3 November 2006 – Globally averaged concentrations of human-caused carbon dioxide (CO2) in the atmosphere, the second most important greenhouse gas blamed for global warming, reached their highest levels ever recorded last year, the United Nations World Meteorological Organization (WMO) reported today.

Quantities of CO2 were measured at 379.1 parts per million (ppm) for 2005, up 0.53 per cent from 377.1 ppm in 2004, WMO said in its latest Greenhouse Gas Bulletin, the second piece of environmental bad news this week. The 35.4 per cent rise in the gas since the late 1700s has largely been generated by emissions from the combustion of fossil fuels.

On Tuesday, the UN Framework Convention on Climate Change (UNFCCC) reported that greenhouse gas emissions by industrialized countries showed a “worrying” upward trend in the 2000–2004 period and called for state policies to be intensified to achieve further cuts.

After water vapour, carbon dioxide, methane (CH4) and nitrous oxide (N2O) are the three most prevalent greenhouse gases in the Earth’s atmosphere respectively.

Today’s release of the figures comes ahead of the second meeting of the Parties to the Kyoto Protocol, which seeks to reduce greenhouse gas emissions, together with the 12th session of UNFCCC Parties in Nairobi, Kenya, from 6 to 17 November.

Concentrations of N2O also reached record highs in 2005, up 0.19 per cent from 318.6 parts per billion (ppb) to 319.2 ppb while methane remained stable at 1783 ppb. Around one third of N2O discharged into the air is a result of human activities such as fuel combustion, biomass burning, fertilizer use and some industrial processes.

Human activity such as fossil fuel exploitation, rice agriculture, biomass burning, landfills and ruminant farm animals account for some 60 per cent of atmospheric CH4, with natural processes including those produced by wetlands and termites responsible for the rest.

Source: UN News Service

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