Dataset Description
Data is based on the largest meta-analysis of food system impact studies to date, from Poore and Nemecek's 2018 study.
The authors note the following about the scope of the studies included in this meta-analysis: "We derived data from a comprehensive meta-analysis, identifying 1530 studies for potential inclusion, which were supplemented with additional data received from 139 authors. Studies were assessed against 11 criteria designed to standardize methodology, resulting in 570 suitable studies with a median reference year of 2010. The data set covers ~38,700 commercially viable farms in 119 countries and 40 products representing ~90% of global protein and calorie consumption".
A tonne-kilometre, abbreviated as tkm, is a unit of measure of freight transport which represents the transport of one tonne of goods (including packaging and tare weights of intermodal transport units) by a given transport mode (road, rail, air, sea, inland waterways, pipeline etc.) over a distance of one kilometre.
These emissions factors by transport mode are those applied in the analysis by Joseph Poore and Thomas Nemecek (2018), published in Science. These emission factors are sourced from Ecoinvent v3.3, a comprehensive database which is commonly used in international life-cycle analyses (LCA). Emission factors can span a range of values depending on factors such as the efficiency of vehicle used; packing/loading density of freight; distribution between passenger and freight allocation in shared transport; amongst other factors.
