Carbon Emissions

If everything you know about carbon emissions comes from Al Gore or from Rush Limbaugh, then you are more ignorant than you realize.

So go fix that by watching Nate Lewis’s presentation. He is a professor at Cal Tech who is very, very careful to distinguish what we know from what we do not know.

It is a long presentation that you really should watch anyway. But just in case you don’t, the executive summary goes something like this. What we know is that the concentration of carbon dioxide in our atmosphere is higher than it has been for at least half a million years. We know that it will double or triple over the next 40 years. These are facts; the consequences of measurements and mathematics. They are not open for debate.

What is open for debate is what the consequences will be. Science cannot tell us this with certainty, because we do not have a bunch of spare planets and a century to experiment. What science can say is that there is almost certainly some level of atmospheric CO2 that will set in motion dramatic positive feedback mechanisms, and nobody knows where that level is. Maybe we will never reach it; maybe we will reach it in 40 years; and maybe we are already past it.

In short, we have pushed our atmosphere into a new, potentially catastrophic regime, and we are still pushing. If we wait for scientific certainty, we will have performed the experiment. That is the course we are on right now. I am a conservative — well, sort of — and I find this unacceptable. (By the way, the Republicans would be wise to ditch all the pseudo-science and get on the right side of this issue sooner rather than later.)

Which brings me to this week, with Obama trumpeting his new CAFE standards. Despite various contorted analyses, it is pretty clear that these standards will make approximately no difference. Like most of what Obama has done so far, this was more of a photo-op than serious policy.

There is only one way to get serious about carbon emissions, and that is to tax them. There is a “cap and trade” bill making its way through the House right now. As Mankiw points out, cap and trade is equivalent to a carbon tax plus a subsidy to politically favored corporations. Unless you auction off the permits, that is, in which case cap and trade is pretty much the same thing as a carbon tax. As Mankiw also points out, Obama seemed to understand this while on the campaign trail, but he has now conveniently forgotten it.

If we must hand billions of dollars to massive energy companies to buy their acquiescence to emissions controls, then so be it. But it is still kind of sad.

And it is still nowhere near enough.

16 comments to Carbon Emissions

  • diek

    So here’s the other point of view. There is a certain amount of carbon-based fuels that we can unearth and use in any practical sense. Various estimates are around but assuming reasonable growth rates of demand (most people forget about including growth rates) it is not totally unreasonable to conclude that we will use all of it up in the next 50 or so years. The time CO2 remains in the atmosphere is somewhere in the 100-200 year range before being absorbed or broken down, etc. Sort of its time constant. So here’s a totally different conclusion: in the long term it makes little difference to our climate whether we use it up in 50 years or 100 or 200. In fact, it is likely we’ll come close enough to using it all up over the next 100 years that we should simply: 1) get used to it and prepare, and 2) put our effort into changing to new forms of energy — a problem that if we don’t solve it right will massively overshadow any climate change problems (if in fact we have much to do with it in the first place — I’m still not convinced we know well enough).

    Lewis’ presentation is one of my favorites for looking at energy issues, but I’m not necessarily in his camp on the GW stuff. After all his grants will benefit from yet more hysteria, and there are plenty of good people who disagree with him. In fact there is no agreement at all that I can detect.

    In other words, energy is the problem; global warming is a side show. Global warming strategy should be to prepare for rising sea levels, changing weather (and how food sources are affected), and hope they don’t happen. Pouring gigantic resources into solving a problem that may already be unsolvable (if we’re too far along anthropogenic GW or if the whole thing is a hoax) is a waste. Getting off fossil fuels *simply because they will run out* is the right problem to solve and happens to solve at least part of the GW issues too.


  • diek

    BTW, entertaining and very well done lecture on growth rates that IMHO is as important as Lewis’: He is the originator of the statement “The greatest shortcoming of the human race is our inability to understand the exponential function”. He draws heavily on Hubbert’s Peak Oil work and related follow-ons for some parts of the video, but there are many other useful parts to it.

