The Questionable Authority

The New York Times has recently taken some flack as the result of Nicholas Dawidoff’s New York Times Magazine profile of Princeton physicist Freeman Dyson. Times science blogger Andrew Revkin has also received some less than favorable reviews of a post he wrote about the article. The bulk of the criticism revolves around the treatment given to Dyson’s views on climate change, and is well warranted.

Neither Dawidoff nor Revkin apparently thought it necessary or desirable to subject any of Dyson’s views or proposals to any sort of reality check. This is at least somewhat strange. Dyson’s views are aggressively opposed to the strong scientific consensus on the issue, and yet he has not been very involved in research in the field. At the same time, some of the ideas that he proposes for climate change mitigation are outlandish, to say the least.

There are times when the perspective of someone outside a particular field can come up with an insight into a problem that has baffled those who have worked on the issue for years, and Dyson’s clearly a pretty bright guy. Luis Alvarez’s work on the Cretaceous-Tertiary mass extinction is a fantastic example of this, and it’s clearly important to keep that possibility in mind. It’s also important to remember that, just like every inventor who gets laughed at is not a Fulton, the distinguished scientist from the other field is not always going to be right.

When the distinguished scientist in question is suggesting specific ideas, it’s not always all that hard to do a quick back-of-the-envelope check to see just how feasible – or not – the idea is. That’s certainly the case with Dyson’s Magic Trees.

I’m referring, of course, to Dyson’s idea that sometime in the next few decades, we will “almost certainly” have genetically engineered “carbon eating” trees within the next 50 years. These trees will suck up the excess carbon dioxide from the atmosphere, and global warming (which Dyson thinks is an overstated problem to begin with) will be solved – once we’ve replaced 1/4 of the world’s trees with the carbon-eating variety.

Just on the surface, that idea looks to be just plain nuts. It’s the kind of thing that works well in sci-fi novels, not in reality. But let’s give it a chance for just a minute or two, and take a (semi-)serious look at it.

We’ll set aside the fact that we don’t currently know how to create a biological process to convert carbon into a form that’s not readily usable by other life forms. We’ll also set aside the difficulties involved in getting numerous species of trees to accept some sort of genetic modification that will get them to use that process. We’ll also ignore the logistical issues involved in getting that modification spread into 25% of the trees living on the planet.

Instead, let’s just look at how much inert carbon these trees will have to somehow output. In 2007, humans released an estimated 8.47 gigatons of carbon into the atmosphere. (Note: that’s the mass of the carbon, not the mass of the carbon dioxide.) That figure has been rising, and I’m just looking for round numbers, so I’m going to say that the last 10 years of output works out to around 80 gigatons.

If we’re looking for a way to store the carbon that’s not going to be readily degraded back into carbon dioxide, the best way is probably going to be to store it in as close a form to pure carbon as possible. Even giving out an enormous amount of the benefit of the doubt, I’m not prepared to say that we’re ever going to be able to make diamonds grow on trees, so that basically leaves graphite – the stuff that we call lead when it’s in a pencil. Graphite has a density that ranges from 2.09 to 2.23 grams per cubic centimeter, but for simplicity I’ll round that up to 2.25.

80 gigatons = 8.0 * 10^10 metric tones.

With a density of 2.25, that should work out to about 3.5*10^10 cubic meters.

If I’m doing the volume conversions correctly – and I’m fairly sure I did, since the first one’s easy – that works out to a 1 meter thick block of graphite that covers an area of 3.55*10^10 square meters, which works out to a bit more than 35,500 square kilometers, or a 10 centimeter thick chunk that covers 355,000 square kilometers.

In terms that are easier to grasp than numbers alone, that’s a 10 centimeter thick sheet of graphite that’s large enough to cover the entire state of New Mexico, with enough left over to cover Delaware and Maryland, and probably still supply the world with pencil lead for a few decades. And that’s just from the last decade of emissions.

We really do burn a lot of carbon-based fossil fuels, don’t we?

And that’s in a solid block form. It’s pretty clear that you’re not going to get a lot of vegetation growth on top of a block of solid graphite, and unless we’re really, really, really good at genetic engineering 50 years from now, the trees probably won’t be able to walk away and plant themselves somewhere else. They’d have to produce the graphite in a form that could mix into the surrounding soil without winding up in such high concentrations that it kills things off. That kind of rules out the single, 10 cm thick block thing. As a 1 cm block of graphite, you’re talking about more than twice the area of Texas, and you still won’t be able to grow anything on it.

I haven’t got to the whole issue of how to figure out what adding that much inert carbon to the soil will do to the ecosystem, or what happens when the trees suck the carbon down to pre-industrial levels – how do you stop it before the level drops too far?

No matter how much slack you cut Dyson, the Magic Trees idea is simply insane. Yet, for reasons beyond understanding, the New York Times seems to have decided to treat it as a serious suggestion from a serious person.

Comments

  1. #1 Ian
    March 27, 2009

    Actually think charcoal instead of graphite, and you have a pretty good soil amendment. It could, I dunno, let you convert the entire Amazon to fertile agricultural land. (Actually not, because you’d still need to nutrient input). Now having trees that do that…no. But making solar-powered ovens that convert biomass to carbon. Maybe.

    Still a crazy idea when you think about it in mass balance terms, but potentially, in areas where there’s a lot of “waste” biomass it probably has some benefit.

  2. #2 Paul Orwin
    March 27, 2009

    I’m very confused by this post – trees don’t convert CO2 into graphite, nor should they – they convert CO2 into tree. Tree wood is obviously biodegradable, but it is equally obviously not VERY biodegradable (i.e. trees are around for a long time, and most of their carbon is kept in the tree. So if you have a fast growing, efficient CO2 fixing tree (and there isn’t any other kind-thats how it gets to be fast growing), it will suck up an amount of CO2 roughly equal to net biomass accumulation (minus the stuff that falls of and dies, or gets eaten by insects/parasites). So while Dyson may be (is almost certainly, imho) wrong, it isn’t for this reason.

