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Wednesday, September 28, 2022

Climate change policy of the United States

States that have declared GHG mitigation strategies or hold action plans

The climate change policy of the United States has major impacts on global climate change and on global climate change mitigation. This is because the United States is the second largest emitter of greenhouse gasses in the world after China, and is among the countries with the highest greenhouse gas emissions per person in the world. In total the United States has emitted over 400 billion metric tons of greenhouse gasses, more than any country in the world.

Climate change policy is developed at the local, state and federal levels of government. Global climate change was first addressed in United States policy beginning in the early 1950s. The Environmental Protection Agency (EPA) defines climate change as "any significant change in the measures of climate lasting for an extended period of time." Essentially, climate change includes major changes in temperature, precipitation, or wind patterns, as well as other effects, that occur over several decades or longer. The policy with the biggest US investment in climate change mitigation is the Inflation Reduction Act of 2022.

The politics of climate change have polarized certain political parties and other organizations. The Democratic Party advocates for an expansion of climate change mitigation policies whereas the Republican Party tends to be skeptical about the effects on business, as well as advocate for slower change, inaction, or outright reactionary reversal of existing climate change mitigation policies. Most lobbying on climate policy in the United States is done by corporations that are publicly opposed to reducing carbon emissions.

Federal policy

International law

The United States, although a signatory to the Kyoto Protocol, has neither ratified nor withdrawn from the protocol. In 1997, the US Senate voted unanimously under the Byrd–Hagel Resolution that it was not the sense of the Senate that the United States should be a signatory to the Kyoto Protocol. In 2001, former National Security Adviser Condoleezza Rice, stated that the Protocol "is not acceptable to the Administration or Congress".

In October 2003, the Pentagon published a report titled An Abrupt Climate Change Scenario and Its Implications for United States National Security by Peter Schwartz and Doug Randall. The authors conclude by stating, "this report suggests that, because of the potentially dire consequences, the risk of abrupt climate change, although uncertain and quite possibly small, should be elevated beyond a scientific debate to a U.S. national security concern."

Congress

In October 2003 and again in June 2005, the McCain-Lieberman Climate Stewardship Act failed a vote in the US Senate. In the 2005 vote, Republicans opposed the Bill 49–6, while Democrats supported it 37–10.

In January 2007, Democratic House Speaker Nancy Pelosi announced she would form a United States Congress subcommittee to examine global warming. Sen. Joe Lieberman said, "I'm hot to get something done. It's hard not to conclude that the politics of global warming has changed and a new consensus for action is emerging and it is a bipartisan consensus." Senators Bernie Sanders (I-VT) and Barbara Boxer (D-CA) introduced the Global Warming Pollution Reduction Act on January 15, 2007. The measure would provide funding for R&D on geologic sequestration of carbon dioxide (CO2), set emissions standards for new vehicles and a renewable fuels requirement for gasoline beginning in 2016, establish energy efficiency and renewable portfolio standards beginning in 2008 and low-carbon electric generation standards beginning in 2016 for electric utilities, and require periodic evaluations by the National Academy of Sciences to determine whether emissions targets are adequate. However, the bill died in committee. Two more bills, the Climate Protection Act and the Sustainable Energy Act, proposed February 14, 2013, also failed to pass committee.

The House of Representatives approved the American Clean Energy and Security Act (ACES) on June 26, 2009, by a vote of 219–212, but the bill failed to pass the Senate.

In March 2011, the Republicans submitted a bill to the U.S. Congress that would prohibit the Environmental Protection Agency (EPA) from regulating greenhouse gasses as pollutants. As of 2012, the EPA was still overseeing regulation under the Clean Air Act.

In 2019, there were 130 elected Congressional leaders who had expressed doubt about the science of climate change.

Clinton administration

Upon the start of his presidency in 1993, Bill Clinton committed the United States to lowering their greenhouse gas emissions to 1990 levels by 2000 through his biodiversity treaty, reflecting his attempt to return the United States to the global platform of climate policy. Clinton's British Thermal Unit (BTU) Tax and Climate Change Action Plan were also announced within the first year of his presidency, calling for a tax on energy heat content and plans for energy efficiency and joint implementations, respectively.

The Climate Change Action Plan was announced on October 19, 1993. This plan aimed to reduce greenhouse gas emissions to 1990 levels by 2000. Clinton described this goal as "ambitious but achievable," and called for 44 action steps to achieve this goal. Among these steps were voluntary participation by industry, especially those in the commercial and energy supply fields. Clinton allotted $1.9 billion to fund this plan from the federal budget and called for an additional $60 billion funding to come voluntarily businesses and industries.

The British Thermal Tax proposed by Clinton in early 1993 called for a tax on producers of gasoline, oil, and other fuels based on fuel content in accordance to the British Thermal Unit (BTU). The British Thermal Unit is a measure of heat corresponding to the quantity of heat needed to raise the temperature of water by one degree Fahrenheit. The tax also applied to electricity produced by hydro and nuclear power, but exempted renewable energy sources such as geothermal, solar, and wind. The Clinton Administration planned to collect up to $22.3 billion in revenue from the tax by 1997. The tax was opposed by the energy-intensive industry, who feared that the price increase caused by the tax would make U.S. products undesirable on an international level, and thus was never fully implemented.

In 1994, the U.S. called for a new limit on greenhouse gas emissions post-2000 in at the August 1994 INC-10. They also called for a focus on joint implementation, and for new developing countries to limit their emissions. Environmental groups, including the Climate Action Network (CAN), critiqued these efforts, questioning U.S. focus on limiting the emissions of other countries when it had not established its own.

The U.S. government under Clinton succeeded in pushing its agenda for joint implementation in the 1995 Conference of the Parties (COP-1). This victory is noted in the Berlin Mandate of April 1995, which called for developed countries to lead the implementation of national mitigation policies.

Clinton signed the Kyoto Protocol on behalf of the United States in 1997, pledging the country to a non-binding 7% reduction of greenhouse gas emissions. He claimed that the agreement was "environmentally strong and economically sound," and expressed a desire for greater involvement in the treaty by developing nations.

In his second term, Clinton announced his FY00 proposal, which allotted funding for a new set of environmental policies. Under this proposal, the President announced a new Clean Air Partnership Fund, new tax incentives and investments, and funding for environmental research of both natural and man-made changes to the climate.

The Clean Air Partnership Fund was proposed to finance state and local government efforts for greenhouse gas emission reductions in cooperation with EPA. Under this fund, $200 million was allotted to promote and finance innovation projects meant to reduce air pollution. It also supported the creation of partnerships between the local and federal governments, and private sector.

The Climate Change Technology Initiative provided $4 billion in tax incentives over a five-year period. The tax credits applied to energy efficient homes and building equipment, implementation of solar energy systems, electric and hybrid vehicles, clean energy, and the power industry. The Climate Change Technology Initiative also provided funding for additional research and development on clean technology, especially in the building, electricity, industry, and transportation sectors.

G.W. Bush administration

In March 2001, the George W. Bush Administration announced that it would not implement the Kyoto Protocol, an international treaty signed in 1997 in Kyoto, Japan that would require nations to reduce their greenhouse gas emissions, claiming that ratifying the treaty would create economic setbacks in the U.S. and does not put enough pressure to limit emissions from developing nations. In February 2002, President Bush announced his alternative to the Kyoto Protocol, by bringing forth a plan to reduce the intensity of greenhouse gasses by 18 percent over 10 years. The intensity of greenhouse gasses specifically is the ratio of greenhouse gas emissions and economic output, meaning that under this plan, emissions would still continue to grow, but at a slower pace. Bush stated that this plan would prevent the release of 500 million metric tons of greenhouse gases, which is about the equivalent of 70 million cars from the road. This target would achieve this goal by providing tax credits to businesses that use renewable energy sources.

The Bush administration has been accused of implementing an industry-formulated disinformation campaign designed to mislead the American public on global warming and to forestall limits on "climate polluters", according to a report in Rolling Stone magazine that reviewed hundreds of internal government documents and former government officials. The book Hell and High Water asserts that there has been a disingenuous, concerted and effective campaign to convince Americans that the science is not proven, or that global warming is the result of natural cycles, and that there needs to be more research. The book claims that, to delay action, industry and government spokesmen suggest falsely that "technology breakthroughs" will eventually save us with hydrogen cars and other fixes. It calls on voters to demand immediate government action to curb emissions. Papers presented at an International Scientific Congress on Climate Change, held in 2009 under the sponsorship of the University of Copenhagen in cooperation with nine other universities in the International Alliance of Research Universities (IARU), maintained that the climate change skepticism that is so prevalent in the USA "was largely generated and kept alive by a small number of conservative think tanks, often with direct funding from industries having special interests in delaying or avoiding the regulation of greenhouse gas emissions".

According to testimony taken by the U.S. House of Representatives, the Bush White House pressured American scientists to suppress discussion of global warming "High-quality science" was "struggling to get out", as the Bush administration pressured scientists to tailor their writings on global warming to fit the Bush administration's skepticism, in some cases at the behest of an ex-oil industry lobbyist. "Nearly half of all respondents perceived or personally experienced pressure to eliminate the words 'climate change,' 'global warming' or other similar terms from a variety of communications." Similarly, according to the testimony of senior officers of the Government Accountability Project, the White House attempted to bury the report "National Assessment of the Potential Consequences of Climate Variability and Change", produced by U.S. scientists pursuant to U.S. law, Some U.S. scientists resigned their jobs rather than give in to White House pressure to underreport global warming and removed key portions of a Centers for Disease Control and Prevention (CDC) report given to the U.S. Senate Environment and Public Works Committee about the dangers to human health of global warming.

The Bush Administration worked to undermine state efforts to mitigate global warming. Mary Peters, the Transportation Secretary at that time, personally directed US efforts to urge governors and dozens of members of the House of Representatives to block California's first-in-the-nation limits on greenhouse gases from cars and trucks, according to e-mails obtained by Congress.

