BBC News has learned the latest data shows CO2 levels now stand at 381 parts per million (ppm) - 100ppm above the pre-industrial average.
The research indicates that 2005 saw one of the largest increases on record - a rise of 2.6ppm.
The chief carbon dioxide analyst for Noaa says the latest data confirms a worrying trend that recent years have, on average, recorded double the rate of increase from just 30 years ago.
The precise level of carbon dioxide in the atmosphere is of global concern because climate scientists fear certain thresholds may be "tipping points" that trigger sudden changes.
"Today we're over 380 ppm," he said. "That's higher than we've been for over a million years, possibly 30 million years. Mankind is changing the climate."
One of these days I am going to sit down and make a blog post containing my predictions for the future along with the degree of certainty I think each prediction carries. One of the predictions will be that, in the not too distant future, mankind will wake up to the reality of the climate having experienced, or clearly entered, a "tipping point". (Yeah, I know, you can't "enter" a "point".)
Among the factors that could change this outcome is a huge human dieoff. But then, even if CO2 concentrations were somehow frozen at today's levels, the warming effects will continue for some time, continuing and accelerating the release of methane from tundra. That we may have already crossed a pre-tipping point, where events were taken out of human hands, seems as likely as any other element in a credible forecast of cataclysmic things like this.