  3. #3 Hank Roberts
    March 27, 2009

    He forgot to mention that the trees will all come with off switches. Heck, they’ll probably have IP addresses and be remotely programmable.

  4. #4 Joseph j7uy5
    March 27, 2009

    It would require a novel enzyme that could convert carbohydrate and/or protein into pure carbon. It is hard to imagine an organism that could do that without killing itself.

    The other problem with Dyson’s idea is that such genetic modifications, even if possible, would have the potential to cause massive ecosystem changes. This is not a simple thing that can be modeled as a simple problem of inputs and outputs. Replacing 25% of the trees on the planet with something that has radical genetic modifications, in the course of a few decades, would be an act of utter desperation. There would be an enormous potential for unintended consequences.

    Even if you could design an organism that could survive the carbohydrate-to-carbon conversion, you have to wonder if it would be smart to have a large concentration of something that could catch on fire. Not only would that release the carbon back into the atmosphere (in very large quantity, very quickly) but it would incinerate a lot of stuff that we might want to keep.

    Plus, in the 50-year time frame that he is proposing, we already will be well into serious global climate change, which may well be irreversible regardless of what we do.

  5. #5 Bruce
    March 28, 2009

    I think you have an over-pessimistic assumption.
    We don’t need to elminate all the carbon we emit, we just need to eliminate the amount of carbon emission that is not absorbed by existing natural processes, so that the whole earth system has a net CO2 decrease going forward.

  6. #6 Robert Grumbine
    March 28, 2009

    Bruce, about half the carbon we emit stays in the atmosphere. All you succeed in doing is making it 1 Texas instead of 2. Unfortunately, it appears that the fraction of emissions that remain airborne has been falling, pushing back towards the 2 Texas answer.

    For some of the balances in a readable article with sources in the scientific literature see Jan Schloerer’s CO2 rise FAQ.

  7. #7 Pierce R. Butler
    March 28, 2009

    … we don’t currently know how to create a biological process to convert carbon into a form that’s not readily usable by other life forms.

    A biological process that constructs a product that no other biological process can deconstruct. Uh-huh.

    I see a world, a century or so from now, with a handful of surviving humans ranging through snowy tropical forests asparkle with diamond-bearing trees, hunting the handful of surviving rabbits with diamond-tipped spears.

    Paging Gregory Benford, Gregory Benford to the white courtesy holodeck please…

  8. #8 SLC
    March 28, 2009

    Re Luis Alvarez

    To be fair, the work on the K/T extinction by asteroid collision was a collaborative effort between the late Dr. Alvarez and his son Walter, who was a geologist.

  9. #9 Acitta
    March 29, 2009

    In Canada, we have large tracks of pine trees being killed off by the pine beetle because climate change has not been killing them off in the winter as would normally happen. Also, how are these carbon sucking trees going to grow when climate change has caused drought conditions in vast areas of the world.

  10. #10 Sean McCorkle
    March 29, 2009

    If I’m doing the volume conversions correctly – and I’m fairly sure I did, since the first one’s easy – that works out to a 1 meter thick block of graphite that covers an area of 3.55*10^10 square meters, which works out to a bit more than 35,500 square kilometers, or a 10 centimeter thick chunk that covers 355,000 square kilometers.
    …snip….
    We really do burn a lot of carbon-based fossil fuels, don’t we?

    I like the way you think! I wish more people, specifically my fellow americans, would similarly sit down and try to get their heads wrapped around these estimates. That graphite layer pretty much represents the oil/coal fields we’ve exhausted.

    We’ll set aside the fact that we don’t currently know how to create a biological process to convert carbon into a form that’s not readily usable by other life forms.

    I think the evidence is pretty strong now that the atmosphere of early Earth (around 2 billion years ago) was much more like that of Venus: 20-40 atmospheres of mostly CO2, but since then almost all of that CO2 was taken up by cocolithophores and diatoms and such, that grew CaCO3 shells, then died, sank, and then accumulated in limestone and chalk deposits of the order of 100m thick. That process seems to lock up the carbon pretty well, provided the oceanic pH levels are not too acidic.

    We can use limestone. Marble is a useful building construction material. Unfortunately, if we tried to artificially sequester carbon in calcium carbonate, we’d have to provide the equally large amounts of calcium. So thats a non-starter.

    However, there is a lot of silicon available on Earth, in the form of silicates. If you want to start a large sequestration project, my money would be on developing/finding an organism/process that can create silicon carbide. Its pretty valuable as a semi-conductor now, but if it could be produced in huge quantities, there might be very useful large-scale uses that no one has thought about yet because of limited supply and prohibitive expense. (i.e things like “can you do cool things with bricks of silicon carbide on the exterior of a house?”)

  11. #11 Anna Haynes PhD
    March 29, 2009

    Does anyone know how I can get in touch with Mr. Dawidoff to ask him some questions about the genesis of this piece?

    I’ve tried asking others to forward my email to him, which they’ve done, but I haven’t (yet?) gotten a response from him.

    Thanks –
    Anna

  12. #12 Jayanta
    March 30, 2009

    I certainly am one who believes we should cut back our fossil fuel consumption. Not for climate change reasons, but simply because they are a valuable resource and belong also to future generations. Also less materialism would do us good.

    Having said that, I however find the “10 centimeter thick chunk that covers 355,000 square kilometers” to be rather superficial.

    Here’s why… we already have trees and other plants that have been consuming CO2 in the air. However we have no masses of land being covered by graphite as the author predicts.

