20 November 2012: According to the 2011 Greenhouse Gas Bulletin released by the World Meteorological Organization (WMO), greenhouse gas (GHG) concentrations reached new record highs in 2011. The WMO Bulletin reports that the atmospheric concentration of carbon dioxide reached 390.9 parts per million in 2011, or 140% of the pre-industrial level.

Atmospheric methane also reached a new high of about 1813 parts per billion in 2011, or 259% of the pre-industrial level. Atmospheric nitrous oxide in 2011 was about 324.2 parts per billion, or 120% of the pre-industrial level. Further, radiative forcing by long-lived GHGs increased by 30% from 1990-2011, according to the National Oceanic and Atmospheric Administration’s (NOAA) Annual Greenhouse Gas Index. Carbon dioxide accounts for about 80% of this increase.

The Bulletin includes a special focus on the role of carbon sinks in the carbon cycle, including on oceans and the terrestrial biosphere, which until now have absorbed nearly half of the carbon dioxide emitted by humans into the atmosphere. Michel Jarraud, WMO Secretary-General, said “oceans are becoming more acidic as a result of the carbon dioxide uptake” and highlighted potential repercussions for coral reefs and the underwater food chain. He called for boosting monitoring capability and scientific knowledge to better understand interactions between GHGs, oceans and Earth’s biosphere.

The Bulletin reports on atmospheric concentrations, which represent what remains in the atmosphere, rather than on emissions, or what goes into the atmosphere. The WMO Secretariat publishes the Greenhouse Gas Bulletin annually in cooperation with the Japan Meteorological Agency’s World Data Centre for Greenhouse Gases, the Global Atmosphere Watch Scientific Advisory Group for Greenhouse Gases and the NOAA Earth System Research Laboratory. [WMO Press Release]