By Andy May

In the previous report, part 6 of this series, I discussed the bias in AR6 WGII. The major bias in the report stemmed from ignoring the benefits of a warmer world with more CO₂ and only considering the possible problems. They also assumed, against nearly all evidence, that extreme weather events are increasing in frequency and impact, and at least part of the increase is likely due to humans.

AR6 WGIII, Climate Change 2022: Mitigation of Climate Change, is intended to assess what is required to achieve net zero CO₂ emissions globally. Given that WG1 and WGII have not established the following, this seems premature:

1. WGI did not show that human emissions of greenhouse gases are causing significant or dangerous warming.
2. WGII did not consider the well-documented benefits of global warming and additional atmospheric CO₂.

The WGIII justification for net zero is as follows:

“Reaching net zero CO₂ emissions globally along with reductions in other GHG emissions is necessary to halt global warming at any level. At the point of net zero, the amount of CO₂ human activity is putting into the atmosphere equals the amount of CO₂ human activity is removing from the atmosphere. Reaching and sustaining net zero CO₂ emissions globally would stabilise CO₂-induced warming.”^[1]

IPCC AR6 WGIII, page 86

In other words, WGIII explicitly equates CO₂ emissions, or the CO₂-equivalent greenhouse gas emissions, with dangerous global warming. We have seen that equating CO₂ emissions with warming is a poorly supported assumption contained in an inaccurate climate model that runs hot compared to observations, not a fact. We have also seen that assuming a warmer world is more dangerous than a cooler world is highly questionable, after all the baseline temperature used is from the end of the Little Ice Age, the coldest and most miserable period in the past 12,000 years.^[2] Further, as discussed in part 5, statistical studies of weather variability, in the sense of extreme weather, since the 19^th century show it has been decreasing, not increasing.^[3] The bottom line is all the benefits of warming and additional CO₂ have not been considered in any of the AR6 reports, so how can they equate greenhouse gas emissions with dangerous warming? They can’t. Thus, without establishing a need to mitigate greenhouse gas emissions, the IPCC produced a 2,000-page report on how to do it. They define mitigation as follows:

“Climate change mitigation refers to actions or activities that limit emissions of greenhouse gases (GHGs) from entering the atmosphere and/or reduce their levels in the atmosphere. Mitigation includes reducing the GHGs emitted from energy production and use (e.g., that reduces use of fossil fuels), and land use, and methods to mitigate warming, for example, by carbon sinks which remove emissions from the atmosphere through land-use or other (including artificial) mechanisms.”^[4]

IPCC AR6 WGIII, page 194

The report doesn’t explain why, they simply assume that reducing emissions and total greenhouse gases is necessary. They presume that WGI and WGII have made the case that these emissions are causing dangerous climate change. This presumption is very controversial.^[5]

The report discusses greenhouse gas emissions in units of “GtCO₂-equivalent” and reports that 2019 emissions were about 59 GtCO₂-equivalent.^[6] Methods of reducing these emissions are listed in the report and they are quite expensive. For example, to install enough wind and solar energy generation to reduce emissions by 4 GtCO₂-eq per year each would cost US$50-100 per tonne. ^[7] That is spending US$100 to 200 billion to reduce emissions by 8 GtCO₂-eq or about 14% per year.

Since 2000 CO₂ emissions have been increasing about 0.5 GtCO₂-eq per year for a total of 10 GtCO₂.^[8] Will this rate of increase, which is 91% linear, change significantly? Doubtful, it has flattened in the past few years, but that is probably due to the Covid shutdowns and the economic downturn in China.

