Experts: CO2 record illustrates 'scary' trend

EDT May 11, 2013 | http://www.usatoday.com/story/weather/2013/05/11/co2-scary-trend/2152717/

Story Highlights

• Carbon levels are rising 100 times faster than at the end of the last ice age
• "We are altering the composition of our atmosphere at an unprecedented rate," Al Gore says
• China spews the most CO2 and its emissions are growing 10% a year

WASHINGTON (AP) — The old saying that "what goes up must come down" doesn't apply to carbon dioxide pollution in the air, which just hit an unnerving milestone.
The chief greenhouse gas was measured Thursday at 400 parts per million in Hawaii, a monitoring site that sets the world's benchmark. It's a symbolic mark that scientists and environmentalists have been anticipating for years.
While this week's number has garnered all sorts of attention, it is just a daily reading in the month when the chief greenhouse gas peaks in the Northern Hemisphere. It will be lower the rest of the year. This year will probably average around 396 ppm. But not for long — the trend is going up and at faster and faster rates.