LONDON — It was a chilly Monday morning at one of the most heavily guarded airports in the world, and Anna Jones was on top of a just-landed British Airways jet, wrapping an outlaw banner around its tail fin.
"It felt quite exhilarating and it felt important," said the longtime Greenpeace activist, who was one of four protesters to attach the "Climate Emergency -- No 3rd Runway" banner to the Airbus A320 at Heathrow Airport. "It felt like we needed to make this stand, and I was proud to be someone who was doing that."
As Europe's appetite for cheap weekend getaways and lower-fare flights across the Atlantic collides with mounting public unease over greenhouse gas emissions, Jones is one of a growing number of environmental activists who have begun to adopt the tactics of civil disobedience in the war on climate change.
Two days after Greenpeace members hit the runway in late February, protesters from the group Plane Stupid circumvented the heavy security that has blanketed London since the city's 2005 transportation bombings, climbing atop the Houses of Parliament and unfurling two banners urging a halt to Heathrow's expansion.
As the airport prepares to open its $9-billion Terminal 5 on Monday, the controversy over building an additional runway for it has taken on a crucial new dimension.
British officials say the country's decade-long economic boom, already threatened by downturns in the markets, could grind to a halt in the quagmire that is Heathrow, Europe's busiest airport. The new terminal could alleviate the massive congestion that has become associated with the international hub, authorities say, but will have little effect on the crowds without the aid of a third runway.
Nigel Rudd, the head of BAA, the company that runs London's airports, said the expansion would launch Britain to the forefront of the competitive aviation industry.
"The nation has to decide whether we want to be a world-class nation or a second-class nation," Rudd told the BBC on Friday, noting that Dubai, United Arab Emirates, has six runways and that Heathrow's two have not been updated since World War II.
But opponents argue that expansion is superfluous when a large portion of the British aviation industry depends on domestic and short-haul travel that could be taken by rail, an option that eases airport congestion and is better for the environment.
"In the U.K., people fly more than anywhere else in the world," said Jones, 27. "There are 32 flights a day between London and Manchester, which is ridiculous when we have a perfectly good train line, and it's 10 times less polluting to take the train."
Greenpeace, which has made aviation a main focus of its British climate campaign, says the airport expansion would make it impossible for the government to meet its own emissions-reduction commitments.
"You can't have both," said Graham Thompson, who was among those who scaled the Parliament building and unleashed a shower of paper airplanes made of copies of confidential documents. The papers, protesters say, suggest that the airport operators influenced the government's consultation report on the runway and misconstrued data to bolster the case for expansion while underplaying the role of jet emissions in climate change.
"This isn't a bunch of hippies trying to save a panda somewhere; the best scientists in the world say you can't do this," Thompson said.
Airport officials have denied trying to influence the report.
Air travel accounted for an estimated 6.9% share of Britain's carbon dioxide emissions in 2004, according to the government's environmental affairs department. But that portion is believed to be rising. Last May, the World Development Movement, an activist group devoted to raising awareness about climate change, reported that aviation accounts for 12.4% of emissions. Globally, international aviation emissions grew by 86.1% from 1990 to 2004, according to a report by the European Federation for Transport and Environment.
Parliament has adopted legislation aimed at reducing overall carbon dioxide emissions by 60% from 1990 to 2050.
"It's mathematically impossible to have the government's aviation expansion plans and hit their climate change targets," Thompson said.
The expansion plan also has drawn fire from the tidy suburbs surrounding Heathrow, now facing even more noise and jet exhaust. Under the expansion plan, the village of Sipson, which lies in the trajectory of the proposed runway, would be paved over, destroying more than 700 homes and displacing an estimated 1,600 people.
In last month's protest at Heathrow, which has been under heavy surveillance since authorities uncovered an alleged plot to bomb transatlantic airliners in 2006, protesters boarded the targeted plane in Manchester and flew to London. They disembarked after all the other passengers and briefly entered the terminal, then returned to the runway through an emergency door that had been left open, Jones said.
From there, they walked to the plane, climbed the boarding stairs and hoisted themselves to the top of the jetliner.
Police are still investigating the incident, as is BAA, which said in a statement, "Whilst the BAA respects people's right to protest lawfully, direct action on the airport is extremely irresponsible, dangerous and illegal."
Jones said the activists did not breach security. "We showed up a hole in the emergency security system, but we didn't get through -- we had to go through the metal detectors like everyone else," she said.
"We've really got to make the government listen when it seems like it's going around with its hands up over its head," she said. "You know, sometimes you have to do those kinds of stunts to get their attention."