CO2 System - GB

The CO2-system from an imaging point of view Let the data speak Guus Berkhout Prologue In short, there are two different ways of improving our knowledge of a system. Traditionally, we use an initial theoretical model, simulate measurements, and then compare the simulated measurements with real measurements. By updating the model parameters, we bring simulated and modeled measurements closer together. The updated model can be used for a better understanding of the systems behavior and for making model-driven projections into the future.

In the second approach, we don’t start with a theoretical model, but we do start with the measurements, analyze those measurements, visualize images and search for patterns in these images. Results are used for a quantitative description of the systems behavior and for making data-driven projections into the future.

My scientific career was in geophysical imaging. With measurements we made images of the complex geology of the upper lithosphere worldwide and, together with the geologists, we compared their geological models with our images. This interaction led to improved models and updated measurement instrumentation. Our slogan was and is: “Let the data speak’.

My experience is that if we deal with complex systems, it is wise to start with measurements and find out what the measurements try to tell us (‘squeezing information out of the data’).

My experience is also that system images provide invaluable information about the level at which theoretical models and real measurements can be best compared and, last but not least, whether the available measurements allow us to estimate the model parameters with any statistical significance.

In the following, I will summarize the properties of the complex CO2-system with the above in mind. I hope it will help in bringing the different CO2-schools closer together.

Introduction During the past 30 years we see three topics that are most often discussed in climate science and climate policy circles: I. II. III.

What is the cause of the increased CO 2-concentration in the atmosphere and what is the role of humans in this process What is the influence of the increased atmospheric CO2-concentration on the temperature in the atmosphere, particularly in the lower troposphere Using the information from topics I and II, what is the most sensible climate policy

The mainstream climate theory states that (1) the increasing CO2 is fully caused by human activities and (2) the increasing CO2 in the atmosphere is the principal cause of global

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warming. This believe explains current climate policies: (3) mankind has the capability to significantly lower the global warming by decreasing its CO2-emission. Looking at the socalled catastrophic consequences of global warming (“There is a climate crisis”), the mainstream message is that CO2-reduction must be done in a great hurry (“It is five minutes to twelve”).

In Clintel we point out that there is NOT enough scientific knowledge and, therefore, NO scientific proof to declare that CO2 is the dominant factor in global warming. Here, it is relevant to point at the research of Will Happer and William van Wijngaarden. They show that the more CO2 in the atmosphere, the smaller the increase in global warming ('decreased warming returns'). In Clintel we also argue that, apart from greenhouse gases, changes in the solar irradiation, changes in the cloud cover and changes in the big ocean circulations must be included in the research on climate change. Climate change is a multifactor phenomenon.

The overall message of Clintel to climate alarmists is that there is no scientific argument to spend billions of dollars to reduce the amount of CO 2 in the atmosphere in order to stop the global warming. This means that the answer of question I is actually not relevant for global warming policies, if the answer of question II is that the CO2-contribution is most likely to be insignificant. If we also look at the fact that more CO 2 is beneficial for nature and mankind, any CO 2-reduction policy is highly debatable.

By the way, for those who still are worried about the large anthropogenic CO2-emission, if we would move to nuclear powerplants, that problem is solved as well.

Let the data speak Summarising, please look at the CO2-data in Figure 1:

a)

Emission, accumulation, aborption

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60 15

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1990

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2010

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b)

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Trend relative to emission

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0 1950

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Trend

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gigaton/year

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0 1950

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Figure 1: a) Full measurements, b) trend data and c) ratios of trend data.

Explanation of Figure 1 Red curve: yearly human emission (in GtCO2/yr)) is large and increases fast (based on measurements in the past 60 years). It is based on the CDIAC archive (now ESS-Dive archive). The input time series could be enriched with uncertainty information.

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Blue curve: yearly net atmospheric accumulation (in GtCO2/yr) is much smaller – about a factor two – and increases less fast (also based on measurements in the past 60 years). It represents the Mauna Loa measurements. As the CO2 mixes well and fast in the atmosphere, it is considered to be a good estimate of the global average. Also, this input time series could be enriched with uncertainty information.

Green curve: yearly net natural absorption (in GtCO2/yr) is computed by obeying the CO2 mass balance equation, i.e., human emission – net atmospheric accumulation = net absorption by the total natural system (land + marine).

If we look at the trend data (b) we see that the total natural system (continents + oceans) is a big net absorber of CO2. The amount of absorption is almost half the amount of human emission. We also see that in the past 60 years the ratio absorption/emission did increase (green curve in c). In the following we will see that in the CO2-cycle the amount of CO2 that moves between the atmosphere and the natural system is about 20 times larger(!) than the human emission.

