Why Has a Drop in Global CO2 Emissions Not Caused CO2 Levels in the Atmosphere to Stabilize?


Note: Readers have asked why there has been no stabilization in the measured levels of the greenhouse gas carbon dioxide in the atmosphere when reported emissions of CO2 have fallen. Scripps CO2 Group Director Ralph Keeling gave this response:

There’s a pretty simple reason why the recent stabilization in global emissions hasn’t caused CO2 levels to stabilize. The ocean and land sinks for CO2 currently offset only about 50 percent of the emissions. So the equivalent of 50 percent of the emissions is still accumulating in the atmosphere, even with stable emissions. To stabilize CO2 levels would require roughly an immediate roughly 50 percent cut in emissions, at which point the remaining emissions would be fully offset by the sinks, at least for a while.

Eventually, additional emissions cuts would be required because the sinks will slowly lose their efficiency as the land and ocean start to saturate. A permanent stabilization at current levels therefore requires both an immediate 50-percent cut as well as a slow tapering thereafter, eventually approaching zero emissions. The recent stabilization in emissions might be viewed as a very small first step toward the required cuts.

­– Robert Monroe


Image: Global Carbon Project

27 thoughts on “Why Has a Drop in Global CO2 Emissions Not Caused CO2 Levels in the Atmosphere to Stabilize?”

  1. Shouldn’t the reduction in the rate of emissions still be detectable as a reduction in rate increase in atmospheric concentrations?

    1. Balance between air, land and oceans change year to year as well I believe, especially due to El Niño and el nina phenomena. Melting and burning peat and forest fires also play a role. Might take a decade to see a significant trend.

    2. Well, as Senator Marco Rubio says “I am not a Scientist”. Even though I am not a Scientist, I will take a stab at it.

      Say we reduce CO2 from whatever it is –30 Billion Tons a year —to “only” 29 Billion tons. As the article says, the Oceans and Land absorb (at least for now) about 50% of the CO2 we emit, (I might quibble about the exact percentage, but say about 50% of our emissions of 29 Billion tons (or 14.5 Billion tons) stays in the air.

      CO2 can stay in the air a long, long time. I believe the CO2 emitted by Model “T” Fords in 1910 is STILL in the air.

      So that might explain why, even though we have reduced CO2 emissions, we saw the CO2 hit a record in April 2016 of 409 PPM (Parts Per Million). And for the year ending April 25, 2016, the CO2 went up 5.64 PPM (over 56 times the Average Annual Rate of 0.1 PPM per year in the 100 years ending in 1880, and 1,128 times the Average Annual Rate of 0.005 PPM in the Interglacial Period as per Drs. Andrew Lacis and James Hansen, et al of NASA GISS.

      Recently, Cape Grim in Australia began reporting CO2 of 400 PPM for the first time.

      Maybe some people can offer a better explanation.


        Oklahoma’s Republican Senator James Inhofe famously (or IN-famously) threw a Snowball on the Senate Floor in February 2015, to “prove” that Man-Made Global Warming is a Liberal Hoax.

        Historically, as NASA GISS was quoted above, the annual rate of CO2 PPM (Parts Per Million) increase was very small, about 1 part in 200 (two hundred) MILLION PER YEAR.

        The Paper was entitled:
        “The role of long-lived greenhouse gases as principal LW [Long Wave] control knob that governs the global surface temperature for past and future climate change” – September 2013
        By ANDREW A. LACIS* PHD (Physics), JAMES E. HANSEN PHD (Physics), GARY L. RUSSELL PHD (Math), VALDAR OINAS and JEFFREY JONAS, http://pubs.giss.nasa.gov/abs/la06400p.html

        One divided by 200 is 0.005, so we say that, in between Ice Ages (the Interglacial Period) the rate of increase back then was 0.005 PPM a year. I understand that we do that since NOW — the rate is so HIGH we have to express it in Parts Per MILLION, not in Parts per 200 Million.

        About 3 months ago, NOAA (National Oceanic and Atmospheric Administration) Scientists in Hawaii were all excited and alarmed that, in 2015, the Global CO2 Level went up for the first time by 3 PPM for the year.