Obama administration

New Energy for America is a plan to invest in renewable energy, reduce reliance on foreign oil, address the global climate crisis, and make coal a less competitive energy source. It was announced during Barack Obama's presidential campaign.

On November 17, 2008, President-elect Barack Obama proposed, in a talk recorded for YouTube, that the US should enter a cap and trade system to limit global warming. The American Clean Energy and Security Act, a cap and trade bill, was passed on June 26, 2009, in the House of Representatives, but was not passed by the Senate.

President Obama established a new office in the White House, the White House Office of Energy and Climate Change Policy, and selected Carol Browner as Assistant to the President for Energy and Climate Change. Browner is a former administrator of the U.S. Environmental Protection Agency (EPA) and was a principal of The Albright Group LLC, a firm that provides strategic advice to companies.

On January 27, 2009, Secretary of State Hillary Clinton appointed Todd Stern as the department's Special Envoy for Climate Change. Clinton said, "we are sending an unequivocal message that the United States will be energetic, focused, strategic and serious about addressing global climate change and the corollary issue of clean energy." Stern, who had coordinated global warming policy in the late 1990s under the Bill Clinton administration, said that "The time for denial, delay and dispute is over.... We can only meet the climate challenge with a response that is genuinely global. We will need to engage in vigorous, dramatic diplomacy."

In February 2009, Stern said that the US would take a lead role in the formulation of a new climate change treaty in Copenhagen in December 2009. He made no indication that the U.S. would ratify the Kyoto Protocol in the meantime. US Embassy dispatches subsequently released by whistleblowing site WikiLeaks showed how the US 'used spying, threats and promises of aid' to gain support for the Copenhagen Accord, under which its emissions pledge is the lowest by any leading nation.

President Obama said in September 2009 that if the international community would not act swiftly to deal with climate change that "we risk consigning future generations to an irreversible catastrophe... our prosperity, our health, and our safety are in jeopardy, and the time we have to reverse this tide is running out."  In 2010, the president said, similarly, that it was time for the United States "to aggressively accelerate" its transition from oil to alternative sources of energy and vowed to push for quick action on climate change legislation, arguably seeking to harness the deepening anger over the oil spill in the Gulf of Mexico.

The 2010 United States federal budget proposed to support clean energy development with a 10-year investment of US$15 billion per year, generated from the sale of greenhouse gas (GHG) emissions credits. Under the proposed cap-and-trade program, all GHG emissions credits would be auctioned off, generating an estimated $78.7 billion in additional revenue in FY 2012, steadily increasing to $83 billion by FY 2019.

New rules for power plants were proposed March 2012.

In US and China's Sunnylands Summit on June 8, 2013, President Obama and Chinese Communist Party leader Xi Jinping worked in accordance for the first time, formulating a landmark agreement to reduce both production and consumption of hydrofluorocarbons (HFCs). This agreement had the unofficial goal of decreasing roughly 90 gigatons of CO2 by 2050 and implementation was to be led by the institutions created under the Montreal Protocol, while progress was tracked using the reported emissions that were mandated under the Kyoto Protocol. The Obama administration viewed HFCs as a "serious climate mitigation concern."

On March 31, 2015, the Obama administration formally submitted the US Intended Nationally Determined Contribution (INDC) for greenhouse gas emissions (GHGs) to the United Nations Framework Convention on Climate Change (UNFCCC). According to the US submission, the United States committed to reducing emissions 26-28% below 2005 levels by 2025, a reflection of the Obama administration's goal to convert the U.S. economy into one of low-carbon reliance.

In 2015, Obama also announced the Clean Power Plan, which is the final version of regulations originally proposed by the EPA the previous year, and which pertains to carbon dioxide emissions from power plants.

In the same year, President Obama announced his aim for a 40-45% reduction below 2012 levels in Methane emissions by 2025. In March 2016, the President would later solidify this goal in an agreement with Prime Minister of Canada, Justin Trudeau, stating that the two federal governments will jointly work together to reduce methane emissions in North America. The nations released a joint statement outlining general methods and strategies to reach such goals within their respective jurisdictions. In adherence to this goal, the Environmental Protection Agency (EPA) would take on the responsibility in regulating methane emissions, requiring information from big-time methane emitting industries. Emission information from these industries would be used in the promotion of research and development for methane reduction, formulating differentiated standards and cost-effective policies. The United States and Canada will jointly exchange any progress in research and development for optimal efficiency, while practicing transparency in regards to their respective progress with each other and the rest of North America, continuing to strengthen the bond with Mexico.

On May 12, 2016, after three public hearings and a review of public comments, the administration released an Information Collection Request (ICR), requiring all methane emitting operations to provide reports of their levels of emissions for EPA analysis so that policies could begin to be formulated and high emitting sources could be identified. New Source Performance Standards (NSPS) were implemented, building off previous requirements to reduce VOC (a byproduct of methane) emissions. The new standards set emission limits for methane; reductions were to be made through transition to newer and cleaner production equipment, fixed monitoring of leaks at operation sites using innovative techniques, and the capturing of emissions from hydraulic fracturing. More specifically, well sites, regardless of size or operation, were to be checked for leaks at least twice a year, while compressor stations were required to monitor every quarter. Owners and operators can make these observances one of two ways, either through optical gas imaging, the use of a portable monitoring instrument, or the use of an approved innovated strategy. Once these checks are made, mandatory surveys must be submitted no later than a year after final results are gathered. Additionally, "green completion" requirements, regarding the process for seizing emissions from hydraulically fractured oil wells, were outlined for owners of oil wells.

A September 2016 study from Lawrence Berkeley National Laboratory analyses a set of definite and proposed climate change policies for the United States and finds that these are just insufficient to meet the US intended nationally determined contribution (INDC) under the 2015/2016 Paris Agreement. Additional greenhouse gas reduction measures will probably be required to meet this international commitment. These additional reduction measures will soon have to be decided on in order to start complying with the agreement's "below 2 degrees" goal, and countries may have to be more proactive than previously thought.

An October 2016 report compares US government spending on climate security and military security and finds the latter to be 28 × greater. The report estimates that public sector spending of $55 billion is needed to tackle climate change. The 2017 national budget contains $21 billion for such expenditures, leaving a shortfall of $34 billion that could be recouped by scrapping underperforming weapons programs. The report nominates the F-35 fighter and close-to-shore combat ship projects as possible targets.

Transportation

President's 21st century clean transportation plan

In June 2015, the Obama administration released the President's 21st Century Clean Transportation Plan with the goal of reducing carbon pollution by converting the nation's century old infrastructure into one based on clean energy. This plan intended to battle climate change by reducing emissions through a switch to more sustainable forms of transportation, resulting from a potential increase of innovation in both public transit and electric vehicle production in the United States. The President stated that the revitalization of the infrastructure would not only create jobs, but also allow for quicker deliveries of goods, and allow for a greater variety of transportation options that would facilitate travel for Americans. The President's multibillion-dollar proposal provided incentives to reduce reliance on international oil and fossil fuels.

This plan fundamentally relied on an increase in investment into sustainable transportation, Previously, such investment into transportation was supported by the Fixing America's Surface Transportation Act (FAST), an act passed in December 2015 by the Obama administration. FAST was formulated to reduce traffic and increase the quality of air by reducing emissions, yet this act proved to be slow in gathering infrastructure investments. Thus, the President proposed a tax on oil, a gradual $10 per barrel, in order to subsidize this plan to improve infrastructure and further drive down the incentive to consume large quantities of oil, possibly furthering the urge to switch to more sustainable forms of transportation. Ultimately, this plan did not appeal to GOP leaders and as a result it was never enacted; the act was denied funding in the House of Representatives by U.S. Congressman Paul A. Gosar and his Republican coalition, enacting their fundamental "power of the purse."

Climate action plan progress report

In June 2015, under Obama's Climate Action Plan Progress Report, the EPA announced that they were going to propose new standards for both medium and heavy-duty engines and vehicles, building off standards that were already enacted. These proposals were projected to decrease emissions by 270 million metric tons and save vehicle owners around $50 billion in fuel costs.

The Climate Action Plan progress report also addressed air craft, transit, and maritime emissions. The EPA released an Advanced Notice of Proposed Rulemaking, increasing transparency around the plans of the International Civil Aviation Organization (ICAO) in tightening carbon pollution standards. Additionally, under the Next Generation Transportation System (NextGen), the Federal Aviation Administration has worked jointly with the aviation industry in formulating technology that supports a reduction in emissions and increase in fuel efficiency. With respect to maritime emissions, the Obama administration oversaw, in cooperation with the Maritime Administration, the increase of investments into more fuel-efficient ships, finalizing the creation of two ships that have been used in the Puerto-Rico to Jacksonville route. Similar investments were pumped into transit, which made it possible for buses and other forms of transit to switch to other forms of energy such as natural gas and electric.

Model year 2012-2016 standards and model year 2017-2025 standards

In April 2010, the Environmental Protection Agency (EPA) and the Department of Transportation's National Highway Traffic Safety Administration (NHTSA) formulated a national program that would finalize new standards for model year 2012 through 2016 passenger cars, light-duty trucks, and medium duty passenger vehicles. With these new standards, vehicles were required to meet an average emissions level of 250 grams of carbon dioxide per mile by model year 2016. This was the first time the EPA had taken measures to regulate vehicular GHG emissions under the Clean Air Act. Additionally, the administration established Corporate Average Fuel Economy (CAFE) standards under the Energy Policy and Conservation Act.

In August 2012, the administration expanded on these standards for model years 2017 through 2025 vehicles, issuing final rules and standards that were to result in a 163 gram emission per mile by model year 2025.

Trump administration

It’ll start getting cooler. You just watch. ...
I don’t think science knows, actually.

—Donald Trump, on climate change
September 13, 2020

During his campaign, Donald Trump promised to roll back some of the Obama-era regulations enacted with the purpose of combating climate change. He questioned the existence of climate change and stated that efforts to curb fossil fuel emissions could harm the United States' global competitiveness. He pledged to roll back regulations placed on the oil and gas industry by the EPA under the Obama administration in order to boost the productivity of both industries.

