IMAGEIntegrated Model to Assess the Global Environment.

Variable overview


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List of all variables per type:

  • Drivers are external model variables that drive the system.
  • Model variables are output of a model component and used as input for another model component or final output.
  • Historical datasets such as 'Nr of wet days'
  • External parameters originate from external models, databases, or other sources. They are mostly used as input for one model component.


Population projections

Population Number of people per region.
Population - grid Number of people per gridcell (using downscaling).
Urban population fraction Urban/rural split of population.

Economic development

Capital supply Capital available to replace depreciated stock and expand the stock to support economic growth.
GDP per capita 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 Scaled down GDP per capita from country to grid level, based on population density.
GINI coefficient 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.
Labour supply Effective supply of labour input to support economic activities, taking into account the participation rate of age cohorts.
Private consumption Private consumption reflects expenditure on private household consumption. It is used in IMAGE as a driver of energy.
Sector value added Value Added for economic sectors: Industry (IVA), Services (SVA) and Agriculture (AVA). These variables are used in IMAGE to indicate economic activity.
Timber demand Demand for roundwood and pulpwood per region.

Trade regimes, tariffs and barriers

Trade policy Assumed changes in market and non-market instruments that influence trade flows.
Trade restriction Trade tariffs and barriers limiting trade in energy carriers (in energy submodel).

Environmental and other policies

Adaptation level 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 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 Policies to foster the use of biofuels in transport, such as financial incentives and biofuel mandates and obligations.
Climate target Climate target, defined in terms of concentration levels, radiative forcing, temperature targets, or cumulative emissions.
Domestic 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.
Energy policy Policy to achieve energy system objectives, such as energy security and energy access.
Equity principles 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).
Protected area - grid Map of protected nature areas, limiting use of this area.
Taxes and other additional costs Taxes on energy use, and other additional costs

Technological change in the energy system

Energy efficiency technology Model assumptions determining future development of energy efficiency.
Energy intensity parameters Set of parameters determining the energy use per unit of economic activity (in absence of technical energy efficiency improvements).
Learning rate Determines the rate of technology development in learning equations.
Technology development of energy conversion Learning curves and exogenous learning that determine technology development.
Technology development of energy supply Learning curves and exogenous learning that determine technology development.

Technological change in agriculture and forestry

Animal productivity Effective production of livestock commodities per animal per year.
Feed conversion 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 Ratio of fertiliser uptake by a crop to fertiliser applied.
Forest plantation demand Demand for forest plantation area.
Fraction of selective logging 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.
Harvest efficiency 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 Increase in irrigated area, often based on external projections (e.g., FAO).
Irrigation conveyance efficiency 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 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.
Livestock rations 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).
Manure spreading fraction Fraction of manure produced in staples that is spread on agricultural areas.
Production system mix Livestock production is distributed over two systems (intensive: mixed and industrial; extensive: pastoral grazing), with specific intensities, rations and feed conversion ratios.
Technological change (crops and livestocks) Increase in productivity in crop production (yield/ha) and livestock production (carcass weight, offtake rate).

Lifestyle parameters

Lifestyle parameters Lifestyle parameters influence the relationship between economic activities and demand for energy.
Preferences Non-price factors determining market shares, such as preferences, environmental policies, infrastructure and strategic considerations, used for model calibration.

Energy and land resources

Built-up area - grid 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 Volume of energy resource per carrier, region and supply cost class (determines depletion dynamics).

