APS Response re: EPA Reconsidering 2009 Endangerment Finding

Filed via Regulations.gov

The Honorable Lee Zeldin
Environmental Protection Agency
1200 Pennsylvania Avenue, N.W.
Washington, DC 20460

Re: Reconsideration of 2009 Endangerment Finding
and Greenhouse Gas Vehicle Standards
(90 Fed. Reg. 36288)
Docket No. EPA-HQ-OAR-2025-0194

Dear Administrator Zeldin:

The American Physical Society (APS) — the largest physics membership organization in the United States, representing more than 50,000 members — appreciates the opportunity to provide written comment on the proposed rule change entitled “Reconsideration of 2009 Endangerment Finding and Greenhouse Gas Vehicle Standards.”

On behalf of APS, I am responding to the question posed in the Federal Register “on whether, due to new scientific information and developments since the 2009 Endangerment Finding, there is a strong enough scientific record to support an affirmative finding that GHG emissions from section 202(a) sources cause or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare.”

As one of the world’s largest physics organizations, APS is well positioned to assess the relevant evidence. Physics is a core science for understanding Earth’s climate, and our membership encompasses thousands of experts in crucial fields like fluid dynamics, nonlinear and complex systems modeling, gas phase physics and chemistry, radiative transfer, phase transitions, measurement science, computational physics, statistics, and biological physics. APS hosts a dedicated topical group on climate science with nearly 700 members, providing a forum for the on-going dissemination and discussion of current climate science research.

Our membership’s varied perspectives and broad expertise inform our policy statements, including our position on Earth’s changing climate. The Society’s deliberative process for generating, creating, and adopting policy statements involves our members, committees, and leadership, including both the APS Council and Board of Directors. Our statement process includes an open comment period for APS members, ensuring that all APS members can provide input. All comments are considered to ensure that we are appropriately articulating the position of the physics community.

Since 2009, APS has reviewed its Statement on Earth’s Changing Climate and performed a rigorous evaluation of the scientific literature twice, issuing an updated statement in both 2015 and 2021. The Society held exercises explicitly incorporating a wide array of voices. In both instances, the Society found the following:

• Earth’s climate is changing.^1,2 This critical issue³ poses the risk of significant environmental,⁴ social,⁵ and economic disruptions⁶ around the globe.
• Multiple lines of evidence strongly support the finding that anthropogenic greenhouse gases have become the dominant driver of global climate warming observed⁷ since the mid-twentieth century.⁸
• Moreover, the deduction that human-induced alterations to many principal components of the climate system are accelerating is supported by the preponderance of observational evidence.⁹
• The potential consequences of climate change are great¹⁰ and the actions taken over the next decade or two¹¹ will determine human influences on the climate for centuries to millennia.¹²

The notice states that “the Administrator reviewed the scientific record as part of the reconsideration process and no longer has the degree of confidence previously expressed in the analyses relied upon in the Endangerment Finding.”

This conclusion is counter to international scientific consensus, which is captured in the APS Statement. Therefore, APS does not support the proposed reconsideration of the 2009 Endangerment Finding. Instead, the Society reaffirms its 2015 call to reduce the emissions, and ultimately the concentration, of greenhouse gases, to increase the resilience of society to Earth’s changing climate, and to support research on technologies that could reduce the climate impact of human activities.

Thank you for the opportunity to comment on this matter. For additional information, please contact the APS government affairs team.

