Posted by: ericgrimsrud | December 11, 2012

It’s our Cumulative Emissions, Stupid!

No insult intended here with this attention-grabing title, but:  After a few years now of trying to improve the public’s understanding of the global warming problem, I have come to realize that the key point in achieving that objective is to understand the single most important factor associated with future increased temperatures.   That factor is the SUM of all CO2 emissions ever caused by the combustion of fossil fuels since man first started to burn fossil fuels in large amounts at the beginning of the Industrial Age about 160 years ago.  The term assigned to this quantity is “Cumulative Emissions”.

So why is this quantity so important?  It is mainly because the additional carbon atoms we transfer from the geological world to the biological world by the combustion of gas, oil, or coal then stay in the biological world for a very long time – for approximately a millennium – and remain distributed between the atmosphere, plants and animals, and in the surface layers of the oceans with about half of that new carbon remaining in the Earth’s atmosphere.  Thus, of the about 500 gigatons of carbon that have been burned since 1850, about 250 gigatons remains in our atmosphere today.  That is why the concentration of CO2 in our atmosphere has risen from 280 to 396 parts per million since 1850 and the mass of carbon in the atmosphere has risen from about 550 to 800 gegatons over that period (note that a gigaton is equal to one billion tons).

Thus, the Cumulative Emissions of carbon over the Industrial Period have been about 500 gegatons and those emissions have increased the temperature of the Earth about 0.8 degrees Centigrade or about 1.5 degrees Fahrenheit so far.   This deceptively small increase in temperature has caused the changes we have observed to data (such as disappearing glaciers, increasing frequency of floods and drought, decreasing ice coverage of the Arctic Ocean, increasing sea levels).   Furthermore, the total amount of warming due to our cumulative emissions to date are expected to reach about 1.0 C within the next decade or two as the thermal inertia of our vast oceans is gradually overcome.  From observations such as these, we can expect that future emissions of another 500 gegatons of carbon will raise the average temperature of the Earth another one degree Centigrade so that the net temperature rise will then be approximately 2.0 C.

A rise of 2.0 C relative to the pre industrial period is now considered to be “very dangerous” and is expected to cause many very  serious problems (see the references to Kevin Anderson provided in my two previous posts).  Yet, the scientific community increasingly believes that this amount of future emissions and temperature increase can no longer be avoided.  That is, we are now so addicted to the use of fossil fuels for energy production that it will be practically impossible to prevent the future use of at least 500 gegatons more of our fossil fuel carbon.   The readily available reserves of gas and oil, alone, throughout the world add up to about 500 gegatons and we are continuously looking for more of these “relatively clean” forms of fossil fuels.  At the same time, we continue to explore the means of extracting and using the other, far dirtier forms of fossil fuels, such as coal, tar sands and shale oil.  The estimated reserves of these are thought to be far, far greater, about 10,000 gegatons.  Thus, it presently appears that the cumulative emission of carbon over the coming century is likely to be much more than  500 gegatons, as “business as usual” continues.   Thus, we are actually headed for state in which the temperature of the Earth is very likely to reach and even exceed 3 or 4 C degrees greater than the pre-industrial period.

As Kevin Anderson explained (see previous two posts), a +4 C state is generally considered to be incompatible with existing forms of civilization on this planet and might very likely set into motion additional irreversible changes that will drive temperature even higher.  I will not repeat that information here, however, and will instead return to the main point being made – that is, is to explain why the term “Cumulative Emissions” is key to understanding where we are and where we are headed.  In summary, we can expect a temperature rise of about 1.0 Centigrade for every successive 500 gegatons of carbon we burn.  We are now assured of a 1.0 C increase from our cumulative use of fossil fuels, to date, and are sure to add another 1.0 C even as we try to turn things around.  If we don’t manage to turn thing around and we continue to burn even more of our all too abundance supplies of fossil fuels, you will be able to predict the future – simply by watching the most reliable predictor of temperture increase called Cumulative Emissions.  When we reach a Cumulative Emission level of about 2,000 gegatons, you will know that we are literally “toast” having achieved a +4 C climate.

