In 2007, then-Governor Sarah Palin (R) established the Climate Change Sub-Cabinet to advise the governor's office on a state-specific climate change strategy to prepare residents for the "anticipated impacts from climate change." The cabinet would conduct scientific research and develop an "action plan" for reducing or mitigating any damage to the state's coasts, infrastructure, forests, and agricultural sector. The administrative order that established the cabinet recommended tapping into Alaska's natural gas reserves as a way to encourage "a clean, low carbon fuel to help the nation reduce its overall greenhouse gas emissions." The cabinet includes several state commissioners, including the commissioners of the Alaska Department of Environmental Conservation and the Department of Natural Resources.^[8]

In January 2010, the Alaska Adaptation Advisory Group (AAG) released a report on the state's recommendations on how "to adapt to climate change," although the report only included recommendations and did not constitute an official change in state policy. The group's recommendations varied from state support for climate research and greenhouse gas emissions data collection to an emphasis on climate change education in grades K-12. Additionally, the Alaska Mitigation Advisory Group—one of five work groups in the Alaska Governor's Sub-Cabinet on Climate Change—released a report on potential mitigation policies the state could adopt to reduce climate change's impact. The policies included an emissions reporting system and a market-based plan to reduce emissions (the group was ordered to remain neutral on the cause or extent of climate change). In addition to encouraging private energy conservation, the mitigation report also recommended potential oil and gas policy changes, such as making fossil fuel consumption more efficient and promoting renewable energy as a substitute for oil and gas use, although the report stated that these policy changes "would be very expensive to implement."^[9][10]

In 2007, Arizona joined the Western Climate Initiative (WCI), originally a group of seven states and four Canadian provinces (as of 2016, California was the only U.S. state that remained in the WCI). The WCI had agreed to design and implement voluntarily a cap-and-trade system. Under this system, emissions would be capped at a certain level, and states would be able to "trade" the unused portion of their emissions allowance to other states. In 2010, then-Governor Brewer signed an executive order refusing to implement the WCI's cap-and-trade program in Arizona, citing its costs to the state's economy. Arizona ultimately withdrew from the WCI under Brewer in 2011, along with Montana, New Mexico, Oregon, Utah, and Washington.^[14][15][16]

In 2007, then-Governor Mike Beebe (D) created the Governor's Commission on Global Warming based on legislation passed by the state legislature. The commission studied climate change's potential effects to the state and recommended a 20 percent reduction in greenhouse gases below 2000 levels by 2020, a 35 percent reduction from 2000 levels by 2025, and a 50 percent reduction by 2035. The commission also recommended renewable energy, energy efficiency standards, and an Arkansas Climate Change Center to oversee an implementation plan for the emissions reductions. As of March 2016, these recommendations has not been implemented by the state government.^[17]

One of California's first climate change initiatives was passed in 2004 when the California Environmental Protection Agency (CalEPA) created a climate change working group to consider greenhouse gas reduction strategies. In June 2005, then-Governor Arnold Schwarzenegger (R) signed an executive order to create an emissions reduction program for state agencies. In September 2006, the state legislature passed the Global Warming Solutions Act that established mandatory and market-oriented programs to reduce greenhouse gases. Statewide, greenhouse gas levels were required to reach 1990 levels before 2020 and reach 80 percent below 1990 levels by 2050. This legislation was the first state law to impose a mandatory cap on emissions with enforceable penalties. It also included a cap-and-trade program, a market-based method of decreasing emissions through the purchase and sale of emissions credits, that was fully implemented in 2011. The legislature also passed Senate Bill 1368, which required retail providers of electricity to limit emissions to 1,100 pounds of carbon dioxide per megawatt hour of electricity delivered. In February 2007, California joined the Western Climate Initiative, originally a group of seven states and four Canadian provinces, but as of 2016, California was the only U.S. state that remained in the agreement. The WCI agreed to design and implement voluntarily a cap-and-trade system for trading greenhouse gas emissions, a system ultimately modeled upon California's own cap-and-trade system, though most states did not implement such a system.^[18]

All 2009 model light trucks like this vehicle (and subsequent models) were required to meet California's greenhouse gas emissions standards.

