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...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2015-11-01
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| Series: | Earth System Dynamics |
| Online Access: | http://www.earth-syst-dynam.net/6/731/2015/esd-6-731-2015.pdf |
| Summary: | 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. |
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| ISSN: | 2190-4979 2190-4987 |