CDIAC - Carbon Dioxide Information Analysis Center CDIAC - Carbon Dioxide Information Analysis Center

NDP-050/R1

Carbon Flux to the Atmosphere From Land-use Changes: 1850 to 1990

Contributed by

Richard A. Houghton
Joseph L. Hackler
The Woods Hole Research Center
Woods Hole, Massachusetts

Please Note:
Revised data through the year 2000 are available in CDIAC's Trends Online.


Prepared by Robert M. Cushman
Carbon Dioxide Information Analysis Center
Environmental Sciences Division
Publication No. 5054
Date Published: February 2001

Prepared for the
Environmental Sciences Division
Office of Biological and Environmental Research
Budget Activity Number KP 12 04 01 0

Prepared by the
Carbon Dioxide Information Analysis Center
OAK RIDGE NATIONAL LABORATORY
Oak Ridge, Tennessee 37831-6335
managed by
University of Tennessee-Battelle, LLC
for the
U.S. DEPARTMENT OF ENERGY
under contract DE-AC05-00OR22725

CONTENTS

ABSTRACT

1. BACKGROUND INFORMATION
2. APPLICATIONS OF THE DATA
3. DATA LIMITATIONS AND RESTRICTIONS
4. DATA CHECKS AND PROCESSING PERFORMED BY CDIAC
5. INSTRUCTIONS FOR OBTAINING THE DATA AND DOCUMENTATION
6. REFERENCES
7. LISTING OF FILES PROVIDED
8. DESCRIPTION OF THE DOCUMENTATION FILE
9. DESCRIPTION, FORMAT, AND PARTIAL LISTINGS OF THE ASCII DATA FILES
10. DESCRIPTION AND FORMAT OF THE LOTUS 1-2-3 BINARY SPREADSHEET FILES
11. SAS AND FORTRAN CODES TO ACCESS THE DATA
APPENDIX A: ECOSYSTEM AREA BY REGION
APPENDIX B: REGIONAL LAND-USE CHANGE AND WOOD HARVEST DATA
APPENDIX C: REGIONAL CARBON-CHANGE COEFFICIENTS
APPENDIX D: FULL LISTING OF NDP050.DAT (FILE 2)
APPENDIX E: FULL LISTING OF COMPARE.DAT (FILE 4)
APPENDIX F: REPRINT OF PERTINENT LITERATURE: Houghton, R. A. 1999. The annual net flux of carbon to the atmosphere from changes in land use 1850 1990. Tellus 51B:298 313.

ABSTRACT

Houghton, R. A., and J. L. Hackler. 2001. Carbon Flux to the Atmosphere from Land-Use Changes: 1850 to 1990. ORNL/CDIAC-131, NDP-050/R1. Carbon Dioxide Information Analysis Center, U.S. Department of Energy, Oak Ridge National Laboratory, Oak Ridge, Tennessee, U.S.A.

The database documented in this numeric data package, a revision to a database originally published by the Carbon Dioxide Information Analysis Center (CDIAC) in 1995, consists of 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).

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.

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 this 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 this documentation are available without charge on a variety of media and via the Internet from CDIAC.

Keywords: agriculture, carbon, deforestation, forests, land cover, land use, pastures, plantations, shifting agriculture, soil, vegetation

1. BACKGROUND INFORMATION
In the attempt to "balance" the global carbon cycle (that is, reconcile the known sources and sinks of carbon), two major unknowns remain: the flux between the atmosphere and the oceans and the flux between the atmosphere and terrestrial ecosystems. To address the latter, several investigators have attempted to estimate the flows of carbon between the atmosphere and both temperate and tropical ecosystems.

Quantification of the role of changing land use in the global cycling of carbon (and, consequently, in controlling atmospheric concentrations of carbon dioxide, the single most important greenhouse gas) requires complete, consistent, and accurate databases of vegetation, land use, and biospheric carbon content. The Carbon Dioxide Information Analysis Center (CDIAC) has previously made available several important quality-assured and documented databases on this topic (Olson et al. 1985, Richards and Flint 1994, Houghton and Hackler 1995, and Brown and Gaston 1996).

