Aviation and Climate Change
James E. McCarthy
Specialist in Environmental Policy
August 4, 2009
Congressional Research Service
7-5700
www.crs.gov
R40090
CRS Report for Congress
P
repared for Members and Committees of Congress
Aviation and Climate Change
Summary
Aircraft are a significant source of greenhouse gases—compounds that trap the sun’s heat, with
effects on the Earth’s climate. In the United States, aircraft of all kinds are estimated to emit
between 2.6% and 3.4% of the nation’s total greenhouse gas (GHG) emissions, depending on
whether one counts international air travel. The impact of U.S. aviation on climate change is
perhaps twice that size when other factors are considered. These include the contribution of
aircraft emissions to ozone formation, the water vapor and soot that aircraft emit, and the high
altitude location of the bulk of aircraft emissions. Worldwide, aviation is projected to be among
the faster-growing GHG sources.
If Congress or the Administration decides to regulate aircraft GHG emissions, they face several
choices. The Administration could use existing authority under Sections 231 and 211 of the Clean
Air Act, administered by the Environmental Protection Agency. EPA has already been petitioned
to do so by several states, local governments, and environmental organizations. Congress could
address aviation or aviation fuels legislatively, through cap-and-trade or carbon tax proposals, or
could require EPA to set emission standards.
Among the legislative options, the cap-and-trade approach (setting an economy-wide limit on
GHG emissions and distributing tradable allowances to emitters) has received the most attention.
Most cap-and-trade bills, including the House-passed energy and climate bill, H.R. 2454, would
include aviation indirectly, through emission caps imposed upstream on their source of fuel—the
petroleum refining sector. By capping emissions upstream of air carriers and eventually lowering
the cap more than 80%, bills such as these would have several effects: they would provide an
incentive for refiners to produce lower-carbon fuels; they would increase the price of fuels, and
thus increase the demand for more fuel-efficient aircraft; and they might increase the cost of
aviation services relative to other means of transport, giving airline passengers and shippers of
freight incentives to substitute lower-cost, lower-carbon alternatives.
Besides regulating emissions directly or through a cap-and-trade program or carbon tax, there are
other tools available to policy makers that can lower aviation’s GHG emissions. These include
implementation of the Next Generation Air Traffic Control System (not expected to be complete
until 2025, although some elements that could reduce aircraft emissions may be implemented
sooner); research and development of more fuel-efficient aircraft and engines; and perhaps the
development of lower-carbon jet fuel.
This report provides background on aviation emissions and the factors affecting them; it discusses
the tools available to control emissions, including existing authority under the Clean Air Act and
proposed economy-wide cap-and-trade legislation; and it examines international regulatory
developments that may affect U.S. commercial airlines. These include the European Union’s
Emissions Trading Scheme for greenhouse gases (EU-ETS), which is to include the aviation
sector beginning in 2012, and discussions under the auspices of the International Civil Aviation
Organization (ICAO).
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Contents
Introduction ................................................................................................................................ 1
Aircraft Emissions ...................................................................................................................... 1
Reducing Emissions: Non-Regulatory Factors............................................................................. 3
Fuel Cost .............................................................................................................................. 3
Air Traffic Control ................................................................................................................ 4
Regulating Aircraft Under the Clean Air Act ............................................................................... 4
Proposed Legislation................................................................................................................... 6
International Developments......................................................................................................... 7
European Union .................................................................................................................... 7
ICAO.................................................................................................................................... 8
Conclusion.................................................................................................................................. 9
Tables
Table 1. CO2 Emissions from U.S. Aviation, 1990-2007 .............................................................. 3
Table 2. Greenhouse Gas Emissions from U.S. Transportation Sectors, 1990-2007 .................... 10
Contacts
Author Contact Information ...................................................................................................... 11
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Aviation and Climate Change
Introduction
Research on climate change has identified a wide array of sources that emit “greenhouse gases”
(GHGs)—compounds that trap the sun’s heat, with effects on Earth’s climate.1 The largest
sources of these emissions, particularly in developed economies, are electric utilities and the
transportation sector.2 In the United States, electricity generation accounts for about 40% of the
emissions of carbon dioxide, the principal greenhouse gas, or about one-third of the emissions of
the six major GHGs combined.3 The transportation sector, including cars, trucks, buses, trains,
ships, and aircraft, accounts for roughly one-third of U.S. CO2 emissions, or 28% of the six
GHGs combined.
