Tar Sands vs. Coal

The term “fossil fuels” is a very large umbrella. Coal, oil, and natural gas are the usual distinctions, but there’s also unconventional oil (such as the Alberta tar sands) and unconventional gas (such as shale gas from fracking). “Unconventional” means that the fuel is produced in a roundabout way that’s less efficient and takes more energy than regular fuel. For example, oil in northern Alberta is mixed with sand and tar that’s difficult to remove. As global supplies of conventional oil and gas decline, unconventional fuels are making up a growing segment of the petroleum market.

The different types of fossil fuels are present in different amounts in the ground. Also, for each unit of energy we get from burning them, they will release different amounts of carbon emissions. Given these variables, here’s an interesting question: how much global warming would each type of fuel cause if we burned every last bit of it?

A few weeks ago, a new study addressed this question in one of the world’s top scientific journals. Neil Swart, a Ph.D. student from the University of Victoria, as well as his supervisor Andrew Weaver, one of Canada’s top climate scientists, used existing data to quantify the warming potential for each kind of fossil fuel. Observations show the relationship between carbon emissions and temperature change to be approximately linear, so they didn’t need to use a climate model – a back-of-the-envelope calculation was sufficient. Also, since both of the authors are Canadian, they were particularly interested in how burning the Alberta tar sands would contribute to global warming.

Swart and Weaver calculated that, if we burned every last drop of the tar sands, the planet would warm by about 0.36°C. This is about half of the warming that’s been observed so far. If we only burned the parts of the tar sands proven to be economically viable, that number drops to 0.03°C. If we don’t expand drilling any further, and stick to the wells that already exist, the world would only warm by 0.01°C, which is virtually undetectable.

Conventional oil and natural gas would each cause similarly small amounts of warming, if the respective global supplies were burned completely. Unconventional natural gas would cause several times more warming – even though it’s cleaner-burning than coal and oil, there’s a lot of it in the ground.

The real game-changer, though, is coal. If we burned all the coal in the ground, the world would warm by a staggering 15°C. There’s a large uncertainty range around this number, though, because the linear relationship between carbon emissions and temperature change breaks down under super-high emission levels. The warming could be anywhere from 8°C to 25°C. In the context of previous climate changes, it’s hard to overemphasize just how dramatic a double-digit rise in average temperatures would be.

The main reason why the warming potential of coal is so high is because there’s so much of it. The Alberta tar sands are a huge resource base, but they’re tiny in comparison to global coal deposits. Also, coal is more polluting than any kind of oil: if you powered a lightbulb for one hour using coal, you would produce about 30% more CO2 emissions than if you ran it using conventional oil.

The tar sands are more polluting than regular oil, but exactly how much more is a very difficult question to answer. The end product that goes into your car at the gas station is essentially the same, but the refining process takes more energy. You can supply the extra energy in many different ways, though: if you use coal, tar sands become much more polluting than regular oil; if you use renewable energy that doesn’t emit carbon, tar sands are about the same. The authors didn’t include these extra emissions in their study, but they did discuss them in a supplementary document, which estimated that, in an average case, tar sands cause 17% more emissions than regular oil. Taking this into account, the tar sands would cause 0.42°C of warming if they were burned completely, rather than 0.36°C.

Therefore, headlines like “Canada’s oil sands: Not so dirty after all” are misleading. Canada’s oil sands are still very dirty. There just isn’t very much of them. If we decide to go ahead and burn all the tar sands because they only cause a little bit of warming, the same argument could be used for every individual coal plant across the world. Small numbers add up quickly.

The authors still don’t support expansion of the tar sands, or construction of pipelines like the Keystone XL. “While coal is the greatest threat to the climate globally,” Andrew Weaver writes, “the tarsands remain the largest source of greenhouse gas emission growth in Canada and are the single largest reason Canada is failing to meet its international climate commitments and failing to be a climate leader.” Nationally, tar sands are a major climate issue, because they enable our addiction to fossil fuels and create infrastructure that locks us into a future of dirty energy. Also, a myriad of other environmental and social problems are associated with the tar sands – health impacts on nearby First Nations communities, threats to iconic species such as the woodland caribou, and toxic chemicals being released into the air and water.

Tar sands are slightly preferable to coal, but clean energy is hugely preferable to both. In order to keep the climate crisis under control, we need to transition to a clean energy economy as soon as possible. From this viewpoint, further development of the tar sands is a step in the wrong direction.

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20 thoughts on “Tar Sands vs. Coal

  1. “…..it’s hard to overemphasize just how dramatic a double-digit rise in average temperatures would be.”

    I think it’s even hard to overemphasize how dramatic a 3 or 4 C rise in average temperature would be.

    Good article. I’ve already seen skeptics using this to say we don’t have to worry about the tar sands.

    The 0.42 warming attributable to burning all the tar sands oil, would still represent a good size percentage of the overall future warming, assuming no or little mitigation and BAU.

  2. Great job on this post. I’ve finally been paying more attention to the Tar Sands debate. I’m in Ontario, and of course here we only hear the good about them, rather than the negative attached. There’s big talk here about the mining companies complying with emissions laws, and we’ve heard about the “cleaning” up of the tar sands, but I’ve definitely had my head in the “sand”!!

    I truly thought Canada WAS a global leader in reducing pollution and carbon footprints. Now I’m embarrassed at my ignorance. This article was extremely helpful in my quest to learn… thank you for writing it!