        But even a “non-Scientist” can think:
        The Earth is about 4.5 Billion Years old.

        CO2 has been around for about 3 Billion Years.

        Suppose that a “Natural” Annual Increase of CO2 PPM was 5 PPM or 4 PPM or even 3 PPM a year?

        Even at 3 PPM a year, after 1,000 years, the “natural” CO2 Level would go up by 3,000 PPM and today, rather than being around 407 PPM, the CO2 Level today would be 3,407 PPM! Even Donald Trump would say: “That’s YUUUUUUUUGE!”

        But suppose CO2 had increased at a supposedly “NATURAL” Annual Rate of 3 PPM a year, for, say, I don’t know, say for about 10,000 years. That’s an increase of 30,000 PPM! So today the CO2 Level would be 30,407 PPM and NOT 407 PPM.

        And that is with an increase of “only” three (3) PPM per year.

        I downloaded the NOAA CO2 Data for 1958 to 2016 into MS Excel. I show for the years ending April 13 and April 15, 2016, the CO2 PPM increase was 4.06 and 4.41 PPM, respectively, the FIRST TIME CO2 went up by 4 PPM or more in a year. On April 15, 2016, CO2 was 408.56 PPM. As noted above, on April 25, 2016, CO2 went up by over 5 PPM, compared to a year ago. That was the FIRST time THAT ever happened.

        And on May 22, and May 23, 2016, we saw the first back-to-back CO2 PPM increases of 5 (five) PPM a year, of 5.39 and 5.29 PPM, respectively, compared to a year earlier. On May 23, 2016, CO2 was 408.86 PPM.

        Of course, we would still have a ways to go before reaching the CO2 level of the Planet Venus, 96% or 960,000 PPM.
        (960,000 PPM is 96% of one Million.) But while, per NOAA, the Earth’s Average Global Temperature in April 2016 was 14.8 Degrees Celsius (58.68 Degrees Fahrenheit) the Temperature on Venus is 864 Degrees “F” or 462.2 Degrees “C”)!

        So let’s hope we NEVER reach Venus’ Level!

        Oh, BTW, if our CO2 Level HAD increased by “only” 3 (three) PPM a year, for 320,000 years (or a little over 7/10ths of 1 percent of 1 percent of the Earth’s age of 4.5 BILLION years), then the Earth’s CO2 Level would have increased by “3 times 320,000” or 960,000 PPM and today our CO2 Level would be higher than Venus’, at 960,408 PPM for Earth and 960,000 for Venus.

        But then everyone on Earth would probably be dead.

        So when CO2 increases by 5 or 4 or even “only” 3 PPM a year, is it “Natural” or is it “Man-Made”? If you really THINK about it, it HAS TO BE MAN-MADE.

        But then some Deniers can only make up Grade-School “jokes” like “Global Warming is full of GLO-BULL”, and words like “Libtards” and lack any real ability to understand the above. I might just as well have written it in Latin or Greek or Pashtun!

        And real scary thing is that people like that VOTE!

        Senator Inhofe thinks that if Man-Made Global Warming were “real”, then there would BE NO MORE SNOWBALLS, only Fireballs. And Senator Inhofe is Chairman of the Senate Environmental Committee, so he MUST be right, or just “right-wing”?

        I suppose I should never use the words “Senator Inhofe” and “thinks” in the same sentence.

      2. Close. But, using your numbers, if we start at 30BT CO2 emissions and a 50% absorption rate, that means 15BT gets absorbed and atmospheric concentrations go up 15BT.

        Now, if in that same year we decreased emissions so only 29BT were emitted instead, absorption does NOT remain 50%, but remains 15BT. Thus, atmospheric concentrations go up 14BT, NOT 14.5BT.

        Absorption is based on atmospheric concentration, NOT emissions. The 50% rule of thumb is pure happenstance and has NO scientific basis at all. That’s why 350PPM might still be possible. Drop to zero emissions, and that 15BT (in the first year) will drop atmospheric concentrations. Of course, absorption is declining. We’ll absorb 15BT (your number) this year, but less and less every year from now on until we reach zero absorption. At that point, we get to pray to the Flying Spaghetti Monster that absorption doesn’t go negative.

