in the News
Date: December 19,
2006, USA TODAY
By Gary Stoller
grows over pollution from jets
Aviation and the environment are
on a collision course. The number of airline flights worldwide is growing and
expected to skyrocket over the coming decades. Aircraft emissions pollute the
air and threaten by 2050 to become one of the largest contributors to global
warming, British scientists have concluded.
Much remains unknown about climate change and the role aviation plays, though
climate scientists express particular concern about jet emissions in the upper
atmosphere, where the warming effect from some pollutants is amplified.
Now, aviation is believed to be less a factor in the Earth's warming than power
plants or vehicular traffic. But its emissions are considerable. On a New
York-to-Denver flight, a commercial jet would generate 840 to 1,660 pounds of
carbon dioxide per passenger. That's about what an SUV generates in a month.
With the projected explosion in worldwide travel, air pollution from aviation is
a growing concern among scientists, and it's drawing increased scrutiny from
governments, particularly in Europe.
"It's an issue that has to be addressed," says Brenda Ekwurzel, a
climate scientist for the Union of Concerned Scientists, an environmental
David Travis, a climate science professor at the University of
Wisconsin-Whitewater, says aircraft emissions "are currently one of the
fastest-growing contributors to global warming."
The European Union is considering strict controls on aircraft emissions, an
action strongly opposed by the White House because of its potential effect on
Some members of the British Parliament favor limiting the growth rate in the
number of air passengers to the rate at which aviation improves its fuel
efficiency. Last month, a local government council rejected a plan to increase
flights at London's Stansted airport because of concerns about the environment
and global warming.
In the USA, a panel of scientists brought together by NASA and the Federal
Aviation Administration agreed in August that the effects of aircraft emissions
on the climate "may be the most serious long-term environmental issue
facing the aviation industry."
The FAA projects that the number of U.S. airline passengers will nearly double
from 739 million last year to 1.4 billion in 2025. Air traffic controllers are
expected to handle 95 million flights by all types of aircraft in 2025, compared
with 63 million last year. Worldwide, a growing middle class with the means to
travel is spawning new airlines and big orders for new planes. China plans more
than 40 new airports to accommodate the growth.
By 2050, emissions from planes are expected to become one of the largest
contributors to global warming, according to the Royal Commission on
Environmental Pollution, an independent group of scientists that advises the
Although the USA is the largest emitter of carbon dioxide a pollutant that
scientists believe is a major contributor to global warming the Bush
administration refuses to ratify the Kyoto Protocol. That 1997 agreement is
limiting emissions from such big polluters as power plants and automobiles in
more than 160 countries. President Bush says the agreement would hurt the
economy. He also says it's unfair because it exempts China, another major
Aviation emissions are not part of the Kyoto Protocol. Emissions from planes
were considered a minor problem when the agreement was negotiated, but several
scientific studies have since shown otherwise, says European Commission
spokeswoman Barbara Helfferich.
In the USA, aircraft emission standards set by the Environmental Protection
Agency mirror those of the International Civil Aviation Organization (ICAO), the
group that sets worldwide standards. The FAA enforces the EPA's standards.
Environmentalists and many state and local air pollution officials argue that
the standards are too weak. The EPA says limits now in place will slow the
growth of aircraft emissions, but more stringent standards "will likely be
necessary and appropriate in the future," says Margo Oge, director of the
agency's Office of Transportation and Air Quality.
Last month, FAA Administrator Marion Blakey proposed changes in air traffic
control procedures and expansion of U.S. airports to accommodate the projected
increase in commercial flights, a strategy widely decried by critics.
"The FAA protects its customers: the airports and the industry," says
Jack Saporito, executive director of the Alliance of Residents Concerning
O'Hare, a Chicago group that opposes plans to expand O'Hare airport. "It
does not protect the public, their families' health or our environment, though
it pretends to."
In written answers to questions from USA TODAY, the FAA says aircraft emissions
"are not expected to be the fastest-growing contributor to global
Don Wuebbles, a University of Illinois professor of atmospheric science who
chaired the panel of scientists brought together by NASA and the FAA, says the
projected growth in aviation could make aircraft emissions one of the
fastest-growing contributors. But he acknowledges many uncertainties, including
aviation's role in global warming and the growth of other pollution sources
What is known, he says, is that it's "much harder" to reduce carbon
dioxide emissions from aviation. Jet engines are already energy efficient, and
technology to significantly reduce carbon dioxide from them isn't as far along
as it is for land-based pollution sources.
Besides carbon dioxide, jet engines emit many pollutants into the atmosphere,
including nitrogen oxides, sulfur oxides, soot and even water vapor. Carbon
dioxide and water vapor are called greenhouse gases, because they trap heat and
contribute to global warming.
Though planes contribute to air pollution while on the ground, scientists
studying global warming are most concerned about pollutants emitted when a plane
is airborne. Jets are the major source of emissions deposited into the upper
atmosphere, where some pollutants have a greater warming effect than when they
are released in the same amount from the ground, according to a 1999 scientific
report sponsored by the United Nations.
Some pollutants emitted from engines during flight warm the Earth by adding to
the heat-trapping gases, both natural and man-made, already in the atmosphere.
Also, jet contrails the vapor trails they leave in the sky add to cloud
cover and may contribute to the warming of the planet. A contrail forms when
water vapor from the engine cools and mixes with air and the humidity becomes
high enough for condensation.
NASA scientist Patrick Minnis has studied contrails and believes they may have a
prominent role in global warming. A 2002 report by the British scientific
commission agrees, concluding that "aviation-induced cirrus clouds
will be a significant contributor to warming." But Minnis says another NASA
study concludes that the contrails have little effect
on global warming. Further research is being done.
