Greenhouse Gases Soar to Record Levels in 2004

GENEVA, Switzerland, March 15, 2006 (ENS) - Concentrations of carbon dioxide (CO2), the most abundant greenhouse gas in the planet's atmosphere, as well as of the greenhouse gases methane (CH4) and nitrous oxide (N2O), reached their highest ever-recorded levels in 2004, mainly due to human activity, the United Nations meteorological agency said in a report issued late Tuesday.

Globally averaged concentrations of carbon dioxide increased by 1.8 parts per million (ppm) to 377.1 ppm, or 0.47 percent compared with 2003, the World Meteorological Organization reported in its first annual Greenhouse Gas Bulletin.

"Global observations coordinated by WMO show that levels of carbon dioxide, the most abundant greenhouse gas in the atmosphere, continue to increase steadily and show no signs of levelling off," said Michel Jarraud, WMO secretary-general.

Michel Jarraud is secretary-general of the World Meteorological Organization. (Photo courtesy WMO)

In contrast, atmospheric levels of methane, at 1,783 parts per billion (ppb), have shown signs of reaching a plateau with virtually no rise in 2004 and changing by less than five ppb per year since 1999.

Human activity such as fossil fuel exploitation, rice agriculture, biomass burning, landfills and ruminant farm animals account for some 60 percent of atmospheric methane, with natural processes including those produced by wetlands and termites responsible for the remaining 40 percent.

Greenhouse gas concentrations are determined by observations from the meteorological agencies of 44 WMO member governments. These observations are archived and distributed by the World Data Centre for Greenhouse Gases (WDCGG), located at the Japan Meteorological Agency.

NASA Space Shuttle image of the Earth's atmosphere (Photo courtesy NASA/JSC)

The WMO Bulletin states that nitrous oxide, at 318.6 ppb, has been steadily rising by about 0.8 ppb per year since 1988. Around one third of nitrous oxide discharged into the air is a result of human activities such as fuel combustion, biomass burning, fertilizer use and some industrial processes.

The rates of greenhouse gas emissions supersede those of pre-industrial times by 35 percent for CO2, 155 percent for CH4 and 18 percent for N2O.

The rates increased over the previous decade by 19 ppm, 37 ppb and 8 ppb, respectively, in absolute amounts, the agency said.

WMO plans to release the 2005 Greenhouse Gas Bulletin in November.