Scaling the size of the CO2 error in Friedlingstein et al

By Bud Bromley | July 2, 2022

The error in Friedlingstein et al is much larger than expected. Friedlingstein et al Page 4. “when the cement carbonation sink is included), ELUC was 0.9 ± 0.7 GtC yr-1 , for a total anthropogenic CO2 emission of 10.2 ± 0.8 GtC yr-1 15 (37.4 ± 2.9 GtCO2).”

The amounts above are their calculation, not mine.

Friedlingstein et al reported their estimate for 1 year’s (2020) increase for human fossil fuel emissions, land use and cement = 37.4 +- 2.9 Gt CO2. This is their estimate of emissions not net emissions. Net CO2 absorption has not been subtracted.

• Using NOAA Mauna Loa data only (no estimates, no theories, no models, no assumptions.) Reported in micromoles/mole = ppm.
• MLO did not report CO2 flask measurements on Jan 1, 2020
• 2 Jan 2020, MLO reported 4 CO2 flask measurements for Jan 2, 2020. Average 412.9875 ppm
• 31 Jan 2020, MLO reported 4 CO2 flask measurement for Jan 31, 2020. Average 415.5225 ppm
• CO2 increase due to all sources human and natural combined for year 2020 is 2.5350 ppm
• 2.5350 ppm CO2 per year times 7.76 Gt CO2 per ppm of CO2 = 19.679 Gt CO2 added to the atmosphere in 2020 from all sources human and natural.

• Thus, net CO2 added by humans cannot exceed 19.679 Gt CO2 in 2020, because this amount includes net CO2 additions by all sources.

• Net global average CO2 concentration reported by Mauna Loa on 31 January 2020, the average of 4 measurements that day was 415.5225 ppm. Multiply by 7.76 Gt per ppm = 3224.455 Gt CO2 total CO2 in atmosphere.

• Then, 19.679 / 3224.455 = 0.006103. Multiply by 100 = 0.610%.

• Net Human CO2 added to air in 2020 cannot exceed 0.610% of total CO2 for 2020. This 0.61% includes net CO2 emissions and net CO2 absorptions from humans including cement, net CO2 from ocean, net CO2 from land, rivers, lakes, CO2 from rotting and decay, net CO2 from biosphere, etc.

37.4 Gt CO2 is the Friedlingstein et al estimate of human emissions only for 2020. It is an excessively complicated estimate.   If you read the Friedlingstein et al paper you will see the complications, uncertainties, and assumptions. But that amount is human emissions only and only emissions, that is CO2 absorptions have not been subtracted from their estimated human CO2 emissions.

Net total CO2 added in 2020 was measured 19.679 Gt CO2. 37.4/19.7 = 52.7%, but this is an apples and oranges comparison. 19.7 is total emissions minus total absorption. 37.4 is human only and emissions only. Friedlingstein et al has a major problem.  We do not know how much of that 37.4 Gt CO2 human emission was absorbed during 2020. But we do know that net human emissions cannot exceed 19.679 Gt CO2.

It is easily proven and observed that ocean is both a CO2 sink and a CO2 source. CO2 flux is non-stop in both directions, into and out of Earth’s surface. Earth’s surface is over 70% ocean. CO2 gas molecules continuously collide with ocean surface, day and night, regardless of season, temperature or location; some of that CO2 is emitted back into air, and some is retained in the surface. The rate of exchange at the surface is the Henry’s Law coefficient at the local surface temperature plus or minus temporary perturbations due to alkalinity, surface and air disturbances, and salinity at that location. The net amount of biosphere CO2 flux is also non-stop in both directions when CO2 emissions due to decay are included.

Friedlingstein et al say on Page 9: “Global emissions and their partitioning among the atmosphere, ocean and land are in reality in balance. Due to the combination of imperfect spatial and/or temporal data coverage, errors in each estimate, and smaller terms not included in our budget estimate (discussed in Section 2.7), the independent estimates  (1) to (5) above do not necessarily add up to zero. We therefore (a) additionally assess a set of global atmospheric inverse model results that by design close the global carbon balance (see Section 2.6), and (b) estimate a budget imbalance (BIM), which is a measure of the mismatch between the estimated emissions and the estimated changes in the atmosphere, land and ocean.”

Apparently, Friedlingstein et al believe nature is in balance, except for humans. Apparently, they believe that nature which balances 3224.455 Gt CO2 total CO2 in atmosphere by continuous emissions and absorptions is unable to balance an additional 37.4 Gt CO2 from humans. Nature is already balancing over 86 times more CO2 than humans emit, but for some unexplained reason they believe nature is unable to balance the tiny human CO2 contribution, a human amount which is definitely much less than 0.61% of the total, because that 0.61% includes net CO2 emissions from all sources, human and natural.

Even the above example understates the size of their error. Since net human emissions would be a cumulative net of two fluxes, if there were a method to measure it, and since net global average CO2 concentration (i.e., NOAA Mauna Loa) is the net of two fluxes, then we should compare these data as integral areas. That is still an apples and oranges comparison because we only have the estimate of human emissions, not net human emissions. But at least the comparison would be in the right order of magnitude.

That comparison would look something like the following graphic. We would be comparing the entire area of the orange quadrangle to the entire blue area, understanding that the tiny blue area shown is much larger than actually is because the amount shown is human emissions only, not net human emissions. Human CO2 absorptions have not been subtracted. Nevertheless, it should be obvious that (1) B is not causing A, and (2) the orange area is enormously larger than the blue area.

Human emissions cannot be driving the growth rate (slope) observed in net global average CO2 concentration.


  1. Friedlingstein et al.
  2. K.W. Thoning, A.M. Crotwell, and J.W. Mund (2022), Atmospheric Carbon Dioxide Dry Air Mole Fractions from continuous measurements at Mauna Loa, Hawaii, Barrow, Alaska,  American Samoa and South Pole. 1973-2021, Version 2022-05 National Oceanic and Atmospheric Administration (NOAA), Global Monitoring Laboratory (GML), Boulder, Colorado, USA.
  3. Dlugokencky, E.J., J.W. Mund, A.M. Crotwell, M.J. Crotwell, and    K.W. Thoning (2021), Atmospheric Carbon Dioxide Dry Air Mole Fractions from the NOAA GML Carbon Cycle Cooperative Global Air Sampling Network, 1968-2020, Version: 2021-07-30,

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