A Systematic Evaluation of Uncertainty Quantification in Transport Carbon Accounting Standards

Transport emissions represent 14% of global greenhouse gases (GHG), yet the reliability of reported emissions remains highly uncertain. This paper provides the first systematic evaluation of uncertainty quantification in transport carbon accounting standards. Four major frameworks: ISO 14083:2023, Global Logistics Emissions Council (GLEC) Framework, EN 16258:2012, and GHG Protocol Initiative, are assessed against the International Panel on Climate Change uncertainty principles across five dimensions: acknowledging uncertainty, characterization, quantification methods, propagation methods, and harmonization. Using systematic keyword searches and context analysis, we find a counterintuitive temporal pattern. The GHG Protocol Initiative (2001-2015), a general organizational-level framework, achieves higher scores across the five dimensions ( 73.3 % ), than transport-specific standards published up to 2023(0−27 %). This suggests a methodological regression rather than evolution. ISO 14083:2023 and EN 16258:2012 contain no uncertainty quantification-specific terminology, methods or guidance, while GLEC merely acknowledges uncertainty existance without offering quantification approaches. As a result, organizations can fully comply with the latest standards while providing no information on measurement uncertainty or data quality. The accounting level hypothesis offers partial explanation: organizational-level standards outperform product-level standards regardless of publication date. However, this creates a contradiction because product-level accounting "should" enable more precise uncertainty assessment through potentially more capacity to perform direct measurement. Across all frameworks, harmonization emerges as a universal weakness, particularly problematic for transport emissions that span multiple accounting levels. Overall, current standards permit emissions reporting without transparency on uncertainty, accuracy or reliability, undermining credible emissions reduction claims. Effective transport decarbonization requires trustworthy emissions data, current standards fail to ensure this.

Keywords: carbon accounting, transport emissions, uncertainty quantification, standards, greenhouse gases.