Quantifying differences in land use emission estimates implied by definition discrepancies

The quantification of CO<sub>2</sub> emissions from anthropogenic land use and land use change (<i>e</i>LUC) is essential to understand the drivers of the atmospheric CO<sub>2</sub> increase and to inform climate change mitigation policy. Reported values in synthe...

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Main Authors: B. D. Stocker, F. Joos
Format: Article
Language:English
Published: Copernicus Publications 2015-11-01
Series:Earth System Dynamics
Online Access:http://www.earth-syst-dynam.net/6/731/2015/esd-6-731-2015.pdf
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spelling doaj-4bde87936f8c41398b6455984908dfbc2020-11-24T22:18:11ZengCopernicus PublicationsEarth System Dynamics2190-49792190-49872015-11-016273174410.5194/esd-6-731-2015Quantifying differences in land use emission estimates implied by definition discrepanciesB. D. Stocker0F. Joos1Department of Life Sciences, Imperial College London, Silwood Park, Ascot, SL5 7PY, UKClimate and Environmental Physics , Physics Institute, University of Bern, Bern, SwitzerlandThe quantification of CO<sub>2</sub> emissions from anthropogenic land use and land use change (<i>e</i>LUC) is essential to understand the drivers of the atmospheric CO<sub>2</sub> increase and to inform climate change mitigation policy. Reported values in synthesis reports are commonly derived from different approaches (observation-driven bookkeeping and process-modelling) but recent work has emphasized that inconsistencies between methods may imply substantial differences in <i>e</i>LUC estimates. However, a consistent quantification is lacking and no concise modelling protocol for the separation of primary and secondary components of <i>e</i>LUC has been established. Here, we review differences of <i>e</i>LUC quantification methods and apply an Earth System Model (ESM) of Intermediate Complexity to quantify them. We find that the magnitude of effects due to merely conceptual differences between ESM and offline vegetation model-based quantifications is ~ 20 % for today. Under a future business-as-usual scenario, differences tend to increase further due to slowing land conversion rates and an increasing impact of altered environmental conditions on land-atmosphere fluxes. We establish how coupled Earth System Models may be applied to separate secondary component fluxes of <i>e</i>LUC arising from the replacement of potential C sinks/sources and the land use feedback and show that secondary fluxes derived from offline vegetation models are conceptually and quantitatively not identical to either, nor their sum. Therefore, we argue that synthesis studies should resort to the "least common denominator" of different methods, following the bookkeeping approach where only primary land use emissions are quantified under the assumption of constant environmental boundary conditions.http://www.earth-syst-dynam.net/6/731/2015/esd-6-731-2015.pdf
collection DOAJ
language English
format Article
sources DOAJ
author B. D. Stocker
F. Joos
spellingShingle B. D. Stocker
F. Joos
Quantifying differences in land use emission estimates implied by definition discrepancies
Earth System Dynamics
author_facet B. D. Stocker
F. Joos
author_sort B. D. Stocker
title Quantifying differences in land use emission estimates implied by definition discrepancies
title_short Quantifying differences in land use emission estimates implied by definition discrepancies
title_full Quantifying differences in land use emission estimates implied by definition discrepancies
title_fullStr Quantifying differences in land use emission estimates implied by definition discrepancies
title_full_unstemmed Quantifying differences in land use emission estimates implied by definition discrepancies
title_sort quantifying differences in land use emission estimates implied by definition discrepancies
publisher Copernicus Publications
series Earth System Dynamics
issn 2190-4979
2190-4987
publishDate 2015-11-01
description The quantification of CO<sub>2</sub> emissions from anthropogenic land use and land use change (<i>e</i>LUC) is essential to understand the drivers of the atmospheric CO<sub>2</sub> increase and to inform climate change mitigation policy. Reported values in synthesis reports are commonly derived from different approaches (observation-driven bookkeeping and process-modelling) but recent work has emphasized that inconsistencies between methods may imply substantial differences in <i>e</i>LUC estimates. However, a consistent quantification is lacking and no concise modelling protocol for the separation of primary and secondary components of <i>e</i>LUC has been established. Here, we review differences of <i>e</i>LUC quantification methods and apply an Earth System Model (ESM) of Intermediate Complexity to quantify them. We find that the magnitude of effects due to merely conceptual differences between ESM and offline vegetation model-based quantifications is ~ 20 % for today. Under a future business-as-usual scenario, differences tend to increase further due to slowing land conversion rates and an increasing impact of altered environmental conditions on land-atmosphere fluxes. We establish how coupled Earth System Models may be applied to separate secondary component fluxes of <i>e</i>LUC arising from the replacement of potential C sinks/sources and the land use feedback and show that secondary fluxes derived from offline vegetation models are conceptually and quantitatively not identical to either, nor their sum. Therefore, we argue that synthesis studies should resort to the "least common denominator" of different methods, following the bookkeeping approach where only primary land use emissions are quantified under the assumption of constant environmental boundary conditions.
url http://www.earth-syst-dynam.net/6/731/2015/esd-6-731-2015.pdf
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