title: Limits of agricultural greenhouse gas calculators to predict soil N2O and CH4 fluxes in tropical agriculture.
abstract: Demand for tools to rapidly assess greenhouse gas impacts from policy and technological change in the agricultural sector has catalyzed the development of 'GHG calculators'- simple accounting approaches that use a mix of emission factors and empirical models to calculate GHG emissions with minimal input data. GHG calculators, however, rely on models calibrated from measurements conducted overwhelmingly under temperate, developed country conditions. Here we show that GHG calculators may poorly estimate emissions in tropical developing countries by comparing calculator predictions against measurements from Africa, Asia, and Latin America. Estimates based on GHG calculators were greater than measurements in 70% of the cases, exceeding twice the measured flux nearly half the time. For 41% of the comparisons, calculators incorrectly predicted whether emissions would increase or decrease with a change in management. These results raise concerns about applying GHG calculators to tropical farming systems and emphasize the need to broaden the scope of the underlying data.
authors.affiliation: CGIAR Research Program on Climate Change, Agriculture and Food Security, University of Copenhagen, Rolighedsvej 21, DK-1958 Frederiksberg C, Denmark.|Gund Institute, 617 Main Street, University of Vermont, Burlington VT 05405 USA.
authors.forename: Meryl
authors.initials: M
authors.lastname: Richards
authors.affiliation: Yale School of Management &Yale School of Forestry and Environmental Studies, 195 Prospect Street New Haven CT 06511 USA.
authors.forename: Ruth
authors.initials: R
authors.lastname: Metzel
authors.affiliation: International Center for Tropical Agriculture, Km 17, Recta Cali-Palmira, Apartado Aéreo 6713 Cali, Colombia.
authors.forename: Ngonidzashe
authors.initials: N
authors.lastname: Chirinda
authors.affiliation: United Nations Development Programme, #53, Pasteur Street, Boeung Keng Kang P.O. Box 877, Phnom Penh, Cambodia.
authors.forename: Proyuth
authors.initials: P
authors.lastname: Ly
authors.affiliation: Department of Soil Science and Agricultural Engineering, P.O.Box MP167 Mount Pleasant, University of Zimbabwe, Harare Zimbabwe.
authors.forename: George
authors.initials: G
authors.lastname: Nyamadzawo
authors.affiliation: Institute for Agricultural Environment, Vietnamese Academy of Agricultural Sciences, Vĩnh Quỳnh, Thanh Trì, Hanoi, Vietnam.
authors.forename: Quynh
authors.initials: Q
authors.lastname: Duong Vu
authors.affiliation: Department of Plant and Environmental Sciences, University of Copenhagen, 1871 Frederiksberg C, Denmark.
authors.forename: Andreas
authors.initials: A
authors.lastname: de Neergaard
authors.affiliation: Department of Plant and Environmental Sciences, University of Copenhagen, 1871 Frederiksberg C, Denmark.
authors.forename: Myles
authors.initials: M
authors.lastname: Oelofse
authors.affiliation: CGIAR Research Program on Climate Change, Agriculture and Food Security, University of Copenhagen, Rolighedsvej 21, DK-1958 Frederiksberg C, Denmark.|Gund Institute, 617 Main Street, University of Vermont, Burlington VT 05405 USA.
authors.forename: Eva
authors.initials: E
authors.lastname: Wollenberg
authors.affiliation: WWF-UK, The Living Planet Centre, Rufford House, Brewery Road, Woking, Surrey GU21 4LL, UK.
authors.forename: Emma
authors.initials: E
authors.lastname: Keller
authors.affiliation: Sustainable Food Lab, 3 Linden Road, Hartland, VT 05048 USA.
authors.forename: Daniella
authors.initials: D
authors.lastname: Malin
authors.affiliation: Department of Agroecology, Blichers Allé 20, Aarhus University, Tjele 8830, Denmark.
authors.forename: Jørgen E
authors.initials: JE
authors.lastname: Olesen
authors.affiliation: School of Biological Sciences, University of Aberdeen, 23 St Machar Drive (G45), Aberdeen, AB24 3UU, UK.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Hillier
authors.affiliation: CGIAR Research Program on Climate Change, Agriculture and Food Security, University of Copenhagen, Rolighedsvej 21, DK-1958 Frederiksberg C, Denmark.|World Agroforestry Centre, PO Box 30677-00100 Nairobi, Kenya.
authors.forename: Todd S
authors.initials: TS
authors.lastname: Rosenstock