Volume 13, issue 20 | Copyright

Special issue: Hotspots of greenhouse emissions from terrestrial ecosystems...

Biogeosciences, 13, 5799-5819, 2016
https://doi.org/10.5194/bg-13-5799-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 24 Oct 2016

Research article | 24 Oct 2016

Multi-gas and multi-source comparisons of six land use emission datasets and AFOLU estimates in the Fifth Assessment Report, for the tropics for 2000–2005

Rosa Maria Roman-Cuesta1,2, Martin Herold2, Mariana C. Rufino1,3, Todd S. Rosenstock4, Richard A. Houghton5, Simone Rossi6, Klaus Butterbach-Bahl7,8, Stephen Ogle9, Benjamin Poulter10, Louis Verchot11,12, Christopher Martius2, and Sytze de Bruin3 Rosa Maria Roman-Cuesta et al.
  • 1Center for International Forestry Research (CIFOR), P.O. Box 0113 BOCBD, Bogor 16000, Indonesia
  • 2Laboratory of Geo-Information Science and Remote Sensing, Wageningen University & Research, Droevendaalsesteeg 3, 6708PB, Wageningen, the Netherlands
  • 3Lancaster Environment Centre, Lancaster University, Lancaster LA14YQ, UK
  • 4World Agroforestry Centre (ICRAF), P.O. Box 30677-00100, Nairobi, Kenya
  • 5Woods Hole Research Center, 149 Woods Hole Road Falmouth, MA, 02540-1644, USA
  • 6Global Environmental Monitoring Unit, Institute for Environment and Sustainability, European Commission, Joint Research Centre, TP, 440 21020 Ispra, Varese 21027, Italy
  • 7International Livestock Research Institute (ILRI) P.O. Box 30709. Nairobi 00100, Kenya
  • 8Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research (IMK-IFU), Garmisch-Partenkirchen, Germany
  • 9Natural Resource Ecology Laboratory, Campus Delivery 1499, Colorado State University, Fort Collins, Colorado 80523-1499, USA
  • 10Ecosystem Dynamics Laboratory, Montana State University, P.O. Box 172000, Bozeman, MT 59717-2000, USA
  • 11International Center for Tropical Agriculture, Km17 Recta Cali-Palmira, Apartado Aéreo 6713, Cali, Colombia
  • 12Earth Institute Center for Environmental Sustainability, Columbia University, New York, USA

Abstract. The Agriculture, Forestry and Other Land Use (AFOLU) sector contributes with ca. 20–25% of global anthropogenic emissions (2010), making it a key component of any climate change mitigation strategy. AFOLU estimates, however, remain highly uncertain, jeopardizing the mitigation effectiveness of this sector. Comparisons of global AFOLU emissions have shown divergences of up to 25%, urging for improved understanding of the reasons behind these differences. Here we compare a variety of AFOLU emission datasets and estimates given in the Fifth Assessment Report for the tropics (2000–2005) to identify plausible explanations for the differences in (i) aggregated gross AFOLU emissions, and (ii) disaggregated emissions by sources and gases (CO2, CH4, N2O). We also aim to (iii) identify countries with low agreement among AFOLU datasets to navigate research efforts. The datasets are FAOSTAT (Food and Agriculture Organization of the United Nations, Statistics Division), EDGAR (Emissions Database for Global Atmospheric Research), the newly developed AFOLU “Hotspots”, “Houghton”, “Baccini”, and EPA (US Environmental Protection Agency) datasets. Aggregated gross emissions were similar for all databases for the AFOLU sector: 8.2 (5.5–12.2), 8.4, and 8.0PgCO2 eq.yr−1 (for Hotspots, FAOSTAT, and EDGAR respectively), forests reached 6.0 (3.8–10), 5.9, 5.9, and 5.4PgCO2 eq.yr−1 (Hotspots, FAOSTAT, EDGAR, and Houghton), and agricultural sectors were with 1.9 (1.5–2.5), 2.5, 2.1, and 2.0PgCO2 eq.yr−1 (Hotspots, FAOSTAT, EDGAR, and EPA). However, this agreement was lost when disaggregating the emissions by sources, continents, and gases, particularly for the forest sector, with fire leading the differences. Agricultural emissions were more homogeneous, especially from livestock, while those from croplands were the most diverse. CO2 showed the largest differences among the datasets. Cropland soils and enteric fermentation led to the smaller N2O and CH4 differences. Disagreements are explained by differences in conceptual frameworks (carbon-only vs. multi-gas assessments, definitions, land use vs. land cover, etc.), in methods (tiers, scales, compliance with Intergovernmental Panel on Climate Change (IPCC) guidelines, legacies, etc.) and in assumptions (carbon neutrality of certain emissions, instantaneous emissions release, etc.) which call for more complete and transparent documentation for all the available datasets. An enhanced dialogue between the carbon (CO2) and the AFOLU (multi-gas) communities is needed to reduce discrepancies of land use estimates.

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The land use sector (AFOLU) is a pivotal component of countries' mitigation commitments under the Paris Agreement. Global land use data are therefore important to complement and fill in countries' data gaps. But how different are the existing AFOLU datasets and why? Here we contrast six AFOLU datasets for the tropics at different levels of aggregation (spatial, gases, emission sources) and point out possible reasons for the observed differences and the next steps to improve land use emissions.
The land use sector (AFOLU) is a pivotal component of countries' mitigation commitments under...
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