Is all of this very alarming and am I being an “Alarmist”?  I certainly hope so.  The more we have learned in very recent years, the more we have come to realize how insufficiently alarmed we have been even during the last decade.   In any case, an understanding of the term, Accumulate Emissions, will help us understand why action is needed right NOW – while annual emissions are the highest they have ever been. We are presently “using up” the lions share of our allowance for all future emissions.  Therefore, we can do the most good by reducing our present way-too-high emissions.  We should not be deceived into thinking that we will “solve the problem” later by decreasing emissions at some later date.  It our Cummulative Emissions that matter and it does not matter if we emit 500 more gegatons carbon tomorrow or whether we spread those emissions out over the next two centuries.  The result will be the same and if we do manage to limit those total future emissions to 500 getatons of carbon, we might be able to limit future temperature increases to 2.0 degress C.


  1. There seems to be very little interest to lower our standard of living. Look at our own lives and that of our own children for examples. And our children have had the opportunity to listen to their father and uncle many times on this subject. My impression is that they don’t care and are more concerned about the present and less about the future. That’s nine young adults which includes doctors, lawyers, teachers and newspaper owners (educated and smart individuals all). Looking to technology (and not conservation) is probably our only hope. I live 20 miles from the nuclear power plant in Red Wing, Minnesota. Next to it is a very popular gambling casino. Nuclear waste is stored there. Our assumption is that we are safe. We aren’t concerned about nuclear power. We understand the merits of this energy source. Environmentalist and coal producers probably won’t appreciate my bias for nuclear but that should be our future. It will be an expensive investment but I’m a “progressive” — meaning that our energy future is government and the private sector working together. This would be a start to your quality and thoughtful writing on this subject. — Best regards, Dave Grimsrud (Eric’s brother)

    [Response from EPG: Dave (yes Dave Grimsrud is indeed my brother),

    I agree with you that things don’t look good if changing the lifestyles of the wealthy, which as you say includes all members of our own families, is the only way. And as you suggest, I will continue to also promote the BIG TECHNOLOGICAL solutions, which you clearly prefer.
    However, you seem to think that that will do the job. You are not a scientist, however, and perhaps as a result, you have the impression that science and technology can do just about anything upon demand whenever the need arises. Perhaps because I am a climate scientist, however, I am quite sure you are wrong with respect to this problem. What you seem to have in much greater abundance than I is what I call “human hubris”. In order to embrace that all-too-common attitude that “we’re been through some tough times before and will find our way out of this one too”, it helps a great deal, I think, to not be a climate scientist. I, for example, know that Man just recently arrived on this planet and does not know “jack” about the severity of the corner he has painted himself into. Thus, my non-scientist brother has the impression that the likes of me will solve this specific problem in a manner that will allow our children to continue their “business-as-usual” life styles. Unless that changes, I think we will all sooner than we realize be concerned merely with coping in a +4 degrees Centigrade world and wondering why we did not do more when viable opportunities for correction existed.

    The fatal flaw in your thinking, Dave, is to not realize that Cumulative Emissions, only, over the next few centuries matter and that our annual emission rates are presently at an all time high and rising – due mostly to the maintenance of our beloved lifestyles – which can be corrected with an ease that will be considered to be trivial later. Thus, this is really a “short term” problem not a long term one in that the only opportunity to address it might be right now. Changes in lifestyles could occur tomorrow while implementation of the BIG TECHNOLOGIES will take one or two decades and very possibly far too late for their desired effects to materialize.

    And as you point out, my own fatal flaw might be to think that Man is capable of change based on the use of his brain for the long term welfare of his descendants. Short term enjoyment and convenience seems to sell so much better as you clearly pointed out. I will be the first to admit that I am the nerd of the family and have to continue to consider additional ways of influencing the public.

    Thanks for your help in that regard, Eric ]

    • Dave and Eric

      I love it. (Frustrating isn’t it?)

      It’s like my brother respecting my opinion and ‘computer system’s’ knowledge, but we can only agree to disagree when it comes to CAGW and the ‘climate system’. (It’s hard to fight against the indoctrination when someone only listens to Minnesota Public Radio – MPR). It only took me two years to convince him of the futility/stupidity of wind power and that came only after a third brother joined in the matter.supporting my position.

