Executive Summary: "No." and "No." (All you executives can leave. Non-executive nerds can hang around for details.)
In 2011, a paper titled, RCP 8.5--A Scenario of Comparatively High Greenhouse Gas Emissions was published. The text in the paper stated, "...RCP8.5 depicts thus a relatively conservative business as usual case..."
In this post, I explore whether RCP 8.5 represents a "business as usual" scenario in 2023; whether it represented a "business as usual" case in 2011; whether it is even plausible in 2023; and finally, whether it was even plausible in 2011?
The answers to those questions are: "No." "No." "No." and "No."
The RCP 8.5 scenario was, even when the paper introducing it was published, a complete fantasy. What made it a fantasy was the assumptions of coal usage in the 21st century. Here is a table of the coal usage assumed in the paper. One column has the global coal use in exajoules (EJ), the units in which coal consumption was presented in the paper. The next column has the coal use converted from EJ to millions of metric tons (MMT), using a conversion factor of 1 EJ = 34.2 MMT of coal.
Table 1. Assumed Coal Usage in RCP 8.5 Scenario
The problem with the coal usage assumptions shown in Table 1 is that they're insanely high, particularly in the later half of the 21st century. The coal consumption is assumed to just keep rising throughout the 21st century, which is completely ridiculous, because coal use is actually declining in several key coal-consuming regions, such as North America and Europe.The real insanity kick in after 2020. For example, in 2040 global coal consumption is assumed to be 2.74 times what it was in 2000; in 2060 it is assumed to be 4.70 times what it was in 2000; in 2080 it is assumed to 6.52 times what it was in 2000; and in 2100 is it assumed to be 8.43 times what it was in 2000. In contrast, simple observation of current and previous trends show that it is likely that global coal consumption will never hit the assumed 2040 value of 2.74 times the 2000 consumption. That is, global coal consumption will never hit the 8,800 MMT projected for 2040...let alone continue rising to the mind-boggling value of 27,140 MMT assumed in RCP 8.5 for the year 2100.
Table 2 shows actual coal consumption, in millions of metric tons of coal for the year 2000, 2010, and 2021. (Note: The year 2021 was chosen, rather than 2020, because the COVID-19 pandemic lowered coal consumption around the world.) Based on Table 1, all the regions of the would have to be at 1.83 times their year-2000 consumption in 2021, in order to be doing their "fair share" of coal consumption. Instead, none of the regions except Asia is doing its "fair share" of coal consumption. In fact, many of the regions--including North America, Europe, the Commonwealth of Independent States (CIS), and the Pacific--actually used less coal in 2021 than in 2000!
Table 2. Actual Coal Usage for 2000, 2010, and 2021
If the assumptions for coal use in RCP 8.5 were so unrealistic, why did the paper published in 2011 call it "business as usual"? Did they not know how utterly implausible the coal usage in RCP 8.5 was? I think the answer is pretty clear. None of the authors was a novice regarding analyzing trends in energy usage and carbon dioxide emissions. In particular, Keywan Riahi (the lead author) and Nebojsa Nakicenovic are senior employees with the International Institute for Applied Systems Analysis (IIASA), and have spent their careers doing energy and environmental analyses. So the only plausible explanation is that they deliberately mischaracterized the RCP 8.5 scenario as "business as usual". But why in the world would they do that? The simple reason is: money. Money would have dried up very quickly if they'd presented a realistic scenario for "business as usual."
The characterization of RCP 8.5 as "business as usual" is a lie. There was no basis in science to ever call it "business as usual." And anyone who writes any paper anywhere that labels it as "business as usual," is either incredibly ignorant or lying.
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