California has operated a Low Emission Vehicle (LEV) program since 1990, which sets emissions standards for cars, light trucks, and medium-duty vehicles. These standards originally targeted conventional types of pollution from vehicles, such as smog-forming emissions and carbon monoxide. In 2002, the state legislature passed Assembly Bill 1493, which became the first state legislation to regulate greenhouse gas emissions from automobiles. All new 2009 and subsequent model year cars and light trucks were required to meet the standards. California's goal was to reduce approximately 30 million metric tons of greenhouse gases by 2020. Although the California Air Resources Board (CARB) had approved the emissions standards in September 2004, under the federal Clean Air Act, California was required to seek a waiver from the U.S. Environmental Protection Agency (EPA) before it could implement any vehicle emissions standards stricter than federal standards. At the time, California was unique in that it was the only state able to seek a waiver for stricter vehicle standards under federal law; Congress has since amended the Clean Air Act so that states can adopt California's stricter standards if they choose.^{[19][20][21][22]}

In December 2005, the California Air Resources Board applied for a waiver from the EPA. The waiver was denied in March 2008 under the Bush administration, but it was ultimately approved in June 2009 under the Obama administration. The waiver allowed California to officially adopt its vehicle standards. Around this time, between 2009 and 2010, the U.S. Environmental Protection Agency (EPA) and the U.S. Department of Transportation had proposed nationwide greenhouse gas emissions standards for new vehicles for model years 2012 to 2016 similar to California's standards. California was also involved in negotiations with the federal government on the national standards. The national standards were officially finalized and adopted in April 2010, and California agreed to adopt the federal standards for those years in lieu of its own standards.^{[19][20][21][22]}

On September 19, California Governor Jerry Brown (D) signed a bill regulating flatulence from dairy cows and other animals, mandating a reduction in hydrofluorocarbons (HFCs, which are organic compounds used in refrigeration and aerosol), and requiring a reduction in soot at landfills. Under the new law, the California Air Resources Board is allowed to regulate bovine flatulence if there are “practical ways to reduce the cows’ belching and breaking wind.” The law is designed to get California to reduce the state’s methane emissions by 40 percent before the year 2030. Methane is a colorless, odorless, flammable, naturally occurring gas that is emitted from natural and human-made sources, including wildfires, volcanoes, livestock cultivation, and natural gas extraction. To justify the new law, Brown cited the theory of human-made climate change and the role that greenhouse gases such as methane may contribute to global warming. Additionally, the law would require a 50 percent reduction of HFCs by the year 2030. Supporters of the bill, including environmental groups, have argued that the law would help reduce pollution that harms human health. Opponents of the bill, including agricultural groups, have argued that the law would force dairy farms to close or move out of state, causing job losses.^[23][24]

As of March 2016, Connecticut was one of the 12 states to adopt greenhouse gas emissions standards for automobiles similar to California's standards. In May 2004, the state legislature passed the Clean Car Act, requiring all new 2009 to 2014 model year cars, light trucks, and medium-duty vehicles to conform to California's greenhouse gas emissions standards.^[28]

The Turkey Point Generating Station near Homestead, Florida

As of March 2016, Florida was one of the 45 states that did not mandate reductions in greenhouse gas emissions at the state level and one of the 38 states that did not impose mandatory greenhouse gas emissions standards for automobiles. Previously, however, the state had begun implementing a cap-and-trade system. In June 2008, then-Governor Charlie Crist (R) signed House Bill 7135, which allowed the Florida Department of Environmental Protection to create a cap-and-trade program for greenhouse gasses generated by electric utilities. The program would have required a reduction in emissions to 2000 levels by 2017, 1990 levels by 2025, and 80 percent below 1990 levels by 2050. Crist had already signed an executive order in 2007 to mandate statewide greenhouse gas standards. In April 2012, Governor Rick Scott (R) signed House Bill 4001, repealing the cap-and-trade system for power plant emissions. The system was never implemented before its repeal.^[30][31]

