Reply to Comment on ‘Carbon intensity of corn ethanol in the United States: state of the science’

Spawn-Lee et al published a comment on our recent paper, ‘Carbon intensity of corn ethanol in the United States: state of the science.’ Their commentary is critical of our methodology and conclusions regarding greenhouse gas (GHG) life cycle analyses (LCAs) for corn starch ethanol and gives particular attention to the estimation of emissions from land use change (LUC). Several of the concerns stated by Spawn-Lee et al were raised in prior publications and are addressed in the recently published literature, thus, we respond to those points in brief and refer readers to those papers for more information. In response to their remaining concerns, we present detailed information in support of our approach for assessing LCAs of corn starch ethanol and our findings. Our original paper and the corroborating information provided here demonstrate that our methods are robust and our results are credible. Further, we hope this response contributes to constructive discussion and research on estimation of GHG emissions and LUC linked to corn starch ethanol.