    Trees and other plants “naturally” consume CO2. There is nothing which says that if you doubled the number of trees, we would start covering the world with graphite. In fact extensive deforestation by man has been going on for thousands of years.

    Like “climate change” is the current fashion, saving the trees of the Amazon was the fashion a few decades back. This would be a good time to bring that fashion back.

  13. #13 Coriolis
    March 30, 2009

    You do not understand the problem Jayanta. Trees consume C02, but then other living things consume them (or they rot and die), and release it back in the atmosphere. What is neccesary is a process that converts C02 into carbon that will just sit there without getting consumed by other organisms and released back as C02 – like oil did before we started using it.

    Of course adding more trees (of any type) would help a little – just because the tree itself contains a fair bit of carbon and that mass of carbon will be removed from the atmosphere. But I’m pretty sure that to create enough trees that would have an appreciable effect in terms of taking up the carbon released from burning fossil fuels would be impossible.

    As a physicist this is pretty embarrassing. If there’s one thing we’re supposed to be good at, it’s not making this type of silly errors that can be shown to be absurd just by the back of the envelope calculations.

  14. #14 CS
    March 30, 2009

    With a density of 2.25, that should work out to about 3.5*10^10 cubic meters.

    You seem to have made a mistake here: 2.25 g/cm^3 = 2250 kg/m^3, not 2.25 kg/m^3. You are overestimating the graphite volume by a factor of 1000; it should be 3.5*10^7 m^3. That would be a 10 cm layer of graphite covering 355 square kilometers, about half the size of New York City.

  15. #15 Mike Dunford
    March 30, 2009

    @CS:
    The weight given for the carbon was in gigatons, not gigakilograms.

    2250 kg/m^3 = 2.25 metric tons per cubic meter.

    80 gigatons = 80,000,000,000 metric tons = 8.0*10^10 metric tons.

    8.0*10^10 metric tons divided by 2.25 metric tons per cubic meter = 3.55*10^10 cubic meters.

  16. #16 CS
    March 30, 2009

    Ahhh! My mistake!

    I am curious — what is the typical mass density of a forest (kg/m^2)? I guess I am wondering how much of that carbon can be sequestered if we grew, say, rain forest over the entire state of New Mexico (via magic beans, of course).

  17. #17 Mike Dunford
    March 30, 2009

    I think I’m going to turn the following into a full blog post in the next day or so, but…

    Woods Hole has done an estimate of the biomass in a forest in central Maine. They report that the biomass works out to 120 Mg of carbon per hectare.

    Tropical forests are going to be denser, of course, but not all that much denser. I found an estimated biomass for the entire Democratic Republic of Congo of around 20 gigatons of carbon. DRC has an area of over 2,300,000 km^2.

  18. #18 Coriolis
    March 30, 2009

    Heh, so yeah it’s pretty much useless like I assumed.

    Of course in principle, something like these magic trees could come along – some magic genetically engineered bacteria that let’s say eats sand (Si02)+C02 and pukes up SiC, as Sean alluded to. Then if we could breed them in huge quantities in isolation somewhere in the Sahara desert…

    So one can certainly think of ways in principle to get around this problem, other then stopping all emissions right now, and we should do research on it. But to claim that one of these solutions *will* materialize is stupid. It’s like basing our energy policy on the idea that we’ll get fusion to work in a few years, or our economic policy on the idea that T-bills will collapse. If that happens, you’ll either never have energy issues again for the first case, or money will be last thing you’d need to worry about in the second.

  19. #19 Sean McCorkle
    March 30, 2009

    Wow, I’m really glad to see this discussion taking place.

    I attended a climate change talk by an atmospheric scientist who presented a graph
    (if pressed, I could probably get a reference from the speaker, if folks here would like)
    which showed predicted temperature increases under various scenarios of carbon usage, ranging from a worst case (i.e. business as usual) to best case (zero carbon emissions starting this instant). Even the best case scenario showed temperature increases, which really bothered me. That is, if I take that prediction at face value, if every last person on earth stops burning fossil fuel for now and ever more, the temperature will still climb.

    The carbon cycle is complicated, with lots of reservoirs, including the oceans (which are a large buffer), and all kinds of biological organisms, and there are exchanges between many of them. I’m coming in from an astronomical perspective: I want to look at totals, because balancing the rates of exchange between the various reservoirs is too complicated for me and I don’t understand them anyway.

    The total terrestrial carbon is conserved. Most of the original atmosphere CO2 has been locked up safely in something on the order of a hundred meters of limestone. A smaller fraction was taken up and buried during the carboniferous period. Its this latter supply that we have been re-injecting into the atmosphere which is the heart of the problem.

    So, what I think should happen is this:
    1) reduce the re-injection of fossil carbon to zero, and
    2) re-sequester–or somehow make use of–an amount of atmospheric carbon equal to the total amount which came from the carboniferous – which has been burned as fossil fuels

    from http://www.noaanews.noaa.gov/stories2005/s2412.htm:

    Atmospheric CO2 levels have increased from about 315 ppm in 1958 to 378 ppm at the end of 2004, which means human activities have increased the concentration of atmospheric CO2 by 100 ppm or 36 percent.

    so I’ll take that as the amount to be sequestered: 100ppm or 1×10-4 of the total mass of the Earth’s atmosphere. From http://en.wikipedia.org/wiki/Earth's_atmosphere

    Total atmospheric mass is 5.1480×1018 kg (1.135×1019 lb).

    so that would make the target 5×1014 kg or 6×1011 tons of CO2 to re-sequester, or 2×1011tons if you want to keep the oxygen. If the world population is 6.7×109, thats 32 tons of carbon per person to bury or make into bricks or tennis rackets or something.

