Tree Debt

Lately I’ve been listening to some talks on climate change, such as this one by Prof. Kevin Anderson, and the news, not surprisingly, keeps getting worse. Anderson discusses many factors that have generally been ignored in official reports that claim to chart a course forward on the climate, including: a) a limit of 2C of warming is no longer really possible based upon the assumptions that they make, b) that 2C was probably the wrong target anyway, c) major reports make very unreasonable assumptions about how quickly emissions can turn around, d) we need to decrease carbon emissions by 70 percent by 2020 to stay below 2C (if we’re serious about that target), and e) 4C is more do-able as a target but also can’t support large-scale agriculture and thus civilization.

Anderson’s and other talks have led me to conclude that:
a) large-scale demand-side changes are really the only option to deal with climate change in the time we have,
b) peak oil will help with that, but the zeal to find new sources of oil/coal/gas will keep peak oil from really being a ‘solution’ to climate change (consider the crazy in-progress moves to drill for oil in the arctic), and
c) the demand-side decrease, however it is implemented, would cause in the near-term (the next decade) a major economic shock.

So my new summary for our predicament is (which hasn’t changed all that much, I suppose), in the vein of the CAP theorem, “Climate or Economy: pick half of one”. That is, if we continue business as usual, and even mine more coal, drill for more oil, etc. we’d be able to keep the economy hobbling along, though peak oil will probably prevent significant economic growth, and we’d fry the climate beyond all repair and that would in the medium and long term cause the economy (and civilization) to collapse. On the other hand, if we downshift demand massively, then the consumer-driven economies of the world will go into a massive (though hopefully temporary) depression, and we’ll still have to deal with warming that’s already in the pipeline. (Not to mention the particulates issue, which is a nasty double-bind in which ending coal use causes warming by removing light-reflecting soot.) Despite these both being bad, the latter still seems like the better one.

I’m in agreement with many prominent thinkers that the right way to approach this problem is to decrease demand by putting a price on carbon. But that’s hoping for a political settlement that may or may not happen in the time we have. As such, I can’t help but feel that we as individuals can and should do more, say in the form of local terraforming that I wrote about previously.

So, in that spirit, I want to answer the following (surely not novel) questions. How many trees would I need to plant to make up for the carbon I directly or indirectly put into the atmosphere? How many trees would we, collectively, as humans on Earth, need to plant to at minimum consume the carbon we put into the atmosphere on an ongoing basis? In other words, what’s my personal, and our collective, tree debt to the planet? (And this is just the Carbon-centric view. Planting trees has so many other benefits: restoring local ecosystems for other plants, and for animals and fungi, holding water in the soil, restoring soil structure, providing food for humans and non-humans, providing shade, regulating local temperatures, restoring natural beauty, etc.)

I’m sure there are good official estimates someplace, but let’s do a simple back of the envelope calculation. Let’s say that a mature tree (say an oak) absorbs about 10 kg of Carbon each year (I’ve seen figures both higher and lower than this, but in this range), and that its lifespan is in the hundreds of years (effectively forever for our current discussion). And for simplicity let’s ignore the sapling phase in which the tree is small and thus isn’t really absorbing as much Carbon annually.

Currently humanity is emitting over 10 billion tonnes (metric) of Carbon each year. That’s 1 trillion trees worth of Carbon absorption. (I’ve looked for estimates of the number of trees on Earth, and haven’t found a good source. I’ve seen huge ranges in estimates, from 1-200 trillion trees on Earth.) Let’s say that each of the 7 billion people on Earth were to plant trees, over the next 10 years. That works out to 14 trees per person, per year for the next 10 years. That’s not bad—about one a month! Of course given that some of us use far more energy than others, we should be planting more trees than that. (Using the 80-20 rule—that is, 80% of the Carbon is caused by 20% of the people and therefore so should the tree planting—it works out to 800 billion trees over 10 years by 1.4 billion people or about 57 trees per person per year.)

Our lived environments have lots of empty, degraded land in need of restoration. On some, or maybe even much of it local terraforming will be required if trees are to live there in the long term without ongoing human effort. (For example, swales might be required in arid and semi-arid areas to ensure sufficient soil moisture.)

In summary: if you use a lot of energy (live a Western lifestyle), plant a tree a week. If you don’t use much, plant a tree a month. This won’t resolve the many other environmental and energy challenges we face, and won’t halt climate change unless everyone does it, but it’s the least we can do to pay back our tree debt.

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Responses to “Tree Debt”

  1. sonchai jitpleecheep November 27th, 2012 - 5:56 pm

    I think this is good advice. But it also seems to me that those of us living Western lifestyles probably lack the time, the skills, the land, etc to truly take this advice.

    In other words, it seems to me that we will need to extricate ourselves from the present economic system before we can seriously begin the work of terraforming our localities.