As president, Trump withdrew the U.S. from the Paris Climate Agreement, a major international convention to address climate change.

Appointment of energy industry-affiliated officials

As president, Trump appointed Scott Pruitt, a climate change denialist with a history of close ties to energy industry interests, to head the EPA. While serving as Attorney General of Oklahoma, Pruitt removed Oklahoma's environmental protection unit and sued the EPA a total of fourteen times, thirteen of which involved "industry players" as co-parties. He was confirmed to head the EPA on February 17, 2017 with a 52–46 vote and resigned on July 5, 2018 amid ethics violation controversies. Trump then nominated Andrew Wheeler, an attorney who worked as a coal lobbyist, who was confirmed as head of the EPA on February 28, 2019 by a 52–47 vote.

Trump nominated Rex W. Tillerson, the former CEO and chairman of Exxon Mobil, the multinational oil and gas giant, as Secretary of State. His nomination was confirmed on February 1, 2017, by a 56–43 vote. He was fired on March 31, 2018, and replaced by Mike Pompeo.

Pipeline expansion and attempts at major cuts to EPA

After less than a week as president, on January 24, 2017, Trump issued an executive order that removed barriers from the Keystone XL and Dakota Access Pipelines, making it easier for the companies sponsoring them to continue with production. On March 28, 2017, President Trump signed an executive order aimed towards boosting the coal industry. The executive order rolls back on Obama-era climate regulations on the coal industry in order to grow the coal sector and create new American jobs. The White House has indicated that any climate change policies that they deem hinder the growth of American jobs will not be pursued. In addition, the executive order rolls back on six Obama-made orders aimed at reducing climate change and carbon dioxide emissions and calls for a review of the Clean Power Plan.

Suppression and politicization of climate science

In his first year in office, President Trump ordered the Environmental Protection Agency to remove references to climate change from its website, suppressed government publication of scientific reports showing the threat of climate change and the effectiveness of renewable energy, and politicized decisions made at the EPA. In a similar vein, the Trump Administration prevented scientists from reporting to Congress regarding the threat of climate change and the urgent need to address it. However, buried inside a 500-page Environmental Impact Statement (EIP) published by the National Highway Traffic Safety Administration, the Trump administration acknowledged that, without a course correction, the planet is on track for global average temperature warming by approximately four degrees Celsius by the end of the century, compared with preindustrial levels. Such warming would be catastrophic for organized human life, according to scientists. The EIP supports the U.S. government's decision to maintain without increase fuel-efficiency standards for cars and other vehicles.

In his budget proposal for 2018, President Trump proposed cutting the EPA's budget by 31% (reducing its current $8.2 billion to $5.7 billion). Had it passed, it would have been the lowest EPA budget in 40 years adjusted for inflation, but Congress did not approve it. Trump tried again unsuccessfully in his budget proposal for 2019 to cut EPA funding by 26%. The EPA provides technical assistance to cities as they update their infrastructure to adapt to climate change, according to Joel Scheraga, the EPA senior advisor for climate change adaptation who has worked for the EPA for three decades. Scheraga said he was working with a reduced staff under the Trump administration.

Environmental justice

The shift in direction of environmental policy in the United States under the Trump administration has led to a change in the environmental justice sector. On March 9, 2017, Mustafa Ali, a leader of the environmental justice office at EPA, resigned over proposed cuts to the agency's environmental justice program. The preliminary budget proposals would cut the environmental justice office's budget by 1/4, causing a 20% reduction in its workforce. The program is one of a dozen vulnerable to losing all governmental funding.

Biden administration

Since taking office in 2021, the Biden administration paused construction of the Keystone XL Pipeline in addition to other actions on climate change, such as creating a National Climate Task Force and pausing oil and gas leases on public lands. Under Biden, the United States re-joined the Paris Agreement. His administration proposed spending on climate change in his infrastructure bill, including $174 billion for electric cars and $35 billion for research and development in climate-focused technology.

In June 2021 the project, Keystone XL, considered by some as dangerous for climate, was cancelled, following strong objection from environmentalists, indigenous peoples, the Democratic Party, and the Joe Biden administration. Biden's goals in developing a federal climate change policy were hampered by the Supreme Court ruling in West Virginia v. EPA, where the court ruled against the EPA's ability to regulate greenhouse gas emissions.

On 21 September 2021, President Joe Biden stated at the UN General Assembly that he would work with Congress to double funds by 2024 to $11.4 billion per year. The plan aimed at helping the developing nations deal with climate change.

The Inflation Reduction Act of 2022 is the largest investment in climate change mitigation in US history. The Act sets out provisions to invest in increasing renewable energy and electrifying areas of the US economy. The bill, passing by a 51-50 vote in the Senate, explicitly defined carbon dioxide as an air pollutant under the Clean Air Act to make the Act's EPA enforcement provisions harder to challenge in court.

State and local policy

Map of states and regions and Climate Registry status, 2008
  RGGI Members
  RGGI Observers
  WRCAI Members
  WRCAI Observers
  MGGRA Members
  MGGRA Observers
  Unaffiliated Registry Participants

Across the country, regional organizations, states, and cities are achieving real emissions reductions and gaining valuable policy experience as they take action on climate change. These actions include increasing renewable energy generation, selling agricultural carbon sequestration credits, and encouraging efficient energy use. The U.S. Climate Change Science Program is a joint program of over twenty U.S. cabinet departments and federal agencies, all working together to investigate climate change. In June 2008, a report issued by the program stated that weather would become more extreme, due to climate change.

As described in a 2007 brief by the PEW Center on Global Climate Change, "States and municipalities often function as "policy laboratories", developing initiatives that serve as models for federal action. This has been especially true with environmental regulation—most federal environmental laws have been based on state models. In addition, state actions can have a significant impact on emissions, because many individual states emit high levels of greenhouse gases. Texas, for example, emits more than France, while California's emissions exceed those of Brazil."

City and state governments often act as liaisons to the business sector, working with stakeholders to meet standards and increase alignment with city and state goals. This section will provide an overview of major statewide climate change policies as well as regional initiatives.

Arizona

On September 8, 2006, Arizona Governor Janet Napolitano signed an executive order calling on the state to create initiatives to cut greenhouse gas emissions to the 2000 level by the year 2020 and to 50 percent below the 2000 level by 2040.

California

California (the world's fifth largest economy) has long been seen as the state-level pioneer in environmental issues related to global warming and has shown some leadership in the last four years. On July 22, 2002, Governor Gray Davis approved AB 1493, a bill directing the California Air Resources Board to develop standards to achieve the maximum feasible and cost-effective reduction of greenhouse gases from motor vehicles. Now the California Vehicle Global Warming law, it requires automakers to reduce emissions by 30% by 2016. Although it has been challenged in the courts by the automakers, support for the law is growing as other states have adopted similar legislation. On September 7, 2002, Governor Davis approved a bill requiring the California Climate Action Registry to adopt procedures and protocols for project reporting and carbon sequestration in forests. (SB 812. Approved by Governor Davis on September 7, 2002) California has convened an interagency task force, housed at the California Energy Commission, to develop these procedures and protocols. Staff are currently seeking input on a host of technical questions.

In June 2005, Governor Arnold Schwarzenegger signed an executive order calling for the following reductions in state greenhouse gas emissions: to reduce GHG emissions to 2000 levels by 2010, to reduce GHG emissions to 1990 levels by 2020, to reduce GHG emissions to 80 percent below 1990 levels by 2050. Measures to meet these targets include tighter automotive emissions standards, and requirements for renewable energy as a proportion of electricity production. The Union of Concerned Scientists has calculated that by 2020, drivers would save $26 billion per year if California's automotive standards were implemented nationally.

On August 30, 2006, Schwarzenegger and the California Legislature reached an agreement on AB32, the Global Warming Solutions Act. He signed the bill into law on September 27, 2006, saying, "We simply must do everything we can in our power to slow down global warming before it is too late... The science is clear. The global warming debate is over." The Act caps California's greenhouse gas emissions at 1990 levels by 2020, and institutes a mandatory emissions reporting system to monitor compliance, representing the first enforceable statewide program in the U.S. to cap all GHG emissions from major industries that includes penalties for non-compliance. It required the State Air Resources Board to establish a program for statewide greenhouse gas emissions reporting and to monitor and enforce compliance with this program, authorizes the state board to adopt market-based compliance mechanisms including cap-and-trade, and allows a one-year extension of the targets under extraordinary circumstances. Thus far, flexible mechanisms in the form of project based offsets have been suggested for five main project types. A carbon project would create offsets by showing that it has reduced carbon dioxide and equivalent gases. The project types include: manure management, forestry, building energy, SF6, and landfill gas capture.

Additionally, on September 26 Governor Schwarzenegger signed SB 107, which requires California's three major biggest utilities – Pacific Gas & Electric, Southern California Edison, and San Diego Gas & Electric – to produce at least 20% of their electricity using renewable sources by 2010. This shortens the time span originally enacted by Gov. Davis in September 2002 to increase utility renewable energy sales 1% annually to 20% by 2017.

Gov. Schwarzenegger also announced he would seek to work with Prime Minister Tony Blair of Great Britain, and various other international efforts to address global warming, independently of the federal government.

Connecticut

The state of Connecticut passed a number of bills on global warming in the early to mid 1990s, including—in 1990—the first state global warming law to require specific actions for reducing CO2. Connecticut is one of the states that agreed, under the auspices of the New England Governors and Eastern Canadian Premiers (NEG/ECP), to a voluntary short-term goal of reducing regional greenhouse gas emissions to 1990 levels by 2010 and by 10 percent below 1990 levels by 2020. The NEG/ECP long-term goal is to reduce emissions to a level that eliminates any dangerous threats to the climate—a goal scientists suggest will require reductions 75 to 85 percent below current levels. These goals were announced in August 2001. The state has also acted to require additions in renewable electric generation by 2009.