The cost of mitigation

WGIII estimates that the cost of mitigation in Agriculture, Forestry, and other land uses, which they abbreviate as “AFOLU” is US$178 billion/year.^[9] If there is an estimated cost to reduce emissions in the transportation sector in WGIII, I missed it. Especially the cost of replacing air travel, if it is even possible, is not mentioned. According to WGIII, “Aviation is widely recognized as a ‘hard to decarbonize’ sector.”^[10] The costs associated with decarbonizing transportation, some 24% of all delivered energy, are probably astronomical, they may have been afraid to calculate the cost. Instead, they created an impenetrable metric called “IAM,” which stands for “Integrated Assessment Model,” that supposedly includes cost as one of its variables.^[11] The IAM also includes the poorly defined, and widely criticized “social cost of carbon” factor.^[12] The social cost of carbon is criticized because it is too easily manipulated to achieve whatever answer you like.^[13]

WGIII seems to think that traditional cost-benefit analysis is not very useful. They write:

“[There are] multiple difficulties in assessing an objective, globally acceptable single estimate of climate change damages, with some arguing that agreement on a specific value can never be expected. A new generation of cost-benefits analysis, based on projections of actual observed damages, results in stronger mitigation efforts as optimal.”^[14]

IPCC AR6 WGIII, page 181

It appears that their obscure IAM model was chosen because it supports their “stronger mitigation efforts.” Why do they not do a proper cost-benefit analysis so we can compare it to their IAM model? That would seem very logical. John Pezzey, for example, prefers using marginal abatement costs to evaluate climate mitigation costs, versus benefits, as they are less uncertain than using the social cost of carbon.^[15]

In WGIII, they write:

“There are few obvious solutions to decarbonising heavy vehicles like international ships and planes. The main focus has been increased efficiency, which so far has not prevented these large vehicles from becoming the fastest-growing source of GHG globally.”^[16]

IPCC AR6 WGIII, page 1120

Increasing efficiency lowers costs, which increases demand, a principle known as “Jevons’ Paradox.”^[17] WGIII wants to limit emissions to the point where temperature increases will not exceed 2°C according to the WGI climate models. Accomplishing this will supposedly reduce global GDP by 1.3 to 2.7% in 2050.^[18] We will remember from part 6 that the cost of climate change is estimated to be 1.3% of global GDP after 2.5°C of warming (about 2100 using SSP2-4.5) according to Richard Tol,^[19] so this does not seem like a very good deal. Why not just put up with or adapt to climate change? It is projected to be cheaper, and the potential damage due to climate change is highly questionable in any case.^[20]

The costs of implementing wind and solar, while high, are minor compared to other industrial costs of reducing greenhouse gas emissions. Only about 18% of the total energy consumed in the world is in the form of electricity according to Exxon’s Outlook.^[21] Compare this to the 24% of consumed energy used for transportation. Industry accounts for 50% of the world’s consumed energy.^[22]

Replacing fossil fuels in electricity generation is relatively easy compared to making plastic, steel, ammonia (fertilizer), and cement without fossil fuels. Perhaps methods of making these critical industrial materials without fossil fuels are technically possible, but the costs are high. According to WGIII, industry overall is a major emitter of greenhouse gases, accounting for 34% of global emissions in 2019.^[23]

Plastic, for example, currently relies on fossil feedstock for 99% of its raw materials.^[24] Some technologies to reduce GHG emissions while producing steel, aluminum, and other materials are listed in table 11.3 of WGIII,^[25] along with the cost when known. All are expensive. Unlike transportation, WGIII does provide estimates of the cost of some decarbonized industrial materials:

“Material Economics (2019) shows that with deep decarbonisation, depending on the pathway, steel costs grow by 20–30%; plastics by 20–45%; ammonia by 15–60%; and cement (not concrete) by 70–115%.”^[26]

IPCC AR6 WGIII, page 1196

These are four of the most critical components of our modern civilization, and doing without them would change our lives drastically, and not for the better. These WGIII estimates of cost increases are large. Since these products are the basis of nearly everything we use, as these increases percolate through the global economy, they will reduce the standard of living of everyone.

WGIII Assessment

WGIII is a comprehensive assessment of greenhouse gas emissions and various methods to reduce them. As I read the report, I kept looking for a proper aggregate cost/benefit analysis chapter or section. If it is there, I missed it. As a member of the public, I am purchasing this United Nations IPCC mitigation product. Is it too much to ask what the costs are and how much I benefit from buying it? I don’t think so.