    3. The rate of emission isn’t the only thing affecting the rate of increase in the atmosphere. It’s a noisy signal, and you need a lot of annual data points to detect a change in the annual rate of change.

      Rob Monroe, I hope can put some numbers on a better answer to this question, as I see the assumption being widely repeated that any change in human fossil fuel use should immediately show up in the global CO2 levels.

      It’s hard to convince someone who hasn’t taken Stat 101.

  2. The first derivative of emissions measurements should go to zero if emissions have indeed been stabilized (as discussed by Graham and Jason). Although it might take as much as a decade to see it in The Keeling Curve, models that account for phenomena like El Niño should not suffer such delay.

    The Carbon Tracker produced by NOAA uses measured data and estimates known sources and sinks. According to their model the rate of emissions is still increasing at least through 2014 (can’t wait to see 2015 numbers).


    Many in the US government jumped on numbers by the IEA that indicate emissions have stabilized worldwide even though their own (NOAA) model suggests otherwise. Personally I think the IEA fudges their numbers–perhaps in a less than conscious way–because it’s what the Obama administration and others would like to see for the purposes of happy talk.

    I’ve even heard someone from the EPA say emissions have been flat for “three years” (2013-2015) although that’s really only two years even by IEA numbers. It has become a talking point.

    I’m not intimately familiar with IEA methodology but simple accounting for emissions based on best guesses or reports from governments seems fraught with difficulties. We have only to review methane emission estimates in the US to see this.

    1. Can you have a derivative of measurements? I think you need a function, like a model to represent the data, before you can go looking for gradient functions.

      Does the EPA estimate global emissions or just for the US?

  3. Thank you for the post Robert. Does Scripts advocate an immediate 50% reduction in emissions?

  4. But the CO2 rate of increase not only has not stabilized but reached record levels. Isn´t that so?

  5. On a business channel the commentator was quite happy to report that liquid fossil fuel consumption is nearing a 100 million barrels a day,thus supporting higher oil prices and greater profits. The economy would surely crash at 50 million a day,good bye jobs ,pensions . We need to reset to a whole new operating system in which scientific reality dictates the modus operandi.

  6. Up until a year or two ago I read on several websites that it took up to 20 years for current GHG emissions to manifest themselves in the atmospheric measurement. Has the thinking on this changed?

  7. Don’t believe that the Co2 has stabilised it has NOT .
    In my Country the Australian government says there has been a drop in emissions of 90million tons but this is a lie .
    Why ! . Well what my government and others have been doing is buying Co2 credits . This is how the Co2 shows up on reports that we have reduced our Co2 output .
    In fact Australia has increased our output of Co2 buy 120 million tons not reduced it . They have also changed the way it is calculated . Understand we are in big trouble and have less than 40 years till we reach 600ppm at witch time new born babies will start to be born with smaller brains and deformities . Do the math , we have 190 ppm left and at 3 ppm that means we have 63 years .
    now take 10 years from that because of El-Nino’s witch increase the Co2 buy at least 50% the year of the El-Nino and you have 53 years now take away 10 and as much as 15 years for the increases from now till we reach 600 ppm and your looking at 43 or 38 years left till we reach 600 ppm .
    Also remember ppm does not mean parts per million it means parts per square Millimetre so what another poster has said about ppm is misleading .
    It may be better to understand that the current O2 rate in our atmosphere is now 20.68% as of about 18months ago and falling . Humans need 21% minimum and 19.5% is considered extremely dangerous . Also remember that there are other gases to consider when talking ppm or % of O2 . The more there is of other gases the less % of Oxygen there will be and Humans need 21% for full functioning of your Brain . (make sense now why the world seems to be going mad and country’s are making very bad choices ?)

      1. Well CO2 doesn’t look right so I do it as Co2 , Cobalt is Co but when you put the 2 on it , it can only mean carbon dioxide !! 🙂
        Still what I have said is not incorrect we are in big trouble and don’t listen to the B/S certain groups would have us all believe . The run away Green house effect is now in play so all simulations can be thrown out .

