Limitsof agriculturalgreenhouse gas calculators to predict soil N2O andCH4 fluxes in tropical agriculture
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 calculateGHG emissions with minimal inputdata.GHGcalculators, however,rely on models calibrated frommeasurements conducted overwhelmingly undertemperate, developed country conditions.Herewe showthatGHGcalculators may poorly estimate emissions in tropical developingcountries by comparingcalculator predictions againstmeasurements fromAfrica,Asia, and LatinAmerica.Estimates based onGHGcalculatorswere greaterthan measurements in 70% ofthe cases, exceeding twice the measured flux nearly half the time. For 41% of the comparisons, calculators incorrectly predicted whether emissions would increase or decreasewith a change in management.These results raise concerns about applyingGHGcalculators to tropical farming systems and emphasize the need to broadenthe scope ofthe underlying data.
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