WMO Greenhouse Gas Bulletin - No.1: The State of Greenhouse Gases in the Atmosphere Using Global Observations up to December 2004

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), m­ethane (CH4), and nitrous oxide (N2O) have all reached new highs in 2004 with CO2 at 377.1ppm, CH4 at 1783ppb, and N2O at 318.6ppb. These values are higher than those in pre-industrial times by 35%, 155%, and 18% respectively. Atmospheric growth rates in 2004 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 2004 the atmospheric radiative forcing by all long-lived greenhouse gases has increased by 20%.