Carbon Flux to the Atmosphere From Land-use Changes, 1850 to 1990 (CDIAC NDP-050/R1)

The database documented in NDP-050/R1 is a revision to a database originally published by the Carbon Dioxide Information Analysis Center (CDIAC) in 1995. The data are annual estimates, from 1850 through 1990, of the net flux of carbon between terrestrial ecosystems and the atmosphere resulting from deliberate changes in land cover and land use, especially forest clearing for agriculture and the harvest of wood for wood products or energy. The data are provided on a year-by-year basis for nine regions (North America, South and Central America, Europe, North Africa and the Middle East, Tropical Africa, the Former Soviet Union, China, South and Southeast Asia, and the Pacific Developed Region) and the globe. Some data begin earlier than 1850 (e.g., for six regions, areas of different ecosystems are provided for the year 1700) or extend beyond 1990 (e.g., fuelwood harvest in South and Southeast Asia, by forest type, is provided through 1995).

Data on land-use change, wood harvest, and carbon in ecosystems were obtained from a number of sources, as detailed in Houghton (1999). First, annual rates of land-use change (expansion and contraction of agricultural area (ha/yr), including croplands, pastures, and shifting cultivation, and rates of wood harvest (m^3/yr) were used to determine the areal extent and the type of ecosystems affected by different land uses. Second, the per ha changes in carbon associated with these changes in land use formed the basis for response curves that were used in a model to calculate annual changes in carbon per ha that follow management or change in land use. The data are thus of two kinds, either related to rates of land-use change or to per ha changes in carbon storage following disturbance and management.

The global net flux during the period 1850 to 1990 was 124 Pg of carbon (1 petagram = 1015 grams). During this period, the greatest regional flux was from South and Southeast Asia (39 Pg of carbon), while the smallest regional flux was from North Africa and the Middle East (3 Pg of carbon). For the year 1990, the global total net flux was estimated to be 2.1 Pg of carbon. Houghton and Hackler (1999) consider at length the uncertainties associated with estimates of net carbon flux from land-use change.

This numeric data package contains a year-by-year regional data set of net flux estimates, a year-by-year data set comparing several estimates of global total net flux, and a documentation file (which includes SAS and Fortran codes to read the ASCII data files; SAS is a registered trademark of the SAS Institute, Inc., Cary, North Carolina 27511). The data files are provided in both flat ASCII and binary spreadsheet format. The data files and the documentation are available without charge on a variety of media and via the Internet from CDIAC.

This database will be useful for studies of the global carbon cycle, especially focusing on fluxes of carbon between terrestrial ecosystems and the atmosphere. The database will also be useful for studies of land-use change, agriculture, and forestry. The region- and ecosystem-specific parameters will be useful for estimating both the recovery of ecosystems following disturbance and the oxidation of carbon in wood products.