Model variables, to/from model and end indicators

Model variableSourceUseDescription
Access to drinking water and sanitation
    Final output
Percentage of the population with sustainable access to safe drinking water and basic sanitation.
Actual crop and grass production - grid Actual crop and grass production on agricultural land, based on potential yield and management intensityÍÍ
Adaptation costs
    Final output
Costs for adaptation measures to reduce the vulnerability of natural and human systems to actual or expected climate change effects.
Agricultural area - grid Total area for crop production (annual and perennial) and intensive grassland.
Algal blooms in lakes
    Final output
Harmful algal blooms in lakes caused by cyanobacteria, producing toxins harmful to humans and animals.
Animal stocks Number of animals per category: non-dairy cattle; dairy cattle; pigs; sheep and goats; poultry.
Aquatic MSA - grid
    Final output
Relative Mean Species Abundance of original species in lakes, rivers and wetlands.
BC, OC and NOx emissions Emissions of BC, OC and NOx per year.
Bioenergy area Area of bioenergy crop production, in model setting where sustainability criteria require that the area for bioenergy crops is not included in the agricultural production area (to avoid competition between bioenergy and food).
Bioenergy production Total bioenergy production.
CO and NMVOC emissions Emissions from CO and NMVOC.
CO2 concentration Atmospheric CO2 concentration.
CO2 emission from energy and industry CO2 emission from energy and industry.
CO2 stored
    Final output
The amount of CO2 stored in underground reservoirs by applying CO2 capture technology..
Carbon pools in soil and timber - grid Carbon biomass in three soil pools (litter, humus and charcoal) and two timber pools (slow decaying, and fast decaying).
Carbon pools in vegetation - grid Carbon pools in leaves, stems, branches and roots).
Carbon price Carbon price on the international trading market (in USD in 2005 per tonne C-eq) calculated from aggregated regional permit demand and supply curves derived from marginal abatement costs.
Carbon sequestration - grid
    Final output
net carbon uptake by terrestrial ecosystems and oceans
Carbon storage price The costs of capturing and storing CO2, affecting the use of CCS technology.
Change in soil properties - grid Change in soil properties, such as clay/sand content, organic carbon content, soil depth (topsoil/subsoil).
Child mortality
    Final output
he probability per 1,000 that a new-born baby will die before reaching the age five, if subject to average age-specific mortality rates.
Child underweight
    Final output
Prevalence of undernourishment in children.
Commodity price
    Final output
Commodity price per sector, including various crop and livestock sectors..
Consumption loss
    Final output
Loss of private consumption due to mitigation and adaptation costs and residual damage.
Crop fraction in agricultural area - grid Fraction of agricultural land by crop type, per grid cell.
Crop irrigation water demand - grid Water requirements for crop irrigation, calculated as daily moisture deficit during the growing season.
Crop production Regional production per crop.
DALYs (disability-adjusted life years)
    Final output
The disability-adjusted life year (DALY) is a measure of overall disease burden, expressed as the number of years lost due to ill-health, disability and early death.
Degraded forest area Permanently deforested areas for reasons other than expansion of agricultural land (calibrated to FAO deforestation statistics).
Demand (all commodities)
    Final output
Demand per sector including various crop and livestock sectors.
Demand for electricity, heat and hydrogen The demand for production of electricity, heat and hydrogen.
Demand for fossil fuels and bioenergy
    Final output
The demand for the production of fossil fuels and bioenergy.
Demand for primary energy Total demand for energy production. Sum of final energy demand and energy inputs into energy conversion processes.
Demand traditional biomass Regional demand for traditional bioenergy.
Electricity price The price of electricity.
Emission abatement Reduction in emission factors as a function of Climate policy.
Emission trading
    Final output
Emission credits traded between regions
Energy and industry activity level Activity levels in the energy and industrial sector, per process and energy carrier, for example, the combustion of petrol for transport or the production of crude oil.
Energy demand and production
    Final output
Aggregated energy demand and production indicators from the energy model.
Energy security indicators
    Final output