  • Michael Robinson

    For what it’s worth, it appears the “billions of dollars to massive energy companies to buy their acquiescence” may not be so bad as it looks at first blush. More here:

  • eak

    You call James Kwak’s analysis contorted, but that was only because it was explained by an Economist. Let me try a simple version without graphs. You replace a single lightbulb in your house with a more efficient variety. The power savings is small. Do you conclude that more efficient lighting is a bad idea? That would be incorrect, because if you change all the lightbulbs in your house, it makes a significant difference. If you then upgrade the other appliances in your house, you’re making a larger improvement. If you then insulate your roof and walls and upgrade your windows, you’ll realize enormous savings. But if someone uses the single lightbulb savings to argue that efficiency is not worth doing, you may do nothing at all. Unfortunately we have blogs that are doing just that.

    All James Kwak argued was that CAFE improvements are the first (or second) step of a process that can make a real difference. I think this is easy to understand.

    In case you still don’t get it, when the solution to a problem consists of many small actions that sum to a large value, criticizing each action as small pretty much guarantees that you will do nothing, when much more is in fact possible. There are approximately 100 things we need to do to address greenhouse pollution; none are sufficient in themselves. If you dismiss all 100 as individually insufficient, when in fact together they are sufficient, then we will fail.

  • eak

    diek wrote, “The time CO2 remains in the atmosphere is somewhere in the 100-200 year range before being absorbed or broken down, etc.” That statement is simplistic. Quite a bit of CO2 does leave the atmosphere over hundreds of years, but some remains; the distribution has a “long-tail”, and continues to have an effect for much longer.

    Contrast diek’s statement with this scientific paper published in the American Geophysical Union’s Journal of Geophysical research: Fate of fossil fuel CO2 in geologic time.
    Here is the abstract:

    A model of the ocean and seafloor carbon cycle is subjected to injection of new CO2 pulses of varying sizes to estimate the resident atmospheric fraction over the coming 100 kyr. The model is used to separate the processes of air-sea equilibrium, an ocean temperature feedback, CaCO3 compensation, and silicate weathering on the residual anthropogenic pCO2 in the atmosphere at 1, 10, and 100 kyr. The mean lifetime of anthropogenic CO2 is dominated by the long tail, resulting in a range of 30 – 35 kyr. The long lifetime of fossil fuel carbon release implies that the anthropogenic climate perturbation may have time to interact with ice sheets, methane clathrate deposits, and glacial/interglacial climate dynamics.

    Here’s an excerpt from the introduction:

    The idea that anthropogenic CO2 release may affect the climate of the earth for hundreds of thousands of years has not reached general public awareness. Goodstein [2004] reports that fossil fuel CO2 will disappear after a millennium. This misconception is widespread in scientific and public discussion. It certainly makes sense to focus our attention on the century timescale within which we live out our lives, and within which most of the CO2 will be absorbed by the natural carbon cycle. According to economic theory, application of a discount rate largely eliminates our concern about an effect that is projected tens of thousands of years in the future [Grossman and Krueger, 1995]. However, the long-term consequences of fossil fuel CO2 release have never reached the same level of public awareness and concern as does the production of long-lived nuclear wastes, for example.

  • diek —

    50 years before we run out of fossil fuels? Prof. Lewis claims you are off by an order of magnitude or two, especially for coal. He also gives 3000 years as the estimate for how long it will take the CO2 to dissipate. Are these numbers really that debatable? Do they even matter when we are talking about CO2 concentrations so far outside our experience (and therefore our ability to model)?

    eak —

    Your analogy is interesting, but “the government” is not “the people”. When I myself replace a light bulb to save energy, I do not immediately go out and use more energy elsewhere. When government forces one particular use of oil to go down, it reduces the overall demand for oil and therefore the cost, which in turn encourages other people and industries (and countries…) to use more oil. Do we want the government playing whack-a-mole and micro-managing every manner in which we consume fossil fuels? That strikes me as a bad idea that will never happen anyway, because politics will intervene at every step.

    Besides, as Prof. Lewis says in the Q&A session, transportation is not the largest piece of the puzzle anyway. On the list of 100 things that need doing, more efficient vehicles is somewhere around 78, I think.

    Make carbon more expensive globally — i.e., across industries and nations, with no exceptions — and the market will do the rest. This is the only realistic option, because people will always gravitate towards the cheapest energy. (I am OK with funding research into alternatives in order to make them cheaper, but this needs to be in addition to a carbon tax. We are out of time.)

