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Climate Change


Under review

Legal efforts to address climate change, which is caused by emission of greenhouse gases, started at the international level with the 1992 United Nations Framework Convention on Climate Change, but have struggled to take root in the United States at the federal, regional and state levels.

Listen to and download materials from the ELI seminar Climate Change: An Introduction. ELI members can listen to ELI’s Monthly Climate Change Briefing live or through archived files to follow the latest climate change law, policy, and management developments. For an in-depth discussion of climate change law, see Tom Mounteer, Climate Change Deskbook.

Climate change and greenhouse gas emissions

Climate change resulting from human activity is one of the most pressing and high-profile environmental issues today. The Intergovernmental Panel on Climate Change (IPCC) drew international attention to climate change in its 1990 Assessment Report, where it reported that increases in greenhouse gas (GHG) emissions were causing substantial warming of the Earth’s surface beyond what would naturally occur. The IPCC’s “Fourth Assessment Report: Climate Change,” released in 2007, stated unequivocally that human activities are causing an increase in GHG concentrations: “The global increases in carbon dioxide concentration are due primarily to fossil fuel use and land use change, while those of methane and nitrous oxide are primarily due to agriculture.” U.S. government reports concur with this assessment.

For a detailed discussion of the science behind climate change, see Reporting on Climate Change: Understanding the Science, 4th ed.

Reconstructed Temperature
Figure 1 from IPCC Third Assessment. http://en.wikipedia.org/wiki/File:1000_Year_Temperature_Comparison.png

Six main greenhouse gases drive climate change, with the most significant contributor being carbon dioxide. Global Warming Potential (GWP) is a relative measure of the amount of heat that a specific gas traps in the atmosphere over specified time periods.  The GWP of carbon dioxide is 1 because it is the baseline unit to which all other gases are compared. Methane has a lifetime GWP of 12 which means that methane in the atmosphere has 12 times the warming potential as carbon dioxide.

GWP values and
lifetimes from
2007 IPCC


Global Warming Potential Time Horizon



20 years


100 years


500 years






Nitrous Oxide





HFC-23  (hydrofluorocarbon)





HFC-134a (hydrofluorocarbon)





Sulfur Hexafluoride






Adapted from https://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch2s2-10-2.html

The human activities in the United States that contribute the largest portion of greenhouse gases to the atmosphere are electric power generation, transportation, industry, agriculture, and commercial buildings.

Sources of Carbon Dioxide Emissions

From http://elr.info//news-analysis/40/10547/implementing-behavioral-wedge-designing-and-adopting-effective-carbon

While this list clearly illustrates that addressing greenhouse gas emissions requires efforts in the energy, transportation, building, industrial, and other vital economic sectors, everyday activities of the general population contribute significantly to GHGs as well:

Sources of Green House Gas Emissions

From http://elr.info//news-analysis/40/10547/implementing-behavioral-wedge-designing-and-adopting-effective-carbon

Thus, GHG regulation touches the entire economy and everyday choices we all make.

International Initiatives

The United Nations Framework Convention on Climate Change (UNFCCC) was introduced in 1992 in an effort to control the emission of greenhouse gases that contribute to global climate change. The Convention established several principles for how the international would go about addressing climate change, including the notion that developed countries, who had contributed the most to global warming in the past, had a duty to take the lead in mitigating the adverse effects of climate change, also known as “common but differentiated responsibilities.” The parties to UNFCCC also agreed to develop national greenhouse gas emissions inventories, share scientific research and technology, and help create measures for climate change adaptation. None of these agreements, however, were legally binding.

In December 1997, the Kyoto Protocol to the UNFCCC established a binding commitment from 37 industrialized nations and the European Community to reduce GHG emissions to an average of 5% below 1990 levels during the commitment period 2008 and 2012. These developed nations agreed to meet nation-specific targets to reduce their GHG emissions. In contrast, developing nations, even large developing nations such as India and China, were not required to meet emission reduction targets during this first round and would not be asked to meet emission targets.

In the summer of 1997, before the Kyoto Protocol was agreed to, the U.S. Senate on a 95-0 vote adopted a resolution to oppose any treaty that failed to impose similar duties on both developing and developed nations. Despite this vote, the U.S. president, Bill Clinton, signed the Protocol. However, the Protocol was never submitted to the Senate for ratification. By 2001, the United States announced that the Protocol would not be ratified. The Protocol entered into force in the ratifying countries on February 16, 2005.

For a discussion of why the United States would not enter into the Kyoto Protocol and issues that constrain U.S. involvement in international efforts against climate change, see the suite of articles including Jody Freeman, “Climate Change and U.S. Interests” and a reply with responses by Jeffrey Hopkins, Richard Morgenstern, Kristen Sheeran, and Laurie Johnson as well as Richard Cooper, “The Kyoto Protocol: A Flawed Concept” and Robert Nordhaus, A Framework for Achieving Environmental Integrity and the Economic Benefits of Emissions Trading Under the Kyoto Protocol.