Aircraft Emissions
Aircraft account for about 10% of the U.S. transportation sector’s GHG emissions, or 2.6% to
3.4% of total U.S. GHG emissions. In the United States, aviation emissions have grown more
slowly than those of other transportation sectors, and slightly less than the emissions of the
economy as a whole over the last two decades, but worldwide aviation has been among the faster-
growing sources of GHG emissions. According to the Commission of the European Union,
emissions from international aviation increased by almost 70% between 1990 and 2002.4 The
United Nations Intergovernmental Panel on Climate Change (IPCC), in a 1999 study that is still
widely cited, projected that the impact of aircraft emissions on climate would be 2.6 to 11 times
as large in 2050 as it was in 1992.5 If, as many argue, GHG emissions must be reduced 50% to
80% in that time period, emissions from aviation would need to be drastically reduced to provide
a proportional share of the targeted reduction.
U.S. emissions from aircraft have run counter to the worldwide trends and projections. Since
1990, aircraft GHG emissions have declined as a percentage of total U.S. emissions (see Table 1).
The biggest factor in the decline was a 54% decrease in emissions from domestic military
1 Six greenhouse gases are the primary focus of concern: carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O),
sulfur hexafluoride (SF6), hydrofluorocarbons, and perfluorocarbons. These six are the subject of international
agreements (the U.N. Framework Convention on Climate Change and its Kyoto Protocol) and are the emissions that
would be subject to control in most climate change cap-and-trade bills that have been introduced in Congress. A
seventh greenhouse gas, nitrogen trifluoride (NF3), is included in H.R. 2454, the Waxman-Markey bill. As will be
noted later in this report, other emissions from aircraft, especially water vapor and the persistent condensation trails
(contrails) that form in jet engine exhaust, may have an impact on climate as well, but in general they have not been the
subject of negotiations, international agreements, or legislation.
2 For data on these and other sectors, see “Trends in Greenhouse Gas Emissions,” Chapter 2 of U.S. EPA, Inventory of
U.S. Greenhouse Gas Emissions and Sinks: 1990-2007, at http://www.epa.gov/climatechange/emissions/
usinventoryreport.html, especially Table 2-1.
3 Because each gas has a different heat-trapping potential (e.g., methane has 25 times the heat-trapping potential of
CO2, and SF6—although emitted in small quantities—has 22,800 times CO2’s heat trapping potential), GHG emissions
are generally converted to tons of CO2 equivalent in order to assess the climate change contribution that an economic
sector makes.
4 See Europa, website of the European Commission’s Directorate General for Environment, “Aviation and Climate
Change” http://ec.europa.eu/environment/climat/aviation_en.htm.
5 IPCC, Aviation and the Global Atmosphere, Summary for Policy Makers, 1999, at http://www.ipcc.ch/ipccreports/
sres/aviation/008.htm. The term for its impact is “radiative forcing.”
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operations, which more than offset increases in domestic commercial and general aviation6
emissions.
Emissions from domestic operation of commercial aircraft grew 13% between 1990 and 2007.
That figure was well below the growth in air travel: according to the Air Transport Association
(the association that represents the domestic airlines) passenger-miles traveled domestically on
U.S. commercial airlines increased 74% between 1990 and 2007 and cargo revenue-ton miles
increased 136%.7
Two types of efficiency increases contributed to the relatively slow growth in U.S. commercial
aircraft emissions. First, load factors (the percentage of seats occupied) increased to 79.8% in
2007, compared with 60.4% in 1990. Second, fuel efficiency itself increased, as older, less
efficient aircraft were retired in favor of newer, more efficient models. These savings can be
substantial. For example, American Airlines estimates that the 18-year old MD-80s currently
flying use 35% more fuel than the Boeing 737-800 aircraft that are to replace them over the next
two years.8
EPA’s Inventory of U.S. Greenhouse Gas Emissions and Sinks shows that domestic flights of all
kinds (military, commercial aircraft, and general aviation) accounted for about 10% of the GHG
emissions from the U.S. transportation sector in 2006—2.6% of overall U.S. GHG emissions.
Aviation’s impact on climate may be greater than these figures suggest, however, for two reasons.