Maryland

Maryland began a partnership with the Center for Climate and Energy Solutions (C2ES) in 2015 to research impacts and solutions to climate change called the Maryland Climate Change Commission.

New York

In August 2009, Governor David Paterson created the New York State Climate Action Council (NYSCAC) and tasked them with creating a direct action plan. In 2010, the NYSCAC released a 428-page Interim Report which outlined a plan to reduce emissions and highlighted the impact climate change will have in the future. In 2010, the New York State Energy Research and Development Authority also commissioned a report about statewide climate change impacts, later published in November 2011. After Hurricanes Sandy and Irene along with Tropical Storm Lee, the state updated vulnerability in regards to the condition of its critical infrastructure.

A snapshot of the destruction caused by Hurricane Sandy, which flooded coastlines and forced many residents to flee for safety. Houses and critical infrastructure were destroyed.

According to the 2015 New York State Energy Plan, renewable sources, which include wind, hydropower, solar, geothermal, and sustainable biomass, have the potential to meet 40 percent of the state's energy needs by 2030. As of 2018, sustainable energy use comprises 11 percent of all energy usage. The New York State Energy Research and Development Authority offers incentives in the form of grants and loans to its residents to adopt renewable energy technologies and create renewable energy businesses.

Other state climate change mitigation laws have gone into effect. The net metering laws make it easier for both residents and businesses to use solar power by feeding unused energy back into electrical fields and receive credit from their power suppliers. Although one version was released in 1997, it was exclusively limited to residential systems using up to 10 kilowatts of power. However, on June 1, 2011, the laws were expanded to include farm and non-residential buildings. The Renewable Energy Portfolio Standard set a statewide target for renewable energy and offered incentives to residents to use the new technologies.

In June 2018, the state announced its first major update in over two decades to its Environmental Quality Review (EQR) regulations. The update involves streamlining the environmental review process and encouraging renewable energy. It also expanded the Type II actions, or "list of actions not subject to further review", including green infrastructure upgrades and retrofits. Furthermore, solar arrays are set to be installed in sites like brownfields, wastewater treatment facilities, and land zoned for industry. The regulations will take effect on January 1, 2019.

New York State Energy Plan

In 2014, Governor Andrew Cuomo enforced the state's hallmark energy policy, Reforming the Energy Vision. This involves building a new network that will connect the central grid with clean, locally generated power. The method for this undertaking falls to the Energy Plan, a comprehensive plan to build a clean, resilient, affordable energy system for all New Yorkers. It will foster "economic prosperity and environmental stewardship" and cooperation between government and industry. Concrete goals thus far include a 40 percent reduction in greenhouse gas from 1990 levels, electricity sourced from 50 percent of renewable energy sources, and a 600 billion Btu increase in statewide energy efficiency.

Regional initiatives

Clean Energy Standards

Clean Energy Standard (CES) policies are policies which favor lowering non-renewable energy emissions and increasing renewable energy use. They are helping to drive the transition to cleaner energy, by building upon existing energy portfolio standards, and could be applied broadly at the federal level and developed more acutely at the regional and state levels. CES policies have had success at the federal level, gaining bipartisan support during the Obama administration. Iowa was the first state to adopt CES policies, and now a majority of states have adopted CES policies. Similar to CES policies, Renewable Portfolio Standards (RPS) are standards set in place to ensure a greater integration of renewable energies in state and regional energy portfolios. Both CES and RPS are helping increase the use of clean and renewable energies in the United States.

Regional Greenhouse Gas Initiative

In 2003, New York State proposed and attained commitments from nine Northeast states to form a cap and trade carbon dioxide emissions program for power generators, called the Regional Greenhouse Gas Initiative (RGGI). This program launched on January 1, 2009 with the aim to reduce the carbon "budget" of each state's electricity generation sector to 10 percent below their 2009 allowances by 2018. 11 Northeastern US states are involved in the Regional Greenhouse Gas Initiative. It is believed that the state-level program will apply pressure on the federal government to support Kyoto Protocol. The Regional Greenhouse Gas Initiative (RGGI) is a cap and trade system for CO2 emissions from power plants in the member states. Emission permit auctioning began in September 2008, and the first three-year compliance period began on January 1, 2009. Proceeds will be used to promote energy conservation and renewable energy. The system affects fossil fuel power plants with 25 MW or greater generating capacity ("compliance entities"). Since 2005, the participating states have collectively seen an over 45% reduction in greenhouse gas emissions by RGGI-affected power plants. This has resulted in cleaner air, better health, and economic growth.

Western Climate Initiative

Western Climate Initiative members, 2008

Since February 2007, seven U.S. states and four Canadian provinces have joined to create the Western Climate Initiative, a regional greenhouse gas emissions trading system. The Initiative was created when the West Coast Global Warming Initiative (California, Oregon, and Washington) and the Southwest Climate Change Initiative (Arizona and New Mexico) joined efforts with Utah and Montana, along with British Columbia, Manitoba, Ontario, and Quebec.

The nonprofit organization WCI, Inc., was established in 2011 and supports implementation of state and regional greenhouse gas trading programs.

Powering the Plains Initiative

The Powering the Plains Initiative (PPI) began in 2001 and aims to expand alternative energy technologies and improve climate-friendly agricultural practices. Its most significant accomplishment was a 50-year energy transition roadmap for the upper Midwest, released in June 2007.

  • Participating states: Iowa, Minnesota, Wisconsin, North Dakota, South Dakota, Canadian Province of Manitoba

Litigation by states

Several lawsuits have been filed over global warming. In 2007 the Supreme Court of the United States ruled in Massachusetts v. Environmental Protection Agency that the Clean Air Act gives the United States Environmental Protection Agency (EPA) the authority to regulate greenhouse gases, such as tailpipe emissions. A similar approach was taken by California Attorney General Bill Lockyer who filed a lawsuit California v. General Motors Corp. to force car manufacturers to reduce vehicles' emissions of carbon dioxide. A third case, Comer v. Murphy Oil, was filed by Gerald Maples, a trial attorney in Mississippi, in an effort to force fossil fuel and chemical companies to pay for damages caused by global warming.

In June 2011, the United States Supreme Court overturned 8–0 a U.S. appeals court ruling against five big power utility companies, brought by U.S. states, New York City, and land trusts, attempting to force cuts in United States greenhouse gas emissions regarding global warming. The decision gives deference to reasonable interpretations of the United States Clean Air Act by the Environmental Protection Agency.

Position of political parties and other political organizations

In the United States, Democrats (blue) and Republicans (red) have long differed in views of the importance of addressing climate change, with the gap widening in the late 2010s mainly through Democrats' share increasing by more than 30 points.
 
The sharp divide over the existence of and responsibility for global warming and climate change falls largely along political lines. Overall, 60% of Americans surveyed said oil and gas companies were "completely or mostly responsible" for climate change.
 
Opinion about human causation of climate change increased substantially with education among Democrats, but not among Republicans. Conversely, opinions favoring becoming carbon neutral declined substantially with age among Republicans, but not among Democrats.
 
National political divides on the seriousness of climate change consistently correlate with political ideology, with right-wing opinion being more negative.

In the 2016 presidential campaigns, the two major parties established different positions on the issue of global warming and climate change policy. The Democratic Party seeks to develop policies which curb negative effects from climate change. The Republican Party, whose leading members have frequently denied the existence of global warming, continues to meet its party goals of expanding the energy industries and curbing the efforts of Environmental Protection Agency (EPA). Other parties, including the Green Party, the Libertarian Party, and the Constitution Party possess various views of climate change and mostly maintain their parties' own long-standing positions to influence their party members.

Democratic Party

In its 2016 platform, the Democratic Party views climate change as "an urgent threat and a defining challenge of our time." Democrats are dedicated to "curbing the effects of climate change, protecting America's natural resources, and ensuring the quality of our air, water, and land for current and future generations."

With respect to climate change, the Democratic Party believes that "carbon dioxide, methane, and other greenhouse gasses should be priced to reflect their negative externalities, and to accelerate the transition to a clean energy economy and help meet our climate goals." Democrats are also committed to "implementing, and extending smart pollution and efficiency standards, including the Clean Power Plan, fuel economy standards for automobiles and heavy-duty vehicles, building codes and appliance standards."

Democrats emphasize the importance of environmental justice. The party calls attention to the environmental racism as the climate change has disproportionately impacted low-income and minority communities, tribal nations and Alaska Native villages. The party believes "clean air and clean water are basic rights of all Americans."

Republican Party

The Republican Party has varied views on climate change. The most recent 2016 Republican Platform denies the existence of climate change and dismisses scientists’ efforts of easing global warming.

The GOP does champion some energy initiatives following: opening up public lands and the ocean for further oil exploration; fast tracking permits for oil and gas wells; and hydraulic fracturing. It also supports dropping "restrictions to allow responsible development of nuclear energy."

In 2014, President Barack Obama proposed a series of Environmental Protection Agency (EPA) regulations, known as the Clean Power Plan that would reduce carbon pollution from coal-fired power plants. The Republican Party has viewed these efforts as a "war on coal" and has significantly opposed them. Instead, it advocates building the Keystone XL pipeline, outlawing a carbon tax, and stopping all fracking regulations.

Donald Trump, the former President of the United States, has said that "climate change is a hoax invented by and for Chinese." During his political campaign, he blamed China for doing little helping the environment on the earth, but he seemed to ignore many projects organized by China to slow global warming. While Trump's words might be counted as his campaign strategy to attract voters, it brought concerns from the left about environmental justice.

From 2008 to 2017, the Republican Party went from "debating how to combat human-caused climate change to arguing that it does not exist," according to The New York Times. In 2011 "more than half of the Republicans in the House and three-quarters of Republican senators" said "that the threat of global warming, as a man-made and highly threatening phenomenon, is at best an exaggeration and at worst an utter 'hoax'", according to Judith Warner writing The New York Times Magazine. In 2014, more than 55% of congressional Republicans were climate change deniers, according to NBC News. According to PolitiFact in May 2014, "...relatively few Republican members of Congress...accept the prevailing scientific conclusion that global warming is both real and man-made...eight out of 278, or about 3 percent." A 2017 study by the Center for American Progress Action Fund of climate change denial in the United States Congress found 180 members who deny the science behind climate change; all were Republicans.

