Aviation balances technology and emissions

Aircraft makers have made significant progress in making airplanes more fuel efficient. But those gains have been drowned out by the simultaneous boom in air traffic. There's no sign of that trend reversing anytime soon — and that's putting pressure on policymakers and activists to cut emissions by slashing demand for flying. Airplanes are becoming greener — just not fast enough to keep with soaring numbers of airplanes. The aviation sector has been gradually improving its energy efficiency. The amount of fuel it takes to carry a passenger a given distance has dropped by some 25 percent since 2005. But at the same time the number of kilometers that are being traveled is growing swiftly. After a brief downturn in 2008 during the height of the financial crisis, air travel in Europe has continued its seemingly inexorable rise.