In March 2015, former employees of the Florida Department of Environmental Protection told an investigative news agency that they were forbidden from using "climate change" and "global warming" in their official government communications. Bart Bibler, a land management plan coordinator for the state, said he was suspended after using the term "climate change" in one of his reports, although the department has stated he was put on leave rather than suspended. "I didn't know there was any sort of ban on the subject or discussion," Bibler said in an interview with the Washington Post. "We should be talking about climate change. If we can't, that's absurd. And it's harming our future." A former department employee, Kristina Trotta, said that the "ban" on the term's use came from the Florida governor's office, although Governor Rick Scott's (R) office denied any sort of ban, official or otherwise.^[32][33]

The news prompted Secretary of State John Kerry to comment on the issue, although he did not mention Florida or Scott by name. "We literally do not have the time to debate whether we can say 'climate change.' We have to solve climate change," Kerry stated. "When science tells us that our climate is changing and human beings are largely causing that change, by what right do people just stand up and say, 'I dispute that,' or 'I deny this elementary truth'?"^[34]

Skepticism about climate change, which Scott has expressed since his 2010 campaign for governor, is more prevalent among Republicans than Democrats. Skeptics have argued in the past that the impact of climate change remains inconclusive and that policies such as greenhouse gas emissions limits for things like cars and power plants would stifle economic growth and reduce jobs.^[35]

The Hawaiian Electric Industries Inc. power plant at in West Oahu is one of the greenhouse gas sources that falls under state regulation.

As of March 2016, Hawaii was one of five states to mandate greenhouse gas emissions reductions, but not one of the 12 states to impose mandatory emissions standards for automobiles. In 2007, the state legislature passed Act 234 (the Global Warming Solutions Act of 2007) that mandated statewide greenhouse gas reductions to 1990 levels by 2020. In June 2014, the Hawaii Department of Health created the Hawaii Greenhouse Gas Program "to combat the threat of climate change and sea level rise." The program requires a 16 percent greenhouse gas emissions cap for large stationary sources that have the potential to produce at least 100,000 or more metric tons of "carbon dioxide equivalent," which is a measuring unit to signify the impact of each greenhouse gas in terms of the amount of carbon dioxide needed to produce the same amount of warming. Each affected facility must submit an emissions reduction plan to meet the 16 percent cap. The Hawaii Department of Health enforces the program through a permit process. The deadline for facilities to submit their plans was June 30, 2015. In 2015, the state government also considers greenhouse gas emissions when it determines an affected facility's annual fees, which are required by all Hawaiian facilities that need an air pollution control permit to operate in the state. At the start of each year, the Clean Air Branch sends out forms for permit holders to calculate and pay their annual fees for their operations in the prior year.^[36][37][38]

Wind turbines in Iowa

As of March 2016, Iowa was one of the 45 states that did not mandate reductions in greenhouse gas emissions at the state level and one of the 38 states that did not impose mandatory greenhouse gas emissions standards for automobiles; however, in 2007, then-Governor Chet Culver (D) signed onto the Midwestern Regional Greenhouse Gas Reduction Accord, a regional agreement among six states and one Canadian premier to reduce greenhouse gas emissions, of which Iowa was a contributing member. The accord first began in 2007 and included governors from Illinois, Kansas, Michigan, Minnesota, and Wisconsin as well as Gov. Culver. Its goal was to design a cap-and-trade system in which a regional emissions target would be set, with states participating by setting their own specific targets. The program's design was completed in 2010, and although the accord had not been formally dissolved as of March 2016, the member states involved never adopted the cap-and-trade system, and each governor that first participated in the accord had left or was voted out of office (Culver lost re-election in 2010).^[40][41]

As of March 2016, Maine was one of the 12 states to adopt greenhouse gas emissions standards for automobiles similar to California's standards (Maine's standards were passed in 2005 and updated in December 2012). The law prohibits any individual, including vehicle manufacturers and dealers, from selling, leasing, importing, or renting new vehicles from 2001 and subsequent model year passenger vehicles and new medium-duty vehicles—as well as light trucks from 2003 and subsequent model years—unless they fall under emissions standards for conventional pollution certified by the California Air Resources Board. Meanwhile, all 2009 and subsequent model year vehicles must meet California's greenhouse gas emissions standards for cars, light trucks and medium-duty passenger vehicles.^[43]

