Carbon footprint accounting has become increasingly more complex as supply chains expand globally. This study examines the methodological limitations of carbon footprint accounting as well as the effects of transparency constraints and inconsistencies in reporting standards across global supply chains, with particular emphasis on Scope 2 and Scope 3 emissions. By utilizing emissions data from countries with the highest levels of emissions, this research compares the industrial combustion and transportation sectors as key components of supply chain systems. This study uses the relationship between sectoral emissions and gross domestic product (GDP) to understand structural differences in supply chains, reporting standards, and methodologies. The findings indicate that the observed variations in cross-country emissions are influenced by supply chain structure, differences in tracking and reporting, and regulatory framework and methodologies. Scope 3 emissions, which frequently account for the largest share of total emissions, are among the least accurately and transparently tracked and reported. Overall, inconsistent tracking and limited transparency create significant disparities not only between countries but also between reported and actual emissions, underscoring that these reports reflect the methodologies used. These findings underscore the need for global reporting standards, transparency in reporting, and the implementation of technology to enhance tracking. Globalized standards lead to more accuracy, comparability, and overall credibility of supply chain accounting.