Factoring out natural and indirect human effects on terrestrial carbon sources and sinks

Josep G. Canadell, Miko U.F. Kirschbaum, Werner A. Kurz, María José Sanz, Bernhard Schlamadinger, Yoshiki Yamagata

Research output: Contribution to journalArticlepeer-review

126 Citations (Scopus)


The capacity to partition natural, indirect, and direct human-induced effects on terrestrial carbon (C) sources and sinks is necessary to be able to predict future terrestrial C dynamics and thus their influence on atmospheric CO2 growth. However, it will take a number of years before we can better attribute quantitative estimates of the contribution of various C processes to the net C balance. In a policy context, factoring out natural and indirect human-induced effects on C sources and sinks from the direct human-induced influences, is seen as a requirement of a C accounting approach that establishes a clear and unambiguous connection between human activities and the assignment of C credits and debits. We present options for factoring out various groups of influences including climate variability, CO2 and N fertilization, and legacies from forest management. These are: (i) selecting longer accounting or measurement periods to reduce the effects of inter-annual variability; (ii) correction of national inventories for inter-annual variability; (iii) use of activity-based accounting and C response curves; (iv) use of baseline scenarios or benchmarks at the national level; (v) stratification of the landscape into units with distinct average C stocks. Other, more sophisticated modeling approaches (e.g., demographic models in combination with forest inventories; process-based models) are possible options for future C accounting systems but their complexity and data requirements make their present adoption more difficult in an inclusive international C accounting system.

Original languageEnglish
Pages (from-to)370-384
Number of pages15
JournalEnvironmental Science and Policy
Issue number4
Publication statusPublished - 2007 Jun
Externally publishedYes


  • C sink processes
  • C source processes
  • Carbon cycle
  • Factoring out
  • Forests
  • Kyoto protocol
  • Marrakesh Accords

ASJC Scopus subject areas

  • Geography, Planning and Development
  • Management, Monitoring, Policy and Law


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