comprising about 97 percent of total CO2 emissions from this sector, is the incineration and open burning of waste containing fossil carbon (e.g., plastics, certain textiles). The practice of waste incineration is currently more common in developed countries, while open burning of waste occurs predominantly in the developing world. However, the basic approach recommended by the IPCC for estimating CO2 emissions from these two sources is the same: the quantity of waste incinerated and/or open-burned is multiplied by default values for the dry matter content, total carbon content, fossil carbon fraction, and oxidation factor for the waste (IPCC, 2006). The major source of uncertainty is the estimation of the fossil carbon fraction of the waste, which is directly related to uncertainties regarding waste composition. Where country-specific data regarding quantities of waste incinerated and/or open-burned are not available, large uncertainties are also associated with the waste amounts determined from the IPCC default values for waste generation and management.

Nitrous Oxide

Nitrous oxide emissions comprise about 6 percent of total emissions (in terms of CO2 equivalents) from the waste sector for Annex I countries.5 The major source, comprising about 82 percent of total N2O emissions from the sector, is wastewater handling. N2O is emitted from the degradation of nitrogen components in the wastewater (e.g., urea, nitrate, protein). Although both wastewater treatment plants and the discharge of effluent into aquatic environments are sources of N2O emissions, the latter is typically a far more significant source. Emissions of N2O from wastewater effluent discharged to aquatic environments are determined using national statistics on population and annual per capita protein consumption to estimate the total amount of nitrogen discharged in wastewater effluent, and a default emission factor for the N2O emitted per unit of wastewater effluent nitrogen content (IPCC, 2006). Large uncertainties are associated with estimates of N2O emissions from wastewater handling, and the major source of uncertainty is the default emission factor for N2O from the effluent.

REFERENCES

EPA (Environmental Protection Agency), 2008, Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2006, EPA 430-R-08-005, Office of Atmospheric Programs, Washington, D.C., available at <http://www.epa.gov/climatechange/emissions/ usgginventory.html>.

IPCC (Intergovernmental Panel on Climate Change), 2006, 2006 IPCC Guidelines for National Greenhouse Gas Inventories, H.S. Eggleston, L. Buendia, K. Miwa, T. Ngara, and K. Tanabe, eds., prepared by the National Greenhouse Gas Inventories Programme, Institute for Global Environmental Strategies, Hayama, Kanagawa, Japan, 5 volumes.

UNFCCC (United Nations Framework Convention on Climate Change), 2005, Sixth compilation and synthesis of initial national communications from Parties not included in Annex I to the Convention, prepared by the UNFCCC Secretariat, October 2005, available at <http://unfccc.int/ghg_data/ghg_data_unfccc/ items/4146.php>.

UNFCCC, 2008, Report on national greenhouse gas inventory data from Parties included in Annex I to the Convention for the period 1990-2006, prepared by the UNFCCC Secretariat, November 2008, available at <http://unfccc.int/ghg_data/ghg_ data_unfccc/items/4146.php>.



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