Variable overview

Drivers

Variable	Model driver group	Description	is used in
Adaptation level	Environmental and other policies	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.
Air pollution policy	Environmental and other policies	Air pollution policies set to reach emission reduction targets, represented in the model in the form of energy carrier and sector specific emission factors.
Animal productivity	Technological change in agriculture and forestry	Effective production of livestock commodities per animal per year.
Biofuel policy	Environmental and other policies	Policies to foster the use of biofuels in transport, such as financial incentives and biofuel mandates and obligations.
Built-up area - grid	Energy and land resources	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.
Capital supply	Economic development	Capital available to replace depreciated stock and expand the stock to support economic growth.
Climate target	Environmental and other policies	Climate target, defined in terms of concentration levels, radiative forcing, temperature targets, or cumulative emissions.
Domestic climate policy	Environmental and other policies	Planned and/or implemented national climate and energy policies, such as taxes, feed-in tariffs, renewable targets, efficiency standards, that affect projected emission reduction.
Energy efficiency technology	Technological change in the energy system	Model assumptions determining future development of energy efficiency.
Energy intensity parameters	Technological change in the energy system	Set of parameters determining the energy use per unit of economic activity (in absence of technical energy efficiency improvements).
Energy policy	Environmental and other policies	Policy to achieve energy system objectives, such as energy security and energy access.
Energy resources	Energy and land resources	Volume of energy resource per carrier, region and supply cost class (determines depletion dynamics).
Equity principles	Environmental and other policies	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).
Feed conversion	Technological change in agriculture and forestry	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).
Fertiliser use efficiency	Technological change in agriculture and forestry	Ratio of fertiliser uptake by a crop to fertiliser applied.
Forest plantation demand	Technological change in agriculture and forestry	Demand for forest plantation area.
Fraction of selective logging	Technological change in agriculture and forestry	The fraction of forest harvested in a grid, in clear cutting, selective cutting, wood plantations and additional deforestation. Fraction of selective cut determines the fraction of timber harvested by selective cutting of trees in semi-natural and natural forest.
GDP per capita	Economic 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.
GDP per capita - grid	Economic development	Scaled down GDP per capita from country to grid level, based on population density.
GINI coefficient	Economic 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.
Harvest efficiency	Technological change in agriculture and forestry	Fraction of harvested wood used as product, the remainder being left as residues. Specified per biomass pool and forestry management type.
Increase in irrigated area - grid	Technological change in agriculture and forestry	Increase in irrigated area, often based on external projections (e.g., FAO).
Irrigation conveyance efficiency	Technological change in agriculture and forestry	Ratio of water supplied to the irrigated field to the quantity withdrawn from the water source, determining the quantity of water lost during transport. This parameter is defined at country level.
Irrigation project efficiency	Technological change in agriculture and forestry	Ratio of quantity of irrigation water required by the crop (based on soil moisture deficits) to the quantity withdrawn from rivers, lakes, reservoirs or other sources. This parameter is given at country level.
Irrigation system		Type of irrigation system: surface, sprinkler or drip. This is allocated at country level, based on Jagermeyr et al (2015).
Labour supply	Economic development	Effective supply of labour input to support economic activities, taking into account the participation rate of age cohorts.
Learning rate	Technological change in the energy system	Determines the rate of technology development in learning equations.
Lifestyle parameters	Lifestyle parameters	Lifestyle parameters influence the relationship between economic activities and demand for energy.
Livestock rations	Technological change in agriculture and forestry	Determines the feed requirements per feed type (food crops; crop residues; grass and fodder; animal products; scavenging), specified per animal type and production system (extensive/intensive/backyard/intermediate/intensive/broiler/laying hens).
Manure spreading fraction	Technological change in agriculture and forestry	Fraction of manure produced in staples that is spread on agricultural areas.
Population	Population projections	Number of people per region.
Population - grid	Population projections	Number of people per gridcell (using downscaling).
Preferences	Lifestyle parameters	Non-price factors determining market shares, such as preferences, environmental policies, infrastructure and strategic considerations, used for model calibration.
Private consumption	Economic development	Private consumption reflects expenditure on private household consumption. It is used in IMAGE as a driver of energy.
Production system mix	Technological change in agriculture and forestry	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.
Protected area - grid	Environmental and other policies	Map of protected nature areas, limiting use of this area.
Sector value added	Economic development	Value Added for economic sectors: Industry (IVA), Services (SVA) and Agriculture (AVA). These variables are used in IMAGE to indicate economic activity.
Taxes and other additional costs	Environmental and other policies	Taxes on energy use, and other additional costs
Technological change (crops and livestocks)	Technological change in agriculture and forestry	Increase in productivity in crop production (yield/ha) and livestock production (carcass weight, offtake rate).
Technology development of energy conversion	Technological change in the energy system	Learning curves and exogenous learning that determine technology development.
Technology development of energy supply	Technological change in the energy system	Learning curves and exogenous learning that determine technology development.
Timber demand	Economic development	Demand for roundwood and pulpwood per region.
Trade policy	Trade regimes, tariffs and barriers	Assumed changes in market and non-market instruments that influence trade flows, subject to WTO rules and country and region regulation.
Trade restriction	Trade regimes, tariffs and barriers	Trade tariffs and barriers limiting trade in energy carriers (in energy submodel).
Urban population fraction	Population projections	Urban/rural split of population.