Guardian: Four Greenpeace activists were arrested today after climbing on top of a British Airways jet at Heathrow airport in a climate change protest. A Greenpeace spokesman described the stunt at terminal 1 as an “incredible security breach”. Protesters unfurled a banner over the plane’s tailfin that read: “Climate emergency – no third runway.” The spokesman said the incident took place at 9.45am, shortly after the plane had landed from …