By Perry Bryant, a proud Highlands Conservancy member since 1990

The United States Environmental Protection Agency’s (EPA) “endangerment finding” may sound geeky and unimportant, but it is neither. The endangerment finding does not directly regulate greenhouse gases. Rather, it is EPA’s finding that greenhouse gases damage public health and welfare. It lays the foundation and provides a rationale for regulating greenhouse gases. Despite sound scientific evidence of the harm to public health that greenhouse gases cause, the endangerment finding was recently rescinded by the Trump Administration.

First, a little history: In 1999, a number of environmental organizations petitioned the George W. Bush Administration to regulate greenhouse gas emissions from new motor vehicles. The Bush Administration rejected this request claiming that greenhouse gas emissions were not pollutants under the Clean Air Act. A number of states, cities and environmental organizations sued, resulting in the 2007 landmark US Supreme Court ruling, Massachusetts v EPA (a 5 to 4 decision with Chief Justice Roberts dissenting). The Court held that greenhouse gases were pollutants under the Clean Air Act, and the reasons provided by EPA for not regulating greenhouse gases was inadequate. The Court remanded the issue back to EPA to determine if there was a legitimate reason not to regulate greenhouse gases from new vehicles.

Based on this Court decision, EPA in 2009 under the Obama Administration issued the endangerment findings concluding that six greenhouse gases, including carbon dioxide and methane, endangered public health and welfare. EPA found that these six greenhouse gas emissions were trapping heat in the atmosphere, which contributes to global warming, and results in greater flooding, more frequent and more severe heat waves, more intense hurricanes, higher sea level rise, as well as other adverse impacts on human health and welfare.

These EPA endangerment findings were the foundation for regulating the tailpipe discharges from new motor vehicles, joining the Paris climate accord, and attempting to regulate carbon dioxide emissions from power plants (the proposal to regulate CO2 at power plants was struck down by the US Supreme Court in West Virginia v EPA).

Rescinding the endangerment findings: From the very beginning of President Trump’s second term in office, EPA began the process of repealing the endangerment findings. Following a perfunctory public comment period, EPA rescinded the endangerment findings last month (February 2026). It is interesting that when EPA first proposed rescinding the endangerment findings, they relied on a US Department of Energy report written by five climate skeptics that argued the dangers of human-induced climate change were being overstated. This report was roundly criticized for cherry-picking data and implying there was a lack of scientific consensus where a consensus was clear. In the final decision to rescind the endangerment findings, EPA dropped any reference to this DOE report or any real scientific reasoning on the harm of greenhouse gases relying instead on economic and legal reasoning.

The science is settled: On this issue of whether greenhouse gases endanger public health or welfare there was no uncertainty in 2009 when the endangerment findings were first developed, and the evidence is even clearer today. For example, the Intergovernmental Panel on Climate Change, the world’s foremost collection of climate change scientists, wrote in 2023:

• “Human activities, principally through emissions of greenhouse gases, have unequivocally caused global warming.
• Human-caused climate change is already affecting many weather and climate extremes in every region across the globe. This has led to widespread adverse impacts and related losses and damages to nature and people (high confidence).
• Increases in extreme heat events have resulted in human mortality and morbidity (very high confidence).
• (And) climate change is a threat to human well-being and planetary health (very high confidence). There is a rapidly closing window of opportunity to secure a liveable and sustainable future for all (very high confidence).”

Where will this all go? First, the Sierra Club, the Natural Resources Defense Council and other environmental organizations have already pledged to challenge the rescinding of the endangerment findings in Court. The Supreme Court may well end up deciding this issue. If so, will they uphold the findings in Massachusetts v EPA that greenhouse gases are pollutants under the Clean Air Act? Or will they require additional Congressional authorization before EPA can regulate greenhouse gases?

Beyond the Courts, it is clear that there will be no meaningful Congressional action on global warming until there is a new President in 2029. And even with a new President, a lot will depend on the make-up of Congress following the 2026 and 2028 Congressional elections. In the meantime, other countries need to step up and continue to curtail their emissions to lessen the impact of global warming. And we all must take steps to reduce our own carbon and methane footprint.