When they do estimate costs, and some of their mentions are noted above, they are never aggregated for an entire section, for example transportation or industry. The values given appear cherry picked and often the method of cost calculation is obscure.

Some independent writers and economists, like Bjorn Lomborg, have estimated aggregate costs. Lomborg, using IPCC data, has estimated that if the Paris climate change agreement^[27] were fully implemented, each dollar spent would return 11₵ of benefit.^[28] This is the sort of summary of costs versus benefits that the IPCC should provide. Although Bjorn Lomborg is a well-known expert in this sort of policy analysis, I notice that searching WGIII for his name turns up nothing. Another indication of bias.

William Nordhaus pioneered cost/benefit analysis of climate change impacts in 1992^[29] and won the Nobel Prize^[30] for Economic Sciences, yet WGIII seems quite dismissive of his work. They write:

“For at least 10 to 15 years after the first computed global cost-benefit estimate (Nordhaus 1992), the dominant conclusions from these different approaches seemed to yield very different recommendations, with cost-benefit studies suggesting lenient mitigation compared to the climate targets typically recommended from scientific risk assessments.”^[31]

IPCC AR6 WGIII, page 180

We notice that their given reason for rejecting Nordhaus’ work is that it suggests less mitigation than the climate targets suggested by the IPCC. Yet, it is well known that there is no scientific basis for either the 2° or the 1.5°C limits, they are arbitrary.^[32] This is classic confirmation bias, selecting methods, models, and studies to reach desired conclusions. That they imply the Nobel Prize winning Willam Nordhaus is less “scientific” than they are, is a sure sign of bias and it betrays unseemly hubris (aka the Dunning-Kruger effect).

The main problem with WGIII is no properly supported reason is given to reduce emissions, either in WGIII or in the first two volumes of AR6. The report has not established a need for the solutions they propose.

Further, their IAM model for computing the cost of climate change, relative to the cost of mitigating greenhouse gas emissions, is unbelievable and disputed.^[33] It is premature to write a volume on methods of reducing emissions, until the emissions are shown to cause problems. So far additional emissions have done little except to make winters, nights, and higher latitudes warmer; and increase plant growth.^[34]

Summary and Conclusions

We have reviewed the models used in the AR6 report and find that all suffer from a biased selection of sources and models. We have found numerous examples of reporting and confirmation bias in all three volumes of the report. WGI completely ignores entire areas of research, such as the effects of solar variability and meridional transport on climate. Their focus is only on their preferred climate change variable: greenhouse gases. We would benefit from their consideration of alternative views and concur with the recommendation of the InterAcademy Council on this point.^[35]

WGII focusses only on the negative effects of climate change and ignores abundant evidence of positive effects. We would benefit, and their report would have much more value and credibility if they considered both.

WGIII has chosen a very questionable method of cost/benefit analysis, the “social cost of carbon,” or IAM analysis for their assessment of the costs and benefits of mitigating greenhouse gases. They ignore the more conventional cost/benefit analysis done by Nobel Prize winning William Nordhaus and by Bjorn Lomborg, because their analyses suggest “more lenient mitigation compared to the climate targets typically recommended.”^[36] Perhaps more lenient mitigation is the best choice, perhaps no mitigation is best? This report does not help us make that decision.

In every volume we see that the selection of papers cited, model input, and models chosen was guided not by a desire to uncover the truth, but by how best to reach their pre-determined conclusions. The three volumes, total 7,519 pages and most of content is made useless by obvious reporting and confirmation bias. In summary, we see that the hundreds, maybe thousands of authors were given the answer, and told to find the data and analysis to support it. What a useless waste of time and money.

This is part 7 of a series of posts, all the post titles begin with “Climate Model Bias” to make searching for the series easier.

Download the bibliography here.

1. 
   

   (IPCC, 2022b, p. 86) ↑

   
   
2. 
   

   (May, Are fossil-fuel CO2 emissions good or bad?, 2022g) and (Behringer, 2010). The last 12,000 years are known as the Holocene. See also: (May, The IPCC AR6 Report Erases the Holocene, 2023d) and (Liu, et al., 2014) ↑

   
   
3. 
   