  • eak


    People do not automatically go out and use more energy when they are efficient; they usually spend the savings more diversely, so only a tiny bit goes back to using more energy. Consider that California policies, incentives, and regulations caused Californians to use only 7032 kWh per capita in 2005. The non-California US used 13,085 kWh per capita, or 86% more. (No, the savings is not from the weather—New York at 7773 is almost as efficient as California because it has similar policies.) California’s policies caused kWh per capita to stop increasing in the 1970s, whereas the US continued to use more and more. Californians don’t have a lower standard of living than the rest of the US; indeed they pay less than the average American for the monthly electricity bill (despite higher rates), and so they spend the savings on other things.

    If you think California is anomalous, consider that Germany uses 7114 kWh per capita, France 7,699, Korea 7,804, and Japan 8,201. The UK uses only 6234. Really it is most of the US that is anomalous. If we adopted California’s policies at the Federal level, we should see our electricity use come down by 40% or more over 30 years (the time it took for out usage to become so bloated).

  • eak

    Nemo wrote, “There is only one way to get serious about carbon emissions, and that is to tax them.” This assertion is made without justification. I think that your assertion is wrong and that policies, incentives, and regulations can be a better route to the end. According to a 28 MPG vehicle emits 6.6 tons (6.0 tonnes) CO2/year on a wells-to-wheels basis, with an annual fuel cost of $1237 (e.g. pick the 2009 Toyota Matrix automatic 4-spd, 1.8L). I chose 28 MPG as it is close to the current passenger car CAFE requirement. If the price of greenhouse pollution is $30/tonne CO2e, then the annual fuel cost increases by $180, or just 34 cents a gallon. The relative inelasticity of gasoline is such that this will not deliver the same savings in transportation as regulations. Only when the price of carbon is more like $200 per tonne will drivers start altering their behavior. Under a cap-grandfather-trade system, prices will eventually reach this level (perhaps in 20 years), but because it takes approximately 20 years to significantly alter the US fleet fleet, we will be stuck with inefficient vehicles paying enormous taxes. The result will be either be a collapse in annual miles driven (and the economic dislocation associated with that), or more likely the cap will be suspended. Obama’s approach is to increase the fleet efficiency first in tandem with a carbon price. This is more likely to be successful because of the long lag required to affect the US vehicle fleet.

  • diek

    nemo — Lewis’ page on coal reserves assumes: 1) no growth rate from 1998 levels; 2) no change in the mix of energy sources. These are obviously poor assumptions. He also doesn’t provide a source so we can’t check a potential bias. Coal will be the last to run out, most likely, but exactly because of that, its use will likely grow to compensate for the others shrinking (becoming more expensive).

    Download the World Statistical Energy Review spreadsheet from BP (their sources are good ones, and explicit): Looking for key data such as coal consumption. China’s is growing about 8%/year and is already 41% of the world’s total use; at that growth rate Lewis’ 1998-consumption assumption is already irrelevant (China’s use exactly doubled from 1998 to 2007). Remember, at that growth rate China’s consumption doubles every 9 years, and of course that means every 9 years they use as much as they’ve used in all previous years combined. That doesn’t jive even remotely with Lewis’ assumption.

    Always look for “at current levels” or “at 19XX levels” in presentations. If no growth is projected, there is an agenda of obfuscation involved somehow. I can guarantee it.

    (I do like Lewis’ research very much, BTW. Nothing against his other work, just seems like sloppiness or bias
    in building his justifications.)

    Re: CO2 dissipation — it matters what you mean by dissipation. For the first 200 or so years it seems to roughly follow an exponential decay, which is why I said it’s a “time constant” — the time required for it to reduce by a factor of e, or 2.7. For a reference, “The dilution of carbon is such that only 15-30% is expected to remain in the atmosphere after 200 years”. Well, that’s about 1.5 time constants. After that, the remaining 15-30% decays very very slowly. So who’s right? If you think 15-30% is the big factor, it’s millenia. If you think the first 70-85% is the dominant factor (like me), it’s 200 years.

    Freeman Dyson says it’s 12 years: Worth reading the interchange on both sides (short) and the obvious complexity of what it is we’re actually talking about.

    A person on either side of this debate has the facts to back up their side, as long as they ignore the other facts. Which is what basically everybody is doing.

  • eak

    I found an old article that I think is worth reading. It that argues that command-and-control works better than cap-grandfather-trade:
    Emissions trading: A mixed record, with plenty of failures.

