"Global greenhouse gas concentrations are analyzed in terms of the changes in radiative forcing for the period beginning in 1979 when NOAA's global network became adequate. The change in annual average total radiative forcing by all the long-lived greenhouse gases since the pre-industrial era (1750) is used to define the NOAA Annual Greenhouse Gas Index (AGGI), which was introduced in 2004 [Hofmann et al., 2006a] and updated in 2006 [Hofmann et al. 2006b]. Researchers measured an additional 16.2 billion tons of carbon dioxide (CO2) — a byproduct of fossil fuel burning — and 12.2 million tons of methane in the atmosphere at the end of December 2008."
Tuesday, April 28, 2009