First, emissions resulting from international transportation are not currently included in the U.S.
emission totals.9 These emissions totaled 52.7 million metric tons in 2007. If they were included
in the U.S. aviation statistics, emissions from aircraft of all types would have accounted for 3.4%
of the U.S. GHG total. Second, the bulk of the aviation sector’s emissions occur high in the
atmosphere, where their impact on climate is greater than that of emissions at ground level.
According to a number of sources, the total impact of aviation could be around twice the impact
of carbon dioxide alone when this factor is taken into account.10 Emissions from jet aircraft also
lead to the formation of cirrus clouds, as the condensation trails (contrails) of water vapor and
sulfur particles emitted from engines at high altitudes form ice crystals that persist as clouds
under some atmospheric conditions. Scientists are uncertain how to measure the occurrence and
impact of such clouds, but they are reasonably certain that the clouds add to the greenhouse effect
of aircraft emissions, perhaps substantially.11
6 The term “general aviation” refers to flights other than those by the military, scheduled commercial airlines, and large
air cargo operators.
7 Data on load factors and revenue passenger miles (as well as other industry data) are available from the Air Transport
Association’s 2008 Economic Report, at http://www.airlines.org/NR/rdonlyres/770B5715-5C6F-44AA-AA8C-
DC9AEB4E7E12/0/2008AnnualReport.pdf for the period 1997-2007. Information for 1990 were provided in personal
communications from ATA staff.
8 “American Speeds Plans to Phase Out Old Planes,” Greenwire, August 14, 2008.
9 The UN Framework Convention on Climate Change refers to such emissions as combustion of “international bunker
fuel,” and categorizes the emissions separately from national emission totals, pending further agreement on how to
address related emissions.
10 See, for example, Testimony of Dr. David W. Fahey, Office of Oceanic and Atmospheric Research, National
Oceanic and Atmospheric Administration, at the Subcommittee on Aviation, House Committee on Transportation and
Infrastructure hearing on Aviation and the Environment: Emissions, May 6, 2008. Dr. Fahey was a lead author of
portions of the 1999 and 2007 IPCC reports that considered the impact of global aviation on climate.
11 Ibid.
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Table 1. CO2 Emissions from U.S. Aviation, 1990-2007
(million metric tons of CO2 equivalent)
Fuel / Aircraft Type
1990
2000
2007
Jet Fuel
Commercial Aircraft
135.5
166.0
153.6
Military Aircraft
34.4
20.7
15.8
General Aviation
6.4
9.3
15.8
Aviation Gasoline
General Aviation
3.1
2.5
2.2
Total 179.4
198.5
187.4
% of Total U.S. GHG Emissions
2.9%
2.8%
2.6%
Source: U.S. EPA, Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2007
Thus, while the precise share of aviation in total greenhouse gas emissions depends on what is
included, and the impact of some emissions is unclear, there is little doubt that aviation is a
significant contributor to U.S. and world GHG emissions.12
Reducing Emissions: Non-Regulatory Factors
Fuel Cost
The cost of jet fuel represents a significant portion of total cost for most air carriers. There is a
great deal of variation depending on the distance traveled, the age and efficiency of the aircraft,
and the price of fuel at any given time, but the total fuel expenses of U.S. airlines consumed an
average of 24% of airline operating revenues in 2007, according to the Air Transport
Association.13
Given the importance of fuel costs, airlines and air freight companies have a major incentive to
purchase more fuel-efficient aircraft, and thus, aircraft manufacturers are constantly seeking to
12 Another source, a report prepared for the International Civil Aviation Organization (ICAO) in 1999, said, “Aircraft
are estimated to contribute about 3.5 per cent of the total radiative forcing (a measure of change in climate) by all
human activities and ... this percentage, which excludes the effects of possible changes in cirrus clouds, was projected
to grow.” ICAO, “Environmental (ENV) Unit, Aircraft Engine Emissions, Definition of the Problem,” at
http://www.icao.int/cgi/goto_m_atb.pl?/icao/en/env/aee.htm. Similar conclusions were reached by the Federal Aviation
Administration, which estimates that emissions of CO2 and NOx from domestic aircraft will increase 60% by 2025. See
FAA, Aviation and Emissions: A Primer, January 2005, p. 10, http://www.faa.gov/regulations_policies/
policy_guidance/envir_policy/media/aeprimer.pdf.
