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Planes 'produce harmful gases'
16/08/2007 11:30 - (SA)
Oslo - The aviation industry may be more
damaging to the environment than widely thought because aircraft
not only release carbon dioxide but they also produce other
harmful gases that warm the Earth, experts said.
A tented camp of about 250 climate protests at London's
Heathrow airport this week highlights pressures to include
aviation in a global pact to fight global warming. But planes
are among the least understood sources of emissions.
"Growth is going to continue, but it is complicated to
estimate the effect of aviation on the climate," said Ivar
Isaksen, a professor at Oslo University who is an expert in how
aviation affects the atmosphere.
He said that aviation's impact went far beyond carbon
dioxide, the main greenhouse gas, that many governments rely on
for calculations.
Aviation accounts for about two percent of world emissions of
carbon dioxide and projected passenger growth of five percent a
year will far outstrip efficiency gains from better fuel or
plane design, UN studies say.
Planes' climate impact may be magnified by factors including
heat-trapping nitrogen oxides that are more damaging at high
altitude. Jet condensation trails may contribute to the
formation of a blanket of high-altitude cirrus clouds.
Cirrus clouds usually warm the Earth's surface, increasing
the impact of aviation on global warming.
A 1999 UN report, for instance, estimated that aviation's
impact on the climate was two to four times greater than simply
the carbon dioxide emitted by burning jet fuel.
'The science around this isn't very clear'
"The science around this isn't very clear," said Sarah
Brown, spokesperson for CarbonNeutral Co, an offset company that
allows travellers to invest in renewable energy projects to soak
up emissions from flights.
The company uses British Environment Ministry data that
excluding climate side-effects of aviation. "The science of
radiative forcing is currently uncertain," it said, referring to
the effects that go beyond carbon dioxide.
Germany's Atmosfair (www.atmosfair.de), whose patrons
include former UN Environment Programme chief Klaus Toepfer,
covers factors such as the release of nitrogen oxide.
"We're trying to estimate the overall effect," said Robert
Muller at Atmosfair. He said airlines such as British Airways or
Scandinavian SAS worked with companies with low estimates when
offering customers offsets.
Take a one-way flight from Sydney to London, for instance -
CarbonNeutral estimates each passenger is responsible for 1.9
tons of greenhouse gases, costing $28.46 to
offset. The same route with Atmosfair works out at 6.4 tons,
and a charge of 130 euros to offset.
Outside Heathrow, about 250 campaigners are camping in tents
on the path of a proposed third runway for the world's busiest
international hub. More and more people fly, partly because
companies have axed ticket prices despite high fuel costs.
International flights are now excluded from the Kyoto
Protocol, the main UN plan for curbing climate change to 2012.
The European Union is among those aiming to include aviation
after 2012 while the United States is opposed.
A report by the UN climate panel said extra charges
for fuel or the inclusion of the aviation sector into a
greenhouse gas trading scheme "would have the potential to
reduce emissions considerably".
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