Carbon dioxide is a heat-trapping gas that can remain in the atmosphere about
100 years. Scientists say planes' engines emit up to 3% of all carbon dioxide
that contributes to global warming, but the figure appears to be on the rise.
University of Washington scientist Richard Gammon says carbon dioxide emissions
from aircraft are rising more rapidly than those from any other source.
Nitrogen oxides emitted from aircraft engines react with other gases in the air
to form another heat-trapping gas, ozone. Their effect on global warming is
unclear because nitrogen oxides have another effect that may be beneficial: They
remove methane, which can cool the air.
Except for carbon dioxide's contribution to global warming, "There remain
significant uncertainties on almost all aspects of aircraft environmental
effects on climate," according to the report this year by Wuebbles and
Though uncertainties about global warming abound, there's no doubt that jet
engines must have stricter emission standards, says the National Association of
Clean Air Agencies, which represents pollution control officials in 49 states
and 165 metropolitan areas. The group is suing the EPA.
The EPA has failed "to put stringent controls on aircraft emissions,"
says William Becker, the group's executive director. In its court filing, the
EPA says it meets international law by adopting standards that "are at
least as stringent" as ICAO's.
Unlike European governments, the FAA doesn't see an immediate threat.
"Compared to other sources of emissions, aviation represents a relatively
small source" of air pollutants and greenhouse gases, the FAA said in
response to USA TODAY questions. "Cars and trucks generate seven times the
amount of emissions that aviation produces."
American Airlines (AMR), the world's No. 1 carrier, would not comment, referring
all questions about its planes' emissions to the Air Transport Association, the
main trade group representing U.S. carriers. The ATA says U.S. airlines reduced
greenhouse gas emissions by improving fuel efficiency 23% since 2000 and 70% in
the past 30 years.
"Our record demonstrates that we are committed to managing our growth
responsibly," says John Meenan, executive vice president.
But those gains don't offset the effect of more travel, scientists say.
More-efficient engines and fuel savings from improved flow of air traffic
"will not fully offset the effects of the increased emissions resulting
from the projected growth of aviation," the 1999 scientific report by the
Jet manufacturer Boeing (BA) says it's working with engine manufacturers to
develop more environmentally friendly engines. Technological advances, says Bill
Glover, Boeing's director of environmental performance, could reduce the amount
of carbon dioxide and other pollutants emitted from jet engines.
Whether climate concerns will require limits on the growth in aviation is not
for his company to decide, he says. "There's great economic value in
aviation," says Glover. "Society has to decide where to cut emissions
and how to retain the lifestyle we enjoy."
Nobody sees easy solutions for reducing aircraft emissions. Wuebbles, the
Illinois professor, says more money for research is part of the answer.
Piers Forster, a professor at the University of Leeds in England, suggests
putting additional taxes on jet fuel, using alternative fuels and redesigning
aircraft. Britain's Royal Commission
on Environmental Pollution says high-speed rail could replace short-haul
Boeing is studying new fuel-cell technology that can power an aircraft and
reduce emissions by combining hydrogen and oxygen to produce electricity. Such
technology may be 10 years away, says Glover. Until then, "Our role is to
keep building the most efficient, best airplanes on the planet."
Other possible solutions
Some other areas where solutions may lie:
Jet engines. The most modern engines on new jets have reduced carbon dioxide
emissions, but they've increased nitrogen oxide emissions. A 2003 report by the
Government Accountability Office estimates that some new engines emit at least
40% more nitrogen oxides than older engines they're replacing. NASA is
developing technology that would permit
Boeing 737 and Airbus A320 jets, in 2018, to burn 25% less fuel and reduce
nitrogen oxide emissions by 80%.
Airports. Environmentalists and some European lawmakers and government
agencies say airports should not be allowed to expand to accommodate more
flights. The FAA disagrees. "Providing sufficient airfield capacity
increases the efficiency of operations and tends to reduce, rather than
increase, emissions," the FAA said.
U.S. airports are not going to lose business and halt runway or terminal
expansion plans because planes are emitting pollutants, says Dick Marchi, senior
vice president of Airport Council International-North America. Instead, the
federal government "needs to adopt more aggressive standards on
emissions," he says.
Virgin Atlantic Chairman Richard Branson, an activist for moving aggressively
against global warming, favors constructing jet parking bays closer to runways
and using tugs to tow them.
University of North Carolina professor John Kasarda, who consulted in the design
of airports in Detroit, Bangkok, Brazil and the Philippines, says a new approach
to airport design could reduce emissions.
He said he sees merit in an untried design by Illinois inventor Jim Starry, who
conceived the design while flying back to the USA from England in the early
Starry envisions parallel runways on an upward slant for landing and a
downward slant for takeoff leading jets directly onto, or off, the roof of a
circular passenger terminal and parking garage. The design, which was first
proposed by Starry to the FAA in the mid-1980s, reduces a jet's taxi time,
cutting emissions and saving fuel.
"I see brilliance in the ideas," says Kasarda, who plans to work with
Starry to refine his design and make it commercially viable.
Individual action. Some European environmentalists are pushing programs that
enable passengers to pay a fee to mitigate their share of the damage from the
carbon dioxide emitted during each flight. A Welsh company, Treeflights.com,
uses the money to plant trees, which remove carbon dioxide from the air. British
Airways has an "emissions calculator" on its website that determines
how much carbon dioxide is emitted and how much each passenger can pay to
another company, Climate Care, to offset it.
But Forster, the professor from Leeds, says there is one foolproof way to reduce
"The best answer, of course, is to fly around less," he says.
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