From Figure 1 we may conclude that the yearly CO2-increase in the atmosphere (A+ – A–) is about half the amount of the yearly anthropogenic emissions (Sant). The other half of Sant is taken up by the natural system (continents + oceans). For example, in the year 2020 the emission by humans Sant ≈ 40 Gt, the atmospheric increase (A+ – A–) ≈ 20 Gt and (N+ – N–) ≈ 19 Gt represents the net absorption by the natural system. This is exactly what you see in the above data picture (see the year 2020). Look also at the other years. Note that Figure 1 provides little direct information about causality.

To further explain the numbers in Figure 1, let me introduce the closed-loop system by showing the CO2-flows between the atmospheric reservoir and the natural (land-marine) reservoir for the year 2020 in Figure 2.

Snapshot for 2020

Anthropogenic sources

+

Cant << Sant

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CO2 round trip

F+=767 Gt/yr

N–

Snat <<Sant Natural sources

Atmosphere

A– Net Accumulation +20 Gt/yr 807 Gt/yr 787 Gt/yr A+

Sant=40 Gt/yr

+

767 Gt/yr

Net Absorption +19 Gt/yr

Antropogenic CCS

F–=787 Gt/yr

N+ 786 Gt/yr

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Cnat ≈1 Gt/yr Natural CCS

Land-Marine

Figure 2: The flow of CO2 between the atmospheric reservoir and the land-marine reservoir, together with the anthropogenic and natural sources. Note that incoming atmospheric flow A+, outgoing atmospheric flow A–, incoming land-marine flow N+ and outgoing land-marine flow N– are theoretical estimates with large uncertainties. The only measured quantities in the CO2-system are incoming anthropogenic flow Sant and net atmospheric accumulation (A+ – A–).

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Notation • S = symbol for carbon dioxide Source: Sant for anthropogenic and Snat for natural; • A = symbol for Atmospheric carbon dioxide: A+ for the incoming atmospheric flow and A– for the outgoing atmospheric flow • N = symbol for Natural (land-marine) carbon dioxide: N+ for the incoming land-marine flow and N– for the outgoing land-marine flow • C = symbol for Carbon, Capture and Storage (CCS): C ant for the anthropogenic sequestration and Cnat for the natural sequestration.

All flows are in GtCO2/yr.

Closed-loop architecture We will use the closed-loop architecture in Figure 2 for the description of the flow dynamics in the CO2-system. This architecture – being used for analysing up- and down-going waves in seismic imaging theory – allows us to recognise two internal flows to (F+) and from (F–) the atmosphere: – The bio-driven circulation flow generated by the continents (‘biological pump’). On the one hand this CO2-flow is due to absorption by plants (photosynthesis) and on the other hand it is due to emission by decomposition of dead organisms. The greener the Earth, the more CO2 is stored in the Earth’s bio system.

– The physics-driven circulation flow generated by oceans (‘physical pump’). Henry’s law tells us that the physics-driven flow is influenced by the CO2-concentration in the atmosphere and in the oceans. The higher the concentration in the atmosphere, the more CO 2 flows into the oceans and vice versa (combination of Raoult’s and Henry’s law). In addition to concentration, ocean temperature is an important parameter. The colder/warmer the water, the more/less CO2 can be stored.

Note that the architecture allows us to properly position two external CO2-sources that generate an incoming flow into the closed loop: – The human-driven flow, caused by the anthropogenic source (Sant). Think of the mass burning of fossil fuels.

– The nature-driven flow, caused by the natural source (Snat). Think of the volcanic eruptions worldwide.

We show the orders of magnitude of these CO2-flows and CO2-sources in Figure 2 for the year 2020. The amount of CO2 is expressed in ‘GtCO2’ (gigaton CO2) per year, 1 gigaton being one billion (109) metric tonnes. In the literature these quantities are often expressed in ‘GtC’ (Gigaton Carbon). Those values are therefore a factor 12/44 = 0.27 smaller. Today, PgC (Petagram Carbon) is often used. Note also that 1 m3 CO2 = 2kg CO2 at atmospheric pressure.

Looking at Figure 2, the total yearly incoming CO2 flow from continents and oceans, volcanos and human activities into the atmosphere is ~ 807 Gt/yr (A+). And the total yearly outgoing CO2 flow is ~787 Gt/yr (A–). This means that there is an increase of CO2 in the atmosphere by ~20 Gt/yr (‘net atmospheric accumulation’).