13 This percentage was even higher in 2008, although it has since declined. Because of the rapid increase in the price of
oil in that year, domestic airlines spent 42% more on fuel for their domestic and international flights in 2008 than in
2007. See “Airline Fuel Cost and Consumption (US Carriers – Scheduled),” at http://www.transtats.bts.gov/fuel.asp?
pn=1. Also see ATA, “Monthly Jet Fuel Cost and Consumption Report,” at http://www.airlines.org/economics/energy/
MonthlyJetFuel.htm.
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improve the efficiency of airplanes and engines. These incentives have resulted in sizeable
efficiency gains: U.S. airlines carried 20.4% more passenger and cargo traffic in 2007 than they
did in 2000, but they used nearly 3% less fuel in doing so. This resulted in a reduction of 5.1
million metric tons of CO2 emissions in 2007, as compared to 2000, according to ATA.14 The
industry has committed to a further 30% increase in fuel efficiency by 2025.15
Air Traffic Control
In addition to improving the efficiency of individual aircraft, there is a general consensus that fuel
use could be reduced by modernizing the Federal Aviation Administration (FAA)’s air traffic
control system. The FAA is in the process of transforming air traffic control from a ground-based
system of radars to a satellite-based system, dubbed the Next Generation (NextGen) Air
Transportation System. The primary objective is to enable the air traffic control system to handle
a projected doubling of current passenger loads by 2025. But, when fully implemented, NextGen
is also expected to cut the GHG emissions of individual aircraft 10% to 15%, by allowing more
direct routing, reducing delays, and through such features as Continuous Descent Approach.16
According to the FAA, United Parcel Service aircraft equipped with some of the NextGen
technologies have reduced emissions as much as 34%.17
Regulating Aircraft Under the Clean Air Act
As policy makers consider whether the federal government should regulate aircraft GHG
emissions (versus continuing to rely solely on market forces to determine the level of emissions),
some have turned their attention to the potential for regulation under the Clean Air Act. In
December 2007, EPA received two petitions requesting that it exercise that authority to regulate
GHG emissions from aircraft engines.18
EPA has not responded to these petitions, nor has it promulgated regulations to control CO2 from
any source, to date. In 2003, responding to an earlier petition to regulate GHGs from cars and
trucks, the agency maintained that it did not have authority under the Clean Air Act to do so. That
determination was challenged by Massachusetts and other petitioners, and in a 2007 decision, the
U.S. Supreme Court found that GHGs are air pollutants within the Clean Air Act’s definition, and
thus, EPA has authority to regulate them if it finds that they “cause, or contribute to, air pollution
which may reasonably be anticipated to endanger public health or welfare.”19
14 ATA, 2008 Economic Report, previously cited, p. 25.
15 Ibid., p. 17.
16 Continuous Descent Approach, in which an aircraft lands by descending at a constant 3-degree angle rather than
descending and holding at a series of altitude “steps,” lowers fuel use and emissions by shortening flight time and
eliminating the need for engine thrust required in a stepped approach to landing.
17 See FAA, “Fact Sheet: Next Generation Air Transportation System 2006 Progress Report,” October 10, 2007, at
http://www.faa.gov/news/fact_sheets/news_story.cfm?newsId=8336.
18 The first petition, submitted December 4, 2007, was filed by California, Connecticut, New Jersey, New Mexico, the
Pennsylvania Department of Environmental Protection, New York City, the District of Columbia, and California’s
South Coast Air Quality Management District (the air pollution control agency for the Los Angeles area). The second
petition was filed December 31, 2007, by Earthjustice on behalf of four environmental organizations.
19 The court case was Massachusetts v. EPA, 127 S. Ct. 1438 (2007). The quoted language is from Section 202(a) of
the Clean Air Act, which requires emission standards for motor vehicles. Similar, but not identical, language regarding
(continued...)
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Using the authority of Section 231 of the act, the EPA Administrator may propose emission
standards applicable to any air pollutant from any class of aircraft engines which in the
Administrator’s judgment causes, or contributes to, air pollution which may reasonably be
anticipated to endanger public health or welfare. The Administrator is required to consult with the
FAA Administrator and hold public hearings before finalizing such standards. The President may
disapprove of such standards if the Secretary of Transportation finds that they would create a
hazard to aircraft safety.
