Polluting gas levels at new highs, says UN study

The levels of the three main gases in the atmosphere that are driving the now unquestionable global warming increased to a record high in 2012, according to a United Nations body monitoring weather changes.

The World Meteorological Organization (WMO) said in a report today that atmospheric carbon dioxide (CO2) grew more rapidly last year than its average rise over the past decade. Concentrations of methane and nitrous oxide also broke previous records.

CO2, which accounts for about 80 per cent of the warming effect of greenhouse gases, gained 0.56 per cent to 393.1 parts per million molecules of air, said the WMO report. Methane concentration increased 0.33 per cent, and the nitrous oxide level climbed 0.28 per cent.

The report says the warming effect on earth's climate has increased by almost a third since 1990 due to increased emission of these gases.

The WMO's annual greenhouse gas bulletin gives a measure of concentrations in the atmosphere, not emissions on the ground.

Carbon dioxide is the most important of the gases that WMO tracks; but only about half of the CO2 that's emitted by human activities remains in the atmosphere. The rest is absorbed by the plants, trees, the land and the oceans.

Since the start of the industrial era in 1750, global average levels of CO2 in the atmosphere have increased by 141 per cent.

"The observations 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.