This database is a revision to Houghton and Hackler (1995). This revised numeric data package provides and documents the data corresponding to the analysis reported by Houghton (1999). It consists of 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 shown in Figure 1 and specified by country in Table 1 (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. Note that South and Central America, Tropical Africa, and South and Southeast Asia, as used in this database, are called Latin America, Sub-Saharan Africa, and Tropical Asia, respectively, in Houghton (1999). 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).

The approach used to derive this time series of flux estimates is described fully in Houghton (1999) and other publications (Houghton et al. 1983, 1987; Houghton and Hackler 1995, 1999). The methodology takes into account not only the initial removal and oxidation of the carbon in the vegetation but also subsequent regrowth and changes in soil carbon. The net flux of carbon to the atmosphere from changes in land use from 1850 to 1990 was modeled as a function of documented land-use change and changes in aboveground and belowground carbon following changes in land use. The changes in carbon, with time, following land-use change are specified by region and ecosystem type.

Data on ecosystem areas in each region are listed in Appendix A, which provides areas for the years 1700 (for six of the nine regions), 1850, and 1990, along with the percent change from 1850 to 1990.

Data on changes in land-use and wood harvest are listed in Appendix B, which provides the regional details of fuelwood (nonindustrial logging) and timber (industrial logging) harvest by forest type, changes in area of pasture, forest plantation, afforestation, forest clearing for croplands, and lands in shifting cultivation.

The approach uses a bookkeeping model to track, with an annual time step, changes in aboveground and belowground carbon in different kinds of ecosystems following changes in land use. Annual rates of expansion and contraction of agricultural area (for cropland, pasture, and shifting cultivation) and of wood harvest were used to estimate the types of ecosystem affected and the change in area of each affected ecosystem type. Then, response curves were generated to estimate the changes in carbon, for years to decades, that follow each type of land management or land-use change. All carbon in the affected area is accounted for: live vegetation, soil, slash (woody debris produced during disturbance), and wood products. However, this procedure does not account for all processes that affect ecosystem carbon storage and fluxes (e.g., natural disturbances, fire suppression, and environmental factors, such as CO2 and climate, that affect vegetation). Furthermore, the analysis ignores fluxes of carbon to or from ecosystems not directly affected by land-use change. Data on land-use change, wood harvest, and carbon in ecosystems were obtained from a number of sources, detailed in Houghton (1999).

The bookkeeping model partitioned the vegetation after land-use change into three pools: standing live vegetation, dead material left on-site, and woody material removed from the site. The model tracked the return of carbon in the remaining live vegetation to pre-disturbance values. Dead material left on-site and woody material removed from the site (e.g., for timber or firewood) decayed at specified rates. Changes in soil carbon included both post-disturbance losses and eventual recoveries. The coefficients and time constants were specified by region, ecosystem type, and land-use type (see Appendix C, which provides details of changes in carbon in vegetation and soils with time as a result of land-use change). Finally, changes in on-site carbon pools and carbon in off-site wood products were used to estimate fluxes to and from the atmosphere.

The estimated global total net flux of carbon from changes in land use increased from 397 Tg of carbon (1 teragram = 1012 gram) in 1850 to 2187 Tg or 2.2 Pg of carbon (1 petagram = 1015 gram) in 1989 and then decreased slightly to 2103 Tg or 2.1 Pg of carbon in 1990 (Figure 2 and Appendix D). The global net flux during the period 1850 to1990 was 124 Pg of carbon. 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; for comparison, the estimated 1990 carbon flux to the atmosphere from fossil-fuel combustion and cement production has been estimated at 6.1 Pg of carbon (Marland et al. 1999).

This revised database provides estimates for all regions through 1990, whereas Houghton and Hackler (1995) provided estimates for only three regions (South and Central America, Tropical Africa, and South and Southeast Asia) through 1990, for one region (the Former Soviet Union) through 1985, and for the remaining five regions (North America, Europe, North Africa and the Middle East, China, and the Pacific Developed Region) through 1980. For some variables (e.g., fuelwood harvest in South and Southeast Asia, by forest type) the data extend beyond 1990.

