WMO Greenhouse Gas Bulletin - No.2: The State of Greenhouse Gases in the Atmosphere Using Global Observations through 2005

The latest analysis of data from the WMO-GAW Global Greenhouse Gas Monitoring Network shows that the globally averaged mixing ratios of carbon dioxide (CO2) and nitrous oxide (N2O) have reached new highs in 2005 with CO2 at 379.1ppm and N2O at 319.2ppb. The mixing ratio of methane (CH4) remains unchanged at 1783ppb. These values are higher than those in pre-industrial times by 35.4%, 18.2% and 154.7%, respectively. Atmospheric growth rates in 2005 of these gases are consistent with recent years. Methane growth has slowed during the past decade. The recently introduced NOAA Annual Greenhouse Gas Index (AGGI) shows that from 1990 to 2005 the atmospheric radiative forcing by all long-lived greenhouse gases has increased by 21.5%.