However, many Republicans see ways to address the issue of climate change using conservative principles. In 2019, Luntz Global released polling indicating that a majority of Republican voters would support government action on emissions reduction, and worry the GOP's position on climate hurts its standing within young voting blocs. Also in 2019, several Republican legislators broke with the party to advocate taking action on climate change, with market-based solutions rather than traditional regulations. Additionally, groups of younger Republicans began advocacy efforts in favor of a climate policy response, such as Citizens for Responsible Energy Solutions and Young Conservatives For Carbon Dividends (YCCD). republicEn.org is a conservative non-profit in support of a national, revenue-neutral carbon tax.

By 2022, a group of Republican state treasurers had formed which actively opposed private sector climate initiatives. The group also raised objections to government appointments and regulations due to climate-related issues.

Green Party

The Green Party of the United States advocates for reductions of greenhouse gas emissions and increased government regulation.

In 2010 Platform on Climate Change, the Green Party leaders released their proposal to solve and integrate the problem and policy of climate change with six parts. First, Greens (the members of the Green Party) want a stronger international climate treaty to decrease greenhouse gases at least 40% by 2020 and 95% by 2050. Second, Greens advocate economic policies to create a safer atmosphere. The economic policies include setting carbon taxes on fossil fuels, removing subsidies for fossil fuels, nuclear power, biomass and waste incineration, and biofuels, and preventing corrupt actions from the rise of carbon prices. Third, countries with few contributions should pay for adaption to climate change. Fourth, Greens champion more efficient but low-cost public transportation system and less energy demand economy. Fifth, the government should train more workers to operate and develop the new, green energy economy. Last, Greens think necessary to transform commercial plants where have uncontrolled animal feeding operations and overuse of fossil fuel to health farms with organic practices.

Libertarian Party

In its 2016 platform, the Libertarian Party states that "competitive free markets and property rights stimulate the technological innovations and behavioral changes required to protect our environment and ecosystems." The Libertarians believe the government has no rights or responsibilities to regulate and control the environmental issues. The environment and natural resources belong to the individuals and private corporations.

Constitution Party

The Constitution Party, in the 2014 Platform, states that "it is our responsibility to be prudent, productive, and efficient stewards of God's natural resources." On the issue of global warming, it says that "globalists are using the global warming threat to gain more control via worldwide sustainable development." According to the party, eminent domain is unlawful because "under no circumstances may the federal government take private property, by means of rules and regulations which preclude or substantially reduce the productive use of the property, even with just compensation."

In regards to energy, the party calls attention to "the continuing need of the United States for a sufficient supply of energy for national security and for the immediate adoption of a policy of free market solutions to achieve energy independence for the United States," and calls for the "repeal of federal environmental protections." The party also advocates the abolition of the Department of Energy.

Nebraska Farmers Union

In September 2019, the Nebraska Farmers Union called for "more government action on climate change." The organization wants better agricultural research that develops tools for increasing carbon sequestration in soils, and increased participation by government at state and national levels.

Climate justice

Per person, the United States generates carbon dioxide at a far faster rate than other primary regions.

Climate justice is part of environmental justice, which EPA defines as: "The fair treatment and meaningful involvement of all people regardless of race, color, national origin, or income, with respect to the development, implementation, and enforcement of environmental laws, regulations, and policies."

Poor and disempowered groups often do not have the resources to prepare for, cope with or recover from climate disasters such as droughts, floods, heat waves, hurricanes, etc. This occurs not only within the United States but also between rich nations, who predominantly create the problem of climate change by dumping greenhouse gases into the atmosphere, and poor nations who have to deal more heavily with the consequences.

State and regional policies

States and local governments are often tasked with defense against climate change affecting areas and peoples under state and local jurisdiction.

Mayors National Climate Action Agenda

The Mayors National Climate Action Agenda was founded by Los Angeles mayor Eric Garcetti, former Houston mayor Annise Parker, and former Philadelphia mayor Michael Nutter in 2014. The MNCAA aims to bring climate change policy into the hands of local government and to make federal climate change policies more accountable.

As a part of MNCAA, 75 mayors from across the United States, known as the "Climate Mayors", wrote to President Trump on March 28, 2017, in opposition to proposed rollbacks of several major climate change departments and initiatives. They maintain that the federal government should continue to build up climate change policies, stating "we are also standing up for our constituents and all Americans harmed by climate change, including those most vulnerable among us: coastal residents confronting erosion and sea level rise; young and old alike suffering from worsening air pollution and at risk during heatwaves; mountain residents engulfed by wildfires; farmers struggling at harvest time due to drought; and communities across our nation challenged by extreme weather." Climate Mayors currently has over 400 cities involved in the network. Their current key initiative is the Electric Vehicle Request for Information (EV RFI). They have also produced responses to the announcement of the plan for the United States to withdraw from the Paris Agreement and opposition to the proposed repeal of the Clean Power Plan.

United States Climate Alliance

The United States Climate Alliance is a group of states committed to meeting the Paris Agreement emissions targets despite President Trump's announced withdrawal from the agreement. Currently, there are 22 states that are members of this network. This network is a bipartisan network of governors across the United States and is governed by three core principles: "States are continuing to lead on climate change", "State-level climate action is benefiting our economies and strengthening our communities", "States are showing the nation and the world that ambitious climate action is achievable." Their current initiatives include green banks, grid modernizations, solar soft costs, short-lived climate pollutants, natural and working lands, climate resilience, international cooperation, clean transportation, and improving data and tools.

California

The California Global Warming Solutions Act of 2006 (commonly known as AB 32) mandates a reduction in greenhouse gas emissions to 1990 levels by the year 2020. The Environmental Defense Fund and the Air Resources Board recruited staffers with environmental justice expertise as well as community leaders in order to appease environmental justice groups and ensure the safe passage of the bill.

The environmental justice groups who worked on AB 32 strongly opposed cap and trade programs being made mandatory. A cap and trade plan was put in place, and a 2016 study by a group of California academics found that carbon offsets under the plan were not used to benefit people in California who lived near power plants, who are mostly less well off than people who live far from them.

Regional

Twenty-eight states have climate action plans and nine have statewide emission targets. The states of California and New Mexico have committed most recently to emission reductions targets, joining New Jersey, Maine, Massachusetts, Connecticut, New York, Washington and Oregon.

Regional initiatives can be more efficient than programs at the state level, as they encompass a broader geographical area, eliminate duplication of work, and create more uniform regulatory environments. Over the past few years, a number of regional initiatives have begun developing systems to reduce carbon dioxide emissions from power plants, increase renewable energy generation, track renewable energy credits, and research and establish baselines for carbon sequestration.

State initiatives

Regional Greenhouse Gas Initiative

In December 2005, the governors of seven Northeastern and Mid-Atlantic states agreed to the Regional Greenhouse Gas Initiative (RGGI), a cap and trade system covering carbon dioxide (CO2) emissions from regional power plants. Currently (at the time of this edit), Connecticut, Delaware, Maine, New Hampshire, New Jersey, New York, and Vermont have signed, and Maryland Governor Robert Ehrlich signed legislation in March 2006 that commits Maryland to join RGGI by 2007. To facilitate compliance with reduction targets, RGGI will provide flexibility mechanisms that include credits for emissions reductions achieved outside of the electricity sector. The successful implementation of the RGGI model will set the stage for other states to join or form their own regional cap and trade systems and may encourage the program to expand to other greenhouse gases and other sectors. RGGI states, along with Pennsylvania, Massachusetts, and Rhode Island, are also developing a GHG registry called the Eastern Climate Registry.

On November 29, 2011, New Jersey withdrew from the initiative, effective January 1, 2012. Groups such as Acadia Center have since reported on lost revenue resulting from New Jersey's departure, and argued for renewed participation.

After the election of Ralph Northam in the 2017 Virginia gubernatorial election and Phil Murphy in the 2017 New Jersey gubernatorial election, New Jersey and Virginia began to make preliminary moves to join RGGI.

The Western Governors' Association

The Western Governors' Association (WGA) Clean and Diversified Energy Initiative, including 18 western states, has begun investigating strategies to increase efficiency and renewable energy sources in their electricity systems. Governors Richardson (NM), Schwarzenegger (CA), Freudenthal (WY) & Hoeven (ND) serve as lead Governors on this initiative. To meet its goals, the Initiative's advisory committee (CDEAC) appointed eight technical task forces to develop recommendations based on reviews of specific clean energy and efficiency options. The CDEAC made final recommendations to the Western Governors' Association on June 11, 2006. Additionally, the WGA and the California Energy Commission are creating the Western Renewable Energy Generation Information State (WREGIS). WREGIS is a voluntary system for renewable energy credits and tracks renewable energy credits (RECs) across 11 western states in order to facilitate trading to meet renewable energy portfolio standards.

Other initiatives

As of 2020, several states in the northeastern United States were discussing a regional cap and trade system for carbon emissions from motor vehicle fuel sources, called the Transportation Climate Initiative. In 2021, Massachusetts withdrew citing as one of the reasons that it was no longer necessary.

The governors of Arizona and New Mexico signed an agreement to create the Southwest Climate Change Initiative in February 2006. The two states collaborated to assess greenhouse gas emissions and address the impacts of climate change in the Southwest and on September 8, 2006, Arizona Governor Janet Napolitano issued an executive order to implement recommendations included in the Climate Change Advisory Group's Climate Action Plan. The West Coast states—Washington, Oregon, and California—are cooperating on a strategy to reduce GHG emissions, known as the Western Coast Governors' Global Warming Initiative. Finally, on February 26, 2007, these five Western states (Washington, Oregon, California, Arizona, and New Mexico) agreed to combine their efforts to develop regional targets for reducing greenhouse emissions, creating the Western Regional Climate Action Initiative.