  • Creative Energy

    I think that you (and Greg Mankiw) are wrong about carbon taxes vs cap and trade. Subsidies to the politically connected are possible under either regime: either through direct $ subsidies or through tax rebates/exemptions or allocated permits, respectively. Unless the US tax code is very different to Australia’s (where I live), there are all sorts of targeted tax exemptions to favoured sectors.

    The real difference is that cap and trade controls the quantity of emissions and carbon taxes control the price. The choice of instrument should depend upon which of these variables you wish to control. Generally, international treaties set limits on emissions quantity (since this can more easily be monitored) rather than price. So, there is some logic in having quantity controlled domestically also (ie cap and trade).

  • jeremyx

    I agree that the policy will do nothing. Here is an attempt to use a system dynamics model to explore another policy which could work, but it turns out, is hard to manage. (You can simulate the model online and try for yourself)

    The policy is to charge a fee for dirty vehicles and apply a rebate for cleaner vehicles when they are sold. Important points:

    * The rebates are funded by the fees so the program is self-financing
    * The program allows manufactures to create any mix of vehicles they choose and let market forces determine sales
    * The fee is just making the consumer aware of, and pay for, the hidden cost of the vehicle over it’s lifetime

  • eak

    diek, Thank you for the link. I’m more familiar with the Bern carbon model (used by IPCC AR4) than the Wigley one. I’ll have to look into how they are related. The Bern model has exponentials with Ï„1 = 172.9 years, Ï„2 = 18.51 years, and Ï„3 = 1.186 years weighted by a0 = 0.217, a1 = 0.259, a2 = 0.338, a3 = 0.186 (note the a0 term). See AR4 chapter 2, Table 2.14; I’m not bold enough to attempt MathML in a blog comment box.

    You might note the line in Wigley model art you cited labeled “Unfavorable feedbacks”. From what I read, unfavorable feedbacks are probably the reality. Just look at just one of the non-linear feedback mechanisms where a little bit more warming may cause massive carbon dioxide releases that once started cannot be stopped for a century. Even if we do eventually pull back our own emissions, we will not be able to stop these natural processes once they are triggered, with the result that the warming snowballs. These feedback mechanisms are not in the Global Climate Models used by the IPCC. In Permafrost and the Global Carbon Budget Sergey A. Zimov et al. point out that the carbon in Earth’s atmosphere has recently increased from its pre-industrial level of 560 Gt to 730 Gt today. This has resulted in warming that is now beginning to melt the permafrost in Siberia and Alaska. They estimate that the frozen yedoma deposits across Siberia and Alaska contain approximately 500 Gt of carbon covering 1 million km^2 to an average depth of approximately 25 m. Peatbogs contain 50 to 70 Gt of carbon, and non-yedoma, non-peat permafrost contains approximately 400 Gt of carbon. They further suggest when thawed most yedoma carbon will be released within a century. Thus once thawing occurs, as much as 4 Gt of carbon might enter the atmosphere each year, in addition to what humankind adds. Even if humankind could suddenly stop its 7 Gt per year emissions completely, the permafrost might keep on going at more than half of this level. Our only option at that point would be to run backward just to stay in the same place; we would have to sequester up to 4 Gt per year, a change of 11 Gt.

  • eak

    diek, as an alternate opinion on coal reserves, consider (e.g. the PowerPoint slides and the 1 hour video lecture).

    One of the things he does is look at reserve estimates change over time (e.g. slides 20 and 30). He suggests that as time goes on the estimates tend to collapse toward a number that can be estimated by curve fitting, and that the numbers we are using today are vastly overstated compared to what the curves suggest.

  • eak

    Wouldn’t it be nice to abolish the imprecise phrase “cap and trade”? Usually that means either cap-grandfather-trade, cap-auction-spend, or cap-auction-rebate. The other ways of putting a price on carbon include also tax-spend, tax-neutral (tax greenhouse pollution, reduce income taxes by an equal amount), and tax-rebate.

    Here is another take on terminology:

  • mittelwerk

    there’s massive, society-wide repression about global warming. many don’t seem to get (as some above do) that the catastrophe has already occurred, that these are irreversible processes underway, that the best-case scenario of immediate, near-total curtailment of CO2 emissions might still not be enough. the most brutal irony is that this era of wholly unpredictable stress is coinciding with the end of the fossil-fuel subsidy (that caused it). society as it stands will not be able to bear the cost of transition. a decrease in social complexity is coming — by force, most likely. i’d say it’s two or three presidencies away, at most.

Leave a Reply