        And the most important thing you all need to understand is it’s not temps or sea level rise that will wipe us all out and we can move to higher ground and survive a 2 degree temp increase , but we CAN NOT SURVIVE 600ppm of CO2 and will start the march back to a lower form of animal AKA: we will become Monkeys living in trees as our ancestors were before we climbed out and started to walk upright on 2 legs. 6 million years ago when CO2 dropped below the 600ppm mark .
        63 years and counting if we are lucky , but more like 38 years and counting …

      2. NIce try but I’m not as much of a ….fill in the blank as some seem to be . But then there is all ways 1 ……fill in the blank . The periodic table is not a good reference to use when talking the atmosphere or molecules of air.
        Hence carbon Dioxide is 1 molecule of C and 1 molecule of O hence it is written as C O2 . Just looks better to do it as Co2 seeing as I can’t make the 2 a smaller character .
        It’s written as a large C a large O and a small 2 .

  8. Karl as to the oxygen well you might wish to read this,

    Oxygen is written as O2 when there are two oxygen atoms in the molecule. Pure oxygen doesn’t generally exist as individual atoms, two oxygen atoms bond together to form an oxygen molecule 🙂

    1. Glen – As a strong advocate of the truth of human-caused global warming and as a 29 year chemistry teacher, I quite understand the role of CO2 in capturing heat in the atmosphere. O atoms are vey reactive; they are found in the atmosphere, mostly, in H2O, NO2, SO2, SO3, O2, O3 (ozone), CO (carbon monoxide) and CO2. Oxygen is represented by a capital O. Although the 2 and 3 above are not here written as proper subscripts, oxygen is never properly written as o.
      I’m very grateful to the Keeling curve people in their effort to educate the public.

  9. The change in CO2 is related to the seasonal ocean heating and cooling as can be seen in the observed oscillation of the monthly CO2 at mauna loa. The increasing leg of the seasonal oscillation is greater than the decreasing leg because at the end of each annual oscillation the sea level rises because of the sequestered heat that releases a corresponding amount of CO2 into the atmosphere. So it is the stored heat in the ocean (as sea level rise) as the result of each annual solar cycle that is the cause of the observed increase in atmospheric CO2. This is because the solubility of CO2 in water decreases with ocean warming. Human emission of CO2 has little role in this because it has no oscillation like the observed CO2. As a result the quoted human emission must be an incorrect order of magnitude over estimate.

    1. Girma maybe you don’t read or watch the news services or read the comments here .
      if what you say is correct then please explain why the Great barrier Reef is Dying or the north pole has since 2007 drooped to record lows in 2007 then even lower in 2012 and this year it may be all but gone here is a link I think you also need to look at and after you do then PLEASE EXPLIN WHY it’s happening.

      1. Henry’s law states that the solubility of gases in water decreases with increasing temperature. This is observed with the annual seasonal oscillation of CO2. Further evidence for the this relationship can be seen with the increase in CO2 during Elnino, and it’s decrease during La Nina and during volcanic eruption. As a result, the Co2 released by the warming ocean (corresponding to the sea level rise) is the main cause of the observed increase in the atmosphere. This increase will stop when the seasonal solar heating stops like it happened during the little ice age.

        Even if we completely stop using fossil fuels, the co2 concentration in the atmosphere will continue to increase at a rate of about 3 ppm per year, because its source is the seasonal heating of the ocean by the SUN

        1. The anthro ca. 10 GTC/yr flux is a one-way flux from the lithosphere (with a minor component taken from the biosphere cycle).
          The atmosphere/ocean ca. 90 GTC/yr flux is a two-way flux, and any net flux resulting from ocean degassing is expected to be much smaller. Ad-hoc models, such as Lon Hocker’s, have been built, pretending that sea surface temperature determines the value of d[CO2]/dt, not of [CO2]: http://wattsupwiththat.com/2010/06/09/a-study-the-temperature-rise-has-caused-the-co2-increase-not-the-other-way-around/
          However, using the values proposed by L. Hocker results in a net flux from ocean to atmosphere of ca. 7 GTC/yr, less than the one-way 10 GTC/yr anthro flux.
          Moreover, if the fluctuations of sea surface temperature determine CO2 release, the maximum value at each annual cycle is expected to be around November, when the average sea level is highest: http://sealevel.colorado.edu/content/2016rel2-global-mean-sea-level-time-series-seasonal-signals-retained
          But the maximum seasonal CO2 level is in May, corresponding to the Northern hemisphere spring – most of the lands. This is an indication of a mostly biospheric origin of the seasonal CO2 fluctuations.

