The amount of greenhouse gases in the atmosphere reached a record high in 2012, continuing an upward trend which is driving climate change and which will shape the future of the planet for hundreds and thousands of years, according to the United Nations World Meteorological Organization (WMO).

By absorbing much of the added heat trapped by atmospheric greenhouse gases, the oceans are delaying some of the impacts of climate change. [Photo/WMO/Olga Khoroshunova]

The agency's annual Greenhouse Gas Bulletin shows that between 1990 and 2012, there was a 32 per cent increase in radiative forcing – the warming effect on the climate – because of carbon dioxide (CO2) and other heat-trapping long-lived gases such as methane and nitrous oxide.

Carbon dioxide, mainly from fossil fuel-related emissions, accounted for 80 per cent of this increase, WMO stated in a news release. The atmospheric increase of CO2 from 2011 to 2012 was higher than its average growth rate over the past 10 years.

What is happening in the atmosphere, said the Geneva-based WMO, is "one part of a much wider picture." Only about half of the CO2 emitted by human activities remains in the atmosphere, with the rest being absorbed in the biosphere and in the oceans.

The latest findings "highlight yet again how heat-trapping gases from human activities have upset the natural balance of our atmosphere and are a major contribution to climate change," said WMO Secretary-General Michel Jarraud.

He recalled that the UN-backed Intergovernmental Panel on Climate Change (IPCC) stressed in its recent Fifth Assessment Report that atmospheric concentrations of carbon dioxide, methane, and nitrous oxide have increased to levels unprecedented in at least the last 800,000 years.

"As a result of this, our climate is changing, our weather is more extreme, ice sheets and glaciers are melting and sea levels are rising," said Mr. Jarraud.