In 2001 six New England states committed to the New England Governors and Eastern Canadian Premiers (NEG-ECP) Climate Change Action Plan 2001, including short and long-term GHG emission reduction goals. Powering the Plains, launched in 2002, is a regional effort involving participants from the Dakotas, Minnesota, Iowa, Wisconsin and the Canadian Province of Manitoba. This initiative aims to develop strategies, policies, and demonstration projects for alternative energy sources and technology and climate-friendly agricultural development.

Municipal initiatives

ICLEI

In 1993, at the invitation of ICLEI, municipal leaders met at the United Nations in New York and adopted a declaration that called for the establishment of a worldwide movement of local governments to reduce greenhouse gas emissions, improve air quality, and enhance urban sustainability. The result was the Cities for Climate Protection (CCP) Campaign. Since its inception, the CCP Campaign has grown to involve more than 650 local governments worldwide that are integrating climate change mitigation into their decision-making processes.

U.S. Mayors' Climate Protection Agreement

On February 16, 2005, Seattle Mayor Greg Nickels launched an initiative to advance the goals of the Kyoto Protocol through leadership and action by at least 141 American cities, and as of October, 2006, 319 mayors representing over 51.4 million Americans had accepted the challenge. Under the terms of the Mayors Climate Protection Center, cities must commit to three actions in striving to meet the Kyoto Protocol in their own communities. These actions include:

  • Strive to meet or beat the Kyoto Protocol targets in their own communities, through actions ranging from anti-sprawl land-use policies to urban forest restoration projects to public information campaigns;
  • Urge their state governments, and the federal government, to enact policies and programs to meet or beat the greenhouse gas emission reduction target suggested for the United States in the Kyoto Protocol—7% reduction from 1990 levels by 2012; and
  • Urge the U.S. Congress to pass the bipartisan greenhouse gas reduction legislation, which would establish a national emission trading system.

Flying and gliding animals

From Wikipedia, the free encyclopedia
 
Greylag geese (Anser anser). Birds are one of only four taxonomic groups to have evolved powered flight.

A number of animals are capable of aerial locomotion, either by powered flight or by gliding. This trait has appeared by evolution many times, without any single common ancestor. Flight has evolved at least five times in separate animals: insects, pterosaurs, birds, bats and humans (through tool use). Gliding has evolved on many more occasions. Usually the development is to aid canopy animals in getting from tree to tree, although there are other possibilities. Gliding, in particular, has evolved among rainforest animals, especially in the rainforests in Asia (most especially Borneo) where the trees are tall and widely spaced. Several species of aquatic animals, and a few amphibians and reptiles have also evolved this gliding flight ability, typically as a means of evading predators.

Types

Animal aerial locomotion can be divided into two categories: powered and unpowered. In unpowered modes of locomotion, the animal uses aerodynamic forces exerted on the body due to wind or falling through the air. In powered flight, the animal uses muscular power to generate aerodynamic forces to climb or to maintain steady, level flight. Those who can find air that is rising faster than they are falling can gain altitude by soaring.

Unpowered

These modes of locomotion typically require an animal start from a raised location, converting that potential energy into kinetic energy and using aerodynamic forces to control trajectory and angle of descent. Energy is continually lost to drag without being replaced, thus these methods of locomotion have limited range and duration.

  • Falling: decreasing altitude under the force of gravity, using no adaptations to increase drag or provide lift.
  • Parachuting: falling at an angle greater than 45° from the horizontal with adaptations to increase drag forces. Very small animals may be carried up by the wind. Some gliding animals may use their gliding membranes for drag rather than lift, to safely descend.
  • Gliding flight: falling at an angle less than 45° from the horizontal with lift from adapted aerofoil membranes. This allows slowly falling directed horizontal movement, with streamlining to decrease drag forces for aerofoil efficiency and often with some maneuverability in air. Gliding animals have a lower aspect ratio (wing length/breadth) than true flyers.

Powered flight

Powered flight has evolved at least four times: first in the insects, then in pterosaurs, next in birds, and last in bats. Studies on theropod dinosaurs do suggest multiple (≥3) independent acquisitions of powered flight however, and a recent study proposes independent acquisitions amidst the different bat clades as well. Powered flight uses muscles to generate aerodynamic force, which allows the animal to produce lift and thrust. The animal may ascend without the aid of rising air.

Externally powered

Ballooning and soaring are not powered by muscle, but rather by external aerodynamic sources of energy: the wind and rising thermals, respectively. Both can continue as long as the source of external power is present. Soaring is typically only seen in species capable of powered flight, as it requires extremely large wings.

  • Ballooning: being carried up into the air from the aerodynamic effect on long strands of silk in the wind. Certain silk-producing arthropods, mostly small or young spiders, secrete a special light-weight gossamer silk for ballooning, sometimes traveling great distances at high altitude.
  • Soaring: gliding in rising or otherwise moving air that requires specific physiological and morphological adaptations that can sustain the animal aloft without flapping its wings. The rising air is due to thermals, ridge lift or other meteorological features. Under the right conditions, soaring creates a gain of altitude without expending energy. Large wingspans are needed for efficient soaring.

Many species will use multiple of these modes at various times; a hawk will use powered flight to rise, then soar on thermals, then descend via free-fall to catch its prey.

Evolution and ecology

Gliding and parachuting

While gliding occurs independently from powered flight, it has some ecological advantages of its own as it is the simplest form of flight. Gliding is a very energy-efficient way of travelling from tree to tree. Although moving through the canopy running along the branches may be less energetically demanding, the faster transition between trees allows for greater foraging rates in a particular patch. Glide ratios can be dependent on size and current behavior. Higher foraging rates are supported by low glide ratios as smaller foraging patches require less gliding time over shorter distances and greater amounts of food can be acquired in a shorter time period. Low ratios are not as energy efficient as the higher ratios, but an argument made is that many gliding animals eat low energy foods such as leaves and are restricted to gliding because of this, whereas flying animals eat more high energy foods such as fruits, nectar, and insects. Mammals tend to rely on lower glide ratios to increase the amount of time foraging for lower energy food. An equilibrium glide, achieving a constant airspeed and glide angle, is harder to obtain as animal size increases. Larger animals need to glide from much higher heights and longer distances to make it energetically beneficial. Gliding is also very suitable for predator avoidance, allowing for controlled targeted landings to safer areas. In contrast to flight, gliding has evolved independently many times (more than a dozen times among extant vertebrates); however these groups have not radiated nearly as much as have groups of flying animals.

Worldwide, the distribution of gliding animals is uneven, as most inhabit rain forests in Southeast Asia. (Despite seemingly suitable rain forest habitats, few gliders are found in India or New Guinea and none in Madagascar.) Additionally, a variety of gliding vertebrates are found in Africa, a family of hylids (flying frogs) lives in South America and several species of gliding squirrels are found in the forests of northern Asia and North America. Various factors produce these disparities. In the forests of Southeast Asia, the dominant canopy trees (usually dipterocarps) are taller than the canopy trees of the other forests. Forest structure and distance between trees are influential in the development of gliding within varying species. A higher start provides a competitive advantage of further glides and farther travel. Gliding predators may more efficiently search for prey. The lower abundance of insect and small vertebrate prey for carnivorous animals (such as lizards) in Asian forests may be a factor. In Australia, many mammals (and all mammalian gliders) possess, to some extent, prehensile tails. Globally, smaller gliding species tend to have feather-like tails and larger species have fur covered round bushy tails, but smaller animals tend to rely on parachuting rather than developing gliding membranes. The gliding membranes, patagium, are classified in the 4 groups of propatagium, digipatagium, plagiopatagium and uropatagium. These membranes consist of two tightly bounded layers of skin connected my muscles and connective tissue between the fore and hind limbs.

Powered flight evolution

Powered flight has evolved unambiguously only four times—birds, bats, pterosaurs, and insects (though see above for possible independent acquisitions within bird and bat groups). In contrast to gliding, which has evolved more frequently but typically gives rise to only a handful of species, all three extant groups of powered flyers have a huge number of species, suggesting that flight is a very successful strategy once evolved. Bats, after rodents, have the most species of any mammalian order, about 20% of all mammalian species. Birds have the most species of any class of terrestrial vertebrates. Finally, insects (most of which fly at some point in their life cycle) have more species than all other animal groups combined.

The evolution of flight is one of the most striking and demanding in animal evolution, and has attracted the attention of many prominent scientists and generated many theories. Additionally, because flying animals tend to be small and have a low mass (both of which increase the surface-area-to-mass ratio), they tend to fossilize infrequently and poorly compared to the larger, heavier-boned terrestrial species they share habitat with. Fossils of flying animals tend to be confined to exceptional fossil deposits formed under highly specific circumstances, resulting in a generally poor fossil record, and a particular lack of transitional forms. Furthermore, as fossils do not preserve behavior or muscle, it can be difficult to discriminate between a poor flyer and a good glider.

Insects were the first to evolve flight, approximately 350 million years ago. The developmental origin of the insect wing remains in dispute, as does the purpose prior to true flight. One suggestion is that wings initially evolved from tracheal gill structures and were used to catch the wind for small insects that live on the surface of the water, while another is that they evolved from paranotal lobes or leg structures and gradually progressed from parachuting, to gliding, to flight for originally arboreal insects.

Pterosaurs were the next to evolve flight, approximately 228 million years ago. These reptiles were close relatives of the dinosaurs, and reached enormous sizes, with some of the last forms being the largest flying animals ever to inhabit the Earth, having wingspans of over 9.1 m (30 ft). However, they spanned a large range of sizes, down to a 250 mm (10 in) wingspan in Nemicolopterus.