The approach used in Houghton (1999) differs from that used in earlier estimates in several respects:

  • The analysis for South and Southeast Asia has been reconstructed (Houghton and Hackler 1999) to directly assess the effects of logging based on mass of harvested material. This analysis is now methodologically consistent with that for other regions, whereas the approach used in Houghton and Hackler (1995) modeled the region based upon estimated degradation of forest biomass.
  • The timber harvest rates for China (files chin-rat.* in Houghton and Hackler 1995, Appendix B in this document) were relabeled to correspond to the correct ecosystem.
  • The clearing rates and harvest mass for the Former Soviet Union are documented in Melillo et al. (1988), replacing the input rates that had been taken from Houghton et al. (1983) and provided in Houghton and Hackler (1995) as files fsu-rat.* (Appendix B in this document).
  • Revised data for South and Central America (Houghton et al. 1991a, 1991b ) were used. The earlier data were provided in Houghton and Hackler (1995) as files scam-re.* and scam.rat.*.
  • Houghton (1999) mentioned three other revisions to the earlier estimates: The residence time of plant debris removed during clearing for agriculture was reduced, forest plantations were considered, and deforestation rates were updated.

2. APPLICATIONS OF THE DATA
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 provided in Appendix B will be useful for estimating both the recovery of ecosystems following disturbance and the oxidation of carbon in wood products.


3. DATA LIMITATIONS AND RESTRICTIONS
The methodology of Houghton (1999) is limited to deliberate changes in land use (e.g., clearing for agriculture and harvest of forests for timber and fuelwood) and does not account for all processes that affect ecosystem carbon storage and fluxes (e.g., natural disturbances; fire suppression and silvicultural practices; and environmental factors, such as CO2, nitrogen deposition, acid precipitation, ultraviolet radiation, and climate, that affect vegetation). Furthermore, the analysis ignores fluxes of carbon to or from ecosystems not directly affected by land-use change. In a study of net flux from land-use change in the United States (Houghton et al. 1999), the authors concluded that such environmental factors as climate and increased CO2 could have accounted for 2 to 4 times as much carbon accumulation as did recovery from previous harvests.

Houghton and Hackler (1999) consider at length the uncertainties associated with estimates of net carbon flux from land-use change. For tropical Asia, they estimate the uncertainty of the long- term flux to be about 30%. The sources of uncertainty are divided into estimating the areas of land affected by change, estimating the biomass of the land (especially in the years before human disturbance), and estimating changes in carbon stocks over time.

Houghton (1999) addresses the simplifications, approximations, and assumptions that are inherent in the estimation of carbon fluxes based on available data, such as estimation of time series of wood harvest or area of cropland by extrapolating from population time series and single-year per capita data.

Additional, region-specific, data limitations are mentioned in Houghton (1999):

  • In China, Europe, North Africa and the Middle East, North America, the Pacific Developed Region, and South and Central America, harvest of timber was not distinguished from harvest of fuelwood, even though they have different carbon oxidation rates.
  • Only in South and Central America and in South and Southeast Asia was shifting cultivation considered.
  • In the Former Soviet Union, the effects of grazing and peat drainage were not considered.
  • In South and Central America, carbon flux from an increase in degraded lands was excluded.
  • In South and Southeast Asia, the extraction of fuelwood during the early years may have been underestimated, because of an inverse relationship between per capita extraction and population density.
  • In Tropical Africa, harvest of wood and shifting cultivation were not included.

The estimates of annual net carbon flux on a global total basis, derived from this database and reported by Houghton (1999), vary somewhat from estimates reported previously (e.g., Houghton et al. 1983, Houghton and Skole 1990, Houghton and Hackler 1995) [Appendix E; but note that the data for the period 1850 to 1859 attributed in Figure 3 and Appendix E to Houghton et al. (1983) were not actually presented in that publication but are present in the data used in that publication]. According to the data presented in this numeric data package, the total flux over the period 1850 to 1980 was 103 Pg of carbon (corrected from the 109 Pg of carbon estimate reported in Houghton 1999). This estimate is considerably lower than that found in Houghton et al. (1983) for the (shorter) period 1860 to 1980, 180 Pg of carbon, which has been characterized (Houghton 1999) as an overestimate for three reasons: (1) The amount of soil carbon lost with cultivation was overestimated, because an observed 50% loss of carbon in the upper 20 to 30 cm of the soil column was applied to the top 1 m of soil; (2) estimates of forest biomass in Latin America and Africa were too high; and (3) there was no distinction between harvests of fuelwood and timber despite their very different efficiencies of wood removal. The estimate of global total net flux over the period 1850 to 1980 derived from the data in this numeric data package (103 Pg of carbon) is closer to the more recent estimate in Houghton and Skole (1990): A value of 110 Pg of carbon is reported in that paper, although the authors (personal communication) have noted that the methodology and data described in the paper actually yield a total of 118 Pg of carbon. It is also closer to the estimate of 106 Pg of carbon in Houghton (1993) and to the estimate of 99 Pg of carbon in Houghton and Hackler (1995).