References

1. In revising this statement, the evidentiary basis for statements contained in it has been drawn from reports prepared by the Intergovernmental Panel on Climate Change (IPCC – see https://www.ipcc.ch/). The last major IPCC assessment was issued in 2021. The evidentiary basis for this APS Statement is drawn from both the 2021 IPCC 6th assessment and three Special Reports (SR) of the IPCC issued in 2018 and 2019. The reports are SR1.5 (“Global Warming of 1.5 ºC”), SROCC (“Special Report on the Ocean and Cryosphere in a Changing Climate”), and SRCCL (“Climate Change and Land”). Each of these reports are in turn comprised of three sections: a Summary for Policy Makers (SPM), a Technical Summary (TS) from which it is traceably derived, and the full text of the underlying report from which the TS is traceably extracted. The full references for the three Special Reports are, respectively [all URLs checked 10/8/2021]:
   • IPCC, 2018: Global Warming of 1.5°C.An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty [Masson-Delmotte, V., P. Zhai, H.-O. Pörtner, D. Roberts, J. Skea, P.R. Shukla, A. Pirani, W. Moufouma-Okia, C. Péan, R. Pidcock, S. Connors, J.B.R. Matthews, Y. Chen, X. Zhou, M.I. Gomis, E. Lonnoy, T. Maycock, M. Tignor, and T. Waterfield (eds.)]. URL: https://www.ipcc.ch/sr15/
   • IPCC, 2019: IPCC Special Report on the Ocean and Cryosphere in a Changing Climate [H.-O. Pörtner, D.C. Roberts, V. Masson-Delmotte, P. Zhai, M. Tignor, E. Poloczanska, K. Mintenbeck, A. Alegría, M. Nicolai, A. Okem, J. Petzold, B. Rama, N.M. Weyer (eds.)]. URL: https://www.ipcc.ch/srocc
   • IPCC, 2019: Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems [P.R. Shukla, J. Skea, E. Calvo Buendia, V. Masson-Delmotte, H.-O. Pörtner, D. C. Roberts, P. Zhai, R. Slade, S. Connors, R. van Diemen, M. Ferrat, E. Haughey, S. Luz, S. Neogi, M. Pathak, J. Petzold, J. Portugal Pereira, P. Vyas, E. Huntley, K. Kissick, M. Belkacemi, J. Malley, (eds.)]. URL: https://www.ipcc.ch/srccl/
   • IPCC, 2021: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press. In press. URL: https://www.ipcc.ch/report/sixth-assessment-report-working-group-i/
2. SR1.5 SPM A.1.1 thru A.1.3 – temperatures and extremes; SROCC A.1 – cryosphere; SROCC A.3 – GMSL
3. SR1.5 SPM A.3.1 – “Impacts already observed.”; SROCC A.2 – examples include ocean heat, changes in PH, and loss of oxygen
4. SR1.5 SPM B.3.1 thru B.3.3 on terrestrial ecosystem impacts; B.4.2 thru B.4.4 on ocean ecosystems; SROCC A.4 on cryospheric terrestrial ecosystems; SROCC A.5 and A.6, on marine and coastal ecosystems; SRCCL A.2, on desertification, land degradation, and adverse impacts on terrestrial ecosystems
5. SR1.5 SPM B.5.1 thru B.5.4, B.5.6 – populations at risk, health, food, water stress, compound stresses; SROCC A.7 – societal impacts of shrinking cryosphere; SROCC A.8 – impacts on fisheries; SROCC A.9 – risks to coastal communities; SRCCL A.2
6. SR1.5 SPM B.5.5 – risks to aggregated economic growth; SROCC C1 – Economic disparities in outcomes
7. SR1.5 SPM A.1.1 thru A.1.3 – temperatures and extremes; SROCC A.1 – cryosphere; SROCC A.3 – GMSL
8. SR11.5 SPM A.1.1, Section 1.2.1; SROCC A.2, which states “Since 1993, the rate of ocean warming has more than doubled (likely).”
9. SR 1.5 section 1.2.1.3 – it is likely that most recent warming is anthropogenic
10. See citations above; SROCC section B on projected change– B.1 cryosphere; B.2 temps and AMOC; B.3 GMSL; B.4 land cryosphere; B.5 marine biomass; B.6 coastal ecosystems; B.7 water resources; B.8 fisheries; B.9 societal impacts of GMSL; SRCCL A.5 – climate stresses on land
11. SR1.5 SPM Section C on scenarios, SROCC B.1 (sentence at end, B.2 (sentence at end), C.4 (opening sentences), SRCCL B.7 on positive impacts of land use scenarios; SRCCL D.1 on near-term actions; D.3 on benefits of rapid GHG emissions reductions
12. SR1.5 SPM Section A.2
13. Guidance Note for Lead Authors of the IPCC Fifth Assessment Report on Consistent Treatment of Uncertainties