Associated Press: Four environmental activists were arrested after they climbed atop a plane at London’s Heathrow Airport on Monday and unfurled a banner protesting climate change. The airport said it was investigating the security breach. The group Greenpeace said four of its members walked across the airport tarmac and climbed onto the British Airways Airbus A320 after it landed on a domestic flight from Manchester. The two men and two women wrapped a banner around the tail fin reading: …