Natural world faces collapse as wildlife population plummets Number of wild animals living on Earth set to fall by two-thirds; Trump hits back at Khizr Khan again; Afghanistan war ignored in US presidential campaign Elephants in Amboseli national park, Kenya. Global wildlife populations are set to have fallen by more than two-thirds on 1970 levels by the end of the decade, conservationists warn. Photograph: Martin Harvey/WWF/PA Edward Helmore Natural world in danger of collapse The number of wild animals living on Earth is set to fall by two-thirds by 2020, according to a new report, part of a mass extinction that is destroying the natural world upon which humanity depends. The Living Planet Index, compiled by researchers from WWF and the Zoological Society of London, shows that vertebrate populations are set to decline by 67% from 1970 levels unless urgent action is taken to reduce humanity's impact. The collapse of wildlife is, with climate change, the most striking sign of the Anthropocene, a proposed new geological era in which humans dominate the planet. Marco Lambertini, director general of WWF, said: "Lose biodiversity and the natural world and the life support systems, as we know them today, will collapse." World on track to lose two-thirds of wild animals by 2020, major report warns Trump reignites feud with Khizr Khan Donald Trump took time out of this campaign to unveil a new Trump hotel in Washington and, almost simultaneously, reignited his feud with Khizr Khan, father of slain Iraq veteran Captain Humayun Khan, when he said the soldier would still be alive if he had been president because he would not have invaded Iraq. Khizr Khan, who is currently touring Virginia on Hillary Clinton's behalf, called Trump's comments "the most cruel thing you can say". "There's no sincerity in those remarks," Khan continued. "He utters these words totally oblivious to the understanding of where we are, where we stand, what our values are, and how to be empathetic." Clinton and Michelle Obama will campaign together for the first time today, in North Carolina. Meanwhile, the citizens of Muncie, Indiana, explain why Trump speaks to them. Khizr Khan: I would stand up to Trump 'again and again and again' Why vote for those losers? For the first time there are as many millennials eligible to vote in the US election as there are baby boomers, and nearly half of them might vote for a third-party candidate. Others are planning to skip participation in the process altogether. We travel to Tucson, Arizona, to explore why large numbers of young people appear poised to sit out the election or vote for either the Libertarian, Gary Johnson, who yesterday lost his temper in an argument over his tax policy proposals, or Jill Stein of the Green party. America's longest war but ignored by Clinton and Trump With all eyes focused on Iraq, Syria and Russia's military buildup in the Middle East, the sharply deteriorating security situation in Afghanistan has been all but ignored by Clinton and Trump. Fifteen years in, Afghanistan is now America's longest war. More than 2,300 US troops have died there, and the conflict has cost an estimated $686bn. But as this week's killing of 30 villagers in Ghor province showed, Afghanistan has a way of forcing itself into the political headlights. Afghanistan is the dirty little secret of the US presidential campaign Microsoft targets creative professionals with Surface Studio Microsoft is getting artsy. The tech giant unveiled its new $3,000 Surface Studio computer for artists and designers on Tuesday in Manhattan. The new tools include a smartphone app that allows users to scan 3D images of everyday objects and move them around in virtual or "mixed" reality. "Much of technology has been slanted toward consumption," said Microsoft's CEO, Satya Nadella. "I believe that the next 25 years will be defined by technology that enables profound creation." Microsoft unveils Surface Studio in bid for creative professionals The spy who couldn't spell The idea of committing espionage began taking shape in Brian Regan's mind through the early months of 1999, after he had spent four years working at the National Reconnaissance Office (NRO), the agency responsible for managing US spy satellites. He was feeling humiliated at work, his financial situation was getting worse, and his marriage was deteriorating. He knew he wasn't going to be promoted any time soon. In our Long Read, Yudhijit Bhattacharjee tells the story of the spy who couldn't spell. How the biggest heist in the history of US espionage was foiled The fascinating story of Paul Beatty's The Sellout Paul Beatty is now the first American to win the UK's Man Booker prize, but he very nearly wasn't published in Britain at all. His rumbustious, lyrically poetic novel was turned down, his agent confirms, by no fewer than 18 publishers. And then, finally, a small independent called Oneworld – founded by a husband-and-wife team in 1986 – took it up. Turned down 18 times. Then Paul Beatty won the Booker … No clowns allowed Clowns are officially too scary for Halloween. School districts, counties and spooky festivals across the country are banning clown costumes this year, after a summer of national hysteria over "killer clowns" and soaring sales of evil clown masks. Scariest Halloween costume of 2016 faces bans across US In case you missed it … As we near the end of an epic, 18-month election cycle, Lucia Graves argues that while a short US election cycle sounds great, it wouldn't be good for democracy – notwithstanding Sheryl Crow's Change.org petition. "Reducing the amount of time we have to learn about the people running for the most powerful job in the world, particularly when so much of what comes out of their mouths is disinformation, won't make it harder to fool the American public: it will make it infinitely easier." A short US election cycle sounds great, but it wouldn't be good for democracy Manage your emails | Unsubscribe | Trouble viewing? You are receiving this email because you are a subscriber to Guardian US Briefing. Guardian News & Media Limited - a member of Guardian Media Group PLC. Registered Office: 222 Broadway, 22nd and 23rd Floors, New York, New York, 10038