The Environment Strategy for Scotland: Delivering the Environment Strategy Outcome on Scotland's Global Footprint - Evidence Base & Policy Levers

8. Appendix B: Footprint and biocapacity accounting methodology

8.1.1 Scotland’s biocapacity

The first estimate of Scotland’s biocapacity was produced by Horsburgh et al. (2022). This assessment was produced using the methods of the National Footprint and Biocapacity Accounts (NFA), the national accounting framework now maintained by York University, Canada (York University 2022, 2023) which generates Ecological Footprint and biocapacity estimates annually for most of the world’s countries, including the UK. Scotland’s biocapacity was estimated for six land types (Crop Land, Grazing Land, Marine Fishing Grounds, Inland Fishing Grounds, Forests and Built-up Land). For each land type, biocapacity was calculated by scaling the bioproductive land area (in hectares) by the relative primary productivity of the land type to yield a productivity-adjusted land area in global hectares (gha) and summed to yield Scotland’s total biocapacity. Peatlands, not currently included in the NFA methodology, cover approximately 1.9 million ha (25% of land area) in Scotland, and were included by Horsburgh et al. (2022) in their estimate of Scotland’s biocapacity. However, to enable comparison with results from the NFA for the UK and other countries from around world, assessments which do not at present contain peatlands, peatland biocapacity from Horsburgh et al.’s study was not included in the Scottish biocapacity estimate used in this report.

8.1.2 Scotland’s Ecological Footprint and its overseas Footprint component

Scotland’s Ecological Footprint is based on a top-down, sub-national calculation methodology. This approach is well documented in the literature and has been most recently applied to Mediterranean cities (Baabou et al., 2017), Canadian Municipalities (Isman et al., 2017), Portuguese Cities (Galli et al., 2020) and Japanese regions (Tsuchiya et al., 2021). One of the key results of the sub-national calculation is an Ecological Footprint calculation with a breakdown by household consumption category (UN COICOP) called the Consumption Land-Use Matrix (CLUM) (Global Footprint Network, 2019).

Building on the NFA, which includes annual results up to the year 2018, the results are derived from an Ecological Footprint Extended Multi-Region Input Output (MRIO) model to calculate the Ecological Footprint of the United Kingdom and derive a CLUM for the UK for the year 2018. The MRIO model is based on GTAPv10 year 2014. A Scotland specific Ecological Footprint is then calculated based on existing financial proxy data, including household expenditure (ONS, 2022) and government expenditure (UK Government 2022) and consumption patterns following a top-down sub-national methodology.

The Scotland specific CLUM is used as the base for estimating the overseas impact of consumption in Scotland. This analysis is built on Global Footprint Network’s Ecological Footprint-MRIO database, which includes the origin (country/sector) and destination (UK) of biocapacity consumed in the UK, as well as all direct input sectors to the UK. To derive a Scotland specific estimate of overseas impact, we apply the basic assumption that UK supply chains are consistent among sub-national regions for each consumption category. For example, the CLUM will tell us the Ecological Footprint associated with the consumption of Fish and Seafood in the UK and in Scotland. If the consumption Footprint of Fish and Seafood in Scotland is double that of UK, we would assume that the origin country and sector of the Fish and Seafood consumed in Scotland are the same as the UK, while the quantity (on a country and sector basis) would be double. This basic assumption is applied to all detailed consumption sub-categories (COICOP) and Footprint categories (cropland, grazing land, fishing grounds, forest products, built-up, and carbon footprint) to obtain estimates of the supply chain origin of Scotland’s consumption.

The underlying MRIO generally provides resolution for trade relationships at the UK level, therefore estimates presented here can only delineate the origin of domestic consumption as coming from within the UK, rather than coming from Scotland.