Indicators on the status of energy security, such as energy self-sufficiency.
Erosion risk - grid Risk of soil erosion caused by water.
Expected nr of affected people - grid
    Final output
Population expected to be exposed to floods per year.
Expected value of affected GDP - grid
    Final output
GDP expected to be exposed to floods per year.
Extensive grassland area - grid Extensive pasture with low productivity used for grazing.
Feed crop requirement Crops required for feeding livestock.
Flood protection - grid
    Final output
Reduction in flood risk by natural vegetation.
Food availability per capita Food availability per capita.
Food availability, including fish and wild food
    Final output
Food availability, including fish and wild food.
Forest management type - grid Forest management type: clear cut, selective logging, forest plantation or additional deforestation.
Forest residues
    Final output
Residues from timber harvest, left in forest after harvest or used as bioenergy.
Global emission pathways
    Final output
Global emission pathway consistent with a specific long-term climate target.
Global mean temperature Average global temperature.
Grass requirement Grass requirement for ruminants (non-dairy cattle, dairy cattle, sheep and goats) in pastoral and mixed systems.
HDI (human development index)
    Final output
HDI: Development level of a country based on income, education and life expectancy.
Harvested wood Wood harvested and removed.
Intensive grassland area Intensively used grassland areas for grazing or mowing, at locations also suitable for crop production.
Irrigation water availability - grid
      Final output
    Irrigation water consumption - grid
      Final output
    Irrigation water consumption by crops.
    Irrigation water supply - grid Water supplied to irrigated fields; equal to irrigation water withdrawal minus water lost during transport, depending on the conveyance efficiency.
    Irrigation water withdrawal - grid Water withdrawn for irrigation, not necessarily equal to irrigation water demand, because of limited water availability in rivers, lakes, reservoirs and other sources.
    Land cover, land use - grid Multi-dimensional map describing all aspects of land cover and land use per grid cell, such as type of natural vegetation, crop and grass fraction, crop management, fertiliser and manure input, livestock density.
    Land suitability - grid Suitability of land in a grid cell for agriculture and forestry, as a function of accessibility, population density, slope and potential crop yields.
    Land supply Available land for agriculture, per grid or region, depending on suitability for crops, and excluding unsuitable areas such as steep slopes, wetlands and protected areas.
    Land supply for bioenergy - grid Land available for sustainable bioenergy production (abandoned agricultural land and non-forested land).
    Land systems - grid Thirty land systems as defined in CLUMondo (Van Asselen and Verburg, 2012), characterized by specific levels of built-up area, cropland area, livestock density and management intensity.
    Land use and land-use intensity - grid High resolution land use and land use intensity based on GLC2000 and IMAGE land cover and land use.
    Land-use CO2 emissions - grid Land-use CO2 emissions from deforestation, wood harvest, agricultural harvest, bioenergy plantations and timber decay.
    Life expectancy
      Final output
    Average life expectancy of a person born in a given year..
    Livestock production Production of livestock products (dairy, beef, sheep and goats, pigs, poultry).
    MSA (mean species abundance) - grid Mean Species Abundance (MSA) relative to the natural state of original species.
    Management intensity crops Management intensity crops, expressing actual yield level compared to potential yield. While potential yield is calculated for each grid cell, this parameter is expressed at the regional level. This parameter is based on data and exogenous assumptions - current practice and technological change in agriculture - and is endogenously adapted in the agro-economic model.
    Management intensity livestock Management intensity of livestock, based current practice and technological change in livestock sectors, describing carcass weight and feed requirements of livestock.
    Marginal abatement cost Cost of an additional unit of pollution abated (CO2eq). A marginal abatement cost curve (MAC curve) is a set of options available to an economy to reduce pollution, ranked from the lowest to highest additional costs.
    Mitigation costs
      Final output
    Net costs of measures to reduce greenhouse gas emissions.
    N and P discharge to surface water - grid N and P discharge to surface water.