4. DATA CHECKS AND PROCESSING PERFORMED BY CDIAC
An important part of the data-packaging process at CDIAC involves the quality assurance (QA) of data before distribution. To guarantee data of the highest possible quality, CDIAC performs extensive QA checks, examining the data for completeness, reasonableness, and accuracy, through close cooperation with the data contributor.

CDIAC did not attempt to run the bookkeeping model to validate the estimates presented in Houghton (1999). Rather, CDIAC focused its QA efforts on the format and consistency of the datasets and on comparing the values in the database with the corresponding values specified in Houghton (1999).

The annual net flux estimates by region for the period 1850 to 1990 were graphed and visually compared with Figure 5 in Houghton (1999), and the annual global total estimates for the period 1850 to 1990 were graphed and visually compared with Figure 6 in Houghton (1999).

The global total net flux estimates, derived from this database, for the periods 1850 to 1980 (103 Pg of carbon) and 1850 to 1990 (124 Pg of carbon) were compared with the corresponding totals reported in Table 3 of Houghton (1999). While the 1850 to 1990 estimates were identical, the 1850 to 1980 total derived from this database differed from the value of 109 Pg of carbon reported in Houghton (1999). This was determined to be an error in Houghton (1999) rather than an error in the database.

Regional total net flux estimates, derived from this database, for the period 1850 to 1990 and the average annual flux for the 1980s were compared with the corresponding totals reported in Table 2 of Houghton (1999). They all agreed, with the exception of the estimate of the 1850 to 1990 total for the Former Soviet Union, which is 10.7 Pg of carbon according to this database but 10.4 Pg of carbon according to Houghton (1999). This discrepancy is attributed to the current explicit specification of volume of timber and fuelwood harvest in the data input and modeling process (as opposed to the previous use of area harvested as a surrogate for the volume of harvest).

Equivalent files compare.dat and compare.wk1 list the year-by-year estimates of global total net flux plotted in Figure 6 of Houghton (1999), corresponding to the estimates presented in Houghton et al. (1983), Houghton and Skole (1990, as corrected), Houghton and Hackler (1995), and Houghton (1999, as corrected).


5. INSTRUCTIONS FOR OBTAINING THE DATA AND DOCUMENTATION

This database (NDP-050/R1) is available free of charge from CDIAC. The files are available via the Internet, from CDIAC's World-Wide-Web site (http://cdiac.esd.ornl.gov), or from CDIAC's anonymous file transfer protocol (FTP) area (cdiac.esd.ornl.gov) as follows:

  1. FTP to cdiac.esd.ornl.gov (128.219.24.36).
  2. Enter "ftp" as the user id.
  3. Enter your electronic mail address as the password (e.g., fred@zulu.org).
  4. Change to the directory "pub/ndp050" (i.e., use the command "cd pub/ndp050").
  5. Set ftp to get ASCII files by using the ftp "ascii" command.
  6. Retrieve the ASCII database documentation file by using the ftp "get ndp050.txt" command.
  7. Retrieve the ASCII data files by using the ftp "mget *.dat" command.
  8. Set ftp to get binary files by using the ftp "binary" command.
  9. Retrieve the binary spreadsheet files by using the ftp "mget *.wk1" command.
  10. Exit the system by using the ftp "quit" command.
  11. Uncompress the files on your computer if they are obtained in compressed format.
For non-Internet data acquisitions (e.g., diskette or CD-ROM) or for additional information, contact:

User Services
Carbon Dioxide Information Analysis Center
Oak Ridge National Laboratory
P.O. Box 2008
Oak Ridge, Tennessee 37831-6335, U.S.A.

Telephone: 1-865-574-3645
Telefax: 1-865-574-2232
E-mail: cdiac@ornl.gov


6. REFERENCES

Brown, S., and G. Gaston. 1996. Tropical Africa: Land use, biomass, and carbon estimates for 1980 (R. C. Daniels, editor). ORNL/CDIAC-92, NDP-055. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee.