    Thats a lot of bricks.

    Now what I’m wondering now is, if this mass came from below the ground, what’s there now? Did land settle? Do oil wells inject water or something to force the fuels out? Or did I make a mistake?

  20. #20 Jayanta
    March 31, 2009

    Coriolis wrote “Trees consume C02, but then other living things consume them (or they rot and die), and release it back in the atmosphere. What is neccesary is a process that converts C02 into carbon that will just sit there without getting consumed by other organisms and released back as C02 – like oil did before we started using it.”

    If it is the re-release of carbon into the atmosphere that you are worried about… well, just derive some benefit from it. Burn wood for fuel! Actually, wood is an important source of fuel in the poorer countries.

    So the entire solution would be… more forests = more wood = more wood fuel = reduce “new” carbon from being introduced into the atmosphere by burning coal or fuel.

    Of course, there still remain some technical issues like “does wood burn at a high enough temperature to run turbines?” etc.

    Wood is a valuable object with a high price. It is used as, for example, building material (where carbon is stored and not re-released).

    I understand the problem that “climate change” advocates are pointing to here, that carbon that is currently under the ground is being pumped into the atmosphere. What effect that will have is still debatable (we after all had an ice age in the recent past). I believe that is part of what Dyson is saying (though the focus in this thread is on his idea that more trees will attenuate the problem).

    While you are worrying about carbon, here is something that I have sometimes thought about. What about all the metals being mined and then being disposed into the biosphere. Aren’t we soon going to be at a point where poisoning of living beings by heavy metal will become a problem?

    Jayanta

  21. #21 Charles Sifers
    March 31, 2009

    All this effort and energy over a totally irrelevant subject.
    How can humans be so completely stupid? (I know it turns people off when I’m honest)
    CO2 is not a problem, and anyone who has a basic understanding of chemistry knows this. Dyson is just playing with the fools.
    Thanks for playing.

  22. #22 Sean McCorkle
    March 31, 2009

    Jayanta,

    IMHO biofuels (trees, ethanol, biodiesel, butanol etc.) are better than fossil fuels because, in principle, they could allow us to balance carbon injection and uptake, that is, ensure that all carbon that is burned came out of the atmosphere recently. Each of these poses its own questions and problems, though, such as land usage, soil health, food crop displacement & economics, energy used to generate fertilizers, and in the case of ethanol, water usage.

    But there still is the question of getting rid of the atmospheric carbon excess. CO2 has whopper absorption bands between 4-5 microns and 15-20 microns which are well within Earth’s 300K Planck curve, and the amount has gone up 35% since we’ve started measuring it. Sure, the climate models are complex, but at the end of the day, that has to result in increased thermal blanketing. Its basic physics.

    Personally, I wouldn’t buy a house thats below 50 ft above sea level.

    Using wood for construction is moving in the right direction, but you need to ensure that it will last a long time, and not burn up, decay, etc. And I think we’re talking about a lot of wood!

    Myself, I would prefer that we take carbon out of the picture entirely and start using H2. In a pinch, it can be made by electrolyzing water using your favorite power source, and that alone makes it worth developing the extra technology to make it safe (no explosions please!)

    Aren’t we soon going to be at a point where poisoning of living beings by heavy metal will become a problem?

    Here I believe biology is already coming to the rescue. Lots of people are working in the fields of phytoremediation and microbial remediation. Microbes have developed all kinds of mechanisms to cope with all kinds of metals and many toxic organics too. (Kenneth Nealson says “prokaryotes are chemists!”) I work with a guy who worked on a strain of Cupriavidus metallidurans that has genes for dealing with just about every environmental metal that you can think of, all in one bug.

  23. #23 Coriolis
    March 31, 2009

    Jayanta, if you make a wooden house, it will eventually decay and again, re-release the carbon in the atmosphere – but that’s not even the main problem. And if you burn it of course you’re directly releasing it back. This may be a good source of energy, but in terms of removing carbon from the atmosphere, it doesn’t do anything. To repeat myself, what you need is a way to store lots of carbon compactly in a way that will not be re-released in the atmosphere. Which is what oil is for example.

    Wood does not store carbon compactly – you can figure that out just by looking at the figure for the total carbon content of the Congo rain forest that Mike gave above – 20 gigatons. That’s probably more wood then you could ever imagine using for construction, yet it’s a mere 1/4 of the carbon emissions we produce per *year*.

    This is why Mike compared it to graphite – because graphite is about the most dense form of storing carbon possible.

    And Sean, I think the main problem is exactly finding “your favorite energy source”. Whether to make H2 or anything else, there just aren’t very many good options for just making alot of energy. People are making progress with solar cells, nuclear can probably be better. We recently had a talk from a physicist who just went over the over of magnitude calculations of the energy we’ll need to make to make up for all the fossil fuels, and if I remember right, you’d need to cover a fairly significant fraction of nevada with solar cells. Without finding some much more cost effective ways of making them, it will be very hard.

    Having said that, I am fairly optimistic that we will get around those problems – but it seems the chances of doing that before oil and natural gas runs out are practically nonexistant. Unless there’s some major breakthroughs we’ll probably burn through most of the coal too.

  24. #24 Jayanta
    April 1, 2009

    @ Coriolis “Jayanta, if you make a wooden house, it will eventually decay and again, re-release the carbon in the atmosphere – but that’s not even the main problem. And if you burn it of course you’re directly releasing it back. This may be a good source of energy, but in terms of removing carbon from the atmosphere, it doesn’t do anything.”

    Yes, wooden houses decay. But the point is that, say you double the amount of wood used for buildings. Yes, some decays, but there is new addition. So in a “dynamic equilibrium”, you have moved to a point where there is more carbon stored in houses. The net effect is that some carbon that was stored as crude oil below ground has now been moved up to being stored as wood in houses.