  3. I have come the very long way around to being concerned about climate change. As a teenager I became interested in geography, then geomorphology, and finally geology. Having tried my hand at that for a few years, I went into hydrogeology but the goal of helping poor people somehow escaped me. Now, however, I believe I have found my niche…

    If Republicans are really as disengaged from reality as polls suggest, i think we’re all stuffed because I see no reason to doubt James Hansen’s integrity and or sincerity when he says stuff like this:
    “I’ve come to conclude that if we burn all reserves of oil, gas and coal, there is a substantial chance we will initiate the runaway greenhouse. If we also burn the tar sands and tar shale, I believe the Venus syndrome is a dead certainty.” James Hansen (2009) Storms of My Grandchildren, page 236.

    Why will the media not take up the baton I have handed them and, at very least, deliver a severe dressing-down to Lindzen for appearing to be so blatantly hypocritical as he was recently in the Palace of Westminster?
    No cause for alarm? – You cannot be serious! (5 March 2012)?

      • China’s percentage of the population is also lower than her emission percentage. India is currently in the reverse situation, but is growing rapidly.
        I would expect Canada’s number to move towards the global average as other countries increase emissions, and perhaps grow in population faster as well. I wouldn’t be surprised if Canada is below 1% of global emissions by 2020.

  4. Well Canada is under 2% according to wikipedia, they are at 1.8%. Then the 2009 and 2010 estimates have that number dropping even more, down to 1.54% in the wikipedia estimate for 2010. This is the problem with the emissions control attempts. The world is responding in a different way, making the countries that are likely to reduce emissions more and more irrelevant to the big picture.

  5. I looked for a quote, that would sum up my thoughts after reading this. And again, Robert Heinlein has come through.

    One can judge from experiment, or one can blindly accept authority. To the scientific mind, experimental proof is all important and theory is merely a convenience in description, to be junked when it no longer fits. To the academic mind, authority is everything and facts are junked when they do not fit theory laid down by authority.
    “Doctor Pinero” in Life-Line (1939)

    That says it all for me.

    • I think that both data and models can have problems, and when there is a discrepancy between the two either (or both!) can be faulty. I expect that most scientists would agree with me. The perception that data is always superior to, and separate from, models is completely false – read Paul Edwards’ “A Vast Machine” for a good rebuttal.

      • I expect that most scientists would disagree with you.
        First I find it hard to understand your distinction between data and models.
        Then you leave out the possibility that any discrepancy between data and models can be proof that both are valid or that one or the other is valid.
        Any data at all has to fit in a model otherwise there will be nothing to talk about.
        There are infinitely many models to choose from and the same goes for data.
        Mr. Euclid made a model of what was known of all or rather most of geometry in his time in a book called The Elements. The model has stood the test of time for more than 2000 years .
        Nevertheless Mr. Gauss, Mr. Bolyai, Mr. Riemann and Mr. Lobachevski came up with different models of geometry full of discrepancies when compared to Mr. Euclid’s geometry model.
        Nevertheless my mathematician friends tell me that all these models are equally valid. In fact if I am not mistaken thay are well on their way to proove that there are infinitely many models of geometry all different and all valid.
        So much to learn and so little time ….

    • I can only come to the conclusion that you blindly accept the authority of Doctor Pinero and/or Robert Heinlein.
      It always amazes me how people know what is going on in the “scientific mind” or in the “academic mind” or any other mind. Hardly ever do the same people tell us what is going on in their own mind.
      Isaac Newton, reportedly, wrote more than a million words full of gibberish (by today’s standards) about chemistry known as alchemy in his time.
      He also wrote extensively about mathematics and physics and that work made him to be considered one of the best scientists of all time.
      Later in life he became the director of the Royal mint and attended every execution of any money forgerer.
      Please tell me which parts of his mind did these three widely different phenomena come from. Was it his scientific mind? His academic mind? His chemical mind? His depraved mind?
      I do not know what to think about that.
      But I can assure you that the quote of Pinero and/or Heinlein is as full of gibberish as the writings of Mr. Newton about alchemy.

  6. Talking about a double digit rise in temperatures ins’t even comprehensible. The consequences would be completely devastating at only a couple of degrees increase.

    “headlines like ‘Canada’s oil sands: Not so dirty after all’ are misleading.” That is by design – it’s marketing BS as the late George Carlin called it. It’s like calling something “less fat” or “lemony”. The lead you to believe one thing without having to support it…

  7. In Swart and Weaver’s paper they say “Note, that here we only consider the effects of anthropogenic carbon dioxide”

    Just for clarification, do the figures they come up with for temperature rises (if all of a particular resource) is burned include projected feedbacks?

      • If it’s a large number it has to include feedbacks. Without positive feedback, you are left with a one degree rise.

      • “Includes feedbacks” is not all or nothing. There are many feedbacks, both positive and negative, that are not adequately represented in GCMs.

      • Miken – you haven’t understood. The 1 degree C without feedbacks is per each doubling of CO2 from 280ppm. The article is about how much temps would rise if all available fossil fuel of each type were selectively entirely burnt at once. For example, if all shale gas were burnt at once, how much would temps rise? It’s a thought experiment

    • Nick. The answer to your question is “yes”, within the constraints of the C4MIP Earth System Climate Models. That, as Kate says, includes climate sensitivity (change in temp. for doubling atm. CO2) but it also includes another quantity referred to as the “carbon-sensitivity” – “the amount by which atmospheric CO2 concentrations increase in response to CO2 emissions, as mediated by natural carbon sinks, and including also the effect of feedbacks between climate change and carbon uptake” (Mathews et al. 2009).

      So, as a brief illustration, with increasing CO2 emissions, the ocean’s ability to take up carbon begins to saturate, and the “airborne fraction” of carbon that remains in the atmosphere increases with increasing emissions. This effect is included.

      Another foreseeable carbon feedback is through heating from past emissions that melts permafrost which releases methane, inducing more warming. But these models generally do not yet include this feedback.

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