GAW Greenhouse Gas Research

The Global Atmosphere Watch (GAW) programme of the World Meteorological Organization (WMO) promotes systematic and reliable observations of the global atmospheric environment. Of the greenhouse gases that are directly affected by anthropogenic activities, carbon dioxide (CO2) has the largest total radiative effect, followed by chlorofluorocarbons (CFCs), methane (CH4), tropospheric ozone (O3), and nitrous oxide (N2O). Reliable long-term estimates of sources and sinks appropriate to particular emission management scenarios require very high accuracy and precision observations of the abundance and the vertical distribution of CO2 and CH4 as well as their isotopes and related reactive (O3, CO, NOx, SO2, VOC, etc.) gases. The data are collected and distributed by the World Data Centre for Greenhouse Gases (WDCGG) at the Japan Meteorological Agency. The GAW Scientific Advisory Group for Greenhouse Gases (SAG-GHG) oversees the programme. GAW also issues the annual Greenhouse Gas Bulletin, which reports on the latest trends and atmospheric burdens of the most influential, long-lived greenhouse gases, carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), as well as a summary of the contributions of the lesser gases.

Last meeting of the SAG-GHG took place on 29th October 2011 in Wellington, New Zealand.

The first Asian GAW greenhouse gases newsletter was written by Asian GAW members on greenhouse gases in Dec. 2010 based on the mutual agreement by Asian GAW members participating in the 2nd International Workshop on Atmosphere Watch in Asia was held in Republic of Korea on October, 2011 (Newsletter vol.2 can be found in "Other" publications) .

WMO Annual Greenhouse Gas Bulletins

2011	2010	2009
2008	2007	2006
2005	2004

The greenhouse effect

The Earth has a natural greenhouse effect due to trace amounts of water vapour (H2O), carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) in the atmosphere. These gases let the solar radiation reach the Earth’s surface, but they absorb infrared radiation emitted by the Earth and thereby lead to the heating of the surface of the planet. One needs to distinguish between the natural greenhouse effect and the enhanced greenhouse effect.

The natural greenhouse effect is caused by the natural amounts of greenhouse gases, and is vital to life. In the absence of the natural greenhouse effect the surface of the Earth would be approximately 33 degrees Celsius cooler.

The enhanced greenhouse effect refers to the additional radiative forcing resulting from increased concentrations of greenhouse gases induced by human activities. The main greenhouse gases whose concentrations are rising are carbon dioxide, methane, nitrous oxide, hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs) and ozone in the lower atmosphere.


Atmospheric concentrations of important long-lived greenhouse gases over the last 2,000 years. Concentration units are parts per million (ppm) or parts per billion (ppb) (IPCC 2007). -click to enlarge-	Annual global mean temperatures (black dots) with linear fits to the data: for the last 24 years (yellow), 50 (orange), 100 (purple) and 150 years (red). The smooth blue curve shows decadal variations and the decadal 90% error range (pale blue band about that line) (IPCC 2007). -click to enlarge-

Greenhouse gas observations

Greenhouse gas observations are carried out at a large number of sites on all continents. The most recent map is shown in the last issue of the WMO Greenhouse Bulletin. The stations are described in the GAW Station Information System (GAWSIS) operated by EMPA, Switzerland.

Forty-five WMO member countries have contributed CO2 data to the GAW World Data Centre for Greenhouse Gases (WDCGG). Approximately 50% of the measurement records submitted to WDCGG are obtained at sites in the NOAA ESRL cooperative air sampling network. The rest of the network is maintained by Australia, Canada, China, Japan and many European countries.

All of the WMO Global Atmosphere Watch (GAW) monitoring stations contribute data to the WDCGG which are used in the Greenhouse Gas Bulletins listed in the List of Contributors on the WDCGG web page.