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The Forest Footprint tool has been developed to help cities clearly understand, and act on, the tropical deforestation caused through the consumption of everyday commodities such as beef, palm oil, and soy products. Tropical deforestation (from land-use change) is a major contributor to climate change that is not captured in current carbon accounting and climate action plans such as the Global Protocol for Community-Scale Greenhouse Gas Emission Inventories (GPC). For climate action planning to be complete, the causes and impacts of tropical deforestation need to be more accessible. 

Tropical forest loss also hurts cities in ways beyond climate change. Loss of biodiversity, shifting rain patterns, and loss of sustainable livelihoods in forest regions all directly impact cities, even when the forests are far away. All told, deforestation is a major threat to the sustainability and resilience of cities, right now and increasingly in the future. Responding to this prerogative, the Forest Footprint tool will show cities:

  1. Their total deforestation impact and resulting carbon impacts
  2. The most significant drivers of deforestation resulting from their city,
  3. Suggested ways to mitigate or even reverse these impacts. 
  4. Potential links to carbon accounting, and climate action planning (coming soon).

Methodology

The Forest Footprint Tool is based on the calculation of two macro-simple categories of very complex data. The first category is the annual rate of city-level consumption of globally-traded commodities that are known to be driving deforestation. The second category is the specific contribution, in terms of area, that each of those commodities is making to tropical deforestation at both domestic and/or global levels. The city-specific consumption multiplied by the impact of each of these commodities adds up to the city’s total “forest footprint”. 

The Forest Footprint “Framework” is the back-end spreadsheet tool that allows us to capture, collate, and manage the diverse data sources, outputs, and formulae that lead to a total footprint for each city. The tool focuses on the commodities responsible for the vast majority of tropical global deforestation: soybeans (food & feed), palm oil (food & fuel), beef (food & leather), and wood fibre (for fuel, construction, and paper). Hotspot Crops include rubber, cocoa, coffee, and tobacco, whereas Other Crops includes tree nuts, oilseeds, rice, cereals, tubers, pulses, fruits, and vegetables. 

Lastly, the Other Forest Loss (using terminology from Pendrill et al.)category represents the 15-39% of tropical and subtropical forest loss not positively attributable to the above categories. This category includes a number of other non-agricultural categories including urban expansion and wildfires Curtis et al. (2018) as well as mining, infrastructure, oil & gas operations, and illegal land-use change. Because of the complexity of assigning this to city -level consumption, our Framework divides this global Other Forest Loss by global population, and attributes it as a global per capita average to urban residents of any city in our study . As the tool is developed, the attribution ofis Other Forest Loss to specific commodities will continue to be improved.

To estimate city-level consumption of these commodities, apparent consumption is first calculated at a national level using data from UN COMTRADE and FAOSTAT as primary sources for commodity production, imports, and exports. To determine how much of this is consumed at the city level, data from national agencies, municipal departments, and other credible sources are incorporated in terms of absolute consumption or ratios. This method parallels that of Ecological Footprint (Wackernagel & Rees, 1996; Wackernagel et al., 2006). Using the most accurate data available, city-level consumption is estimated and multiplied against the tool’s Forest Impact Factors, resulting in the city’s deforestation footprint from the consumption of each commodity. From this, CO2 emissions are calculated following the results of Pan et al. (2011) to quantify carbon emissions from embodied tropical deforestation not currently required to be calculated by GPC standards. 

In order to determine the city’s impact, the Framework aggregates a large body of research that traces the connections between the production of global commodities and tropical deforestation. Data from Pendrill et al.’s (2019) Land Balance and Crop Attribution models are used to calculate the area of deforestation caused by commodity production. Compared against global and national production, this provides a specific Forest Impact Factor for each commodity. This data builds on the pioneering research of Martin Persson (Persson et al., 2014) in physical resource theory and Thomas Kastner (Kastner et al., 2011) in global multi-regional input-output (GMRIO) trade modelling. It is important to note that this tool only considers tropical and subtropical deforestation, defined by legal land use change from forest land to crop, pasture, or other land use. The models used refer to official FAO land use change statistics and compared against remote-sensed forest loss (Hansen et al., 2013) to assess their accuracy. 

The Framework is currently undergoing revisions to the methodologies specifically related to data collection, processing, and end user feedback are refined following initial tests. It is currently assumed that most data processing and validation will be done by Cities4Forests, both to assure the integrity of the information supplied by the tool and to ensure its stability. Cities will be able to submit data on commodity consumption should they have the resources to do so, however. The end user experience will be presented through the dashboard, which will ultimately be accessible through the Cities4Forests website.  

Illustrated methodology of the Forest Footprint tool
Illustrated methodology of the Forest Footprint tool

Frameworks