As of March 2016, Maryland was one of the 12 states to adopt greenhouse gas emissions standards for automobiles similar to California's standards. In 2007, then-Governor of Maryland Martin O'Malley (D) signed into the law the Maryland Clean Cars Act, mandating that Connecticut adopt California's greenhouse gas emissions standards for all new model year 2011 vehicles (the Maryland standards also target volatile organic compound emissions and nitrogen oxide emissions).^[44][45]

Massachusetts is also a member of the Regional Greenhouse Gas Initiative (RGGI), a voluntary, market-oriented regulatory program to reduce greenhouse gas emissions among Northeastern states. The RGGI also includes Connecticut, Delaware, Maine, Maryland, New Hampshire, New York, Rhode Island, and Vermont. Under the program, emissions are capped at a certain level each year; the cap is lowered 2.5 percent each year from 2015 to 2020. According to the RGGI, the emissions cap acts as a budget for the entire program and its state members. In 2015, the cap was 88.7 million tons of carbon dioxide (CO₂) for the nine states total. States can sell their emission allowances to other states through auctions, and the proceeds are used to invest in renewable energy technologies and equipment to improve energy efficiency.^[40][41]

As of March 2016, Massachusetts was one of the 12 states to adopt greenhouse gas emissions standards for automobiles similar to California's standards. In 2006, Massachusetts required greenhouse gas emissions standards for new cars and light trucks for the 2009 model year and subsequent model years.^[47]

As of March 2016, New Jersey was one of the 12 states to adopt greenhouse gas emissions standards for automobiles similar to California's standards. It adopted the California Low Emission Vehicle Program in January 2004. Known as the Clean Car Program in New Jersey, it requires all new passenger vehicles manufactured in the state for model year 2009 and beyond to conform to California's greenhouse gas emissions standards.^[54][55]

New York is also a member of the Regional Greenhouse Gas Initiative (RGGI), a voluntary, market-oriented regulatory program to reduce greenhouse gas emissions among Northeastern states. The RGGI also includes Connecticut, Delaware, Maine, Maryland, New Hampshire, Massachusetts, Rhode Island, and Vermont. Under the program, emissions are capped at a certain level each year; the cap is lowered 2.5 percent each year from 2015 to 2020. According to the RGGI, the emissions cap acts as a budget for the entire program and its state members. In 2015, the cap was 88.7 million tons of carbon dioxide (CO₂) for the nine states total. States can sell their emission allowances to other states through auctions, and the proceeds are used to invest in renewable energy technologies and equipment to improve energy efficiency.^[40][41]

As of March 2016, New York was one of the 12 states to adopt greenhouse gas emissions standards for automobiles similar to California's standards. In 1990, New York adopted California's Low Emission Vehicle program to reduce conventional vehicle pollution (such as volatile organic compounds) that began with 1993 model year passenger cars and light trucks. The standards were updated in 2005 to include all new 2009 model year vehicles manufactured and/or sold in New York and mandated those vehicles conform to California's greenhouse gas standards.^[59][60]

Wastewater treatment facilities in Oregon are required to submit greenhouse gas emissions information each year.

As of March 2016, Oregon was one of the 45 states that did not mandate reductions in greenhouse gas emissions at the state level. In 2007, however, the Oregon State Legislature created non-binding, recommended goals for the state to reduce greenhouse gas emissions. By 2010, the state was expected to stop the growth of its emissions. Greenhouse gas levels were expected to be 10 percent below 1990 levels by 2020 and at least 75 percent below 1990 levels by 2050. Oregon's Environmental Quality Commission mandates the submission of greenhouse gas emissions information each year from industrial facilities (specifically those requiring state permits), wastewater treatment facilities, electricity suppliers, fuel distribution centers, and landfills.^[61][62]

As of March 2016, Oregon was one of the 12 states to adopt greenhouse gas emissions standards for automobiles similar to California's standards. Oregon's Environmental Quality Commission adopted California's standards in 2006.^[63]