The December 2007 petitions request that EPA make a finding that aircraft GHG emissions do
endanger public health or welfare, and that the agency adopt regulations that allow a range of
compliance approaches: these might include emission limits, operational practices, fees, a cap-
and-trade system, minimizing engine idling time, employing single engine taxiing, or use of
ground-side electricity measures to replace the use of fuel-burning auxiliary power units at airport
gates.20
The aircraft petitions are among several others that EPA has received to regulate GHG emissions
from cars and trucks, ships, and nonroad engines and vehicles. As a result, whatever decision is
made (for any one of these sectors) is considered likely to affect the decisions regarding all the
others—ultimately, a large portion of the economy.21 Furthermore, as soon as greenhouse gases
become “subject to regulation” under any section of the act, new stationary sources, such as
electric generating units, would be required to install best available GHG control technology
under the act’s New Source Review/Prevention of Significant Deterioration provisions.22
Given the relative size of aircraft emissions as compared to power plants, cars, and trucks,
aviation was never likely to be the first sector whose GHG emissions EPA would regulate. Thus,
not surprisingly, EPA has taken no action on the aircraft petitions, to date. The agency is moving
ahead with regulation of GHG emissions from cars and trucks, however: on May 19, at a press
conference in the White House Rose Garden, the President announced that EPA would proceed to
set greenhouse gas emission standards for new motor vehicles, in coordination with new fuel
efficiency standards to be established by the National Highway Traffic Safety Administration.23
Both EPA and the President have made clear that, despite their action under existing authority,
they support legislation targeted more specifically at GHGs, and would prefer that Congress enact
a bill addressing GHG emissions specifically rather than EPA using its current authority. New
(...continued)
endangerment appears as the prerequisite to the setting of emission standards for other categories of sources elsewhere
in the act.
20 For a brief discussion of the petitions, see 73 Federal Register 44460, July 30, 2008. Some of these measures, such
as minimizing engine idling time, employing single engine taxiing, and use of ground-side electricity measures to
replace the use of fuel-burning auxiliary power units, are already widely used by the airlines as fuel-saving measures.
21 The wording of these “endangerment” requirements varies, however, from one section of the act to the next, and, of
course, the amount of pollution from each category of sources may affect the Administrator’s judgment as to whether
emissions from the category are sufficient to cause or contribute to endangerment.
22 The phrase “subject to regulation” appears in Section 169(3) of the act, and would trigger regulation under Section
165. For a further discussion, see CRS Report R40585, Climate Change: Potential Regulation of Stationary
Greenhouse Gas Sources Under the Clean Air Act, by Larry Parker and James E. McCarthy, pp. 22-24.
23 The President’s announcement was followed three days later by a more detailed “Notice of Upcoming Joint
Rulemaking to Establish Vehicle GHG Emissions and CAFE Standards,” in the Federal Register. See 74 Federal
Register 24007, May 22, 2009.
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legislation might be more efficient—clearly allowing sources in different industries to trade
emission allowances to each other, for example—and it might avoid challenge in the courts if
Congress were specific regarding the authority it was giving EPA to control GHG emissions. The
current language of the act, while arguably providing regulatory authority, is sufficiently vague
that legal challenges are considered almost a certainty as EPA proceeds. This might delay
implementation of controls.
The two options—proceeding under the Clean Air Act or supporting new legislation—are not
mutually exclusive, however. Existing EPA authority under the Clean Air Act can be used as a
backstop, while Congress considers granting new authority. In the meantime, EPA’s development
of regulations is among the factors motivating Congress and interested parties to agree on a
legislative approach.
Proposed Legislation
GHG legislation is a high priority of the current Congress. Attention has centered on legislation
(H.R. 2454 in the House) that would cap emissions of GHGs economy-wide and establish an
allowance trading system for major emitters. (For a general discussion of how such cap-and-trade
systems work, see CRS Report RL34502, Emission Allowance Allocation in a Cap-and-Trade
Program: Options and Considerations, by Jonathan L. Ramseur, especially Appendix A.)
As noted, aviation is considered a significant source of GHG emissions. Nevertheless, the
aviation sector has not generally been targeted directly by the climate change bills introduced in
Congress to date. An exception was the reported version of H.R. 2454, the Waxman-Markey bill.
