Variable overview

Drivers

Variable	Model driver group	Used_in	Description
GDP per capita	Economic development	Energy supply and demand Agricultural economy Climate policy Emissions Energy demand Human development	Gross Domestic Product per capita, measured as the market value of all goods and services produced in a region in a year, and is used in the IMAGE framework as a generic indicator of economic activity.
Labour supply	Economic development	Agricultural economy	Effective supply of labour input to support economic activities, taking into account the participation rate of age cohorts.
Capital supply	Economic development	Agricultural economy	Capital available to replace depreciated stock and expand the stock to support economic growth.
GDP per capita - grid	Economic development	Ecosystem services Nutrients Flood risks	Scaled down GDP per capita from country to grid level, based on population density.
Private consumption	Economic development	Energy supply and demand Energy demand	Private consumption reflects expenditure on private household consumption. It is used in IMAGE as a driver of energy.
GINI coefficient	Economic development	Human development	Measure of income disparity in a population. If all have the same income, GINI equals 1. The lower the GINI, the wider the gap between the lowest and highest income groups.
Timber demand	Economic development	Forest management	Demand for roundwood and pulpwood per region.
Sector value added	Economic development	Energy supply and demand Energy demand	Value Added for economic sectors: Industry (IVA), Services (SVA) and Agriculture (AVA). These variables are used in IMAGE to indicate economic activity.
Built-up area - grid	Energy and land resources	Land cover and land use	Urban built-up area per grid cell, excluded from all biophysical modelling in IMAGE, increasing over time as a function of urban population and a country- and scenario-specific urban density curve.
Energy resources	Energy and land resources	Energy supply and demand Energy supply	Volume of energy resource per carrier, region and supply cost class (determines depletion dynamics).
Taxes and other additional costs	Environmental and other policies	Energy demand	Taxes on energy use, and other additional costs
Adaptation level	Environmental and other policies	Climate policy	Level of adaptation to climate change , defined as the share of climate change damage avoided by adaptation. This level is be calculated by the model to minimise adaptation costs and residual damage, or set by the user.
Energy policy	Environmental and other policies	Energy conversion	Policy to achieve energy system objectives, such as energy security and energy access.
Climate target	Environmental and other policies	Climate policy	Climate target, defined in terms of concentration levels, radiative forcing, temperature targets, or cumulative emissions.
Protected area - grid	Environmental and other policies	Land-use allocation Land cover and land use Terrestrial biodiversity Ecosystem services	Map of protected nature areas, limiting use of this area.
Equity principles	Environmental and other policies	Climate policy	General concepts of distributive justice or fairness used in effort sharing approaches. Three key equity principles are: Responsibility (historical contribution to warming); capability (ability to pay for mitigation); and equality (equal emissions allowances per capita).
Domestic climate policy	Environmental and other policies	Climate policy	Planned and/or implemented national climate and energy policies, such as taxes, feed-in tariffs, renewable targets, efficiency standards, that affect projected emission reduction.
Air pollution policy	Environmental and other policies	Energy conversion	Air pollution policies set to reach emission reduction targets, represented in the model in the form of energy carrier and sector specific emission factors.
Biofuel policy	Environmental and other policies	Agricultural economy	Policies to foster the use of biofuels in transport, such as financial incentives and biofuel mandates and obligations.
Lifestyle parameters	Lifestyle parameters	Energy supply and demand Energy demand	Lifestyle parameters influence the relationship between economic activities and demand for energy.
Preferences	Lifestyle parameters	Energy demand	Non-price factors determining market shares, such as preferences, environmental policies, infrastructure and strategic considerations, used for model calibration.
Urban population fraction	Population projections	Human development	Urban/rural split of population.
Population - grid	Population projections	Land-use allocation Nutrients Human development Flood risks	Number of people per gridcell (using downscaling).
Population	Population projections	Energy supply and demand Agricultural economy Climate policy Energy demand	Number of people per region.
Technological change (crops and livestocks)	Technological change in agriculture and forestry	Agricultural economy	Increase in productivity in crop production (yield/ha) and livestock production (carcass weight, offtake rate).
Feed conversion	Technological change in agriculture and forestry	Livestock systems	Measure of an animal's efficiency in converting feed mass into the desired output such as meat and milk (for cattle, poultry, pigs, sheep and goats).
Harvest efficiency	Technological change in agriculture and forestry	Forest management	Fraction of harvested wood used as product, the remainder being left as residues. Specified per biomass pool and forestry management type.
Forest plantation demand	Technological change in agriculture and forestry	Forest management	Demand for forest plantation area.
Increase in irrigated area - grid	Technological change in agriculture and forestry	Land-use allocation	Increase in irrigated area, often based on external projections (e.g., FAO).
Production system mix	Technological change in agriculture and forestry	Livestock systems Nutrients	Livestock production is distributed over two systems for dairy and beef production (intensive: mixed and industrial; extensive: pastoral grazing), and to three systems for pigs (backyard, intermediate, intensive) and poultry (backyard, boilers, laying hens) with specific intensities, rations and feed conversion ratios.
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