Houghton, R. A. 1993. The flux of carbon from changes in land use. pp. 39-42. In I. G. Enting and K. R. Lassey (eds.). Projections of Future CO2. Technical paper 27, CSIRO Division of Atmospheric Research, Mordialloc, Australia.

Houghton, R. A. 1999. The annual net flux of carbon to the atmosphere from changes in land use 1850-1990. Tellus 51B:298-313.

Houghton, R. A., R. D. Boone, J. R. Fruci, J. E. Hobbie, J. M. Melillo, C. A. Palm, B. J. Peterson, G. R. Shaver, G. M. Woodwell, B. Moore, D. L. Skole, and N. Myers. 1987. The flux of carbon from terrestrial ecosystems to the atmosphere in 1980 due to changes in land use: Geographic distribution of the global flux. Tellus 39B:122-139.

Houghton, R. A., and J. L. Hackler. 1995. Continental scale estimates of the biotic carbon flux from land cover change: 1850-1980 (R. C. Daniels, editor). ORNL/CDIAC-79, NDP-050. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee.

Houghton, R. A., and J. L. Hackler. 1999. Emissions of carbon from forestry and land-use change in tropical Asia. Global Change Biology 5:481-492.

Houghton, R. A., J. L. Hackler, and K. T. Lawrence. 1999. The U.S. carbon budget: Contributions from land-use change. Science 285:574-578.

Houghton, R. A., J. E. Hobbie, J. M. Melillo, B. Moore, B. J. Peterson, G. R. Shaver, and G. M. Woodwell. 1983. Changes in the carbon content of terrestrial biota and soils between 1860 and 1980: A net release of CO2 to the atmosphere. Ecological Monographs 53:235-262.

Houghton, R. A., D. S. Lefkowitz, and D. L. Skole. 1991a. Changes in the landscape of Latin America between 1850 and 1980 (I). A progressive loss of forests. Forest Ecology Management 38:143-172.

Houghton, R. A., and D. L. Skole. 1990. Carbon. pp. 393-408. In B. L. Turner, W. C. Clark, R. W. Kates, J. F. Richards, J. T. Mathews, and W. B. Meyer (eds.), The Earth as Transformed by Human Action. Cambridge University Press, Cambridge, U.K.

Houghton, R. A., D. L. Skole, and D. S. Lefkowitz. 1991b. Changes in the landscape of Latin America between 1850 and 1980 (II). A net release of CO2 to the atmosphere. Forest Ecology Management 38:173-199.

Marland, G., A. Brenkert, and J. Olivier. 1999. CO2 from fossil fuel burning: A comparison of ORNL and EDGAR estimates of national emissions. Environmental Science & Policy 2:265-273.

Melillo, J. M., J. R. Fruci, R. A. Houghton, B. Moore, and D. L. Skole. 1988. Land-use change in the Soviet Union between 1850 and 1980: Causes of a net release of CO2 to the atmosphere. Tellus 40B:116-128.

Olson, J. S., J. A. Watts, and L. J. Allison. 1985. Major world ecosystem complexes ranked by carbon in live vegetation: A database. NDP-017. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee.

Richards, J. F., and E. P. Flint. 1994. Historic land use and carbon estimates for South and Southeast Asia (R. C. Daniels, editor). ORNL/CDIAC-61, NDP-046. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee.


7. LISTING OF FILES PROVIDED

The database consists of five files (see Table 2), including this documentation file. The data files (ndp050.dat and ndp050.wk1; and compare.dat and compare.wk1) are available in two formats: as flat ASCII files and as binary spreadsheet files (in Lotus 1-2-3 format, but readable by other spreadsheet programs).


8. DESCRIPTION OF THE DOCUMENTATION FILE

The ndp050.txt (File 1) file is an ASCII text equivalent of this document.


9. DESCRIPTION, FORMAT, AND PARTIAL LISTINGS OF THE ASCII DATA FILES

Table 3 describes the format and contents of the ASCII data file ndp050.dat (File 2) distributed with this numeric data package. Table 3 also indicates the column in the corresponding spreadsheet file ndp050.wk1 in which each variable is found. There are no missing-values in these two files.