      JohnB (Bob’s Brother)

  2. Eric,
    David Archer says that the accessible fossil fuels amount to around 5,000 Giga-tonnes. While he may be “In the Ball Park” with that estimate there is a great deal of uncertainty about what effect burning all that carbon would have.

    Archer estimates that burning 5,000 Gt of carbon would raise global CO2 concentrations to 800 parts per million or roughly twice current levels. He says that will postpone the next “Ice Age” by 500,000 years. I would love to get my hands on whatever he is smoking.

    In the late Ordovician era the CO2 concentration was ~4,400 ppm but that was not enough to prevent an “Ice Age”.

    [EPG response: All that is needed to prevent another ice age is about 350 ppm CO2. Too much of a good thing will send us back to an ice free world such as we had when CO2 was about 1,500 ppm about 50 Myrs ago. ]

  3. Getting back to grand technogical solutions I would like to point out that “Generation IV” nuclear power plants delivering one GW of electricity (e.g. the Liquid Fluoride Thorium Reactor) consume about 1 tonne of fuel per year. An equivalent coal powered plant consumes 3,000,000 tonnes of fuel.

    Imagine for a moment that nuclear fusion can be used for generating electricity, Now it only takes 200 kg of hydrogen per year to deliver 1 GW of electrical power.

    Let’s get really silly and imagine power generators using anti-matter as in “Star Trek”. Now it only takes 30 kg of fuel, You could carry that much in a suitcase.

    [EPG response: I too wish that we had continued our research and development of better nuclear power plants and think that we should once again get on that track. However, as related in my recent posts and by Dr. Anderson’s talk THE BIG TECHNOLOGY approaches alone will no longer solve the more immediate problem of reducing CO2 emissions right now. Listen to Anderson’s talk again if you don’t understand what I just said. ]

  4. Eric, You are right. I’m not a scientist and; therefore, don’t have all the answers. My point is that some of your considerable passion be directed, toward greater use of nuclear power. A “start” was the word I used. Your tone is too personal (ego, like your friend Dr. James Lovelock from England). Look for common ground even with conseratives who believe in nuclear power.

  5. Dave Grimsrud,
    Great sentiments! Maybe we could start something right here.

    While I see rising CO2 levels as a net benefit to living things I do agree with Eric when he wants to eliminate the burning of fossil fuels. My reason is that we should leave the fossil fuels in the ground knowing that our ancestors will find better uses for them than we have.

    Eric wants us “First Worlders” to consume less which boils down to self imposed poverty. That is like asking Al Gore to emulate Mahatma Ghandi who wove his own clothes and extracted salt from sea water. It won’t happen in spite of the efforts of Neo-Luddites (Greenies) who have acquired real political power in many nations.

    In a nuclear powered future we could go on consuming at our present rate while raising up the “Have Nots” by bringing electricity to every dusty hamlet in the “Third World”. The USA was once capable of turning out four 10,000 tonne liberty ships in a day. How many modular nuclear reactors could be built in a day?

  6. Eric,
    You say that 350 ppm of CO2 will prevent another glaciation from ocurring. We are already in an “Ice Age” as can clearly be seen in slide 3B of your “Short Course”; the present warmth is an “Inter-glacial”.

    In slide 3E you state that “Sensitivity to CO2” amounts to “3 degrees C” per doubling. In sllde 4H you mention an additional “slow feedback” of 3.5 degrees C bringing the total sensitivity in this era (the past 800,000 years) to 6.5 C.

    During the early work on Antarctic ice cores the strong correlation between CO2 concentration and temperature was seen as hard scientific evidence for the hypothesis that CO2 drives global temperatures.

    More recently the time resolution of ice core measurements improved so we now know that CO2 concentration lags temperature by 600-800 years. This supports the hypothesis that temperature drives CO2 concentration. There is a simple physical process to explain this. The solubility of CO2 in water falls as temperature rises. As the upper layers of the oceans warm, CO2 is expelled. This also explains the time delay as the ocean warming takes centuries.\

    [ Response by EPG: During the glacial / interglacial changes of the last million years, of course, CO2 change lacked behind the T change as expected for the reason you say – due to decreased retention of CO2 by the warmer oceans. But then this increased amount of CO2 further increased T. This is called a positive feedback effect. What is happening today is entire different. Atmospheric CO2 in rising for a different reason. Man is converting geological carbon (fossil fuels) to biological carbon (found in the atm, in plants, animals and the surface layers of the ocean. CO2 is presently preceding an expected as will as observed T increase. ]

  7. Dave Grimsrud,
    You said “I’m not a scientist and; therefore, don’t have all the answers.”

    I am a scientist (a physicist) and it is my duty to tell you that physicists NEVER have the answers. They never have and they never will.

