* Carbon dioxide levels rising rapidly
* Trends point to most pessimistic scenario
* Urgent action needed by governments
(Adds quotes, background, details)
By Robert Evans
GENEVA, Nov 23 Reuters - Concentrations of greenhouse gases, the major cause of global warming, are at their highest levels ever recorded and are still climbing, the U.N. World Meteorological Organisation (WMO) said on Monday.
The head of the agency, Michel Jarraud, said the trend could be pushing the world towards the most pessimistic assessments of the rise in temperatures expected in coming decades and said this underlined the need for urgent action.
The worst-case scenario envisaged by the IPCC (Intergovernmental Panel on Climate Change) in a 2007 report was that temperatures could rise by between 2.4 and 6.4 Celsius by the end of this century.
The Group of Eight and other major economies agreed at a summit in Italy in July to try to limit the rise to 2 Celsius.
Carbon dioxide <CO2/EUR> is entering the atmosphere at an accelerating rate, Jarraud told a news conference in Geneva to present the agency’s annual Greenhouse Gas Bulletin.
"The CO2 content in the atmosphere rose slightly faster in 2008 than over the last decade when the growth rate was 1.9 parts per million," he said.
"Levels of most greenhouse gases continue to increase," said the WMO, in the report issued before next month’s U.N. climate change conference in Copenhagen, aimed at reaching a new international accord to fight global warming.
It said the amount of carbon dioxide in the atmosphere was 385.2 parts per million in 2008, up 2 parts per million in one year.
GREENHOUSE GASES AT RECORD
"In 2008 global concentrations of carbon dioxide, methane and nitrous oxide, which are the main long-lived greenhouse gases in the atmosphere, reached the highest levels recorded since pre-industrial times," the WMO said.
The major focus at the Copenhagen summit, from December 7-18, is how targets for cuts in greenhouse gas emissions, caused mainly by burning fossil fuels like oil and gas, can be agreed and put into a new international treaty. [ID:nNGEESAL07Q]
Hopes of a legally binding agreement have slipped amid continuing disagreements between rich and poorer nations over how the burden should be shared.
Jarraud said the data showed "we are actually closer to the pessimistic scenario" for warming in the coming years.
"This reinforces the fact that action has to be taken as soon as possible," he said. "We are looking to Copenhagen to come up with a strong decision on greenhouse gases. The more we delay the decision, the bigger the impact will be."
The WMO coordinates the observation of greenhouse gases in the atmosphere through a network of stations in more than 50 countries. It has been issuing its annual bulletin since 2005.
In 1997, the U.N. held an international conference on cutting greenhouse gas emissions in Kyoto, Japan, at which most developed nations — minus the United States — agreed to reduce their emissions by 2008-2012 to 5 percent below 1990 levels.
Jarraud said the fact that levels were still increasing steadily showed that the reductions agreed in the Kyoto Protocol were not sufficient.
"But without it (the Protocol), the situation today would have been far worse," he declared.
(For WMO bulletin go to www.wmo.int/gaw ) (Editing by Jonathan Lynn and Tim Pearce) ((email@example.com; tel.: +41 22 733 38 31))r