    N and P in wastewater discharge - grid
      Final output
    Discharge of N and P to surface water from wastewater.
    NEP (net ecosystem production) - grid Net natural exchange of CO2 between biosphere and atmosphere (NPP minus soil respiration), excluding human induced fluxes such as decay of wood products.
    NH3 emissions - grid
      Final output
    Ammonia emissions from applied nitrogen fertiliser and manure.
    NPP (net primary production) - grid CO2 sequestered by plants and incorporated in new tissue in plant carbon pools.
    Nitrogen deposition - grid Deposition of nitrogen.
    Non-CO2 GHG concentrations
      Final output
    Atmospheric concentration of non-CO2 greenhouse gases.
    Non-CO2 GHG emissions (CH4, N2O and Halocarbons) Non-CO2 GHG emissions (CH4, N2O, Halocarbons).
    Ocean carbon uptake Ocean carbon uptake.
    People dependent on solid fuel Proportion of population using traditional biomass and coal for cooking and heating.
    People living on less then USD 1.25 per day
      Final output
    People living on less than $1.25 a day
    Pollination - grid
      Final output
    Additional yield due to natural pollination.
    Potential bioenergy yield - grid Potential yields of bioenergy crops.
    Potential crop and grass yield - grid Potential crop and grass yield, changing with time due to climate change and possibly soil degradation.
    Potential natural vegetation - grid Potential natural vegetation type/biome, based on distribution of plant functional types.
    Precipitation - grid Monthly total precipitation.
    Presence of natural pest control - grid
      Final output
    Presence of natural pest control.
    Prevalence of undernourishment
      Final output
    Proportion of the population with insufficient food intake to meet dietary energy requirements.
    Primary energy price The price of primary energy carriers based on production costs.
    Radiative forcing
      Final output
    Radiative forcing of greenhouse gases, ozone, and aerosols.
    Rainwater consumption - grid
      Final output
    Rain water consumption by crops.
    Reduced erosion risk - grid
      Final output
    Reduction in erosion risk by natural vegetation.
    Regrowth forest area - grid Areas of re-growing forests after agricultural abandonment or timber harvest.
    Residual damage
      Final output
    Climate change damage remaining after adaptation.
    River discharge - grid Average flow of water through each grid cell.
    SO2 emissions SO2 emissions, per source (e.g. fossil fuel burning, deforestation).
    SRI (species richness index) - grid
      Final output
    Species richness calculated from MSA and species area curves.
    Soil N budget - grid
      Final output
    N budget in the soil, used to calculate fate of nitrogen in the soil-hydrology system and for determining emissions to the atmosphere.
    Soil P budget - grid
      Final output
    P budget in the soil, used to calculate fate of nitrogen in the soil-hydrology system (residual soil P or surface runoff).
    Soil respiration - grid
      Final output
    CO2 release from soils into the atmosphere due to the decay of soil carbon pools and respiration of soil organisms.
    Statistics of inundation extent - grid
      Final output
    Annual statistics of flooded fraction per grid cell.
    Statistics on inundation depth - grid Annual statistics of water depth in flooded areas of a grid cell.
    Statistics on river discharge - grid
      Final output
    Annual statistics on river discharge.
    Suitability for nature-based tourism - grid
      Final output
    Attractiveness for nature-based tourism.
    Temperature - grid Monthly average temperature.
    Timber use fraction Fractions of harvested timber entering the fast-decaying timber pool, the slow-decaying timber pool, or burnt as traditional biofuels.
    Total primary energy supply
      Final output
    Total primary energy supply.
    Trade (all commodities)
      Final output
    Bilateral trade between regions per sector, including various crop and livestock sectors.
    Water availability - grid
      Final output
    Water availability in rivers, lakes and reservoirs.
    Water erosion sensitivity index - grid
        Final output
      Water stress - grid
        Final output
      Water stress expressed as the ratio of mean annual water demand to availability, aggregated to basin level (0.2-0.4 medium water stress; >0.4 severe water stress).
      Water withdrawal other sectors - grid Total annual water withdrawal by non-agricultural sectors.
      Wilderness area - grid
        Final output
      Non-agricultural areas close to their natural state, with MSA values above 0.8.

