Background:

Federal and State Regulation of Greenhouse Gases.

The United States Environmental Protection Agency (EPA) and the Washington State Department of Ecology (Ecology) identify carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride as greenhouse gases because of their capacity to trap heat in the earth's atmosphere. Under the federal Clean Air Act, greenhouse gases are regulated as an air pollutant and are subject to several air regulations administered by the EPA. At the state level, greenhouse gases are regulated by Ecology under the state Clean Air Act.

In 2008 Washington enacted legislation that set a series of limits on the emission of greenhouse gases within the state. Ecology is responsible for monitoring and tracking the state's progress toward the emission limits.

The state's current limits on the emission of greenhouse gases are:

by 2020, overall greenhouse gas emissions in the state must be reduced to 1990 levels;
by 2035, overall greenhouse gas emissions in the state must be reduced to 25 percent below 1990 levels; and
by 2050, overall greenhouse gas emissions in the state must be reduced to 50 percent below 1990 levels, or 70 percent below the state's expected emissions for that year.

The 2008 legislation also required Ecology to consult with the Climate Impacts Group at the University of Washington regarding the science on human-caused climate change, and to provide a report to the Legislature making recommendations regarding whether the greenhouse gas emissions reductions needed to be updated.

Ecology issued its most recent such report in December 2016. The report recommended the following greenhouse gas emission limits:

by 2020, reduce overall emissions of greenhouse gases in the state to 1990 levels;
by 2035, reduce overall greenhouse gas emissions in the state to 40 percent below 1990 levels; and
by 2050, reduce overall greenhouse gas emissions in the state to 80 percent below 1990 levels.

In addition to the above reporting, Ecology and the Department of Commerce are required to the report to the Governor and to the Legislature, every two years, concerning the total emissions of greenhouse gases for the preceding two years, as well as totals in each major source sector.

The United Nations Framework Convention on Climate Change.

The United Nations Framework Convention on Climate Change (UNFCCC) took effect in 1994 and sets an overall framework for intergovernmental efforts to address challenges posed by climate change. The UNFCCC proclaims that the climate system is a shared resource and that its stability can be affected by industrial and other emissions of carbon dioxide and other greenhouse gases. Governments engage in a variety of collaborative activities under the UNFCCC, including gathering and sharing information on greenhouse gas emissions, national policies, and best practices; launching national strategies for addressing greenhouse gas emissions and adapting to expected impacts, including the provision of financial and technological support to developing countries; and agreeing to international treaties such as the Kyoto Protocol, which set binding targets for 37 industrialized countries and the European community for reducing greenhouse gas emissions.

The 2015 round of talks under the UNFCCC took place in Paris, France, and resulted in what is commonly referred to as the Paris Agreement. Under the Paris Agreement, each participating nation determines the contribution, known as the intended nationally determined contribution, that it will make toward a global reduction in greenhouse gas emissions. The Paris Agreement also contains a mechanism for developed countries to fund climate change adaptation and mitigation in developing countries. A total of 197 countries, including the United States, have signed the Paris Agreement.

The Paris Agreement includes a provision regarding the Non-State Actor Zone for Climate Action, also referred to as NAZCA. The NAZCA is a reporting platform under which sub-national actors — such as states, companies, cities, private investors, and nonprofit organizations —– report and track the pledges and efforts they have made to address climate change.

The United States signed the Paris Agreement on April 22, 2016. Under the intended nationally determined contribution that the United States submitted to the United Nations, the United States committed to reducing greenhouse gas emissions to twenty-six percent below 2005 levels by 2025, and to making best efforts to reduce greenhouse gas emissions to twenty-eight percent below 2005 levels. On June 1, 2017, the United States announced that it would withdraw from the Paris climate agreement.