EARTHTRENDS DATA TABLES TECHNICAL NOTES: Carbon Dioxide Emissions by Source 2005 For more information, please consult http://earthtrends.wri.org VARIABLE DEFINITIONS AND METHODOLOGY Carbon Dioxide (CO2) Emissions by Source refers to the amount of CO2 emissions due to a specified cause. All data are converted to their actual mass of CO2 by using a multiplier of 3.664, the ratio of the mass of CO2 to that of Carbon (C). Moreover, data do not include bunker fuels used in international transportation due to the difficulty of apportioning these fuels among the countries benefiting from that transport. CO2 emission estimates from 1950 to the present are derived primarily from energy statistics published by the United Nations in its Energy Statistics Yearbook 2001. The statistics are compiled by the U.N. from annual questionnaires filled out by countries and supplemented by official national statistics. Some official sources are "supplemented by [the U.N. through] other means and estimates, where these have been subjected to professional scrutiny and debate and are consistent with other independent sources." However, the process of verifying and supplementing national data is not as extensive as that undertaken by the International Energy Agency. The Carbon Dioxide Information Analysis Center (CDIAC) calculates CO2 emissions for gas flaring, cement manufacturing, and solid, liquid, and gaseous fuels. The data is derived from statistics on fuel production, trade, and net apparent consumption by applying emissions factors for each fuel and its use. The basic equation used is CO2 emissions = P * FO * C, where P = production or consumption of a fuel, FO = the emissions factor, and C = the carbon content of the fuel in tons of C per ton of fuel. The FO of crude oil, for example, is 0.918 + 3%, while C is 0.85 per ton of fuel + 1%. Solid Fuels refer to the mass of CO2 emitted primarily, but not exclusively, from burning coal. Liquid Fuels refer to CO2 emissions primarily, but not exclusively, from burning petroleum products. Gaseous Fuels refer to CO2 emissions primarily, but not exclusively, from burning natural gas. Gas Flaring refers to CO2 emissions that result from the burning of gas released in the process of petroleum extraction. U.N. gas flaring estimates are supplemented with data from the U.S. Energy Information Administration, data provided by G. Marland at CDIAC, and a 1974 paper, “First Estimates of Global Flaring of Natural Gas” by R.M. Rotty. Cement Manufacturing refers to CO2 emissions produced as cement is calcined to form calcium oxide. Based on data from the United States Geologic Survey (USGS), it is estimated that approximately 0.5 metric tons of carbon is released for each metric ton of cement production. For further information on the data, methodology, and sources used for gas flaring, cement manufacturing, and solid, liquid, and gaseous fuels, please consult following web page maintained by CDIAC: http://cdiac.esd.ornl.gov/trends/emis/meth_reg.htm. A complete record of the formulas and assumptions used to calculate CO2 emissions is available on-line at http://cdiac.esd.ornl.gov/trends/emis/factors.htm. CO2 Emissions from Land-Use Change measures the total mass of carbon dioxide absorbed or emitted into the atmosphere as a result of man-made land use changes (e.g. deforestation, shifting cultivation, vegetation re-growth on abandoned croplands and pastures). Positive values indicate a positive net flux ("source") of CO2; for these countries, carbon dioxide has been released into the atmosphere as a result of land-use change. Negative values indicate a negative net flux ("sink") of CO2; in these countries, carbon has been absorbed as a result of the re-growth of previously removed vegetation. Data include emissions from both living and dead vegetation disturbed at the time of clearing or harvest, emissions from wood products (including fuelwood), and emissions from the oxidation of soil organic matter in the years following initial cultivation. Those ecosystems that are not directly affected by human activities such as agriculture and forestry are not included in these estimated sources and sinks. The net flux of CO2 was calculated on a global and regional level by R.A. Houghton. Regional fluxes (changes in above- and below-ground carbon) were modeled based on annual rates of wood harvest and changes in agricultural area. Once regional fluxes were calculated, they were divided among countries. For