The extra carbon dioxide in the atmosphere amounts to how much in tonnes?

Factual Questions
1

In another thread, I got to thinking about carbon as a building material. And I got to wondering about the excess carbon dioxide in the atmosphere.

If we can figure out a way to use carbon as a building material, and we wanted to bring the CO[sub]2[/sub] levels in the atmosphere back to historical levels, how much CO[sub]2[/sub] would we have to pull out of the atmosphere to do this? Millions of tonnes? Billions? How much oxygen would we get as a byproduct after we split it from the carbon? How much energy would it take?

2

Each part-per-million in the atmosphere is about 1.2 gigatons (billion tons.) Given that we’re about 120 ppm over the pre-Industrial Revolution average (400 now, 280 then), I’d say about 144 billion tons. Once you take those tons out, you’ll be able to harvest a fairly equivalent amount of carbon that’ll come out of the oceans as the atmospheric concentration drops. So start thinking about what to do with about 300 billion tons.

3

We already have a way to use atmospheric carbon as a building material. It’s called a tree.

4

Cool, thanks! It’s a lot more than I was expecting.

Now we just need to figure out what to build with 300 billion tonnes of carbon.

Now, if we can get it as diamond blocks… Wikipedia tells me that diamond has a density of 3.5 g/cm[sup]3[/sup].

So 300 billion tonnes of diamond would take up… lessee…
300 billion tonnes =
3 * 10[sup]11[/sup] tonnes =
3 * 10[sup]17[/sup] grams of carbon.

3 * 10[sup]17[/sup]g / 3.5 g/cm[sup]3[/sup] =
8.7 * 10[sup]16[/sup] cm[sup]3[/sup] =
8.7 * 10[sup]10[/sup] m[sup]3[/sup] =
a cube 4.4 km on a side, if I’m doing my math right. :slight_smile:

5

you wood say that.

6

Aw geez, are you gonna lumber us saps with a bunch of tree puns?

7

Until he leaves.

8

or gets to the root of the problem.