Place your bets now: When will the world's airlines operate for an entire year without emitting any carbon dioxide?

Airlines pledge carbon-neutral growth by 2020 | Grist

KUALA LUMPUR, June 8, 2009 (AFP) - The world’s airlines have committed themselves to a global cap on emissions in 2020, even allowing for a return to growth after the worldwide economic slump, the industry chief said Monday.
...
“Two years ago we set a vision to achieve carbon-neutral growth on the way to a carbon-free future. Today we have taken a major step forward by committing to a global cap on our emissions in 2020,” IATA chief Giovanni Bisignani said.