    Also increasing availability of wood means that there is more wood available as fuel, which can reduce the rate at which carbon is extracted from below ground and put into the atmosphere.

    Okay, here is the big picture.

    I think the idea behind Dyson’s statement was also that biosphere is a “stable equilibrium”. That is, suppose you increase the quantity of something in it, then whatever uses that as a resource thrives, thus reducing its amount.

    There is indeed some evidence that the biosphere is a “stable equilibrium”. There have not been extreme outcomes in the biosphere, and it has continued for a very long time. Extreme swings like the extinction of dinosaurs were triggered by external events (meteor hit?).

  25. #25 Coriolis
    April 1, 2009

    Of course if you put more wood in buildings, then on average you’d have somewhat less carbon in the atmosphere. But I adressed that in my second paragraph – the density of carbon in wood is small enough that all the wood in the congo rainforests is only about 1/4 of our yearly emissions. I.e., it’s trivial. The same applies to the energy that you could obtain from burning wood – even on the scale of what you can get from solar cells, it’s far too small to make any difference.

    And your “stable equilibrium” idea is just hand-waving. Human industrialization is an “external event” as far as the previous functioning of the biosphere is concerned. Stability does not happen by magic – you need to actually have something that can quickly take up huge amounts of carbon and store it in a stable form like oil. And that just doesn’t exist.

  26. #26 Jayanta
    April 1, 2009

    The increase in CO2 in the atmosphere should favor those plant species that consume more CO2. I will wait for some actual scientific evidence about the magnitude of this effect. Arguments both for and against “stable equilibrium” are hand-waving till then.

  27. #27 Jayanta
    April 1, 2009

    I do agree with Coriolis and others, that carbon in increased amounts of wood will be small in comparison to the amount being injected into the atmosphere by burning fossil fuels. Thus my hope that wood will be able to store increased amounts of carbon therefore has to be discarded.

  28. #28 the_forester
    April 1, 2009

    A scientific study at Duke University has been exposing loblolly pine trees in an open canopy to CO2 at rates 2.5 times what is in the atmosphere today for over 14 years. The result is that unless there is some biological constraint (water, nutrients, or sunlight) existing forests can consume and store up to 40% more carbon by just being exposed to increases in CO2. No genetics are necessary. However, improving the genetics of the forests could certainly increase CO2 uptake and sequestration.

    The research can be found at http://face.env.duke.edu

    Dyson, may be out there but he has a point on the biolology.

  29. #29 Sean McCorkle
    April 1, 2009

    And Sean, I think the main problem is exactly finding “your favorite energy source”.

    Exactly right! I deliberately sidestepped this very important point.

    Whether to make H2 or anything else, there just aren’t very many good options for just making alot of energy.

    It is my sincere hope that we as a society sit down and enumerate our options on a blackboard (metaphorically speaking) and honestly appraise the pros and cons of all the generation methods we can think of, solar, wind, biofuels, nuclear, hydroelectric, tidal – all of them. We should do a serious compare-and-contrast analysis in the public forums before we chart a new course. Personally I’ve come to the conclusion that no one of these is without drawbacks of some kind.

    Two other related and thorny issues are how to store power when its being generated but not being used, and what to do about a society which has structured itself around automobiles to the extent that we have.

  30. #30 Coriolis
    April 2, 2009

    Jayanta, the rate at which they are consuming it by itself is irrelevant – since it will all be released back when they die. The only thing that matters are whether they secrete a significant fraction in some non-degredable way (either while living or when they die), and the total biomass.

    And the_forester, let me repeat these numbers from Mike one more time:

    yearly emissions = 80gigatons
    Carbon content of congo rainforest = 20 gigatons

    Even if all of a sudden all the plants in the congo rainforest had 40% more carbon it would still be a mere 28gigatons.

    So just to understand the scale of the problem – if you managed to increase the carbon content of plant biomass, not by 40%, but by 500% (4x), for every plant, you’d need to plant an area the size of the the congo rainforest, every year, just to break even.

    Now you tell me how workable that sounds to you.

  31. #31 llewelly
    April 2, 2009

    yearly emissions = 80gigatons
    Carbon content of congo rainforest = 20 gigatons

    No, yearly carbon emissions are much closer to 8 gigatons. 80 gigatons is Dunford’s estimate for a decade.
    (Of course, planting a Cong-sized forest every 10 years isn’t feasible either.)

  32. #32 AK
    April 2, 2009

    I haven’t read through all the comments here (I started scanning about 1/2 way through, they didn’t seem to be saying anything interesting). But from what I’ve seen here, few if any posters, including Mike Dunford, are really getting into what Dyson is saying. Let me quote from the latest post (at the time I started writing this):

    yearly emissions = 80gigatons
    Carbon content of congo rainforest = 20 gigatons

    Even if all of a sudden all the plants in the congo rainforest had 40% more carbon it would still be a mere 28gigatons.

    So if these trees fixed 400% (x4) of their living carbon content as non-degradable carbon each year, they would do the trick. It wouldn’t have to be above ground, it wouldn’t have to be in the form of cellulose, or graphite, or any other currently existing material. For that matter, it’s been shown that charcoal in the soil has a very long lifetime (KYears). I’ll use one of my two links for Soil Charcoal Amendments Maintain Soil Fertilityand Establish A Carbon Sink–Research AND Prospects by Christoph Steiner. From the introduction:

    Terra Preta soils contain up to 70 times more black C than the adjacent soils. Due to its polycyclic aromatic structure, black C is chemically and microbially stable and persists in the environment over centuries (Glaser, et al., 2001b).