In 2007, under then-Governor Ted Kulongoski (D), Oregon joined the Western Climate Initiative (WCI), originally a group of seven states and four Canadian provinces (as of 2016, California was the only U.S. state that remained in the WCI). The WCI had agreed to design and implement voluntarily a cap-and-trade system. Under this system, emissions would be capped at a certain level, and states would be able to "trade" the unused portion of their emissions allowance to other states. Oregon ultimately withdrew from the WCI under Governor John Kitzhaber (D) in 2011, along with Arizona, Montana, New Mexico, Utah, and Washington.^[64]

As of March 2016, Rhode Island was one of the 12 states to adopt greenhouse gas emissions standards for automobiles similar to California's standards. In 2005, Rhode Island adopted California's greenhouse gas emissions standards for all new and subsequent model year vehicles beginning with 2009 model year vehicles and beyond.^[67]

In 2007, however, under then-Governor Jon Huntsman (R), Utah joined the Western Climate Initiative (WCI), originally a group of seven states and four Canadian provinces (as of 2016, California was the only U.S. state that remained in the WCI). The WCI had agreed to design and implement voluntarily a cap-and-trade system. Under this system, emissions would be capped at a certain level, and states would be able to "trade" the unused portion of their emissions allowance to other states. Utah ultimately withdrew from the WCI under Governor Gary R. Herbert (R) in 2011, along with Arizona, Montana, New Mexico, Oregon, and Washington.^[68]

As of March 2016, Vermont was one of the 12 states to adopt greenhouse gas emissions standards for automobiles similar to California's standards. In November 2005, the Vermont Air Pollution Control Division adopted California's greenhouse gas emissions standards for new automobiles beginning in model year 2009 and subsequent model years. Manufacturers of these vehicles must meet a certain average emissions standard for greenhouse gases.^[70][71]

In July 2015, Governor Jay Inslee (D) directed the state's Department of Ecology to consider a mandatory cap on greenhouse gas emissions in the state to achieve the legislature's goals passed in 2008. Inslee took these steps to enforce caps on greenhouse gas emissions after other proposals stalled in the Washington State Senate, which was controlled by Republicans at the time.^[74]

In March 2016, the department withdrew its proposal for a mandatory emissions cap. The rule was withdrawn because a large number of companies had requested exemptions, and there were questions about how precisely the system would work. Critics of the proposal pointed to the possibility that companies already planning to reduce their emissions would have seen large profits from the proposed cap.^[75]

As of March 2016, Washington was one of the 12 states to adopt greenhouse gas emissions standards for automobiles similar to California's standards. In 2005, Washington adopted California's greenhouse gas vehicle standards for passenger vehicles, light trucks, and medium-duty passenger vehicles. All new model year 2010 and subsequent model year cars, light trucks, and medium-duty vehicles in the state were required to have a label from the manufacturer detailing that the vehicle meets greenhouse gas emissions standards.^[76][77]

In 2007, under then-Governor Christine Gregoire (D), Oregon joined the Western Climate Initiative (WCI), originally a group of seven states and four Canadian provinces (as of 2016, California was the only U.S. state that remained in the WCI). The WCI had agreed to design and implement voluntarily a cap-and-trade system. Under this system, emissions would be capped at a certain level, and states would be able to "trade" the unused portion of their emissions allowance to other states. Oregon ultimately withdrew from the WCI under Gregoire in 2011, along with Arizona, Montana, New Mexico, Oregon, and Utah.^[78]

Wisconsin was a member of the Midwestern Regional Greenhouse Gas Reduction Accord, a regional agreement among six states and one Canadian premier to reduce greenhouse gas emissions. The accord first began in 2007 and also included governors from Illinois, Iowa, Kansas, Michigan, and Minnesota, including then-Governor of Wisconsin Jim Doyle (D). The accord's goal was to design a cap-and-trade system in which a regional emissions target would be set, with states participating by setting their own specific targets. The program's design was completed in 2010, and although the accord had not been formally dissolved as of March 2016, the member states involved never adopted the cap-and-trade system, and each governor that first participated in the accord had left or was voted out of office (Doyle left office in 2011 after two terms as governor).^[40][41]