   (Yan, et al., 2001) ↑

   
   
4. 
   

   (IPCC, 2022b, p. 194) ↑

   
   
5. 
   

   (Lomborg, The Alarming Thing About Climate Alarmism, 2015) and (Lomborg, We’re Safer From Climate Disasters Than Ever Before, 2021) ↑

   
   
6. 
   

   GtCO2-eq. = gigatonnes of CO2, or 10⁹ tonnes or one billion tonnes. One tonne = 1,000 kg. Ref: (IPCC, 2022b, p. 59) ↑

   
   
7. 
   

   (IPCC, 2022b, p. 38) ↑

   
   
8. 
   

   Ourworldindata: https://ourworldindata.org/co2-emissions ↑

   
   
9. 
   

   (IPCC, 2022b, p. 824) ↑

   
   
10. 
    

    (IPCC, 2022b, p. 1086) and (Gota, Huizenga, Peet, Medimorec, & Bakker, 2019) ↑

    
    
11. 
    

    (IPCC, 2022b, pp. 1098-1100) ↑

    
    
12. 
    

    (Pezzey, 2018) and (IPCC, 2022b, pp. 173-174) ↑

    
    
13. 
    

    (Pezzey, 2018) ↑

    
    
14. 
    

    (IPCC, 2022b, p. 181) ↑

    
    
15. 
    

    (Pezzey, 2018) ↑

    
    
16. 
    

    (IPCC, 2022b, p. 1120) ↑

    
    
17. 
    

    Jevons’ Paradox. (Jevons, 1865). ↑

    
    
18. 
    

    (IPCC, 2022b, p. 37) ↑

    
    
19. 
    

    (Tol R. S., 2018) ↑

    
    
20. 
    

    (Lomborg, The Alarming Thing About Climate Alarmism, 2015), (Lomborg, We’re Safer From Climate Disasters Than Ever Before, 2021), and (Lomborg, Welfare in the 21st century: Increasing development, reducing inequality, the impact of climate change, and the cost of climate policies,, 2020) ↑

    
    
21. 
    

    Exxon’s Global Outlook data pages. Divide residential and industrial electricity consumption by the total consumption: https://corporate.exxonmobil.com/what-we-do/energy-supply/global-outlook#Keyinsights ↑

    
    
22. 
    

    Exxon’s Global Outlook data pages. Divide residential and industrial electricity consumption by the total consumption: https://corporate.exxonmobil.com/what-we-do/energy-supply/global-outlook#Keyinsights ↑

    
    
23. 
    

    (IPCC, 2022b, p. 1163) ↑

    
    
24. 
    

    (IPCC, 2022b, p. 1163) ↑

    
    
25. 
    

    (IPCC, 2022b, p. 1197) ↑

    
    
26. 
    

    (IPCC, 2022b, p. 1196) ↑

    
    
27. 
    

    https://unfccc.int/process-and-meetings/the-paris-agreement ↑

    
    
28. 
    

    (Lomborg, Welfare in the 21st century: Increasing development, reducing inequality, the impact of climate change, and the cost of climate policies,, 2020) ↑

    
    
29. 
    

    (Nordhaus W. D., 1992) ↑

    
    
30. 
    

    (Nordhaus W. , 2018) and https://www.nobelprize.org/prizes/economic-sciences/2018/nordhaus/lecture/ ↑

    
    
31. 
    

    (IPCC, 2022b, p. 180) ↑

    
    
32. 
    

    (May, The Two-degree limit, 2022h), (Victor & Kennel, 2014), and (Knutti, Rogelj, & Sedláček, 2016) ↑

    
    
33. 
    

    (Pezzey, 2018) ↑

    
    
34. 
    

    (May, Are fossil-fuel CO2 emissions good or bad?, 2022) and (Zhu, Piao, & Myneni, 2016) ↑

    
    
35. 
    

    (InterAcademy Council, 2010, p. 18) ↑

    
    
36. 
    

    (IPCC, 2022b, p. 180) ↑