    Obviously, it would be necessary to tailor enzymes to produce a form of black carbon that has this resistance. Moreover, I can’t deny that this would be, in the long run, a temporary expedient unless our carbon burning was converted from fossil fuels to this “black carbon”, presumably mined from these soils every few decades. I would envision a system of “deciduous” roots, growing rapidly, depositing large amounts of black carbon within their structure, then dieing back and being replaced with new roots. In addition to depositing black carbon, such roots could work to aerate the soil, providing tracks for earthworms and other soil processors in the decaying “deciduous” roots.

    Even if Dyson is mistaken that GM trees are the answer (and I think he is), his concept remains correct if any GM plants are successfully deployed to remove fossil carbon from the air. This is because he is actually talking at the level of abstract generalizations, and his “Dyson’s Magic Trees” are actually just examples of the kind of thing humanity could do with our latest current knowledge of what is possible.

    Other comments:

    I think the evidence is pretty strong now that the atmosphere of early Earth (around 2 billion years ago) was much more like that of Venus: 20-40 atmospheres of mostly CO2, but since then almost all of that CO2 was taken up by cocolithophores and diatoms and such, that grew CaCO3 shells, then died, sank, and then accumulated in limestone and chalk deposits of the order of 100m thick. That process seems to lock up the carbon pretty well, provided the oceanic pH levels are not too acidic.

    Not true. Best evidence is that the Earth’s atmosphere 2 GYA had no more than a few times the level of CO2 it has today. See the papers listed in this blog comment: http://planetologist.net/2009/03/17/mutate-or-die/#comment-555.

    A biological process that constructs a product that no other biological process can deconstruct. Uh-huh.

    This shows a common misperception. While it may be that after a few million years bacteria will have discovered a way to degrade something, there is no natural relationship between how easy it is to synthesize a product and how easy to degrade it.

    My Own Solution

    IMO the best way to sequester atmospheric CO2 is using GM sphagnum moss. This plant can grow very rapidly, and will produce peat as it builds up and compresses older layers. The moss could be established on vast floating platforms offshore of major river deltas or in sterile parts of the open ocean that are subject to large rainfalls. The peat fields would require non-biodegradable bottoms (and sides), which could be made of carbonizing concrete or fiber glass reinforced plastic. When they grow to appropriate depth, the lower levels could be removed and sunk into anoxic trenches, where the extra carbon would eventually be subducted into the mantle.

    I know there are many who object to the whole idea of “picking up afterwards”, but they can generally be classified in three groups:

    – Those too ignorant of modern industrial realities to understand why fossil fuel use won’t be reduced in the next few decades

    – Those who favor a massive “human die-off” until the population reaches a “sustainable” level of a few hundred million

    – Those who don’t really care about the environment but are using environmental concerns as a stalking horse for their own political ideologies.

  33. #33 llewelly
    April 2, 2009

    I intended, ‘Congo-sized’.

  34. #34 AK
    April 2, 2009

    @Mike Dunford:

    I’ve got a comment stuck in the review queue, could you free it up?

    Thanks.

  35. #35 Mike Dunford
    April 2, 2009

    @llwelly
    Thanks for making the correction. I spotted the error, planned to write a correction of my own, and totally forgot to.

    @AK:
    Actually, I do get the idea. I picked graphite not because it’s the only form that could be used to store the carbon, or because Dyson suggested it (he didn’t), but because it’s about the densest possible form that the carbon could possibly be stored in. Anything else will require more space than the graphite. The moss might store the carbon, but even compressed moss only has a density of around 0.6 (compared with the ~2.25 for the graphite). And that’s the density of the moss – remember, the moss, unlike the graphite, isn’t pure carbon.

    Non-woody plants have a carbon density of about 1/3. So, really rough ballpark guess, even dried and packed into pellets with 0.6 density, you’d have to bury an area the size of the State of Maine in moss to a depth of something around 6-7 meters to take care of just the carbon burned in the last decade.

  36. #36 Jayanta
    April 2, 2009

    Coriolis wrote “Jayanta, the rate at which they are consuming it by itself is irrelevant – since it will all be released back when they die. The only thing that matters are whether they secrete a significant fraction in some non-degredable way (either while living or when they die), and the total biomass.”

    It doesn’t have to be bio non-degradable forever. All it needs to be is to store it for some years. As carbon is released back into the atmosphere, new trees die and add to the stored mass. Sort of a “dynamic equilibrium”. Though carbon is finally being released back into the atmosphere, the amount of carbon stored has increased.

    Also notable is AK’s idea of “GM sphagnum moss”. Indeed, these moss fields would be a valuable energy resource once we run out of oil and coal.

    I personally believe that nuclear energy is an important part of the solution. But as AK points out, it probably does not sit well with “Those who don’t really care about the environment but are using environmental concerns as a stalking horse for their own political ideologies.” They would rather prefer the “oh so gentle” solar or wind energy, both of which I think probably will never provide a significant amount of our energy needs.

    As for nuclear energy, I have had this idea for a while. These are very expensive to construct these power plants as they require a lot of safety measures (not sure, maybe I am wrong). So why not just build automated plants a mile under rock without much safety measures. If it blows up, won’t do much damage. I think I need to find another blog to post this to, and guidance will be appreciated.

    Finally I think telecommuting can significantly cut down our gas consumption. The government needs to subsidize telecommuting as a “social good”. This is an idea that I myself am working on.

  37. #37 Coriolis
    April 2, 2009

    Well thanks for the correction llewelly, but as you point out it doesn’t really matter for that case. As to your general point, I agree – I don’t think we’ll actually stop burning fossil fuels until they run out (and when you include coal that will be a very long time and a whole lot of C02). And it’s also true that what Dyson says is possible in principle, if you have any organism that can transform C02 into carbon that would stay out of the atmosphere for a long time, on a large scale.

