Do we need a unified appraisal framework to synthesize biofuel impacts?

► We lack coherent, comprehensive and policy-relevant syntheses of biofuels' environmental and socioeconomic impacts. ► Assessing whether (and how) it is desirable to synthesize biofuel impacts with a unified framework is a major research gap. ► Sustainability science and the ecosystem services approach are two frameworks that can provide such unified syntheses. ► Unified syntheses are appropriate in “structured” policy situations, when facts are certain and policy priorities consensual. ► Unified syntheses might be counterproductive when high scientific uncertainty and disagreement on values/policy goals prevail.