Save the Earth, Sacrifice a Tree!

by Michael Tobis     Department: Earth

Last time, I explained how recent research had shown some of the problems with the artificial volcano approach to fighting global warming. It turns out it doesn't work as well as you might want.

Another concern, which did come up in the AGU session, which was covered nicely by our sister site, WIRED, in an article entitled "Climate Engineering is Doable,  as Long as We Never Stop". The problem is that carbon is persistent and effectively cumulative, and even if a human volcano approach were to work, it would have to get bigger and bigger every year to match the accumulated carbon, even if emission rates stabilized. (Unfortunately, they are still going the wrong way.)

However, there are climate engineering strategies that are very different in character from the artificial volcano. What if, instead of trying to cancel out the ever-increasing carbon-dioxide signal, we endeavored to actually remove the carbon from the air?

This is called the "carbon capture and sequestration" strategy.

The sequestration angle seems pretty much decided.

When this idea first came up there was some talk about injecting the captured CO2 into the deep ocean, but this idea looks infeasible at present. Far more promising is the idea of pumping the CO2 back into the ground in certain rock formations. When  first I heard of this I believed it was nonsense. What would keep the CO2 from seeping back out? But consider this: the natiral gas molecule is smaller than the CO2 molecule (and hence more capable of finding paths up through the rock. Yet n atural gas deposits do exist, containing methane that is many millions of years old! If the natural gas will stay down there, wouldn't the CO2? The experts, some of whom I know and trust personally, assure me that it will.

There are two competing broad strategies for the capture.

One is to capture carbon dioxide at the energy source. This works reasonably well at fixed sources but not at moving vehicles which produce their own energy. That is OK since we are probably going to move fairly quickly to electric vehicles for efficiency and security reasons anyway.

The second is to capture ambient carbon dioxide from the whole atmosphere. This seems at first blush as though it would be much less efficient, but people are making the case that it is possible still leaving a positive energy return on investment on the fuel.

We are left with something of a quandary. Some people think that global warming is a symptom of something fundamentally wrong with how we operate, while others thing it is an unfortunate fluke. People in the first category see it as an opportunity to completely rethink who we are and how we live, while people in the second camp are eager for an escape hatch. The trouble with the first approach is that it is a very tall order. The trouble with the second approach is that, well, there is something wrong with the first idea; nothing grows forever and our whole economic system is based on an assumption of perpetual growth. I think that's ultimately a recipe for disaster one way or another, which puts me in the first "deep green" camp.

But then I have ideas that get me summarily kicked out of the deep green camp.

Can carbon capture work? Yes, it seems unlikely, but think about it. This is actually what plants do. They capture carbon from atmospheric CO2 when they grow. The problem is that they release it when they die and decay back into earth. Chopping down a forest puts CO2 into the air. Regrowing a forest takes CO2 out of the air. A mature unmanaged forest breaks even.

What if we buried some of the fastest growing plants before they decayed?

Some people will object simply on the grounds that this is a violation of nature. But you can turn this argument on its head! Most plants decay back into CO2, but a few of them fall into bogs and swamps. These plants eventually get buried deep within the earth, and form fossil fuels. Burying plants is a way of converting solar energy to fossil fuels! Carbon capture and sequestration in nature!

So is anyone considering this idea of growing plants just to bury them?

But wait! Isn't that what we used to do before we started recycling newspaper? Sort of. The dumps we have are very nasty and dangerous things because we mix evey old thing in them. The less "miscellaneous trash" we have, the less damage we will do because of it, so removing any waste stream from that monstrous flow is a good idea.

On the other hand, now that we do collect used paper, maybe saving a tree is the wrong thing to be doing with it! Maybe we should be collecting the paper and burying it to form fossil fuels for the distant future. Maybe saving a tree isn't the way to save the earth at all! Maybe we should be using up plantation trees as fast as we can. (Of course this isn't to say we shouldn't protect the remnant old growth forests!)

Presuming there's no hole in my analysis, an idea like this would have to battle preconceptions on all sides. I'm not sure it's a great idea, but it is sort of difficult to think about because of all the green righteousness built up about saving paper.

If we're going to get through the future very well, though, we will need for people to get much better at re-examining their preconceptions.

So am I deep green, or technophile, or what? When it comes to preserving a viable planet I am a pragmatist. Whatever works, I say, whatever works!

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