While I was on vacation in Portugal last month, I really made sure I wasn't paying attention to politics or the media circus. One of those moments that I missed around that time was this post from President Trump:
It was in reference to some recent news about climate change modeling. In its 2014 Intergovernmental Panel on Climate Change (IPCC) report, the United Nations prepared four main scenarios. The gloomiest of these scenarios was the RCP8.5 scenario.
In late April of this year, the IPCC retired the RCP8.5 scenario as a plausible future emissions pathway. There are those who believe, including the authors of the IPCC paper, that this is being scrapped because there has been enough progress with climate change policy intervention to merit its retirement. I did not buy in 2018 that the RCP8.5 scenario was plausible back then.
American Enterprise Institute scholar Roger Pielke, Jr. and Competitive Enterprise Institute scholar Marlo Lewis Jr. explain why the scenario was never plausible to begin with. For one, coal production would have had to implausibly increase by 900 percent and become the predominant form of energy, which is peculiar given that coal was already declining as a form of energy in the 2010s. The RCP8.5 also assumed that the population would reach 12 billion, which is a far cry from the 10.2 billion that is projected. And the idea that low-income countries would stay considerably poorer than other countries? Then there are the assumptions of unabated fossil fuel use and no negative emissions technologies.
The problem here was not mere theoretical modeling for its own sake. As this article from Carbon Brief details, RCP8.5 was treated as a "business as usual" and likely outcome when it came to climate change policy and activism. At best, it was meant to be an upper-bound, highly improbable stress test. When such scenarios are used as a baseline, they exaggerate projections of future warming and damages.
This exaggeration leads to a form of policy overcorrection, and results in regulatory and fiscal responses that are larger, faster, and more intrusive than would be justified if a more accurate model were being used. That is how we get such policies as emission standards for electric vehicles, gas stove bans, carbon capture & sequestration mandates, and energy efficiency standards.
Trying to prevent a scenario that is essentially not going to happen is a waste of money, time, and resources. If we are basing policy on false assumptions, it means that we cannot begin to understand the costs and benefits of each policy decision. As we learned during the COVID pandemic, a miscalibration at that scale is a form of harm in which the cure is worse than the disease. Retiring RCP8.5 is a "better late than never" moment, but this whole debate acts as a reminder that we should let skepticism be at the helm of energy and climate policy instead of hyperbole and alarmism.
