There's striking new evidence that Earth's atmosphere is increasingly saturated with carbon dioxide, the major gas from fossil fuel emissions that trigger climate change.

Measurements of the climate-changing gas by instruments high on a mountain in Hawaii and around the world show that global emissions from burning fossil fuels rose last month to levels higher than at any time in human history - and higher than it has been in hundreds of thousands of years.

"This should be taken as a warning," said Ken Caldeira, an atmospheric scientist with the Carnegie Institution's department of global ecology at Stanford University. "It is time to stop building things with tailpipes and smokestacks.





"And they were probably that low millions of years ago," he said.

"The rise of carbon dioxide levels above 400 parts per million is an indicator that the problem of global warming is getting worse, not better," said Mark Z . Jacobson, a Stanford atmospheric scientist and environmental engineer, in an e-mail. "This means we need to focus more heavily on solutions to this problem, namely converting to wind, water and solar power for all purposes.


The record that reveals strikingly high levels of the gas is known to climate scientists as the Keeling Curve. It was developed by the late Charles D. Keeling, a climate scientist at the Scripps Institute of Oceanography in San Diego. His son, Ralph Keeling at Scripps, continues to compile the record from eight monitoring stations around the world.
