EPA’s Justification for Reversing the Endangerment Finding Not Based on Gold Standard Science, According to Professor Justin Ritchie

       In a guest post on Roger Pielke Jr.’s blog, The Honest Broker, Justin Ritchie, a professor at the University of British Columbia, and a collaborator and co-author with Pielke Jr., wrote about the EPA citing their research in a questionable way. The post is titled "Not Gold Standard Science": Justin Ritchie evaluates EPA's use of his research.

     The EPA’s proposal intends to roll back GHG emissions limits for “new motor vehicles and new motor vehicle engines,” saying that the EPA does not have the authority to do this. As a result, it is likely that EPA will no longer require the “measurement, control, and reporting of GHG emissions for any highway engine and vehicle, including model years manufactured prior to this proposal.”

     The post is a response to the Associated Press’s request to Ritchie about his views on how his research was used by the EPA in its proposal to roll back the greenhouse gas endangerment finding. Ritchie first notes that the EPA document accurately cites his two papers and that they correctly argue that worst-case scenarios have been misleadingly portrayed as” business as usual" scenarios in climate science.

“Both verbatim citations by EPA are technically accurate. However, the broader context and interpretation that follows from EPA is scientifically problematic and, at best, significantly incomplete, resulting in a biased scientific foundation for the proposal, that reads like a bait-and-switch.”

     Ritchie gives the proposal a C- in overall accuracy. He details that the reasons for this is that they took his conclusions out of context.

“None of the papers cited in EPA footnote #90 and #91 have argued that the RCP8.5 scenario’s overshoot of actual CO2 emissions has occurred because of higher than expected terrestrial CO2 uptake - it was always about energy technology, policy and economic growth trajectories. Therefore, the EPA proposal authors do not demonstrate a full understanding of the work they cited from my papers.”

     Ritchie gives three scientific concerns:

1)        Incomplete Causal Explanation – he notes that while the EPA correctly noted that the higher emissions scenarios failed to occur, they do not explain why, according to his papers that they cite, instead incorrectly assuming that it was increased CO2 uptake by natural processes that caused the divergence, a conclusion that is not supported by the papers cited. Instead, he notes that the real reason for the divergence is “per-capita GDP and carbon intensity growth slower than projected in baseline scenarios.”

2)        Transportation Technology Irony – here he notes that the high emissions scenarios were based on assumptions in his 2017 paper that coal-to-liquids technology would be developed for transportation. Instead, EV and battery technology improved, became economic, and was adopted faster than expected.

3)        Unsupported Natural Process Claims – “The document follows from accurate citations to claim divergence in emission scenarios "may be explained by greater capacity for the climate to reuptake GHGs through natural processes" but provides no quantitative analysis separating natural uptake effects from reduced emissions due to technology and policy changes. There needs to be a clearer analysis of scenario components for this argument to carry any weight.”

     Finally, he argues that the high emissions scenarios were never really plausible to begin with, and were changed as technology caught up and made lower emissions scenarios more plausible.

“…the high-end scenarios were based on implausible economic and energy assumptions, particularly about fossil fuel expansion and the economics of coal resources needed for technologies like coal-to-liquid synthesis to outcompete electrified transportation alternatives.”

“Using the fact that implausible extreme scenarios didn't materialize as justification to eliminate emission standards represents a fundamental misunderstanding of both scenario plausibility and scientific evidence.”

“The EPA’s proposal is not gold standard science.” 

     

References:

"Not Gold Standard Science" Justin Ritchie evaluates EPA's use of his research. A Guest Post by Justin Ritchie — A Response to the AP. The Honest Broker. Blog of Roger Pielke Jr. August 16, 2025. "Not Gold Standard Science" - by Roger Pielke Jr.

Proposed Rule: Reconsideration of 2009 Endangerment Finding and Greenhouse Gas Vehicle Standards. U.S. EPA. Proposed Rule: Reconsideration of 2009 Endangerment Finding and Greenhouse Gas Vehicle Standards | US EPA