As reported by the House Energy and Commerce Committee in May, the bill would have required
EPA to promulgate best achievable control technology standards for emissions of GHGs from
new aircraft and new engines used in aircraft by December 31, 2012. This requirement was
removed from the version of the bill that passed the House June 26.
Instead, the House-passed version encourages the development of a global framework for the
regulation of GHG emissions from civil aircraft within the International Civil Aviation
Organization. And, instead of direct regulation, the bill would deal with aviation emissions
indirectly: by including the refining sector in its overall emissions cap, it would address the
aviation sector’s emissions “upstream.”24
Capping emissions from fuels upstream of the air carriers and eventually lowering the cap more
than 80%, as the bill would do, could have several effects: first, it would provide an incentive for
refiners to produce lower-carbon fuels25; second, it would increase the price of fuels, as refiners
either purchased additional allowances for their emissions or were forced to reduce production, in
24 S. 2191/S. 3036 (the Lieberman-Warner bill, reported in the 110th Congress) would have provided for a National
Academy of Sciences study of the aviation sector’s emissions, including the identification of existing best practices to
reduce emissions, recommendations for research for technologies and operations with the highest potential to reduce
emissions, and recommendations of actions that the Federal Government could take to encourage or require additional
emission reductions.
25 The Lieberman-Warner bill, as reported in the 110th Congress, would have required the production of low carbon
fuels, although it is not clear whether the requirement would have applied to aviation fuels. For further discussion, see
CRS Report RL34489, Climate Change: Costs and Benefits of S. 2191/S. 3036, by Larry Parker and Brent D.
Yacobucci, pp. 54-55.
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essence rationing fuels through a higher price in order to stay beneath the emissions cap; third, as
the cost of fuel increased, the demand for fuel-efficient aircraft would increase; and fourth,
consumers of aviation services (airline passengers and shippers of freight) would have incentives
to replace higher-cost air transportation with lower-cost alternatives (e.g., video-conferencing by
business and government entities, increased reliance on lower-emission forms of transport,
greater reliance on local sources of goods, etc.).
The cost of air travel and of air freight has been reduced substantially since its inception, as
aircraft have become more efficient and airlines have reduced other costs in competitive markets.
According to ATA, the cost of domestic air travel in real (inflation-adjusted) terms has declined
by 51.9% since 1978.26 By contrast, controlling GHG emissions, if it were done, would likely
increase the price of air travel and air freight, reducing demand in comparison to a business-as-
usual (i.e., without GHG controls) scenario.
International Developments
European Union
Unlike the upstream approach of U.S. cap-and-trade bills, the European Union (EU) has chosen
to regulate aviation directly, by including the sector in its Emission Trading Scheme (ETS),
beginning in 2012. The ETS began operation in 2005, capping emissions of CO2 from more than
10,000 energy-intensive stationary sources of emissions. The currently covered sectors (power
plants; petroleum refining; iron and steel production; coke ovens; pulp and paper; and cement,
glass, lime, brick, and ceramics production) account for about half of EU CO2 emissions.27
On January 1, 2012, the aviation sector’s CO2 emissions are to be added to the ETS. The scheme
is to cover all aircraft operators landing in or departing from the EU, with the exception of
military aircraft, some small carriers, emergency services, research, and humanitarian flights.
Thus, flights to and from the EU by U.S. air carriers would be subject to the emission limits. For
the first year, the total quantity of allowances would be equivalent to 97% of the sector’s average
2004-2006 emissions. The cap would be reduced to 95% in 2013, with further reductions to be
agreed on as part of the ongoing review of the ETS. In allocating the emissions allowed under the
cap, 85% of the sector’s 2012 allowances are to be given to aircraft operators at no cost, and 15%
of the allowances auctioned. The EU Commission has proposed that 80% of allowances be
distributed free of charge in 2013, with 20% being auctioned; the percentage of free allowances is
expected to continue declining with a goal of auctioning all allowances in 2020.
Operators emitting more than their allowed cap would need to buy additional allowances on the
carbon market. A special reserve fund, taken from the sector’s overall cap, is to allocate up to one
million tons worth of allowances a year to ensure access to the market to new operators and to
provide allowances to rapidly growing airlines.28
26 ATA, 2008 Economic Report, previously cited, p. 11.
27 For a description of the EU ETS, see CRS Report RL34150, Climate Change and the EU Emissions Trading Scheme
(ETS): Kyoto and Beyond, by Larry Parker.
