The Trump administration’s Environmental Protection Agency (EPA) on June 19 published its “Affordable Clean Energy” (ACE) rule to replace the Obama EPA’s Clean Power Plan (CPP).

The replacement plan is essentially the Trump administration’s attempt to adhere to the letter of the law mandating that carbon pollution be regulated, while requiring the smallest possible changes from the power utility industry. Preliminary research suggests that the ACE rule will barely reduce carbon emissions more than a scenario with no EPA policy whatsoever.

Current law says EPA must regulate carbon pollution

This story begins in 2003, when in response to a petition that the federal government regulate greenhouse gas emissions from motor vehicles, the George W. Bush EPA concluded that it did not have authority to do so under the Clean Air Act. Disagreeing with that determination, Democratic attorneys general of 12 states teamed up with several cities and environmental organizations to challenge that EPA action in court. The resulting litigation made it to the Supreme Court in 2007, and in the landmark Massachusetts v. Environmental Protection Agency ruling, the justices ruled 5-4 against the Bush administration and its EPA.

As a result, the agency was required to determine whether carbon dioxide and other greenhouse gases are air pollutants under the Clean Air Act, meaning that they “cause or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare.”

In December 2009, EPA under President Obama completed its Endangerment Finding review of the scientific evidence and concluded that carbon pollution and other greenhouse gas emissions responsible for human-caused climate change clearly endanger public health and welfare. That determination led directly to the conclusion that the Clean Air Act requires that EPA regulate those pollutants, leading in turn to the Obama EPA’s CPP to strictly regulate utilities’ greenhouse gas emissions.

Emissions from motor vehicle tailpipes are addressed through corporate average fuel economy (CAFE) standards, which the Trump administration is also proposing to dramatically weaken in a battle with California and several other states, again all Democratically-controlled. To address pollution from power plants, the Obama EPA developed the CPP, which, if implemented, would have established national carbon emissions performance rates for coal and natural gas power plants while giving individual states some flexibility in finding ways to meet those standards.

Efforts to repeal and replace the Clean Power Plan

Opponents to the Obama EPA rulemaking wasted little time in launching numerous legal attacks against the CPP. The argument that had the most traction interpreted the Section 111(d) New Source Performance Standards elements of the Clean Air Act as giving EPA the authority to regulate only “within the fence line” of individual power plants. Under that interpretation, the agency would have exceeded its authority by regulating emissions from the power sector as a whole.

States, cities, and environmental organizations supportive of that CPP rule have argued that it is on solid legal ground with supporting precedents. But in 2016, the Supreme Court issued a stay to temporarily halt EPA enforcement of the plan pending lower court rulings on associated lawsuits. Barely two months into his term, President Trump signed an executive order calling on EPA under then-Administrator Scott Pruitt to review the CPP. Soon thereafter, the administration requested an indefinite suspension of the rule (a continued temporary suspension was granted).

Some persistent opponents of climate change rule-making efforts, like Trump EPA transition team members Myron Ebell and Steven Milloy and the fossil fuel-funded Competitive Enterprise Institute, have pressed the agency to challenge the Endangerment Finding. However, Pruitt disagreed with that strategy, fearing such an effort could backfire and be overruled by the courts in light of the compelling scientific basis for health concerns arising from climate change impacts. In fact, a February 2019 study published in the prestigious journal Science found that the scientific evidence supporting the Endangerment Finding has only strengthened over the past decade.

Instead, Pruitt and his successor at EPA, Andrew Wheeler, opted to replace the CPP with a more industry-friendly alternative, the “Affordable Clean Energy” rule, which is designed to help extend the lifetimes of expensive and heavily polluting coal-fired power plants. The June 19 release of the ACE rule now renders the CPP and associated lawsuits moot.

The new rule effectively implements the legal argument against the CPP by applying EPA regulations only to within the fence lines of individual power plants. Once implemented, it would provide states with various technological options that coal plants can install to help make them more efficient, thus potentially extending their lifespans. Because the new ACE rule establishes no numerical target for greenhouse gas emissions and allows states to consider factors like a plant’s “remaining useful life,” it could also allow state decisionmakers to conclude that no changes are needed at individual power plants.

The Trump administration has also argued that the CPP is no longer necessary. The plan’s goal was to cut carbon emissions from the power sector by 32 percent below 2005 levels by 2030; in 2017 they were already 28 percent below 2005 levels. However, U.S. power plant emissions rose slightly in 2018, a reflection of increased demand for natural gas. Critics of the new EPA rule caution that the trend toward cleaner electricity could certainly be slowed by fossil fuel-friendly policies such as the new ACE rule.

In addition, critics of ACE argue that since the power sector has been meeting the CPP targets so easily, EPA should be issuing more stringent targets and regulations to accelerate the clean energy transition, especially considering America’s current “critically insufficient” climate policies. A study published in Environmental Research Letters in April 2019 estimated that the ACE rule would lead to a negligible reduction in greenhouse gas emissions as compared to a “no policy” scenario. An analysis by the Natural Resources Defense Council (NDRC), a key national environmental organization, estimates that with the falling costs of clean energy, a stronger rule could cut power sector carbon pollution by 60 percent below 2005 levels by 2030, and do so at less cost than the initial estimated costs of the CPP. The NRDC study claimed billions of dollars in health benefits would result from cleaner air along with thousands of prevented premature deaths, consistent with EPA’s own analysis of ACE.

What comes next? Litigation and a big election

Numerous state attorneys general and environmental groups are certain to sue EPA over the new rule, arguing that it’s insufficient in scope to meet the agency’s regulatory obligations. Some legal experts have said they think the Trump administration would welcome a court challenge that could result in a Supreme Court ruling limiting EPA’s ability to regulate sector-wide greenhouse gas emissions from power plants.

The court challenges are expected to move forward slowly and incrementally, and if President Trump wins re-election for a second term in 2020, the Supreme Court will almost certainly be presented the case in the early 2020s. Those hoping for a supportive Supreme Court finding backing the new Trump rules appear hopeful – perhaps even confident – that the Court’s 2016 decision to temporarily halt the CPP is a sign that a majority of current justices are sympathetic to the Trump administration’s arguments.

With 2019 presidential campaign jockeying now well under way, most of the nearly two-dozen 2020 Democratic presidential hopefuls have said they plan to restore and/or strengthen the Obama-era CPP. But their succeeding with such an effort would require surviving an inevitable Supreme Court challenge. Congressional climate legislation – perhaps reflecting the general approach of the Green New Deal conceptually supported by most of the Democratic presidential candidates – could potentially negate the need for EPA power plant regulations. However, passage of comprehensive climate legislation would require that Democrats not only take control of the White House, but also win a majority in the Senate and maintain their majority in the House … and then also pass reforms to current Senate rules on filibusters.

None of those steps will come easily or, perhaps, come at all. So, in short, curbing carbon pollution is a major challenge under the current U.S. political system. Most conservative policymakers oppose climate legislation of the scale needed to address the problem, and the conservative-leaning Supreme Court – let alone a future Court that could have more Trump-nominated and Senate-confirmed justices – may be friendly to arguments against EPA’s authority to regulate the power sector under the existing Clean Air Act.

When it comes to U.S. action on climate change, uncertainty, for the time being, appears to be the only certainty.

Dana Nuccitelli, research coordinator for the nonprofit Citizens' Climate Lobby, is an environmental scientist, writer, and author of 'Climatology versus Pseudoscience,' published in 2015. He has published...