Critical Review of Impacts of Greenhouse Gas Emissions on the U.S. Climate

This post is part of my continuing coverage of the draft New York State Energy Plan (Draft Plan).  In late July the United States Department of Energy (DOE) published a draft report titled “A Critical Review of Impacts of Greenhouse Gas Emissions on the U.S. Climate”.  This post describes differences between that report and the Draft Plan Climate Change, Adaptation and Resiliency chapter.

I am convinced that implementation of the New York Climate Leadership & Community Protection Act (Climate Act or CLCPA) net-zero mandates will do more harm than good if the future electric system relies only on wind, solar, and energy storage because of reliability and affordability risks.  I have followed the Climate Act since it was first proposed, submitted comments on the Climate Act implementation plan, and have written over 550 articles about New York’s net-zero transition. 

The opinions expressed in this article do not reflect the position of any of my previous employers or any other organization I have been associated with, these comments are mine alone. 

Net-Zero Aspirations

The Climate Leadership & Community Protection Act (Climate Act) established a New York “Net Zero” target (85% reduction in GHG emissions and 15% offset of emissions) by 2050 and has two electric sector targets: 70% of the electricity must come from renewable energy by 2030 and all electricity must be generated by “zero-emissions” resources by 2040. The Scoping Plan that outlined how to “achieve the State’s bold clean energy and climate agenda” was based on an Integration Analysis prepared by the New York State Energy Research and Development Authority (NYSERDA). 

The rationale of New York’s net-zero transition plan is that climate change is a threat to society that must be addressed by eliminating the use of fossil fuels. Because I believe that the climate change threat narrative has become religious dogma for many, I have not addressed this position much.  However, I believe that climate change is an exaggerated problem that is diverting attention away from other serious environmental and societal issues to the detriment of us all.

The Draft Energy Plan Climate Change, Adaptation and Resiliency (Climate Chapter) document represents the extreme “consensus” view of climate change.  In my opinion, New York’s climate change position represents the extreme end of the consensus because there have been instances (e.g. sea level rise projections) where state policy is based on a more extreme position than that taken by the Intergovernmental Panel on Climate Change.

Critical Review

On July 29, 2025 the Department of Energy released the Critical Review report.  Rather than drafting a summary of the report I am going to quote the Background and Overview from the Federal Register Notice of Availability: A Critical Review of Impacts of Greenhouse Gas Emissions on the U.S. Climate (NOA).  I am also going to highlight differences in the review relative to statements in the Draft Energy Plan chapter on climate change

The draft report was prepared by independent scientists, assembled by Energy Secretary Chris Wright with diverse expertise in physical science, economics, climate science and academic research. The authors are John Christy, Judith Curry, Steven Koonin, Ross McKitrick, and Roy Spencer.  The press release describes their backgrounds.  In my opinion, they are all first-rate experts.  The Background in the Notice of Availability (NOA) states that:

The draft report titled “A Critical Review of Impacts of Greenhouse Gas Emissions on the U.S. Climate” was developed by DOE’s 2025 Climate Working Group, a group of five independent scientists assembled by Energy Secretary Chris Wright with diverse expertise in physical science, academic research and climate science. The landing page for the CWG Report, including a press release, can be found here.

The following quotations are from the NOA “Overview of the CWG Report”. 

The report reviews scientific certainties and uncertainties in how anthropogenic carbon dioxide (CO2) and other greenhouse gas emissions have affected, or will affect, the Nation’s climate, extreme weather events, and selected metrics of societal well-being. Those emissions are increasing the concentration of CO2 in the atmosphere through a complex and variable carbon cycle, where some portion of the additional CO2 persists in the atmosphere for centuries.

Increasing concentration of CO2 is uncontroversial.

Elevated concentrations of CO2 directly enhance plant growth, globally contributing to “greening” the planet and increasing agricultural productivity. They also make the oceans less alkaline (lower the pH). That is possibly detrimental to coral reefs, although the recent rebound of the Great Barrier Reef suggests otherwise.

Many of the other statements are controversial.  The Climate Chapter does not mention any potential benefits to increased CO2 concentrations.  I suspect that the only reason coral reef threats are not mentioned is because New York does not have any coral.

Carbon dioxide also acts as a greenhouse gas, exerting a warming influence on climate and weather. Climate change projections require scenarios of future emissions. There is evidence that scenarios widely-used in the impacts literature have overstated observed and likely future emission trends.

