we don’t realize the mass of the exhaust. In fact, the equation tells us if you burn 228g (2 x 114) of gasoline, you consume 800g (25 x 32) of oxygen and the result is 704g (16 x 44) of CO2 plus 324g (18 x 18) of water. Expressed another way, for every gram of gas, you consume 800 / 228 (about 3.5g) of oxygen from the atmosphere and produce 704 / 228 (about 3.1g) of CO2 and 324 / 228 (about 1.4g) water. A litre of gas weighs approximately 770g and the resultant CO2 would weigh 770 x 3.1 (about 2.4kg).
For comparison, the combustion equation for heptane is:
C7H16+11O2 = 7CO2+8H2O
You can do the calculations yourself if you want to, but the end result for the purpose of this post is that it’s close enough to the octane equation and it’s a relatively small fraction of the gasoline, so it can be ignored.
There’s the bottom line, 1 litre of gasoline in produces about 2.4kg of CO2 out.
In gallons, 1 US gallon of gas produces almost 20 pounds of CO2!!! Here’s a separate citation for this number.
Depending on your vehicle and the number of miles you drive, you can easily produce 20 tonnes of CO2 each year (for example, assuming 15 mpg x 25,000 miles/year). Using fueleconomy.gov, you can estimate your own annual “carbon footprint”.
That’s one vehicle, multiply that by the number of cars on the road in the world, say 500,000,000 (estimates vary, but we’re looking for rough numbers here), you get 10,000,000,000 tonnes of CO2, just from vehicles, i.e. not including heating and generating electricity from fossil fuels or even burning wood. Current estimates of total CO2 emissions from human activity are about 27,000,000,000, or 27 gigatonnes, per year, so you can see that my numbers are close enough.
Now, the weight of Earth’s atmosphere is 5,000,000,000,000,000 tonnes or 5,000,000 gigatonnes, and it is approximately 390ppm CO2, which would translate to 5,000,000 x 390/1,000,000, or about 2,000 gigatonnes CO2. Here, Wikipedia says 3,000 gigatonnes, so I’ll use that number, but again you can see how close my calculations are.
So there’s currently 3,000 gigatonnes CO2 in the atmosphere, and we’re creating about 27 gigatonnes more each and every year. You might notice that’s 0.9% (27/3000), so if CO2 is increasing by that much each year, then it would seem from these calculations that it’s caused by us. In fact, it’s not even that much. In two years, from July 2007 to July 2009, CO2 went from 384.4ppm to 387.8ppm, >1.5ppm per year, but only an increase of 0.8%.
I’m not a climate scientist, but I think my methodology is close enough, and I believe it shows that the amount of CO2 we’re currently dumping into the atmosphere is actually significant enough to change its composition, which is another point that just doesn’t seem intuitive because we tend to think of the atmosphere as basically infinite. Remember that before the Industrial Revolution, the amount of CO2 in the atmosphere was relatively stable, the natural “sources” and “sinks” more or less balanced each other, the one thing that has changed is us producing almost 30,000,000,000 tonnes of CO2 a year.
We’re currently at about 390ppm, and increasing by more than 1ppm each year, imagine where we’ll be in 10, 50 or 100 years.
At around 600ppm, people perceive the air as “stuffy” and CO2 poisoning starts around 1000ppm. We are in fact on a path to extinction. But the problem is not dying of CO2 poisoning, it’s the greenhouse effect, which John Tyndall discovered in 1859, exactly 150 years ago this year. It doesn’t matter whether CO2 is a naturally-occurring by-product of life or how minute the concentration of CO2 is, the point is, it does act as a greenhouse gas at the level currently in the atmosphere.
In 1896, Svante Arrhenius calculated that if CO2 were to double, it would increase the temperature by up to 6C (almost 11 degrees F).
Any talk about “natural cycles” is also invalidated by this one point: The one difference between past climate changes and the current one is the amount of CO2 we’re creating.
The pre-industrial level of CO2 has been estimated at about 270ppm, so it has already increased by almost 50%. Anyone who tells you the CO2 level hasn’t changed since pre-industrial times is assuming you’re not smart enough to follow the basic math above. They would also have to account for how CO2 went from 390ppm down to 315ppm when measurements at Mauna Kea began in 1959, then has gradually increased back to 390.
Good one
Comment by greenfyre — 2009-09-05 @ 12:55 am
Coming from you, that means a lot to me, thanks
Comment by stone1343 — 2009-09-05 @ 11:10 am