A recent study by DeCicco et al. (Climatic Change 138:667–680, 2016) claims that corn used for ethanol should not be considered to be inherently biogenically carbon-neutral because not all that corn was grown additional to the level otherwise. By assessing the extent of carbon neutrality of corn for ethanol using the reference point baseline approach and historical data that study concluded that the carbon intensity of US corn ethanol is 27% higher than that of gasoline. We develop a framework to determine the carbon neutrality of corn for ethanol by assessing the additional carbon uptake by crops using an anticipated baseline approach. We also apply this framework to determine the additional corn produced for ethanol and include the direct life cycle carbon emissions of only that portion of corn in the direct life cycle carbon intensity of corn ethanol. We implement this framework by integrating an economic model of the agricultural sector in the USA with a biogenic carbon model and life cycle analysis to quantify biogenic carbon uptake and direct life cycle emissions with and without corn ethanol expansion over the 2007–2027 period. We find that the combined biogenic carbon emissions and direct life cycle carbon emission intensity of corn ethanol (not including indirect land use related emissions) is 21% lower than gasoline. The lower value of this carbon intensity of corn ethanol compared with gasoline is robust to a wide range of parametric assumptions.

DeCicco等人的最新研究。（Climatic Change 138：667–680，2016）声称，用于乙醇的玉米不应该被视为具有固有的生物中性碳中性，因为并非所有玉米的生长都超过了其他水平。通过使用基准点基线方法和历史数据评估玉米对乙醇的碳中和程度，该研究得出的结论是，美国玉米乙醇的碳强度比汽油高27％。我们建立了一个框架，通过使用预期的基准方法评估农作物的额外碳吸收量来确定玉米对乙醇的碳中性。我们还应用此框架来确定为乙醇生产的额外玉米，并将仅玉米这一部分的直接生命周期碳排放量包括在玉米乙醇的直接生命周期碳强度中。我们通过将美国农业部门的经济模型与生物碳模型和生命周期分析相结合来实现此框架，以量化在2007–2027年期间有或没有玉米乙醇扩大的生物碳吸收和直接生命周期排放。我们发现玉米乙醇的综合生物碳排放量和直接生命周期碳排放强度（不包括与土地使用有关的间接排放量）比汽油低21％。与汽油相比，玉米乙醇的这种碳强度的较低值对于各种参数假设都具有鲁棒性。我们通过将美国农业部门的经济模型与生物碳模型和生命周期分析相结合来实现此框架，以量化在2007–2027年期间有或没有玉米乙醇扩大的生物碳吸收和直接生命周期排放。我们发现玉米乙醇的综合生物碳排放量和直接生命周期碳排放强度（不包括与土地使用有关的间接排放量）比汽油低21％。与汽油相比，玉米乙醇的这种碳强度的较低值对于各种参数假设都具有鲁棒性。我们通过将美国农业部门的经济模型与生物碳模型和生命周期分析相结合来实现此框架，以量化在2007–2027年期间有或没有玉米乙醇扩大的生物碳吸收和直接生命周期排放。我们发现玉米乙醇的综合生物碳排放量和直接生命周期碳排放强度（不包括与土地使用有关的间接排放量）比汽油低21％。与汽油相比，玉米乙醇的这种碳强度的较低值对于各种参数假设都具有鲁棒性。