Birds have an extensive fossil record, along with many forms documenting both their evolution from small theropod dinosaurs and the numerous bird-like forms of theropod which did not survive the mass extinction at the end of the Cretaceous. Indeed, Archaeopteryx is arguably the most famous transitional fossil in the world, both due to its mix of reptilian and avian anatomy and the luck of being discovered only two years after Darwin's publication of On the Origin of Species. However, the ecology of this transition is considerably more contentious, with various scientists supporting either a "trees down" origin (in which an arboreal ancestor evolved gliding, then flight) or a "ground up" origin (in which a fast-running terrestrial ancestor used wings for a speed boost and to help catch prey).

Bats are the most recent to evolve (about 60 million years ago), most likely from a fluttering ancestor, though their poor fossil record has hindered more detailed study.

Only a few animals are known to have specialised in soaring: the larger of the extinct pterosaurs, and some large birds. Powered flight is very energetically expensive for large animals, but for soaring their size is an advantage, as it allows them a low wing loading, that is a large wing area relative to their weight, which maximizes lift. Soaring is very energetically efficient.

Biomechanics

Gliding and parachuting

During a free-fall with no aerodynamic forces, the object accelerates due to gravity, resulting in increasing velocity as the object descends. During parachuting, animals use the aerodynamic forces on their body to counteract the force or gravity. Any object moving through air experiences a drag force that is proportion to surface area and to velocity squared, and this force will partially counter the force of gravity, slowing the animal's descent to a safer speed. If this drag is oriented at an angle to the vertical, the animal's trajectory will gradually become more horizontal, and it will cover horizontal as well as vertical distance. Smaller adjustments can allow turning or other maneuvers. This can allow a parachuting animal to move from a high location on one tree to a lower location on another tree nearby. Specifically in gliding mammals, there are 3 types of gliding paths respectively being S glide, J glide, and "straight-shaped" glides where species either gain altitude post launch then descend, rapidly decrease height before gliding, and maintaining a constant angled descent.

During gliding, lift plays an increased role. Like drag, lift is proportional to velocity squared. Gliding animals will typically leap or drop from high locations such as trees, just as in parachuting, and as gravitational acceleration increases their speed, the aerodynamic forces also increase. Because the animal can utilize lift and drag to generate greater aerodynamic force, it can glide at a shallower angle than parachuting animals, allowing it to cover greater horizontal distance in the same loss of altitude, and reach trees further away. Successful flights for gliding animals are achieved through 5 steps: preparation, launch, glide, braking, and landing. Gliding species are better able to control themselves mid-air, with the tail acting as a rudder, making it capable to pull off banking movements or U-turns during flight. During landing, arboreal mammals will extend their fore and hind limbs in front of itself to brace for landing and to trap air in order to maximize air resistance and lower impact speed.

Powered flight

Unlike most air vehicles, in which the objects that generate lift (wings) and thrust (engine or propeller) are separate and the wings remain fixed, flying animals use their wings to generate both lift and thrust by moving them relative to the body. This has made the flight of organisms considerably harder to understand than that of vehicles, as it involves varying speeds, angles, orientations, areas, and flow patterns over the wings.

A bird or bat flying through the air at a constant speed moves its wings up and down (usually with some fore-aft movement as well). Because the animal is in motion, there is some airflow relative to its body which, combined with the velocity of its wings, generates a faster airflow moving over the wing. This will generate lift force vector pointing forwards and upwards, and a drag force vector pointing rearwards and upwards. The upwards components of these counteract gravity, keeping the body in the air, while the forward component provides thrust to counteract both the drag from the wing and from the body as a whole. Pterosaur flight likely worked in a similar manner, though no living pterosaurs remain for study.

Insect flight is considerably different, due to their small size, rigid wings, and other anatomical differences. Turbulence and vortices play a much larger role in insect flight, making it even more complex and difficult to study than the flight of vertebrates. There are two basic aerodynamic models of insect flight. Most insects use a method that creates a spiralling leading edge vortex. Some very small insects use the fling-and-clap or Weis-Fogh mechanism in which the wings clap together above the insect's body and then fling apart. As they fling open, the air gets sucked in and creates a vortex over each wing. This bound vortex then moves across the wing and, in the clap, acts as the starting vortex for the other wing. Circulation and lift are increased, at the price of wear and tear on the wings.

Limits and extremes

Flying and soaring

  • Largest. The largest known flying animal was formerly thought to be Pteranodon, a pterosaur with a wingspan of up to 7.5 metres (25 ft). However, the more recently discovered azhdarchid pterosaur Quetzalcoatlus is much larger, with estimates of the wingspan ranging from 9 to 12 metres (30 to 39 ft). Some other recently discovered azhdarchid pterosaur species, such as Hatzegopteryx, may have also wingspans of a similar size or even slightly larger. Although it is widely thought that Quetzalcoatlus reached the size limit of a flying animal, the same was once said of Pteranodon. The heaviest living flying animals are the kori bustard and the great bustard with males reaching 21 kilograms (46 lb). The wandering albatross has the greatest wingspan of any living flying animal at 3.63 metres (11.9 ft). Among living animals which fly over land, the Andean condor and the marabou stork have the largest wingspan at 3.2 metres (10 ft). Studies have shown that it is physically possible for flying animals to reach 18-metre (59 ft) wingspans, but there is no firm evidence that any flying animal, not even the azhdarchid pterosaurs, got that large.
Comparison of Quetzalcoatlus northropi with a Cessna 172 light aircraft
  • Smallest. There is no minimum size for getting airborne. Indeed, there are many bacteria floating in the atmosphere that constitute part of the aeroplankton. However, to move about under one's own power and not be overly affected by the wind requires a certain amount of size. The smallest flying vertebrates are the bee hummingbird and the bumblebee bat, both of which may weigh less than 2 grams (0.071 oz). They are thought to represent the lower size limit for endotherm flight.
  • Fastest. The fastest of all known flying animals is the peregrine falcon, which when diving travels at 300 kilometres per hour (190 mph) or faster. The fastest animal in flapping horizontal flight may be the Mexican free-tailed bat, said to attain about 160 kilometres per hour (99 mph) based on ground speed by an aircraft tracking device; that measurement does not separate any contribution from wind speed, so the observations could be caused by strong tailwinds.
  • Slowest. Most flying animals need to travel forward to stay aloft. However, some creatures can stay in the same spot, known as hovering, either by rapidly flapping the wings, as do hummingbirds, hoverflies, dragonflies, and some others, or carefully using thermals, as do some birds of prey. The slowest flying non-hovering bird recorded is the American woodcock, at 8 kilometres per hour (5.0 mph).
  • Highest flying. There are records of a Rüppell's vulture Gyps rueppelli, a large vulture, being sucked into a jet engine 11,550 metres (37,890 ft) above Côte d'Ivoire in West Africa. The animal that flies highest most regularly is the bar-headed goose Anser indicus, which migrates directly over the Himalayas between its nesting grounds in Tibet and its winter quarters in India. They are sometimes seen flying well above the peak of Mount Everest at 8,848 metres (29,029 ft).
Airborne flying squirrel.

Gliding and parachuting

  • Most efficient glider. This can be taken as the animal that moves most horizontal distance per metre fallen. Flying squirrels are known to glide up to 200 metres (660 ft), but have measured glide ratio of about 2. Flying fish have been observed to glide for hundreds of metres on the drafts on the edge of waves with only their initial leap from the water to provide height, but may be obtaining additional lift from wave motion. On the other hand, albatrosses have measured lift–drag ratios of 20, and thus fall just 1 meter for every 20 in still air.
  • Most maneuverable glider. Many gliding animals have some ability to turn, but which is the most maneuverable is difficult to assess. Even paradise tree snakes, Chinese gliding frogs, and gliding ants have been observed as having considerable capacity to turn in the air.

Flying animals

Extant

A bee in flight.

Insects

  • Pterygota: The first of all animals to evolve flight, they are also the only invertebrates that have evolved flight. As they comprise almost all insects, the species are too numerous to list here. Insect flight is an active research field.
Birds are a successful group of flying vertebrate.

Birds

  • Birds (flying, soaring) – Most of the approximately 10,000 living species can fly (flightless birds are the exception). Bird flight is one of the most studied forms of aerial locomotion in animals. See List of soaring birds for birds that can soar as well as fly.
Townsends's big-eared bat, (Corynorhinus townsendii) displaying the "hand wing"
 
A Airbus A380 in flight. Commercial airlines are an example of how humans use tools to achieve flight without having a natural ability to fly on their own using their body parts.

Mammals

  • Bats. There are approximately 1,240 bat species, representing about 20% of all classified mammal species. Most bats are nocturnal and many feed on insects while flying at night, using echolocation to home in on their prey.

Extinct

Pterosaurs included the largest known flying animals

Pterosaurs

  • Pterosaurs were the first flying vertebrates, and are generally agreed to have been sophisticated flyers. They had large wings formed by a patagium stretching from the torso to a dramatically lengthened fourth finger. There were hundreds of species, most of which are thought to have been intermittent flappers, and many soarers. The largest known flying animals are pterosaurs.

Non-avian dinosaurs

  • Theropods (gliding and flying). There were several species of theropod dinosaur thought to be capable of gliding or flying, that are not classified as birds (though they are closely related). Some species (Microraptor gui, Microraptor zhaoianus, and Changyuraptor) have been found that were fully feathered on all four limbs, giving them four 'wings' that they are believed to have used for gliding or flying. A recent study indicates that flight may have been acquired independently in various different lineages though it may have only evolved in theropods of the Avialae.

Gliding animals

Extant

Insects

  • Gliding bristletails. Directed aerial gliding descent is found in some tropical arboreal bristletails, an ancestrally wingless sister taxa to the winged insects. The bristletails median caudal filament is important for the glide ratio and gliding control
  • Gliding ants. The flightless workers of these insects have secondarily gained some capacity to move through the air. Gliding has evolved independently in a number of arboreal ant species from the groups Cephalotini, Pseudomyrmecinae, and Formicinae (mostly Camponotus). All arboreal dolichoderines and non-cephalotine myrmicines except Daceton armigerum do not glide. Living in the rainforest canopy like many other gliders, gliding ants use their gliding to return to the trunk of the tree they live on should they fall or be knocked off a branch. Gliding was first discovered for Cephalotes atreus in the Peruvian rainforest. Cephalotes atreus can make 180 degree turns, and locate the trunk using visual cues, succeeding in landing 80% of the time. Unique among gliding animals, Cephalotini and Pseudomyrmecinae ants glide abdomen first, the Forminicae however glide in the more conventional head first manner.
  • Gliding immature insects. The wingless immature stages of some insect species that have wings as adults may also show a capacity to glide. These include some species of cockroach, mantid, katydid, stick insect and true bug.

