Climate change activists have been camped out for a week at Heathrow, west of London. Organisers estimated there were 1,000-1,200 protesters at the camp. British police with truncheons skirmished with groups of climate change protesters on Sunday (August 19) near the headquarters of the operator of Heathrow airport. More than 1,000 climate change activists pledged a mix of peaceful protest and civil disobedience to draw attention to the impact of aviation on global warming. They want Heathrow's expansion plans dropped and the growth of air travel halted. "We have had enough of the prioritisation of economic growth over the future of our planet. The people are taking action themselves, in the knowledge that we are the only people that can put the brakes on climate chaos," said camp organiser Leila Harris. The scuffles in a field close to airport operator BAA's building came after largely peaceful marches. About 50 marchers skirted police and made it to the BAA car park by slipping through residential gardens but they were corralled into a designated area. Police chased another group into fields, hitting some with truncheons, before ringing them. The protest comes at the height of the holiday season at the world's busiest international airport that handles nearly 70 million passengers a year. BAA said the airport was operating normally and there was no disruption to passengers. Inside the terminal, where thousands of people were preparing to fly, the response to the protest was mixed. "I think they have got a point, definitely. It's very hard because someone wants to go on a holiday, flying is so much cheaper so people fly. So they've definitely got a point because we've got to do something because we're ruining the planet. But what the answer is, I don't know," said passenger Carol Lloyd. "I fly with my job so I'm one of the worst people actually probably," added passenger Adam Anderson. Scientists say air transport contributes to global warming, and that the carbon dioxide gas and water vapour emitted by aircraft are four times more potent at high altitude than at sea level. The British government says it is committed to tackling climate change and plans to set legally binding targets for cutting CO2 emissions -- but it also backs an expansion of air travel, which is set to double in the next 25 years.