    But there’s a big difference between saying that something is true in principle and another thing to demonstrate that it’s workable on the scale that will be necessary for it to make any difference. In principle, if we could actually use fusion power like we use nuclear power, it would provide more energy then we can currently think of using for (almost) ever. And we could use that with any reaction no matter how energetically unfavorable to remove C02 from the atmosphere, heck we could probably turn it back into benzene for fun. And we’re certainly trying to figure out how to make a stable fusion power plant.

    Dyson is acting in the worst traditions of a theoretical physicist by assuming that all the engineering challenges will be sorted out easily (and I say that as a theoretical physicist in training myself hehe).

  38. #38 Coriolis
    April 2, 2009

    My apologies I mixed up writers, I suppose everything except for my first sentence should be adressed to AK.

  39. #39 AK
    April 2, 2009

    @Mike Dunford:

    You’re confusing my favorite idea with Dyson’s proposal. In my interpretation of Dyson’s proposal, the carbon would be added to the soil as relatively inert material, filler, which would support water and nutrient storage but not oxidize (except very slowly). Six (or sixty) meters of soil probably aren’t that great a problem.

    My own GM spagnum proposal includes burying compacted material in anoxic trenches where it will be subducted into the mantle. I’m pretty sure there’s room, although I admit it would damage the unique ecosystems currently there. OTOH, like most life, those ecosystems would probably adapt, creating brand new unique ecosystems.

    @Jayanta :

    I’m all for nuclear power, but let’s not build reactors, let’s use the one that’s been working for the last few billion years.

    @Coriolis:

    Sometime early in WWII, a science fiction story was published about a nuclear fission device (in a magazine called Astounding). The FBI showed up looking for a security leak.

    The point of that vignette is that it’s possible to predict with some accuracy what could be done by engineers with currently known scientific principles. I’m not a professional in directed mutation of plant development genes, but I’ve studied the subject enough to agree with Dyson that it’s almost certainly possible to find some engineering solution to the general problem of biosequestering of atmospheric carbon. If people working on the subject are lacking in suggestions, I can offer some; although the vast majority might be unfeasible for one or another reason, a few would probably work, and many more would stimulate more feasible ideas from experts. And I’m not unique, there are plenty of others who can come up with such ideas (such as Dyson himself).

  40. #40 Coriolis
    April 2, 2009

    You have too much of an naive view of how easy it is to move from theoretically possible, to actually possible in an effective way. Einstein postulated the photoelectric effect in 1905, and we still don’t have cheap solar power. Research into fusion power for civilian uses was started in the 1950s and it may never be workable. High T_c superconductors were found in the 1970’s if I remember right, and only now do we have some idea of the principles of how they even work – and still no big practical uses.

    The problem for all those subjects was never a lack of smart people thinking about the problem, since they were and still are major research effort on all of these topics. And let me note that all those effects are realised in certain situations – you can have fusion reactions in bombs just fine, just not for civilian purposes. You can make high T_c superconductors to much higher temperature then anyone believed would be possible, but not at room temperature or from a material that is easy to make a wire from. You can make solar cells, but not cost-effectively.

    Unless biologists are uncommonly foolish, which I somehow doubt, what is necessary is not obvious and vague suggestions but alot of hard work and deep thought.

    It’s not to say that it cannot be done or shouldn’t be tried – but to rely on such a solution appearing is foolish.

  41. #41 Marion Delgado
    April 3, 2009

    Searching the science blogs over the last 2-4 years on Dyson I think is instructive. Just on the science blogs alone a writer could have used a search engine to see what the main critiques are of Dyson’s approach, and even to see whether Dyson or a surrogate had ever responded to any of them (not to my knowledge).

  42. #42 AK
    April 3, 2009

    @Coriolis:

    You have too much of an naive view of how easy it is to move from theoretically possible, to actually possible in an effective way.

    Bullshi*t! I spent many years as a software engineer, and my constant observation was that the majority of my fellow “engineers” were unable to think out of the small box of tools they were familiar with. Projects that were labeled “impossible” turned out to be fairly easy using a few more tools. (Granted, I had to invent some of them myself, but others I just rescued from obscurity caused by fancy newer technology.) While there are certainly differences between engineering business software and genetic modifications to plant development, IMO the principles are much more similar than different.

    An example is your references to “cheap solar power“. While the cost hasn’t reached that of fossil fuel-fired power, Concentrating Solar Power has all the potential. It requires only well established methods to bring this technology from expensive to cheap, and the most important method is economy of scale (i.e. do a lot of it).

    Note that your focus on fancy technology has blinded you to an out-of-the-box solution that is certainly much more suited to immediate deployment, and can be confidently predicted to solve the immediate problem.

    Thinking a little more out of the box, consider that solar power (on Earth) is very intermittent (and somewhat unpredictable depending on location). If large areas of the American Southwest desert are given over to this, consider also the proximity to salt water (Gulf of California), and the possibility of using the waste heat (from the cool side of the generators) for distillation. Use part of the energy during midday for pumping water uphill, both distilled and salt, and then during the night (or cloudy times) the salt water could be used to recover energy. Part of the fresh water, meanwhile, could be piped via aqueduct to the cities nearer the Pacific coast. Another part could be used for agriculture right there on the spot.

    By leveraging the synergy of these disparate requirements (see, I can do corpspeak) the overall cost of meeting all of them together can be lowered.

    I’ve seen estimates that a square 92 miles on a side (8464 sq miles) could capture enough energy to meet the entire fixed plant needs of the US. While I’m skeptical of the exact numbers, they do give an order of magnitude.