  2. Sonchai – That’s true, and when writing the post I was wondering to what degree most people living in urban environments have access to open land. In some ultra-dense cities I can imagine it’ll be hard. However, I think even in urban environments it’s possible to plant trees in every little patch of empty ground, or patches where only weeds or shrubs currently stand. (I live in a dense area by U.S. standards and yet there’s still open ground available for me to plant here and there.)

    In addition to that, I wonder whether time is really an issue; after all, we all spend time on things that are less important. Since I’m planning on doing a tree a week myself starting this coming weekend, I’ll record how long it takes me to prepare and plant each tree.

  3. Barath,
    During my teenage years in India, I was eco-crazy [a rare species in the city I grew up!] and almost created a forest in our garden, several of the trees I planted and nurtured are fully mature now. I however think that as a net, I have done more damage to the environment than these carbon sequestering trees [which by the way have a grim future given the city is among the top 10 "fastest growing" cities in the world].

    Your calculations may be carbon neutral but what about the carbon that has been spewed already since a century back when we started burning fossil fuels, which are massive stores of solar energy over long periods of time? What we need to do is sequester a substantial amount of the carbon that has been emitted since industrial revolution began, not just be neutral on our year to year current burning, even with 1 C we are already seeing severe civilization threatening effects [massive floods, droughts etc] and note that this is coming with a lag, the target of 2 C seems to be wrong, let alone 4 C. I read one statement that says we burn about 4 centuries worth of biota in just one year [400x], I would think we would need several earths worth of space to plant trees to bring back down the carbon levels to pre-industrial and this is under the increasingly questionable assumption that positive feedback loops that are accelerating can be stopped [google AMEG]. Some ways in which this may be possible:
    1) civilization collapses completely by the joint effects of climate change and peak energy [in some ways climate change solving itself] and ecology restores itself slowly over long periods of time.
    2) We invent some magic technology that sequesters net carbon [ratio carbon sequestered/carbon burned to sequester it must be high, this is an equivalent of EROEI, call it CROCI] fast and converts back to highly concentrated energy like oil etc and buries it back into the empty oil reservoirs [this is a practical space available to get the carbon back in where it came from]. This means employing large amounts of solar energy available to convert to liquid fuel [e.g but using this tech not to produce energy for transportation but to sequester carbon].
    3) If you have read Allan Savory’s idea of grazing management to rapidly sequester carbon in the soil and similar ideas, they claim this can solve the problem while feeding and employing people.

    Either of these kind of paths looks like a tall order. And this while struggling to keep 7 billion of us fed and sheltered and growing aspirations of developing countries [India and China alone are planning to burn so much coal that everything else seems to be inconsequential].
    That said, we should still do what we can because we don’t fully understand the complex anatomy and physiology of the planet, the models are after all models and however little a chance, there is still a possibility that our little actions may nudge the planet in a less inhospitable direction.
    I am in MD and they have some programs to plant trees but that is mostly symbolic in designated places like parks. While there is a good amount of suburban land on which trees can be planted, most of it is locked with cosmetic lawns that are net carbon emitters [due to fossil powered mowing operations] and increasing sprawl is destroying remaining landbase. It is sheer idiocy!

  4. Piyush -

    It’s most definitely not enough, but I’ve come to the point of view that I (and we collectively) have to start somewhere. It’s a bit crippling for people to think only in terms of large-scale collective action (which is largely what big environmental organizations tend to push, maybe for self-serving reasons) — the scale of the challenges we face in climate change, energy descent, etc. can become paralyzing. Once we are taking that first step on a regular basis (planting trees, for example), my hope is we’ll naturally start to ask what else we can do.

    As for the target, I figure first we need to aim to stop increasing CO2 levels, and then we can start decreasing them to get back to below 350 ppm, but the latter is a much longer term goal (that won’t be achieved in my lifetime).

  5. Senior moment, take 2: I now see that my SM, take 1 was less of one. The blog post “Climate Change vs Peak Oil is from December of 2011. My failure to recall it after a year is less embarrassing than after a month. Anyway, if my second effort to respond to your questions are, due to software preferences, lost, I can post again–I saved the comment before posting it.

    That said, I note that this blog’s content remains oriented to a trusted, but failed, strategy regarding effecting human sapience. Not only is 1° C the new 2° C, the old 2° C was a madeup number based, primarily, on wishful thinking and a trust in pragmatism. The old 1° C, which was dangerous, is now revealed to be well below that, perhaps .5° C? The shifting of the political target being an immediately quantitatively measurable atmospheric level of CO2, to a temperature that has built into its measurement about a thirty year delay between cause and effect is a story worth writing about if you haven’t done so. Since, a year after my first commenting here, you continue to write as though there is time left, I doubt you have.

    And few do. We love to delude ourselves. As primarily unconscious creatures addicted to an unstatinable hegemony and a pious perception of its privilege, our sense of health requires that we do so. Motivated reasoning is an adaptation to the terror of being conscious that keeps us blogging (and commenting) as near-term extinction hides in plain sight.

  6. Only about 17% of land carbon is in trees, etc. The rest is in soil. Think growing soil!