        2. Nope. The solubility of gasses in water is a function of BOTH temperature AND concentration of the gas SURROUNDING the water. Since atmospheric pressure can be taken as a constant, you are correct that total gases dissolved in seawater declines as water temperature increases.

          But from there, your argument is pure tripe. First, seawater temperature is NOT increasing significantly. You’re conflating atmospheric temperature with water temperature.

          Second, atmospheric CO2 levels are going up (seriously) while oxygen levels are declining (a bit). So, OXYGEN levels in the ocean are declining while CO2 levels are INCREASING.

          Third, there is NO significant seasonal change in ocean temperature. The ocean is deep. Change the surface temperature for part of the year and the vast majority of the ocean doesn’t even notice. Plus, the world has two opposing hemispheres. When one hemisphere’s surface is warming, the other’s is cooling. They cancel out!

          1. John Morrison not shore who your statement is in reply to

            But ocean temps are going up otherwise the north pole would not be melting so fast as the ice melts both from the Atmosphere and the warmer currents ergo the bottom due to the warming .
            The top 75 meters is going up fast and the 75-150 meters is also going up but not as much in temp and that is why the north pole is melting fast you can see the difference between the north pole and south as the south has not melted as fast because most of the ICE is on land and not floating on a ocean like the north pole is .
            Also because the surface temp of the ocean is warming it has caused a major Bleaching of the Great Barrier Reef this last summer.
            Some 90 % of the northern reef has damage
            45%-55% of the middle reefs are damaged
            only the bottom 1/3 of the reef in the south has got away with 15% damage .
            If there is more CO2 and other gasses then the concentration of Oxygen we breath goes down as you inhale more of these gases and less oxygen even thou the same amount of oxygen is in the Atmosphere if you where to measure it in tons it’s just that there is also more CO2 and other gases now.
            I do not know if the atmosphere is thicker or not , if it is not then there is less Oxygen if it has increased then there is the same amount but there will be a lower % of it when you take a breath
            Also Marco Rubio is a Republican so represents BIG OIL and Polluters so I don’t listen to a word he says seeing as the Republicans are run by the Tea Party and are endorsing the nutter Trump
            The Republicans are like our LNP party the current Party in office
            The Party that as I said in a previous post have lied about how much CO2 Australia has reduced it’s CO2 . All they have done is buy carbon offsets and now claim that the CO2 in Australia has been reduced by 90 millon tons when it has actually gone up 129 million tons .
            It’s called cooking the books and is what the Republican Party will also do .
            This is not tackling the problem of Climate change or reducing it but you keep B/S to yourself so you can vote for them and don’t worry about your grandchildren as there the ones whom will have the deformed children’s brains when we hit 600ppm

  10. In a chart from 1980 to 2009 81% of all countries had increases in emissions. There has been a 25% increase in emissions during that period. That is due to population growth and all the countries trying to improve their quality of life by using more oil, more coal and natural gas. We currently get only .4% of all our energy needs from solar. We get 4.5 percent from wind. Population is growing in 80 percent of all nations. Decreasing CO2 by mandate is impossible. 400 ppmv overall and 3% of that is human. that is 12 ppmv for the entire globe. The US occupies 3% of the land mass on the planet so 3% of 12 ppmv is ours to fix. That is .36% of 1 ppmv. It would cost us billions to lower that by 10%. That means we could only control 3.6% of 1 ppmv. China at 28% of world emissions and India at 9% = 37% coming from those two nations and they are exempt from having to reduce emissions in Kyoto Treaty the USA refused to sign. Cutting our CO2 emission by 50% is a pipe dream. Totally impossible. No chance in hell. You keep talking about we need to do but getting the entire globe to do it is a non-starter. China is over 25% of all emission and exempt from having to do anything. Why waste so much time complaining about problem of which we have absolutely no control. did I mention that the ocean soaks up 40% of ours and methane is exploding globally?

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