The Protocol put in place three flexibility mechanisms to help member countries reach emissions targets in addition to direct lowering of emissions: emissions trading, the clean development mechanism, and joint implementation.

For a discussion of how offsets might work in the United States, see Kyle Danish, “International Offsets and U.S. Climate Change Legislation.

The first compliance period of the Kyoto Protocol was 2008-2012. At the Durban conference of the parties, this was extended. The parties agreed to negotiate by 2015 an agreement to take effect not later than 2020 that would involve both developed and developing countries to mitigate climate change and seek to keep global warming no greater than 2ºC.

As part of its effort to implement the Kyoto Protocol, the European Union has implemented perhaps the most advanced emissions trading scheme, the European Trading System (ETS). Europe’s declared goal is for emissions in 2020 to be 21% lower than in 2005.

For a discussion of California’s attempt to link to the ETS, see Hanna Chang, Foreign Affairs Federalism: The Legality of California's Link With the European Union Emissions Trading Scheme.

Federal Greenhouse Gas Efforts

Congress has made multiple attempts to enact comprehensive greenhouse gas legislation, but so far no bill has passed both legislative houses. The most recent bill, the American Clean Energy and Security Act of 2009 (H.R. 2545), was passed by the House only to die in the Senate. The Act’s central mechanism was an economy-wide cap-and-trade program for greenhouse gas emissions. Under such a program, a regulatory agency sets a maximum level for annual GHG emissions and distributes emissions allowances for a specified amount of carbon dioxide equivalent. Emitters subject to regulation must then reduce their emissions or acquire enough permits to cover their total output. The Act also included renewable electricity generation standards, a number of energy efficiency incentives, and support to industries that would be particularly affected by GHG regulation. Congress did require, and EPA has implemented, GHG emissions reporting.

For a discussion of the Senate bills that addressed climate change, see Kenneth Richards, Comparative Analysis of Climate Change Bills in the U.S. Senate.

For one approach to getting Congress to act on climate, and a reaction to that approach, see Richard Lazarus, Super Wicked Problems and Climate Change: Restraining the Present to Liberate the Future.

For a discussion of the EPA reporting rules, listen and download materials from the ELI Seminar GHG Reporting Rule So Far: Lessons Learned and Changes to Consider.

The Environmental Protection Agency is currently regulating GHGs under the Clean Air Act. While the Clean Air Act regulates many forms of air pollution, it does not mention GHGs by name. On October 20, 1999, a group of private non-profit organizations petitioned EPA to begin regulating greenhouse gas emissions from automobiles as air pollutants under the Clean Air Act. After EPA determined that GHGs were not “air pollutants” subject to CAA regulation and denied the petition, these groups were joined by several states, cities, and citizens’ groups seeking review of EPA’s decision in federal court. In the landmark 2007 decision Massachusetts v. EPA, the Supreme Court held GHGs can be regulated under the Clean Air Act, and that the plaintiffs in the case had standing[SES18] to sue EPA to ask the agency to begin regulating GHGs.

The result of the case was that greenhouse gases from mobile sources were officially considered “air pollutants.” Under the CAA, EPA was obligated to determine whether they “cause or contribute to air pollution which may reasonably be anticipated to endanger health or welfare.” In December 2009, the EPA Administrator issued an endangerment finding, declaring that “six greenhouse gases taken in combination endanger both the public health and the public welfare,” and that emissions from new motor vehicles “contribute to the greenhouse gas air pollution.”

In light of the endangerment finding, EPA and the National Highway Traffic Safety Administration (NHTSA), issued regulations in May 2010 regulating emissions of these GHGs from cars and light trucks under Title II of the Clean Air Act.

With GHGs now regulated under the CAA, EPA’s interpretation of the Clean Air Act requires it to develop permitting standards for new stationary sources that are major sources of GHGs, such as power plants or manufacturing facilities. EPA is promulgating and implementing regulations for such sources under the new source performance standards and new source review provisions of the CAA. EPA’s efforts are the subject of significant political controversy and litigation, although challenges to the foundational EPA GHG rulemakings failed to gain traction in court.

For ELR articles addressing the ability of the Clean Air Act to tackle climate change, see Franz Litz, What to Expect From EPA: Regulation of Greenhouse Gas Emissions Under the Clean Air Act, Robert McKinstry, The Clean Air Act: A Suitable Tool for Addressing the Challenges of Climate Change, and Brigham Daniels, Regulating Climate: What Role for the Clean Air Act?

Listen to and download materials from the ELI seminar The D.C. Circuit’s Rulings on EPA’s Greenhouse Gas Rulemakings to learn how the court upheld EPA’s regulatory program and watch and download materials from a seminar immediately after the court’s oral arguments at Debrief of the D.C. Circuit’s Oral Arguments on EPA’s GHG Rulemakings.

