(Bloomberg News) Carbon dioxide, methane and nitrous oxide, the main man-made greenhouse gases blamed for global warming, increased to record post-industrial concentrations last year, the United Nations said.

Carbon dioxide, the most important heat-trapping gas, last year rose to 386.8 parts per million molecules of air, the UN's World Meteorological Organization said today in an e-mailed statement. That's 1.6 ppm higher than in 2008. The methane concentration increased by 6 parts per billion while nitrous oxide rose by 0.7 parts per billion.

The atmospheric gases, stemming mainly from burning fossil fuels, changes in land use and deforestation, continued a rising trend that began with industrialization in the 18th century. The WMO report occurs before envoys from more than 190 nations meet next week in Cancun, Mexico, for negotiations aimed at developing a treaty to fight climate change.

"Greenhouse gas concentrations have reached record levels despite the economic slowdown," WMO Secretary-General Michel Jarraud said in a statement. "They would have been even higher without the international action taken to reduce them."

Methane emissions have now risen for the past three years after stalling from 1999 through 2006, according to the statement. That may be because of releases from natural sources, the WMO said. Scientists have said warmer temperatures could unlock methane from thawing permafrost soils, adding to climate change.

"Potential methane release from northern permafrost and wetlands, under future climate change is of great concern and is becoming a focus of intensive research," Jarraud said.