Are land-use change emissions in southeast Asia decreasing or increasing?

Masayuki Kondo*, Stephen Sitch, Philippe Ciais, Frédéric Achard, Etsushi Kato, Julia Pongratz, Richard A. Houghton, Josep G. Canadell, Prabir K. Patra, Pierre Friedlingstein, Wei Li, Peter Anthoni, Almut Arneth, Frédéric Chevallier, Raphael Ganzenmüller, Anna Harper, Atul K. Jain, Charles Koven, Sebastian Lienert, Danica LombardozziTakashi Maki, Julia E.M.S. Nabel, Takashi Nakamura, Yosuke Niwa, Philippe Peylin, Benjamin Poulter, Thomas A.M. Pugh, Christian Rödenbeck, Tazu Saeki, Benjamin Stocker, Nicolas Viovy, Andy Wiltshire, Sönke Zaehle

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)
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Abstract

Southeast Asia is a region known for active land-use changes (LUC) over the past 60 years; yet, how trends in net CO2 uptake and release resulting from LUC activities (net LUC flux) have changed through past decades remains uncertain. The level of uncertainty in net LUC flux from process-based models is so high that it cannot be concluded that newer estimates are necessarily more reliable than older ones. Here, we examined net LUC flux estimates of Southeast Asia for the 1980s−2010s from older and newer sets of Dynamic Global Vegetation Model simulations (TRENDY v2 and v7, respectively), and forcing data used for running those simulations, along with two book-keeping estimates (H&N and BLUE). These estimates yielded two contrasting historical LUC transitions, such that TRENDY v2 and H&N showed a transition from increased emissions from the 1980s to 1990s to declining emissions in the 2000s, while TRENDY v7 and BLUE showed the opposite transition. We found that these contrasting transitions originated in the update of LUC forcing data, which reduced the loss of forest area during the 1990s. Further evaluation of remote sensing studies, atmospheric inversions, and the history of forestry and environmental policies in Southeast Asia supported the occurrence of peak emissions in the 1990s and declining thereafter. However, whether LUC emissions continue to decline in Southeast Asia remains uncertain as key processes in recent years, such as conversion of peat forest to oil-palm plantation, are yet to be represented in the forcing data, suggesting a need for further revision.

Original languageEnglish
Article numbere2020GB006909
Number of pages19
JournalGlobal Biogeochemical Cycles
Volume36
Issue number1
Early online date24 Dec 2021
DOIs
Publication statusPublished - Jan 2022

Bibliographical note

Funding Information:
This paper is a contribution to the REgional Carbon Cycle Assessment and Processes (RECCAP) phase 2 under the umbrella of the Global Carbon Project. M. Kondo and T. Maki acknowledge support by JSPS KAKENHI grant No. 19K12294 and No. 19K12312, respectively. M. Kondo and P. K. Patra were partly funded by the Environment Research and Technology Development Fund (JPMEERF20172001) of the Environmental Restoration and Conservation Agency of Japan. P. K. Patra, Y. Niwa, and T. Maki were funded by the Environment Research and Technology Development Fund (JPMEERF21S20813) of the Environmental Restoration and Conservation Agency of Japan. J. Pongratz and J. E. M. S. Nabel were supported by the German Research Foundation's Emmy Noether Program (PO 1751/1‐1). T. A. M. Pugh, S. Lienert, and S. Zaehle acknowledge funding from the European Union's Horizon 2020 research and innovation program under the Grant Agreement No. 758873, No. 821003 (Project 4C), and No. 821003, respectively. A. K. Jain acknowledges support by the U.S. Department of Energy (No. DE‐SC0016323). S. Lienert acknowledges support by Swiss National Science Foundation (No. 200020_200511).

Keywords

  • atmospheric inversions
  • book-keeping models
  • Dynamic Global Vegetation Models
  • forest area
  • land-use changes
  • Southeast Asia

ASJC Scopus subject areas

  • Global and Planetary Change
  • Environmental Chemistry
  • General Environmental Science
  • Atmospheric Science

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