Terminology as a key uncertainty in net land use and land cover change carbon flux estimates

J. Pongratz*, C. H. Reick, R. A. Houghton, J. I. House

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)

81 Citations (Scopus)
339 Downloads (Pure)

Abstract

Reasons for the large uncertainty in land use and land cover change (LULCC) emissions go beyond recognized issues related to the available data on land cover change and the fact that model simulations rely on a simplified and incomplete description of the complexity of biological and LULCC processes. The large range across published LULCC emission estimates is also fundamentally driven by the fact that the net LULCC flux is defined and calculated in different ways across models. We introduce a conceptual framework that allows us to compare the different types of models and simulation setups used to derive land use fluxes. We find that published studies are based on at least nine different definitions of the net LULCC flux. Many multi-model syntheses lack a clear agreement on definition. Our analysis reveals three key processes that are accounted for in different ways: the land use feedback, the loss of additional sink capacity, and legacy (regrowth and decomposition) fluxes. We show that these terminological differences, alone, explain differences between published net LULCC flux estimates that are of the same order as the published estimates themselves. This has consequences for quantifications of the residual terrestrial sink: the spread in estimates caused by terminological differences is conveyed to those of the residual sink. Furthermore, the application of inconsistent definitions of net LULCC flux and residual sink has led to double-counting of fluxes in the past. While the decision to use a specific definition of the net LULCC flux will depend on the scientific application and potential political considerations, our analysis shows that the uncertainty of the net LULCC flux can be substantially reduced when the existing terminological confusion is resolved.

Original languageEnglish
Pages (from-to)177-195
Number of pages19
JournalEarth System Dynamics
Volume5
Issue number1
DOIs
Publication statusPublished - 27 Mar 2014

Keywords

  • Land use change
  • Climate change
  • methods
  • models
  • emissions
  • CARBON DIOXIDE

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