Estimates of deforestation in the last decade are greatest for Brazil, Colombia, the Ivory Coast, Indonesia, Laos, and Thailand. It is not clear that all of the major sources of CH4 have been identified, and the emissions rates of those that have been identified are subject to significant uncertainty. The three principal human activities that have been identified as emissions sources are cattle raising, rice production, and energy production and use. Roughly a quarter of the total atmospheric CH4 emission is attributable to the production, transfer, conversion and consumption of energy. Because the sources of CH4 are uncertain, forecasts of emissions are also uncertain.
Most forecasts simply project the rate of accumulation in the atmosphere to continue.
Ice core data indicate that the concentration of N2O was stable for approximately 3000 years and began to increase slightly since the beginning of the industrial period. The sources of N2O emissions are poorly known. The dominant human activities associated with N2O emissions are agricultural and energy use. Forecasts of future N2O emissions are very uncertain. The term chlorofluorocarbons refers to a family of compounds derived from the CH4 or higher carbon-content hydrocarbon molecule.