The Clean Air Act as enacted in 1970 and revised in 1990 does not specifically address the issue of climate change from greenhouse gases (GHGs). However, in Massachusetts v. EPA, 549 US 497 (2007), the US Supreme Court held that GHGs fit within the Act's definition of an air pollutant that EPA may regulate. Subsequently, in December 2009, EPA issued a finding that six classes of GHGs endanger public health and welfare by causing global climate change, and that the GHGs emitted from new motor vehicles contribute to GHG pollution. Subsequently, in May 2010, EPA promulgated GHG emission standards for light-duty motor vehicles in model years 2012 to 2016.
EPA also determined that the Clean Air Act required major stationary sources of GHGs to obtain construction and operating permits. To reduce regulatory burdens, in December 2010, EPA issued Timing and Tailoring Rules (PSD and Title V permitting). The Tailoring Rule focuses on the largest GHG emitters: power plants, refineries and cement production facilities.
In June 2013, President Obama announced a Climate Action Plan containing the following key components:
- develop new rules to cut carbon pollution;
- prepare the United States for the impacts of climate change by helping state and local governments strengthen roads, bridges and shorelines from severe weather; and
- lead international efforts by galvanising international action to significantly reduce emissions, prepare for climate impacts and drive progress through the international negotiations.
Pursuant to these objectives, on 13 May 2010, EPA set GHG emissions thresholds to define when permits under the New Source Review Prevention of Significant Deterioration (PSD) and Title V Operating Permit programmes are required for new and existing industrial facilities. This final rule 'tailors' the requirements of these Clean Air Act permitting programmes to limit covered facilities to the nation's largest GHG emitters: power plants, refineries and cement production facilities.Clean Power Plan
On 3 August 2015, EPA issued the Clean Power Plan, which was designed to cut pollution from the power sector by 32 per cent below 2005 levels, while also cutting smog- and soot-forming emissions by 20 per cent. The final Clean Power Plan for Existing Power Plants is a state-based programme under Section 111(d) of the Clean Air Act for existing sources with EPA establishing guidelines and states then designing programmes that fit in those guidelines to get the needed reductions in CO2. EPA also published a proposed Federal Plan for the Clean Power Plan that serves as a model rule for those states that are developing their own Clean Power Plan state plans. Finally, EPA promulgated final standards of performance to address CO2 emissions from new, modified and reconstructed power plants. These Clean Power Plan regulations were stayed by the US Supreme Court and are being challenged in the US Court of Appeals in Washington, DC.
In August 2018, the Trump administration issued proposals to repeal and replace Obama's climate change regulations with less stringent requirements. The proposed replacement, the Affordable Clean Energy rule, focuses 'on-site, heat-rate efficiency improvements' to lower GHG emissions from coal-powered and other currently operating power plants. It would provide states with leeway to set limits for plants within their borders. Several states and municipal governments, including New York, California and Los Angeles, submitted comments to EPA opposing the proposal, arguing that it allows an increase in pollution that would harm human health. On 19 June 2019, EPA issued the final Affordable Clean Energy (ACE) rule, replacing the prior administration's Clean Power Plan.138 The ACE rule establishes emission guidelines for states to use when developing plans to limit CO2 at their coal-fired electric generating units. EPA also repealed the Clean Power Plan, and issued new implementing regulations for ACE and future rules under Section 111(d). This action to replace the existing Clean Power Plan has been challenged in court by 23 states and two public health groups in federal court. The challengers argue that Section 111(d) of the Clean Air Act does not authorise the EPA to implement the Clean Power Plan as currently written. Oral arguments were held on 8 October 2020 in the US Court of Appeals for the District of Columbia and the case is pending at the time of writing. It remains to be seen whether the Biden administration will seek to revise the 2019 rule or support the 2015 Clean Power Plan.Oil and Natural Gas Air Pollution Standards
On 12 May 2016, EPA issued three final rules that together will curb emissions of methane, smog-forming VOCs and toxic air pollutants such as benzene from new, reconstructed and modified oil and natural gas sources, while providing greater certainty about Clean Air Act permitting requirements for the industry. EPA estimates that the rules will reduce methane emissions by 510,000 short tons of methane in 2025, the equivalent of reducing 11 million metric tons of CO2.
