Atmospheric volumes of greenhouse gases blamed for climate change hit a new record in 2012, the World Meteorological Organisation (WMO) said on Wednesday (November 6).

"So the news are not good news. The news are, if you look at the major greenhouse gases in particular CO2, methane and Nitrous Oxide, for all these major greenhouse gases the concentrations are reaching once again record levels," WMO Secretary-General Michel Jarraud told a news conference in Geneva at which he presented the U.N. climate agency's annual Greenhouse Gas Bulletin.

"This year is worse than last year, 2011. 2011 was worse than 2010. Every year we are reaching new things. And the more time is passing without action, the more the concentration and as a result the more the impact on the climate change," he said.

Greenhouse gas emissions are set to be 8-12 billion tonnes higher in 2020 than the level needed to keep global warming below two degrees, the U.N. Environment Programme said on Tuesday.

If the world pursues its "business as usual" trajectory, it will probably hit the two degree mark in the middle of the century, Jarraud said, noting that this would also affect the water cycle, sea levels and extreme weather events.

"We are worried not only about the impact on temperature, which is important, but also the impact on the water cycle: more droughts, more floods in other parts of the world. We are worried about the impact on a number of extreme weather events, we are worried about the impact on the sea level. So we often tend to focus on the temperature but we should not forget that it's more than temperature and the more we wait for action of course the more difficult it will be to stay under this limit and the more the impact will be for many countries therefore the more expensive it will be to adapt," Jarraud said.

The WMO bulletin said the volume of carbon dioxide, or CO2, the primary greenhouse gas emitted by human activities, grew faster in 2012 than in the previous decade, reaching 393.1 parts per million (ppm), 41 percent above the pre-industrial level.

The amount of the gas in the atmosphere grew by 2.2 ppm, higher than the average of 2.02 ppm over the past 10 years.

The second most important greenhouse gas, methane, continued to grow at a similar rate to the last four years, reaching a global average of 1819 parts per billion (ppb) in 2012, while the other main contributor, nitrous oxide, reached 325.1 ppb.

Presented by Adam Justice