The U.N. weather agency says concentrations of carbon dioxide pollution in the atmosphere have accelerated and reached a record high in 2012, AP reported. The World Meteorological Organization says carbon dioxide was measured at 393.1 parts per million last year, up 2.2 ppm from the previous year. Its annual inventory released Wednesday of the chief gases blamed for global warming showed that the 2012 increase in CO2 outpaced the past decade's average annual increase of 2.02 ppm. Based on that rate, the WMO says the world's carbon dioxide pollution level is expected to cross the 400 ppm threshold by 2016 - beyond the 350 ppm that some scientists and environmental groups promote as a safe level.