GENEVA - Carbon dioxide levels in the atmosphere reached a record high in 2013 as increasing levels of man-made pollution transform the planet, the U.N. weather agency said Tuesday. In an annual report, the World Meteorological Organization said that carbon dioxide, the heat-trapping gas blamed for the largest share of global warming, rose to global concentrations of 396 parts per million last year, the biggest year-to-year change in three decades. That's an increase of 2.9 ppm from the previous year — and is 42 percent higher than before the Industrial Age, when levels were about 280 parts per million.

"We know without any doubt that our climate is changing and our weather is becoming more extreme due to human activities such as the burning of fossil fuels," said WMO Secretary-General Michel Jarraud. "Time is not on our side, for sure." The report also said the rate of ocean acidification, which comes from added carbon absorbed by oceans, "appears unprecedented at least over the last 300 million years."

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- The Associated Press