28 “Airline Emissions Covered in EUETS from 2012,” ENDS Report, July 2008, p. 51. The text of the ETS amendment
adding the aviation sector to the scheme can be found at http://www.europarl.europa.eu/sides/getDoc.do?pubRef=-//EP/
(continued...)
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The directive provides sanctions for failure to comply with the scheme, including the possibility
that a non-complying airline might be banned from operating in the EU.29 According to press
reports, “This warning shot is aimed at foreign airlines—including US carriers—that have said
they will not recognise the scheme.”30 For its part, the United States has responded by threatening
trade sanctions if the EU makes an attempt to force foreign airlines to comply with the emissions
trading system.31
This dispute highlights a general problem in directly regulating emissions from sectors such as
aviation or shipping, a substantial portion of whose total emissions occur outside of national
borders. Without international agreement, it may be difficult to enforce emission limits, and the
imposition of controls by any one country or bloc of countries is likely to be challenged through
existing international institutions.
Regulating upstream of the aviation industry, as most U.S. climate change bills would do, may
avoid some of these issues, maintaining a level playing field for U.S. and foreign airlines and air
freight companies, without imposing emission limits that could be directly challenged or
circumvented. Whether enactment of such legislation would be sufficient to address European
concerns over U.S. airlines’ emissions, resolving the dispute, remains to be seen.
ICAO
The EU is not the only international body addressing aircraft emissions. The International Civil
Aviation Organization (ICAO), the international organization that administers standards and
recommended practices for the aviation authorities of more than 190 countries, agreed in
September 2007 to support the development of an “aggressive” action plan on aviation and
climate change, but without a fixed timetable or specific emission reduction targets.32 The United
States has supported the ICAO as the proper venue for international regulation of emissions, and
maintains that the EU’s approach is contrary to ICAO’s charter, the Chicago Convention on
International Civil Aviation.33 A majority of ICAO’s members agree with the United States that
participation in an emissions trading scheme (such as EU-ETS) should only be on the basis of
mutual consent.34
(...continued)
/TEXT+TA+P6-TA-2008-0333+0+DOC+XML+V0//EN&language=EN. The agreement on an EU-wide directive does
not complete the legislative process. The 27 Member States now must “transpose” the directive into national laws.
29 The threat of a ban is found in Whereas clause (26): “In the event that an aircraft operator fails to comply with the
requirements of this Directive and other enforcement measures by the administering Member State have failed to
ensure compliance, Member States should act in solidarity. The administering Member State should therefore be able to
request the Commission to decide on the imposition of an operating ban at Community level on the aircraft operator
concerned, as a last resort.”
30 “Airline Emissions Covered in EUETS from 2012,” ENDS Report, July 2008, p. 51.
31 “Aviation and Emissions Trading,” July 10, 2008, EurActive.com at http://www.euractiv.com/en/climate-change/
aviation-emissions-trading/article-139728.
32 “ICAO Backs Mutual Agreement Approach to Emissions Reductions but Europe Objects,” Daily Environment
Report, October 1, 2007.
33 “Emissions Trading: EU Lawmakers Back Plan to Add Aviation To Emissions Trading Scheme in 2012,” Daily
Environment Report, July 9, 2008.
34 ICAO, Annual Report of the Council, 2007, pp. 41-42.
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As noted earlier, the House-passed version of H.R. 2454 encourages the development of a global
regulatory framework through ICAO. Section 276 of the bill declares it to be the sense of
Congress that the United States should actively promote an ICAO framework and work with
foreign governments to reconcile emissions reduction programs to “minimize duplicative
requirements” and avoid “unnecessary complication for the aviation industry, while still
achieving the environmental goals.”
Conclusion
Greenhouse gas emission controls of some sort may affect U.S. aviation in the next few years, be
they specific controls on engine emissions, emission caps applied to the sector as a whole,
upstream caps (on fuel refiners), or carbon taxes.35 Depending on their stringency, the effects of
most of these approaches could ripple through the economy, providing additional incentives for
aircraft manufacturers to improve the fuel efficiency of aircraft, raising the cost of air travel and
air freight, and providing further pressure to improve the air traffic control system.