It is interesting to realise that one person exhales ~1 kg CO2 per day. This means that today, all humans (~8 billion) emit each day 8 billion kg CO2 in the atmosphere. That is ~3 GtCO2/yr.

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Looking again at Figure 2, the total annual incoming flow to the natural system N+ ≈ 786 Gt/yr and the total annual outgoing flow N– ≈ 767 Gt. This means that there is a net annual increase of CO2 in the land-marine reservoir by +19 Gt/yr (‘net land-marine absorption).

Summarizing, we see that all external sources and internal flows are leading to (A+–A–) ≈ 807– 787 = +20 Gt/yr net accumulation in the atmosphere and (N+–N–) ≈ 786–767 = +19 Gt/yr net absorption in the land-marine reservoir. We see that incoming anthropogenic flow Sant is very small (about 5%) compared to the incoming natural flow F+. This means that Sant is a perturbation on the internal incoming total flow A+. On the other hand, Sant is twice the accumulation (A+–A–)!

It is important to realize that many incoming (F+) and outgoing (F–) internal flows satisfy the emission, net atmospheric accumulation, and net land-ocean absorption data (what counts is F+ – F–). It explains why so many theories about what happens with the CO 2 in the landmarine system fits the measurements and the mass balance equation. Bear in mind that F+ and F– are the result of all complex processes at the boundary between the atmosphere and the land-marine reservoir.

CO2 mass balance In the proposed closed-loop CO2-system all values should adhere to the CO2 mass balance equation at any time (whatever the source and system changes are):

(1a) where A+ is the total incoming atmospheric flow per year: (1b) with F+(t) = N–(t) + Snat(t).

Similarly, A– is the total outgoing atmospheric flow per year: (1c) with F–(t) = N+(t) + Cnat(t).

Equation (1a) may also be rewritten as: (2a) where (2b) all quantities being in Gt/yr. Equations (2a) and (2b) show how the yearly net atmospheric accumulation (A+–A–) is affected by the yearly net anthropogenic emission [Sant – Cant], the yearly net land-marine absorption (N+–N–) and the yearly net natural emission (Snat – Cnat).

Note from (2b) that small changes in F+ or F– – due to internal changes in the land-marine reservoir – may lead to large changes in the net atmospheric accumulation (A+–A–).

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For the past 60 years (1960 – 2020) the net anthropogenic emission is much larger than the net volcanic contribution, i.e. [Sant – Cant] >> [Snat– Cnat]. In addition, Cant << Sant, meaning that we may simplify equation (2a) for this period to: (3a) Bear in mind that in expression (3a) anthropogenic emission Sant is the superposition of many anthropogenic sources, N– is the result of many internal natural sources and N+ is the result of many internal natural sinks.

We assume that the values of Sant and (A+–A–) are reliable input quantities for this period. By substituting these empirical quantities in the material balance equation (2c), the net landocean absorption data (N+–N–) is also known, being the residue [Sant – (A+–A–)]. In Figure 2 we showed for 2020: Sant = 40 Gt/yr and (A+–A–) = 20 Gt/yr and therefore residue (N+–N-) = 19 Gt/yr. If (Snat – Cnat) cannot be neglected, then we need to replace (N+–N–) by (F––F+). Similarly, if Cant would give a significant contribution, then we need to replace Sant by [Sant – Cant].

It is interesting that if we make Sant = 0 and Cant = 0, equations (1a,b,c) and (2a,b) describe the pre-industrial era. In Figure 3 two situations are shown. Note that without any anthropogenic input, it does not mean that the CO2-system is in equilibrium. Figure 3b describes an oscillating system (‘two communicating vessels’) with [A+(t) – A–(t)] = – [N+(t) – N–(t)]

(3b)

at every tn. From ice core measurements we know that in the past million years the oscillations were driven by the large temperature changes between the glacial and interglacial periods. We also know that the natural CCS has taken a lot of CO2 out of the loop (calcification, formation of coal and fossil fuels), making the current atmospheric CO 2-concentration an alltime low (in 2020 ca. 412 ppm).

CO2 closed loop with net source contributions being zero

CO2 closed loop with natural-driven flow only

A+

land

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Net Accumulation

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CO2 round trip

F+ Volcanic CO2

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CO2 round trip

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Figure 3: a) The closed- loop CO2 system in the situation that there are no anthropogenic net source contributions [Sant – Cant = 0], b) the oscillating flow of CO2 to and from the atmosphere in the situation that [Svlc – Cnat = 0] as well. Now, there are internal flows only.