tropical regions, each flux was distributed among countries in proportion to the product of change in forest area (1990-2000) and average forest biomass as reported by the Food and Agricultural Organization (FAO)’s Forest Resources Assessment 2000 (see http://www.fao.org/docrep/004/y1997e/y1997e00.htm). For regions outside the tropics, the flux was divided among countries in proportion to annual rates of wood production (harvest) as reported by FAOSTAT (see http://apps.fao.org). The only exception to this method was for European countries between 1975 and 2000. For this interval, the regional sink was distributed among countries by the 1990-2000 change in forest area (similar to the approach for tropical regions). Three of the “regions” (Canada, the United States, and China) provided national estimates directly. FREQUENCY OF UPDATE BY DATA PROVIDERS Solid Fuels, Liquid Fuels, Gaseous Fuels, Gas Flaring, and Cement Manufacturing As of January 2005, data were available on-line through 2000 at http://cdiac.esd.ornl.gov/trends/emis/meth_reg.htm. CDIAC updates the data annually in July or August. Land Use Change Annual country-level data are provided by R.A. Houghton at the Woods Hole Research Center in Woods Hole, MA. While a number of regional and global estimates have been calculated for carbon flux from land-use change, this is the first global data set with country-level data. DATA RELIABILITY AND CAUTIONARY NOTES Solid Fuels, Liquid Fuels, Gaseous Fuels, Gas Flaring, and Cement Manufacturing Although CDIAC’s estimates of world emissions are probably within 10 percent of actual emissions, individual country estimates may depart more severely from reality. The trends demonstrated in a consistent, uniform time series are usually more accurate than individual values in the time series. CDIAC annually recalculates the entire time series from 1950 to the present, incorporating its most recent understanding and the latest corrections to the database. The carbon emissions estimates have therefore become more consistent, and probably more accurate, each year. The sum of individual country totals listed does not equal the global totals because emissions from fuels used in international trade (i.e., bunker fuels) are not included in national totals. In addition, global totals include the oxidation of fuels used for non-energy purposes, but do not include annual changes in national fuel stocks, and statistical differences exist between the sum of exports for all exporters and the sum of imports by all importers. Land Use Change These data provide a very rough picture of the level of carbon entering the atmosphere from land-use change and should be treated as order-of-magnitude estimates. Houghton states that yearly flux estimates are uncertain on the order of ±150% for large fluxes, and ±50 million metric tons of carbon per year for estimates near zero. The estimates do not explicitly include changes in carbon stocks that may result from various forms of management such as agricultural intensification, fertilization, no-till agriculture, thinning of forests, changes in species or varieties, and other silvicultural practices. Furthermore, the analysis ignores fluxes of carbon to or from ecosystems not directly affected by land-use change. SOURCES Solid Fuels, Liquid Fuels, Gaseous Fuels, Gas Flaring, and Cement Manufacturing Data are compiled by G. Marland and T.A. Boden of CDIAC and R.J. Andres of the University of North Dakota. Carbon Dioxide Information Analysis Center (CDIAC), Environmental Sciences Division, Oak Ridge National Laboratory: 2005. Global, Regional, and National CO2 Emission Estimates from Fossil Fuel Burning, Cement Production, and Gas Flaring: 1751-2000, NDP-030 (Available online at http://cdiac.esd.ornl.gov/trends/emis/meth_reg.htm). CDIAC, Oak Ridge, Tennessee. Land Use Change World Resources Institute. 2003. Carbon Emissions from Land Use, 1950 to 2000. Report to the World Resources Institute from the Woods Hole Research Center. Available on-line through the Climate Analysis Indicators Tool (CAIT) at http://cait.wri.org. Washington, DC: World Resources Institute. Adapted from Houghton, R.A. 2003. "Data Note Emissions (and Sinks) of Carbon from Land-Use Change." (Estimates of national sources and sinks of carbon resulting from changes in land use, 1950 to 2000). Report to the World Resources Institute from the Woods Hole Research Center. Available at: http://cait.wri.org/downloads/DN-LUCF.pdf.