There are many other federal statutes and provisions that can be used to try to control GHGs, ranging from the National Environmental Policy Act to the Clean Water Act and Endangered Species Act and presidential Executive Orders. In addition, some are trying to use the courts by arguing there are federal and state common law causes of action against emitters of GHGs as well as public trust doctrine claims.

State Initiatives

States have taken various approaches to address climate change, including the formation of regional programs to address GHG emissions. Among states, California has taken the most comprehensive steps toward GHG control, and many localities have also undertaken GHG reduction initiatives.

Regional Initiatives

The Regional Greenhouse Gas Initiative (RGGI) in the Northeast was the first regional GHG reduction effort to be formed, followed by the Western Climate Initiative and the Midwestern Greenhouse Gas Reduction Accord. RGGI, formed in December 2005, includes several states in the Northeast and the mid-Atlantic. The agreement applies only to fossil-fuel powered electric generators above a certain size, and covers only CO2 emissions. The core mechanism of RGGI is a market-based cap-and-trade program. The agreement caps CO2 emissions at 2009 levels and requires regulated power plants to hold allowances for each ton of CO2 they emit using a cap and trade program. States are given broad discretion over many aspects of implementation, including initial allocation of allowances, permitting procedures, and exemptions for certain types of facilities. All states are required to direct some percentage of allowance auction proceeds toward energy reinvestment programs that benefit consumers. For example, Maine uses a portion of auction proceeds to subsidize construction of combined heat and power units to improve energy efficiency in factories. In May 2011, New Jersey indicated it is withdrawing from RGGI, and the state legislatures in other states have attempted to withdraw other states from RGGI.

Two other regions have begun to take steps toward implementing their own GHG reduction programs. The Western Climate Initiative (WCI), comprising several western states and parts of Canada, was formed in 2007. However, Mexico, Arizona, Washington, Oregon, Montana and Utah have all recently withdrawn leaving only California and four Canadian provinces in the program. WCI intended to implement a cap-and-trade program, similar to RGGI, beginning in 2012, but that is no longer likely, although California may push ahead, perhaps with Canadian partners or on its own. . The withdrawn states have all joined North America 2050, a new initiative within WCI that does not include a cap-and-trade program. Seven Midwestern states and Canadian provinces formed the Midwestern Regional Greenhouse Gas Accord (MGGRA) and agreed to develop a regional cap-and-trade program, but the initiative has stalled.

California Global Warming Solutions Act

California passed the Global Warming Solutions Act in 2006, containing several major climate change initiatives. The Act’s overall goal is statewide reduction of GHG emissions to 1990 levels by 2020. The California Air Resources Board (CARB) is charged with developing and enforcing the implementing regulations of the Act, most of which are to become effective in 2012.

CARB’s Scoping Plan outlines the implementation of the Global Warming Solutions Act, including:

CARB has implemented rules requiring GHG emissions reporting and verification and identified “early action items” reduction measures that could be acted on quickly while the larger implementing regulations are under development.

To further support the goals of the Global Warming Solutions Act, California passed the Sustainable Communities and Climate Protection Act of 2008 and a companion bill Senate Bill 732. The Sustainable Communites law requires ARB to develop regional GHG emission reduction targets for passenger vehicles and to establish targets for the State's 18 metropolitan planning organizations (MPOs). The MPOs are required to develop a “sustainable communities strategy” that will meet the emissions reduction targets through adopting sustainable land use, housing and transportation policies. Senate Bill 732 establishes and funds a Strategic Growth Council to support these sustainable planning activities.

Local Initiatives

Many localities have undertaken efforts to reduce GHG emissions, such as through the U.S. Conference of Mayors Climate Protection Agreement and ICLEI. Municipal government steps to address climate change have included developing climate change mitigation and adaptation plans, developing plans to encourage green development and encouraging new programs such as solar energy programs and energy efficiency drives that serve as models for other cities.

For a discussion of the role of localities in climate law and policy, read Patricia Salkin,Cooperative Federalism and Climate Change: New Meaning to "Think Globally--Act Locally" and Michael Burger, Empowering Local Autonomy and Encouraging Experimentation in Climate Change Governance: The Case for a Layered Regime.

Climate Adaptation Efforts

While many efforts to address climate change focus on greenhouse gas emission reduction, also known as mitigation, adaptation to climate change is also an important aspect of climate change governance. Increasingly, federal, state and local governments are recognizing the importance of planning for a changing climate and the effects it will have on public health, the environment, and the built environment. For example, a Council on Environmental Quality task force developed recommendations for federal agencies to follow in integrating climate change adaptation planning into their regular planning activities. Many U.S. cities, such as Chula Vista, CA, and Keene, NH, have begun the process of adaptation planning at the local level. International efforts are also beginning to focus on adaptation as well as mitigation.