Note also that if we want to know the total amount of CO2 (cumulative CO2) in the atmosphere and in the natural system (expressed in GtCO2 or ppm), we must know two initial values (A0 and N0) and need to integrate the yearly contributions (A+–A–) and (N+–N-): A(t) = A0 + ∑(𝐴+ − 𝐴+ )

in GtCO2

(4a)

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N(t) = N0 + ∑(𝑁 + − 𝑁 + )

in GtCO2

(4b)

A(t) is generally expressed in ppm, where 1 ppm = 7.8 GtCO2. Note that N0>>A0.

In Figure 1a I also showed the variations around the trend. In Figure 4 they are separately visualized. We see that the anthropogenic emission variation (𝛿Sant) is much smaller than the net atmospheric accumulation variation [𝛿(A+–A–)]. Note that the shapes are very different as well (in the full paper I have carried out an extensive Fourier analysis on the variations). Note also that the relatively large 𝛿(A+–A–) is caused by the large variation in the internal flows 𝛿(F+–F–). This empirical evidence may explain that the anthropogenic emission dip during the corona period could not be detected in the net atmospheric accumulation measurements.

a)

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Figure 4: a) Variation around the anthropogenic emission trend, b) variation around the net atmospheric accumulation trend, c) variation around the net natural absorption trend.

Finally, also note that in the discussions on atmospheric CO2 we make very clear whether we refer to the total amount A(t) or the total incoming flow A+(t) or the total outgoing flow A–(t) or the net accumulation [A+(t) – A–(t)]. The same applies to discussions on natural CO 2: the total amount N(t) or the total incoming flow N+(t) or the total outgoing flow N–(t) or the net absorption [N+(t) – N–(t)]. For instance, in 2020: A ≈ 3250 Gt, A+ ≈ 807 Gt/yr, A– ≈ 787 Gt/yr and (A+–A–) ≈ 20 Gt/yr.

Conclusions 1. All external sources and internal flows in the CO2-system are leading to a CO2increase in the atmospheric reservoir by (A+–A–) ≈ +20 Gt/yr (net accumulation) and a CO2-increase in the natural reservoir by (N+–N–) ≈ +19 Gt/yr (net absorption).

2. The net atmospheric accumulation (A+ – A–) is about half the amount of the anthropogenic emission (Sant ≈ +40 Gt/yr). Using the CO2 mass balance equation, the other half is explained by the net natural absorption (N+–N–).

3. The yearly anthropogenic CO2-flow (Sant) is only ~5% of the yearly natural incoming CO2-flow F+. In addition, ~2.5% of the total incoming flow A+ = Sant + F+ stays behind in the atmosphere. These numbers do not provide direct information on causality.

4. Small changes in A+ due to small changes in the outgoing flow of the natural system (N–) has a large influence on the net atmospheric accumulation (A+ – A–). For

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instance, if N– is increasing by only a few percent, then the increase in (A+ – A–) is of the same order as the human contribution (Sant).

The same applies to changes in A– by changes in the incoming flow of the natural system N+. If N+ is decreasing by only a few percent, then the increase in (A + – A–) is of the same order as the human contribution (Sant).

If the total yearly flows A+ and A– are not measured but modelled, then the modeled net accumulation (A+ – A–) must be compared with the measured net accumulation (A+ – A–).

If the total yearly flows N+ and N– are not measured but modelled, then the modeled net absorption (N+ – N–) must obey the mass balance equation.

The measured variations around the trend provide evidence that the anthropogenic emission dip during the corona period is masked by the relatively large atmospheric accumulation variation.

It is scientifically a desirable step to split the natural system in continents and oceans.

However, we should realise that if we split the natural system into subsystems the estimation problem becomes more complex, because of the dynamic interrelationships between the subsystems (CO2 mixes well in the atmosphere): + + F+ = Fland + Fmar

(5a)

– – F– = Fland + Fmar

(5b)

+ – + – F+ – F– = (Fland − Fland ) + (Fmar − Fmar )

(5c)

and a spatially finely sampled measurement system close at the Earth’s surface must be available.

Anyway, whatever we do, the condition must be that the combined behavior of all (local) subsystems must obey the behavior of the total system at all times. And this means: 'yearly human emission – yearly net atmospheric accumulation = yearly net absorption of the total natural system'. Measurements do tell us that today, the total natural system behaves as a big net CO2-absorber that increases its relative capacity (Figure 1c). Of course, all numbers should be enriched by uncertainty information.

Finally, the above conclusions are based on measurements and the mass balance equation.

If criticists do not accept the conclusions, they must make clear why they don’t trust the measurements and/or why they don’t accept the mass balance equation. That would be an interesting discussion indeed.

Guus Berkhout, October, 2022

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