However, on 12 June 2017, the Trump EPA proposed a two-year stay of the fugitive emissions, pneumatic pump and professional engineer certification requirements in the rule while the agency reconsiders them. In 2018, EPA announced a proposal to relax requirements that companies monitor and repair methane leaks by repealing a restriction on the flaring or burning or methane from drilling operations. On 13 August 2020, EPA took final action to relieve oil and gas companies of the need to detect and repair leaks of methane, a greenhouse gas, based on a cost-benefit analysis and a finding that leaks from domestic oil and gas wells have remained steady over the past decade.139 Several environmental groups and at least one state have indicated that they will challenge EPA's action.Transportation or mobile sources
EPA and the National Highway Traffic Safety Administration were taking coordinated steps to enable the production of a new generation of clean vehicles – from the smallest cars to the largest trucks – through reduced GHG emissions and improved fuel use. Together, the enacted and proposed standards were expected by EPA to save more than 6 billion barrels of oil by 2025 and reduce more than 3,100 million metric tons of carbon dioxide emissions. However, the Trump administration announced that it was reconsidering the current fuel-efficiency standards for cars and trucks.
On 11 August 2018, EPA announced, for public comments, proposed revisions to the fuel economy standards that would freeze the prior Obama-era standards after 2021 and also revoke the ability of California and other states to set their own rules.140 In the summer of 2019, four auto companies (Ford, Honda, BMW and Volkswagen) voluntarily agreed to comply with California's rules, under which autos would attain an average fuel economy of 51 miles per gallon by 2026. On 19 September 2019, the Trump administration formally revoked the waiver allowing California to set stricter auto emission standards, waivers that California has received over several decades. California and 22 other states have filed a lawsuit challenging this decision.Renewable Fuel Standard programme
In August 2018, the Trump administration proposed to freeze the average auto fuel economy after 2012 at 37 miles per gallon. This contrasts with the 54 miles per gallon standard previously required by 2025, which would have spurred increased production of electric vehicles. The EPA proposal would also revoke a long-standing waiver allowing California to set stricter standards, which is opposed by California and other states that have followed the stricter California standards.
EPA is also responsible for developing and implementing regulations to ensure that transportation fuel sold in the United States contains a minimum volume of renewable fuel. EPA estimates that by 2022 the Renewable Fuel Standard programme will reduce GHG emissions by 138 million metric tons, about the annual emissions of 27 million passenger vehicles, replacing about 7 per cent of expected annual diesel consumption and decreasing oil imports by $41.5 billion.
In addition, various US state and local governments have adopted programmes to address climate change. A discussion of these efforts is beyond the scope of this chapter.Paris Agreement
Two decades after creation of the UN Framework Convention on Climate Change, parties have reached a general political consensus in support of reducing global GHG emissions. As part of the December 2015 Paris Agreement, countries submitted nationally determined contributions for GHG mitigation. The governments agreed to a long-term goal of keeping the increase in global average temperature to well below 1.5°C above pre-industrial levels and to undertake rapid reductions thereafter in accordance with the best available science. The agreement traces the way to achieving this target. The agreement went into effect in November 2016. The Paris Agreement, with its emphasis on consensus-building, allows for voluntary and nationally determined targets. The specific climate goals are thus politically encouraged, rather than legally binding. On 1 June 2017, President Trump announced that the United States would withdraw from the 2015 Paris Agreement. On 4 November 2019, the US submitted its formal notification of withdrawal to the United Nations. The withdrawal took effect on 4 November 2020, one day after the election. It was expected that President-elect Biden would rejoin the Paris climate accord after becoming President in January 2021.
In the meantime, a number of states and local government entities are proceeding with their own agendas with regard to climate change. On 10 September 2018, California Governor Jerry Brown signed The 100 Percent Clean Energy Act of 2018, which establishes a state policy that eligible renewable energy and zero-carbon resources supply 100 per cent of all retail sales of electricity in California by 2045. The governor also issued a new executive order, EO B-55-18, establishing a new state-wide goal 'to achieve carbon neutrality as soon as possible, and no later than 2045, and achieve and maintain net negative emissions thereafter'.