Context-specific assessments of carbon footprints of the rice value chain: from product labeling to potential mitigation impacts

This study presents three contrasting applications using calculation tools for greenhouse gas (GHG) emissions and carbon footprints (C-footprint) that were specifically developed for rice production. This includes a new digital information system for labeling, tracking, and optional auditing of product-specific C-footprints that complements calculation tools developed to quantify GHG emissions and C-footprints. Collectively, these tools are used in different contexts to show their versatility for a variation of purposes.

The digital system requires product-specific information on the rice value chain encompassing cultivation, harvest, and post-harvest processes. The tool provides comprehensive GHG data for tracking C-footprints along the value chain and generates a QR code that can be printed as a product label for marketing purposes. The 2nd and 3rd applications are based on calculation tools with coherent equations as the digital system but with different output formats and scopes. While this C-footprint data in the 2nd application encompasses the entire rice value chain, our 3rd application illustrates the intricacies of quantifying the climate change impacts of technological mitigation options in rice cultivation depending on different GHG metrics and time horizons.

The digital information system comprises a two-pronged approach for private sector applications: (i) GHG tracking along the rice value chain and (ii) product labeling for communicating information on product-specific C-footprints to end users. The principal distinction of GHG emission versus C-footprints was elucidated through (i) a sequential assessment of both parameters along the individual stages of the value chain and (ii) a comparative assessment of different yield levels showing that the reduction in C-footprints does not necessarily equal overall mitigation of GHG emissions in case of higher resource inputs. The juxtaposition of global warming potential (GWP), global temperature potential (GTP), and GWP* highlighted the pivotal role of the short-lived GHG CH₄ in assessing potential mitigation impacts.

The digital system opens up a pathway to marketing low-carbon rice products that could incentivize investments in improved technologies. The impact assessment underlines the significance of selecting the most appropriate GHG metrics for mitigation planning–especially for GHG sources like rice that are dominated by CH₄ emissions.