    Three hundred and fifty years ago “Natural Scientists” thought there were scientific “Laws”. Today we realize that all we have is hypothesis.

    The current fracas over “Climate Science” reminds me of the battles between Fred Hoyle (Continuous Creation) and the “Big Bang” theorists. I read Fred’s book in 1958 as an undergraduate studying at the Cavendish Laboratory in Cambridge, UK. It struck me as craziness but the “Big Bang” seemed even crazier. I went with Fred Hoyle as he was “our guy”.

    It was all pretty passionate back then but the observations eventually vindicated the “Big Bang” hypothesis. Even so the “Big Bang” theory is just that……….a theory. It seems to fit the facts today but it will fail like all the other physics theories. Einstein had it right when he pointed out:
    “No amount of experimentation can ever prove me right; a single experiment can prove me wrong.”

    If someone tells you “The Science is Settled” that person does not understand what science is. My advice is to challenge every word he says while clutching your wallet.

    [Comment by EPG: Concerning your opinion, Galloping Camel, that the Science of global warming is not “settled”, you are merely stating and misused and well known aspect of all science. Of course, the issues of science alway remain open for continuous future study and review. No scientific issue of some complexity has ever been “settled” beyond all levels of doubt. You can prove me wrong by just telling us all one issue of some complexity that is true “settled”. Thus your commont carries no real meaning. In science we study something and at some point a large majority often become sufficiently convinced of what is happening as to recommend that corrective action be taken. When scientists do reach that point on an issue, the point then becomes “settled” only in the sense that the evidence strong supports action. Thus your piss-ant definition of “settled” means absolutely nothing in the practical world. Since you claimed to be a physicist, I am disappointed that you would inject this meaningless “argument” here. ]

  8. I am not a climate scientist but have followed the AGW pros and cons for the last ten years. Some of your basic assumptions are at odds with this seemingly well thought out summary,
    What would be your refutation to this?

    [Response from EPG: Julian, life is too short for me to do reviews here of Deniers’ long articles. At the same time, I am pleased to address specific questions of relevance to AGW? In other word, rather than send me a chapter out of the Encyclopedia, tell me in your own words what important point this Denier made that puzzles you.

    And you should not be perplexed that different “bottom lines” are out there. That will always be the case – even long after the scientific case has been made clear to 97% of the professional scientists whose day jobs is to study climate change. The finanical losers of this environmental question will never give up. How do you convince someone of something if being convinced means one’s business would be damaged? ]

  9. Julian Braggins,
    The link you provided gives multiple observations showing that CO2 is a pretty weak “Driver” when it comes to global temperatures.

    As you point out, there is convincing evidence that the concentration of CO2 in the atmosphere has been rising monotonically since 1900. I am also persuaded that this is the result of burning fossil fuels.

    If CO2 was a major “Driver” of global climate, HADCRUT4 would correlate with the Mauna Loa CO2 measurements. The fact that there is little correlation demonstrates that other factors overwhelm whatever effect CO2 may have.

    No matter what time scale you choose (other than 1975-1998) there is poor correlation between CO2 concentration and global temperature. When it comes to ice core measurements that extend 750,000 years into the past, the observations show that temperature drives CO2 concentration. The owner of this site is a chemist so he understands why this is so.

    While correlation does not imply causation, lack of correlation implies non-causation.

  10. Dave Grimsrud,
    I was not puzzled or perplexed, just trying to gently point out that your conclusions of CO2 being the main driver of temperature increase do not agree with the observations.
    Empirical evidence means more to finding the real picture of climate than any theory or model.
    To mangle Einstein,” It only needs one observation to prove me wrong” 🙂

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