U.S. airlines and air freight companies, like many other sectors, would prefer that they be allowed
to address the GHG issue through voluntary measures. Unlike some other sectors, they have
achieved substantial increases in fuel economy over the last three decades or more, and in the
current recession, their GHG emissions are at roughly their 1990 levels.
Compared to other means of transportation, in fact, U.S. commercial aviation’s record on GHG
emissions over the last two decades is much better. As shown in Table 2, GHG emissions from
U.S. commercial aviation increased less than those of any other segment of the transportation
market, despite the demand for aviation services (measured in passenger-miles traveled)
increasing at a faster pace than the other sectors.
But the sector is still an important source of emissions, and its projected growth indicates that it
may outstrip the economy as a whole’s rate of emission growth in future years. Thus, it is likely
to be included in some fashion in any mandatory economy-wide approach to reducing GHG
emissions.
On a practical level, reducing emissions from aviation may be complicated:
• The sector is composed of tens of thousands of mobile emission sources; thus,
direct controls on engines or aircraft face obstacles that do not apply in industries
composed of fewer and stationary emission sources. Even monitoring the
relevant emissions for this sector is difficult.
• The sector’s emissions affect climate in several ways. Controlling only CO2
emissions might leave other impacts of aircraft on climate unaffected. More
research is needed to identify the precise effects of some of these, such as the
impact of contrails on cirrus cloud formation, and the effect of such clouds on
climate change.
35 Carbon taxes are not discussed in this report, but their effects might be similar to the imposition of an upstream cap
on emissions. They would raise the cost of fuel, thus encouraging the development of more fuel-efficient and lower
carbon alternatives.
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Table 2. Greenhouse Gas Emissions from U.S. Transportation Sectors, 1990-2007
(million metric tons of CO2 equivalent)
Transportation
Level of Activity,
Greenhouse Gas
Greenhouse Gas
Sector
1990-2007
Emissions, 1990
Emissions, 2007
% Change
Commercial
+74% 135.5 153.6 +13.4%
Aviation
Rail +71%
38.5
57.9
+50.3%
Medium- and
+55% 228.8 410.7 +79.5%
Heavy- Duty
Trucks
Passenger Cars
+40% 993.0 1,227.1
+23.6%
and Light Duty
Trucks
Transportation
1,546.7 2,000.1 +29.3%
Total
U.S.
Total
6,098.7 7,150.1 +17.2%
Source: EPA, Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2007; trade association data for level of
activity.
Notes: Level of activity is measured as vehicle miles traveled for cars and trucks, passenger miles traveled for
commercial aircraft, and revenue ton miles for rail. The data for commercial aviation actually understates the
increase in activity, since it excludes cargo operations, which rose 136% during the period, as measured by cargo
revenue-ton miles.
• The sector’s impressive progress in making itself more energy-efficient in recent
years poses obstacles as well: improving load factors was relatively easy when
they were at 60%; at the current level, roughly 80%, one begins to approach the
limits of further improvement.
• Some means of emission reduction are beyond the industry’s control, including
the pace of modernization of the air traffic control system, and the degree to
which aeronautical research and engine modifications can reduce fuel
consumption. In both cases, emission reduction may depend, at least in part, on
the actions of government agencies—the FAA and NASA, in particular.
According to ATA, funding for NASA and FAA aviation environmental R&D
programs has been cut by approximately 50 percent in the past 10 years.36
• Finally, the sector faces controls from foreign countries, particularly the
European Union. International negotiations for a post-Kyoto-Protocol emissions
control scheme may give rise to emission limits in other countries, as well.
As discussed, Congress and the Administration have a number of options, including several forms
of legislation; regulation by EPA under the existing Clean Air Act is another possibility. If the
36 ATA, 2008 Economic Report, previously cited, p. 17. The FAA’s efforts on NextGen have already been discussed.
For an overview of aeronautics research goals, in which NASA plays a leading role, see National Science and
Technology Council, National Plan for Aeronautics Research and Development and Related Infrastructure, December
2007,especially pp. 50-52, at http://www.aeronautics.nasa.gov/releases/aero_rd_plan_final_21_dec_2007.pdf.
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Administration so chooses, the existing Clean Air Act might prove a particularly important tool to
bring interested parties to the table, while providing a backdrop to consideration of legislation by
Congress.
Author Contact Information
James E. McCarthy
Specialist in Environmental Policy
jmccarthy@crs.loc.gov, 7-7225
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