The Climate Chapter references the 2024 New York State Climate Impacts Assessment (NYSCIA).   It claims that it “offers a thorough evaluation of historical climate data”.  The Draft Review reference to a widely-used scenario refers to the use of Representative Concentration Pathway 8.5.  That scenario was used extensively in the NYSCIA apparently because it provided the biggest potential impacts.  In my opinion, that approach invalidates projections in the assessment because the scenario is impossible.

The world’s several dozen global climate models offer little guidance on how much the climate responds to elevated CO2, with the average surface warming under a doubling of the CO2 concentration ranging from 1.8° C to 5.7° C. Data-driven methods yield a lower and narrower range. Global climate models generally run “hot” in their description of the climate of the past few decades. The combination of overly sensitive models and implausible extreme scenarios for future emissions yields exaggerated projections of future warming.

NYSCIA used the “hot” models and the implausible extreme scenarios to claim that “in order to limit the global average increase in temperature to 2°C (if possible, 1.5°C) and minimize the risk of the most severe climate impacts, substantial reductions in GHG emissions by mid-century are required.”  In my opinion, the models that used are not fit for policy decisions.

Most extreme weather events in the U.S. do not show long-term trends. Claims of increased frequency or intensity of hurricanes, tornadoes, floods, and droughts are not supported by U.S. historical data. Additionally, forest management practices are often overlooked in assessing changes in wildfire activity. Global sea level has risen approximately 8 inches since 1900, but there are significant regional variations driven primarily by local land subsidence; U.S. tide gauge measurements in aggregate show no obvious acceleration in sea level rise beyond the historical average rate.

NYSCIA concludes that “New York State’s climate has already changed, with impacts evident across economic sectors, industries, natural systems, communities, and regions.”  The Critical Review directly contradicts these claims. 

Attribution of climate change or extreme weather events to human CO2 emissions is challenged by natural climate variability, data limitations, and inherent model deficiencies. Moreover, solar activity’s contribution to the late 20th century warming might be underestimated.

Ditto.

Both models and experience suggest that CO2-induced warming might be less damaging economically than commonly believed, and excessively aggressive mitigation policies could prove more detrimental than beneficial. Social Cost of Carbon estimates, which attempt to quantify the economic damage of CO2 emissions, are highly sensitive to their underlying assumptions and so provide limited independent information.

The Climate Act is based on a fundamentally different outlook.  The Preamble to the Climate Act legislation claims that: “Action undertaken by New York to reduce greenhouse emissions will have an impact on global greenhouse gas emissions and the rate of climate change.”  The NYSCIA document is completely consistent with the law and there isn’t even a suggestion that there might be uncertainties.

U.S. policy actions are expected to have undetectably small direct impacts on the global climate, and any effects will emerge only with long delays.

This point is not addressed in the Climate Act, NYSCIA, or any New York GHG emission reduction regulation.  Nothing that the United States can do will have a detectable impact on the global climate so anything New York does is going to have an even less detectable impact.  There is no justification whatsoever for the Climate Act schedule even if we must “do something”.

Discussion

In my opinion, the Critical Review is long overdue. I appreciate the commitment of the authors.  An interview with Steven Koonin by John Robson from the Climate Discussion Nexus makes the important point that we don’t know nearly as much as proponents claim and that consideration of what we know and what we don’t know should be reflected in policy approaches.  Roy Spencer and Judith Curry both wrote blog posts explaining why they got involved in the report.  All five authors provided a joint written response to Nature magazine, stating they are “committed to a transparent and fact-based dialogue on climate science” and that they will respond publicly “to all serious scientific comments” during the NOA public comment period.

The usual suspects response has been outrage that anyone could possibly question their “settled science”.   They are demanding systematic fact-checking efforts and a public debate.  All the while hey are oblivious to the point that all five of the authors have been asking for just such an approach for years.  I agree with the need for an open debate of the climate science.

Conclusion

The key point for New York is that we have the same situation here.  The Draft Energy Plan stakeholder process has no forum for public debate.  I believe that the arguments that make the case that the net-zero transition ambition and schedule will result in an affordable and reliable energy system are much weaker than the arguments that GHG emission reductions are necessary to control the climate.  The failure to openly discuss the differences between the Draft Energy Plan and New York Independent System Operator projections is unacceptable.  If the stakeholder process for the Draft Energy Plan continues to ignore public input, then I think New York will be saddled with a false solution that will take years to fix.