The volume of greenhouse gases causing global warming rose to a new high last year, the UN World Meteorological Organization said Tuesday, warning it is becoming increasingly unlikely the world can limit rising temperatures to UN-backed targets.
Levels of carbon dioxide (CO2) — the single most important man-made contributor to climate change — rose to 390.9 parts per million in 2011, which is 2.0 ppm higher than in 2010, the WMO said.
Pointing out that the worst warming gases — CO2, methane and nitrous oxide — had all reached new highs last year, the agency’s Secetary-General Michel Jarraud said “it is getting increasingly unlikely” that a UN-backed pledge to limit global warming to two degrees Celsius (3.6 degrees Fahrenheit) could be achieved.
“Even if we were able to stop them tomorrow, these greenhouse gases will continue to have an effect for centuries,” Jarraud said at the launch of the annual Greenhouse Gas Bulletin report in Geneva.
CO2 levels are at 140 percent of the pre-industrial level before 1750, Jarraud said. According to the WMO, about 375 billion tonnes of carbon have been released into the atmosphere as CO2 in the past 260 years.