“Do I need to pay attention to this?” Asked Mrs R. as she ate her lunch.

I was a bit offended. I had been speculating aloud on how much carbon the beech tree outside contained and whether it was more or less than the carbon produced by the car during one year of commuting.

I was about to start calculating the size of forest that would be required to offset my entire working life. I would have needed to use a calculator if I wanted to be accurate, but this was probably not required. Especially since Mrs R. was clearly in no mood to help me estimate the weight of the beech tree, including the roots but excluding the leaves because they fall off every year and I couldn’t guarantee whether or not their carbon remained captured.

My speculation had been triggered by a news story about cloning giant redwood trees to help offset CO2 emissions in the United States. In particular I was interested in a statement that the trees were mostly comprised of carbon… But now that I have had time to think about it, I’m sure that a lot of the weight of a tree is water, not just carbon. After all, charcoal is much lighter than the same volume of fresh wood.

At breakfast tomorrow I will see if Mrs R. is interested in helping me calculate how much the beech tree would weigh if we dried it out. I’m sure that we can devise an experiment involving some twigs, the kitchen scales and the oven.

7 Responses to “Laboratree”

  1. 1 Graham


    I was reading an article about this a couple of weeks ago and managed to find it again, here are the figures from the article.

    “Each person in the U.S. generates approximately 2.3 tons of CO2 each year. A healthy tree stores about 13 pounds of carbon annually — or 2.6 tons per acre each year. An acre of trees absorbs enough CO2 over one year to equal the amount produced by driving a car 26,000 miles. An estimate of carbon emitted per vehicle mile is between 0.88 lb. CO2/mi. – 1.06 lb. CO2/mi. (Nowak, 1993). Thus, a car driven 26,000 miles will emit between 22,880 lbs CO2 and 27,647 lbs. CO2. Thus, one acre of tree cover in Brooklyn can compensate for automobile fuel use equivalent to driving a car between 7,200 and 8,700 miles.”

    I’m not sure how accurate these figures are but I think it’s safe to say, your beech tree is going to need some friends.

    • 2 ann

      I suspect this solution requires a far bigger garden than I have! Can someone calculate how much of the earth’s surface needs to be covered to compensate for all the vehicle miles driven annually? I’m interested to know if it is more than 100% (but not interested enough to actually calculate it!).

      • 3 Graham

        I’m not sure why I started this but I’ve had a stab at the calculation you asked for, so here goes, but remember these are estimated figures.

        The surface area of the earth is 510,000,000 square kilometres which is 126,023,000,000 acres. There are 7,000,000,000 people on the earth each producing 2.6tonns of CO2 per year and that would take about 1 acre of trees to compensate, so we only need 7,000,000,000 acres of trees, which is a very small proportion of the earths surface. However, the earth currently only has 9,800,000 acres of trees so we need another 6,990,200,000 acres of trees to have enough to compensate for all the CO2 created by us humans.
        I just remembered that a large portion of the earths surface is covered in salty water which most tress don’t like, so that needs to be taken into account.

        Sorry Alex to have taken up so much of this blog, I’m off for a lie down and rub down with the Radio Times.

    • Graham – this is why I like blogging. There is always someone smarter and more well-read who can shine a light in the darkness! Thanks 🙂

      BTW I expect that the tree calculation also depends on where in the world the trees are growing. My beech tree hasn’t seen much sun this year.

      • 5 ann

        Thanks to Graham for the calculation, actually less trees in proportion to surface than I had thought. But still an awfully big number which makes me thinking planting the odd one or two won’t achieve anything measurable, even if all Alex’s blog readers do it. I guess mangrove swamps probably count and are OK with salty water.
        Alex – would your beech tree like to be a beach tree to get more sun? Though I suppose it really wouldn’t like the salt water.
        I seem to be going off on a tangent tonight, but if we have more global warming we will use less heating and therefore emit less carbon so have less global warming and use more heating and emit more carbon ad infinitum keeping things on an even keel. But I have a feeling there is a big flaw in this argument somewhere!

  2. Don’t forget that if the average US person produces 2.3 tonnes the world-wide average will be considerably lower.

  1. 1 Pi-eyed « Alex's Blog

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