First two data records: 

    1850   87.28      42.48    55.04         3.98      5.61     58.56    
56.52      85.63       2.05   397.145
    1851   87.22      42.18    55.02         3.98      6.47     58.55    
56.50      85.20       2.04   397.164
Last two data records: 
    1989    9.47     579.12   -18.42        22.47    337.54     21.19    
49.85    1180.05       5.29  2186.550
    1990   12.42     577.16   -18.08        23.24    341.50     20.11    
48.69    1094.39       3.92  2103.342

Table 4 describes the format and contents of the ASCII data file compare.dat (File 4) distributed with this numeric data package. Table 4 also indicates the column in the corresponding spreadsheet file compare.wk1 in which each variable is found. The missing-value indicator in the ascii file is -9.999 (in the spreadsheet file, cells representing missing values are simply left blank).

First two data records: 

1850         0.458             0.278              0.352       0.397
1851         0.464             0.319              0.383       0.397

Last two data records: 

1989        -9.999            -9.999              1.611       2.187
1990        -9.999            -9.999              1.614       2.103

10. DESCRIPTION AND FORMAT OF THE LOTUS 1-2-3 BINARY SPREADSHEET FILES

Lotus 1-2-3 binary spreadsheet file ndp050.wk1 (File 3) contains the same information as the corresponding ASCII file ndp050.dat (File 2), and Lotus 1-2-3 binary spreadsheet file compare.wk1 (File 5) contains the same information as the corresponding ASCII file compare.dat (File 4).

Table 3, which describes the contents and format of ndp050.dat, also indicates the column of ndp050.wk1 in which each variable is found, and Table 4, which describes the contents and format of compare.dat, also indicates the column of compare.wk1 in which each variable is found.


11. SAS AND FORTRAN CODES TO ACCESS THE DATA

The following is SAS code to read file ndp050.dat: 
/*** SAS code to read ndp050.dat ***/
data ndp050;
infile 'ndp050.dat' firstobs=10;
input YEAR 5-8 NAM 11-16 SCAM 22-27 EUROPE 31-36 NAFRME 45-49 
      TRAFR 54-59 FSU 64-69 CHINA 74-79 SSEASIA 84-90 PACDR 97-101 
      TOTAL 104-111;
run;
The following is Fortran code to read file ndp050.dat: 

C *** Fortran program to read the file "ndp050.dat"
C *** from Houghton's CDIAC NDP-050 that corresponds
C *** with the 1999 Tellus article.
C
      INTEGER YEAR
      REAL NAM, SCAM, EUROPE, NAFRME, TRAFR, FSU, CHINA,
     +     SSEASIA, PACDR, TOTAL 
C 
      OPEN (UNIT=1, FILE='ndp050.dat')
C
C *** SKIP OVER HEADER INFO.
    9 READ (1,100) 
  100 FORMAT (////////)
C *** READ DATA
   10 READ (1,101,END=99) YEAR, NAM, SCAM, EUROPE, NAFRME,
     + TRAFR, FSU, CHINA, SSEASIA, PACDR, TOTAL
  101 FORMAT (4X,I4,2X,F6.2,5X,F6.2,3X,F6.2,8X,F5.2,4X,
     + F6.2,4X,F6.2,4X,F6.2,4X,F7.2,6X,F5.2,2X,F8.3)
C
      GO TO 10
   99 CLOSE (UNIT=1)
      STOP
      END
The following is SAS code to read file compare.dat: 
/*** SAS code to read compare.dat ***/
data compare;
infile 'compare.dat' firstobs=14;
input YEAR 1-4 HETAL83 13-18 HS90 31-36 HH95 51-55 H99 63-67;
run;
The following is Fortran code to read file compare.dat: 
C *** Fortran program to read the file "compare.dat"
C *** from Houghton's CDIAC NDP-050 that corresponds
C *** with the 1999 Tellus article.
C
      INTEGER YEAR
      REAL HETAL83, HS90, HH95, H99
C 
      OPEN (UNIT=1, FILE='compare.dat')
C *** SKIP OVER HEADER INFORMATION
    9 READ (1,100)
  100 FORMAT (////////////)
C *** READ DATA
   10 READ (1,101,END=99) YEAR, HETAL83, HS90, HH95, H99
  101 FORMAT (I4,8X,F6.3,12X,F6.3,14X,F5.3,7X,F5.3)
C
      GO TO 10
   99 CLOSE (UNIT=1)
      STOP
      END
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