current co2 levels not seen in a million years

The readings at this 2-mile-high station show a troubling upward curve as the world counts down to crucial climate talks: Global-warming gases are building in the atmosphere at record levels from emissions that match scientists' worst-case scenarios.

Carbon dioxide concentrations this fall are hovering at around 385 parts per million, on their way to a near-certain record high above 390 in the first half of next year, at the annual peak.

"For the past million years we've never seen 390," said physicist John Barnes, the observatory director. "You have to wonder what that's going to do."

One leading atmospheric scientist, Stephen Schneider, sees "coin-flip odds for serious outcomes for our planet."