    Returning to the issue of carbon sequestration, all the ways I can think of off-hand for doing this with trees involve some complexity of genetic modification, but I doubt it will be beyond what’s available a decade from now. I stay very current with what research is saying about how genes control development, and just with today’s information, such modifications can probably be considered feasible. Note, however, that I don’t consider trees the best choice (as I said above).

    My own suggestion of GM sphagnum moss is another matter. The actual rates of carbon capture by C3 plants are sufficient for this application, it requires only tailoring the moss to grow at full speed. The level of tweaking would probably not be more than is currently used in GM applications.

  43. #43 Coriolis
    April 3, 2009

    What “fancy”, new technology? The photoelectric effect is from 1905, superconductivity (the non high T_c kind) was discovered in 1911, and we had hydrogen (fusion) bombs in the 1950s. These are all things that are about 80 years old, and all the theory is known in much greater detail then anything as complex as an actual plant. If you genuinely think that you’re so much smarter then the people around you, perhaps you took the wrong job – get into research, win a nobel prize, and if at that point you’re convinced everyone else is a fool who can’t think out of the box maybe you’d have a point to make.

  44. #44 AK
    April 3, 2009

    What “fancy”, new technology? The photoelectric effect is from 1905, superconductivity (the non high T_c kind) was discovered in 1911, and we had hydrogen (fusion) bombs in the 1950s.

    and Archimedes is at least claimed to have used focusing mirrors 2300 years ago.

    As for the photoelectric effect, there’s a lot more to solar panels than that, as I’m sure you know. My point was that solar panels may not be the right solution to the solar power problem, and that “experts” may get trapped into a box created by their own training.

    Personally, I don’t believe there’s going to be any problem creating the kind of modifications to plant development needed for this sort of thing.

  45. #45 Sean McCorkle
    April 3, 2009

    I’ve seen estimates that a square 92 miles on a side (8464 sq miles) could capture enough energy to meet the entire fixed plant needs of the US. While I’m skeptical of the exact numbers, they do give an order of magnitude.

    92 miles = 1.5×105m, so thats 2×1010 m2. The solar constant is 1360 W/m2 but when you take into account latitude, day/night etc., the radiation budget guys I know quote something like 350 W/m2, so that gives 7×1012 W, 7 terrawatts incident on that area, which I think is comparable to US. energy usage. Harvesting that power is going to be another story: if you can get 1% efficiency at the end of the day, even with GM plants, I’ll be impressed.

    The 92 miles number may be off, but the bigger point stands: There’s enough incident sunlight to keep us happy.

    What are the cons? Is it feasible to cover that kind of area with mirrors or photovoltaics? What kinds of lifetimes can we expect from photovoltaics? Aren’t they made of some nasty metals? Do we want the old ones going into dumps? If we generate electricity, how do we run cars? So many americans use fossil fuels for heating homes – isn’t it better to have double or triple pain windows on the south side of houses for direct conversion of sunlight into heat?

    If we use plants, what are the consequences to the soil? Will energy crops seriously displace food crops or wild species? Will energy-intensive ferHow will you collect the energy – will you need fuel-powered tractors to maintain and harvest the crop? how water-intensive will it be? (thats a REAL drawback for ethanol).

    (I’m throwing these out for the purposes of discussion: Im a fan of solar power).
    BTW AK: thanks for the ancient atmosphere refs above. I realize I’m about 20yrs behind on this stuff and need to seriously catch up.

  46. #46 AK
    April 4, 2009

    @Sean McCorkle:

    I’m running short of time but I’ll try some quick answers:

    AFAIK the 92-mile figure was created specifically for concentrating solar power, and includes allowance (of some sort) for spacing the mirrors (so they’ll continue to get full power until the sun hits a fairly low angle). But, if I’m wrong, as you say the order of magnitude is still right.

    My discussion of using mirrors was a specific example of thinking “out-of” rather than “in” the box: PV cells may not be the solution: the problem needs to be defined in a way that doesn’t make them required.

    I certainly wasn’t suggesting using trees to harvest energy, not for industrial use. My discussion of trees had to do with the fact that Dyson’s proposal wasn’t as unfeasible as the main article made it seem: again there was some thinking “in-the-box” regarding how the carbon was to be stored. My point was that there are other options, even using trees (which, again, aren’t my favorite solution).

    Despite their not being my favorite solution, here’s another “out-of-the-box” idea for trees: leaves. Rather than depending on trees storing the carbon as wood, have them deposit it as modules of non-biodegradable reduced carbon in their leaves. Most tropical trees are using sunlight at a tiny fraction of what’s available (even after filtering through the chlorophyll z-scheme). This is mostly because their need for nutrients limits growth. But photosynthesis could run at full speed creating sugar, if the sugar were converted to lignins and sterols, and the sterols were built up into small modules and infused with lignins, which then polymerized. Polysterols infused with lignin would be particularly resistant to biodegradation, as lignins are basically random polymers rather than having a single specific structure like cellulose. The leaves would be GM’ed to drop (and be replaced) as soon as they’d developed a full crop of carbon modules. As the leaves themselves were biodegraded, the modules would be added to the soil as filler, improving its water and nutrient retention.

    If trees could be developed that deposit 10 Kg/M^2*year of this reduced carbon (equivalent by weight to 1 cm of water), it would take only 2 million square kilometers to sequester 20Gigatons of carbon/year, enough to counteract industrial usage as well as draw the CO2 back down towards pre-industrial levels. 100 Kg/M^2*year would allow for only 200,000 square kilometers needed for this.

    (It could even be combined with a solar power/distillation scheme that would allow currently topical desert regions to be planted in these trees, so that current tropical forests could be left in peace.)

    Oh, and you’re welcome for the link re early atmosphere.

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