Spiders

  • Ballooning spiders (parachuting). The young of some species of spiders travel through the air by using silk draglines to catch the wind, as may some smaller species of adult spider, such as the money spider family. This behavior is commonly known as "ballooning". Ballooning spiders make up part of the aeroplankton.
  • Gliding spiders. Some species of arboreal spider of the genus Selenops can glide back to the trunk of a tree should they fall. 
Neon flying squid

Molluscs

  • Flying squid. Several oceanic squids of the family Ommastrephidae, such as the Pacific flying squid, will leap out of the water to escape predators, an adaptation similar to that of flying fish. Smaller squids will fly in shoals, and have been observed to cover distances as long as 50 metres (160 ft). Small fins towards the back of the mantle do not produce much lift, but do help stabilize the motion of flight. They exit the water by expelling water out of their funnel, indeed some squid have been observed to continue jetting water while airborne providing thrust even after leaving the water. This may make flying squid the only animals with jet-propelled aerial locomotion. The neon flying squid has been observed to glide for distances over 30 metres (100 ft), at speeds of up to 11.2 metres per second (37 ft/s).

Fish

  • Flying fish. There are over 50 species of flying fish belonging to the family Exocoetidae. They are mostly marine fishes of small to medium size. The largest flying fish can reach lengths of 45 centimetres (18 in) but most species measure less than 30 cm (12 in) in length. They can be divided into two-winged varieties and four-winged varieties. Before the fish leaves the water it increases its speed to around 30 body lengths per second and as it breaks the surface and is freed from the drag of the water it can be traveling at around 60 kilometres per hour (37 mph). The glides are usually up to 30–50 metres (100–160 ft) in length, but some have been observed soaring for hundreds of metres using the updraft on the leading edges of waves. The fish can also make a series of glides, each time dipping the tail into the water to produce forward thrust. The longest recorded series of glides, with the fish only periodically dipping its tail in the water, was for 45 seconds (Video here). It has been suggested that the genus Exocoetus is on an evolutionary borderline between flight and gliding. It flaps its enlarged pectoral fins when airborne, but still seems only to glide, as there is no hint of a power stroke. It has been found that some flying fish can glide as effectively as some flying birds.
  • Halfbeaks. A group related to the Exocoetidae, one or two hemirhamphid species possess enlarged pectoral fins and show true gliding flight rather than simple leaps. Marshall (1965) reports that Euleptorhamphus viridis can cover 50 metres (160 ft) in two separate hops.
  • Freshwater butterflyfish (possibly gliding). Pantodon buchholzi has the ability to jump and possibly glide a short distance. It can move through the air several times the length of its body. While it does this, the fish flaps its large pectoral fins, giving it its common name. However, it is debated whether the freshwater butterfly fish can truly glide, Saidel et al. (2004) argue that it cannot.

Amphibians

Gliding has evolved independently in two families of tree frogs, the Old World Rhacophoridae and the New World Hylidae. Within each lineage there are a range of gliding abilities from non-gliding, to parachuting, to full gliding.

  • Rhacophoridae flying frogs. A number of the Rhacophoridae, such as Wallace's flying frog (Rhacophorus nigropalmatus), have adaptations for gliding, the main feature being enlarged toe membranes. For example, the Malayan flying frog Rhacophorus prominanus glides using the membranes between the toes of its limbs, and small membranes located at the heel, the base of the leg, and the forearm. Some of the frogs are quite accomplished gliders, for example, the Chinese flying frog Rhacophorus dennysi can maneuver in the air, making two kinds of turn, either rolling into the turn (a banked turn) or yawing into the turn (a crabbed turn).
  • Hylidae flying frogs. The other frog family that contains gliders.

Reptiles

Several lizards and snakes are capable of gliding:


  • Gliding Draco lizard
    Draco lizards. There are 28 species of lizard of the genus Draco, found in Sri Lanka, India, and Southeast Asia. They live in trees, feeding on tree ants, but nest on the forest floor. They can glide for up to 60 metres (200 ft) and over this distance they lose only 10 metres (30 ft) in height. Unusually, their patagium (gliding membrane) is supported on elongated ribs rather than the more common situation among gliding vertebrates of having the patagium attached to the limbs. When extended, the ribs form a semicircle on either side the lizard's body and can be folded to the body like a folding fan.
  • Gliding lacertids. There are two species of gliding lacertid, of the genus Holaspis, found in Africa. They have fringed toes and tail sides and can flatten their bodies for gliding or parachuting.
  • Mammals

    Bats are the only freely flying mammals. A few other mammals can glide or parachute; the best known are flying squirrels and flying lemurs.

    • Flying squirrels (subfamily Petauristinae). There are more than 40 living species divided between 14 genera of flying squirrel. Flying squirrels are found in Asia (most species), North America (genus Glaucomys) and Europe (Siberian flying squirrel). They inhabit tropical, temperate, and Subarctic environments, with the Glaucomys preferring boreal and montane coniferous forests, specifically landing on red spruce (Picea rubens) trees as landing sites; they are known to rapidly climb trees, but take some time to locate a good landing spot. They tend to be nocturnal and are highly sensitive to light and noise. When a flying squirrel wishes to cross to a tree that is further away than the distance possible by jumping, it extends the cartilage spur on its elbow or wrist. This opens out the flap of furry skin (the patagium) that stretches from its wrist to its ankle. It glides spread-eagle and with its tail fluffed out like a parachute, and grips the tree with its claws when it lands. Flying squirrels have been reported to glide over 200 metres (660 ft).
    • Anomalures or scaly-tailed flying squirrels (family Anomaluridae). These brightly coloured African rodents are not squirrels but have evolved to a resemble flying squirrels by convergent evolution. There are seven species, divided in three genera. All but one species have gliding membranes between their front and hind legs. The genus Idiurus contains two particularly small species known as flying mice, but similarly they are not true mice.
    • Colugos or "flying lemurs" (order Dermoptera). There are two species of colugo. Despite their common name, colugos are not lemurs; true lemurs are primates. Molecular evidence suggests that colugos are a sister group to primates; however, some mammalogists suggest they are a sister group to bats. Found in Southeast Asia, the colugo is probably the mammal most adapted for gliding, with a patagium that is as large as geometrically possible. They can glide as far as 70 metres (230 ft) with minimal loss of height. They have the most developed propatagium out of any gliding mammal with a mean launch velocity of approximately 3.7 m/s; the Mayan Colugo has been known to initiate glides without jumping.
    • Sifaka, a type of lemur, and possibly some other primates (possible limited gliding or parachuting). A number of primates have been suggested to have adaptations that allow limited gliding or parachuting: sifakas, indris, galagos and saki monkeys. Most notably, the sifaka, a type of lemur, has thick hairs on its forearms that have been argued to provide drag, and a small membrane under its arms that has been suggested to provide lift by having aerofoil properties.
    • Flying phalangers or wrist-winged gliders (subfamily Petaurinae). Possums found in Australia, and New Guinea. The gliding membranes are hardly noticeable until they jump. On jumping, the animal extends all four legs and stretches the loose folds of skin. The subfamily contains seven species. Of the six species in the genus Petaurus, the sugar glider and the Biak glider are the most common species. The lone species in the genus Gymnobelideus, Leadbeater's possum has only a vestigial gliding membrane.
    • Greater glider (Petauroides volans). The only species of the genus Petauroides of the family Pseudocheiridae. This marsupial is found in Australia, and was originally classed with the flying phalangers, but is now recognised as separate. Its flying membrane only extends to the elbow, rather than to the wrist as in Petaurinae. It has elongated limbs compared to its non-gliding relatives.
    • Feather-tailed possums (family Acrobatidae). This family of marsupials contains two genera, each with one species. The feathertail glider (Acrobates pygmaeus), found in Australia is the size of a very small mouse and is the smallest mammalian glider. The feathertail possum (Distoechurus pennatus) is found in New Guinea, but does not glide. Both species have a stiff-haired feather-like tail.

    Extinct

    Reptiles

    • Life restoration of the Weigeltisaurid Weigeltisaurus jaekeli from the Late Permian (259-252 million years ago). Weigeltisaurids represent the oldest known gliding vertebrates.
      Extinct reptiles similar to Draco. There are a number of unrelated extinct lizard-like reptiles with similar "wings" to the Draco lizards. These include the Late Permian Weigeltisauridae, the Triassic Kuehneosauridae and Mecistotrachelos, and the Cretaceous lizard Xianglong. The largest of these, Kuehneosaurus, has a wingspan of 30 centimetres (12 in), and was estimated to be able to glide about 30 metres (100 ft).
    • Sharovipterygidae. These strange reptiles from the Upper Triassic of Kyrgyzstan and Poland unusually had a membrane on their elongated hind limbs, extending their otherwise normal, flying-squirrel-like patagia significantly. The forelimbs are in contrast much smaller.
    • Hypuronector. This bizarre drepanosaur displays limb proportions, particularly the elongated forelimbs, that are consistent with a flying or gliding animal with patagia.

    Non-avian dinosaurs

    • Life restoration of Yi qi a gliding scansoriopterygid dinosaur from the Middle Jurassic of China.
      Scansoriopterygidae is unique among dinosaurs for the development of membranous wings, unlike the feathered airfoils of other theropods. Much like modern anomalures it developed a bony rod to help support the wing, albeit on the wrist and not the elbow.

    Fish

    Volaticotherids predate bats as mammalian aeronauts by at least 110 million years

    Mammals

    Inhalant

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