Global Patterns of Carbon Dioxide Emissions from Soils on a 0.5 Degree Grid Cell Basis (DB-1015)

Semi-mechanistic, empirically based statistical models are used to predict the spatial and temporal patterns of global carbon dioxide emissions from terrestrial soils. Emissions include the respiration of both soil organisms and plant roots. Geographically referenced data of mean monthly air temperature and precipitation, soil organic carbon and nitrogen content, soil type and natural vegetation type were used in the model development (For discussion of underlying data for the model, see Raich, J.W. and W.H. Schlesinger. 1992. The global carbon dioxide flux in soil respiration and its relationship to vegetation and climate. Tellus. Ser. B81-99).

The investigators found that, at the global scale, rates of soil CO2 efflux correlate significantly with temperature and precipitation; they do not correlate well with soil carbon pools, soil nitrogen pools, or soil C:N. Wetlands cover about 3% of the land area but diminish predicted CO2 emissions by only about 1%. The estimated annual flux of CO2 from soils to the atmosphere is estimated to be 76.5 Pg C yr-1, 1-9 Pg greater than previous global estimates, and 30-60% greater than terrestrial net primary productivity. Historic land cover changes are estimated to have reduced current annual soil CO2 emissions by 0.2-2.0 Pg C yr-1 in comparison with an undisturbed vegetation cover. Soil CO2 fluxes have a pronounced seasonal pattern in most locations, with maximum emissions coinciding with periods of active plant growth. The models suggest that soils produce CO2 throughout the year and thereby contribute to the observed wintertime increases in atmospheric CO2 concentrations.
The DB1015 data are the predicted CO2 emissions of the model based on untransformed precipitation data and the exponential relationship between soil biological activity and temperature. The data at the 0.5° latitude by longitude spatial and monthly temporal resolution represents the best resolved estimate to date of global CO2 fluxes from soils and should facilitate investigations of net exchanges between the atmosphere and terrestrial biosphere.

The data files (~10 MB total) consist of 12 monthly and one annual model output files, one geographic information file, and a Read-Me file with simple FORTRAN data access information. The files are available from CDIAC's anonymous FTP area (http://cdiac.ornl.gov/ftp/db1015/).

PLEASE NOTE: DB1015 has been updated by NDP-081. Specifically, DB1015 used long-term climate data as model input while NDP-081 utilizes new climate and land cover data files. For more information, please refer to metadata for Interannual Variability in Global Soil Respiration on a 0.5 Degree Grid Cell Basis (1980-1994) (NDP-081) registered in Mercury or download Raich et al. (2002) at [http://cdiac.ornl.gov/epubs/ndp/ndp081/GCB2002.pdf] (provided with permission from Blackwell Science Ltd.).