      External parameters

      External parameterUseDescription
      Accessibility - grid Accessibility expressed as travel time.
      Biome and eco-region - grid Biomes are groups of plants and animals, often referred as ecosystems. Their spatial distribution on Earth is defined by climatic and geographical conditions defined as contiguous areas with similar climatic conditions. Biomes are often referred to by climatic conditions (such as, tropical, temperate, boreal) and physiological characteristic (such as, grassland, deciduous trees, coniferous trees).
      CLUmondo specific input - grid CLUMondo specific input.
      Coastal storm surges Estimates on storm surge/tide water levels for a large number of coast segments.
      Conversion assumptions Conversion assumptions.
      Daily climate dataset - grid Bias corrected daily precipitation, temperature and potential evaporation input. This data set is according to the monthly Precipitation and Temperature.
      Digital water network - grid Digital water network DDM30 describing drainage directions of surface water, with each cell only draining into one neighbouring cell, organising cells to river basins.
      Distance to water - grid Distance to water.
      Ecosystem services effect values Database on relationships between environmental factors and ecosystem services.
      Emission factors Exogenous emission factors per sector, activity and gas, mostly based on the EDGAR database.
      Empirical MSA effect values Database of empirical relationships between environmental pressures and reduction in mean species abundance for aquatic ecosystems.
      Exogenously set market shares Market shares of traditional biomass and secondary heat, for all demand sectors except the residential sector, exogenous scenario parameter.
      FAO deforestation rates Historical deforestation rates according to FAO.
      Fish landing - grid Fish landings according to statistics from "Sea around us".
      Flood statistics - grid Annual statistics of water depth and the flooded fraction per grid cell.
      GCM pattern (temperature, precipitation) - grid Climate change patterns of General Circulation models used to downscale changes in global mean temperature to changes in temperature and precipitation at grid level; default pattern from HadCM3 of the Hadley Centre.
      GLWD (global lakes and wetlands database) - grid Global map of lakes and wetlands.
      High resolution land cover (GLC2000) - grid The database contains two levels of land cover information—detailed, regionally optimized land cover legends for each continent and a less thematically detailed global legend that harmonizes regional legends into one consistent product. The land cover maps are all based on daily data from the VEGETATION sensor on-board SPOT 4.
      Income and price elasticities Assumptions on income and price elasticities of demand, substitution elasticities, and many other elasticities,
        infrastructure map from external model
        Initial land cover, land use - grid Includes current state (intensive agriculture use, extensive agricultural use, no use) of land area and erosion protection represented by greenness index (NDVI = Normalized Difference Vegetation Index).
        Initial production costs The costs of energy conversion technologies at the start of the simulation.
        Initial technology cost The costs of energy conversion technologies at the start of the simulation..
        Initial temperature, precipitation - grid Global high resolution climate data from WorldClim.
        LOD (location of dams and reservoirs) Location, building year, purpose and size of 7000 largest reservoirs.
        Lake depth - grid Database of lake depths.
        MAGICC parameter settings MAGICC 6.0 parameters calibrated to emulate one out of 19 climate models.
        MSA effect values Database on empirical relationships between environmental pressures and reduction in mean species abundance for terrestrial ecosystems.
        Nitrogen critical load Level of N deposition or concentration that should not be exceeded.
        No-go areas - grid Indicator to account for the fact that tourists do not visit countries in war, with high poverty rates or poor safety conditions. This index includes hunger, refugees, war, corruption, homocides and theft
        Other crops Fraction of other, not modelled crops in agricultural area, assumed constant in the future.
        Other energy and land-use models Emission projections and marginal abatement costs curves based on external models, such as the IIASA land-use models or the POLES database.
        Radiative forcing factors Radiative forcing per greenhouse gas.
        Regression parameters Regression parameters of suitability assessment.
        Relationship income and emission factor Relationship between GDP and emission factors.
        Residue management Assumptions on residue management in agriculture.
        Road-map - grid Global road map.
        Rules on use of technology Rules determining how different types of power plants are used.
        Slope - grid Terrain slope index.
        Soil properties - grid Soil properties that have an effect on vegetation growth and hydrology. These characteristics differ between soil types. Relevant characteristics are soil texture and depth and water holding capacity
        Soil types and profiles (S-World) Soil profiles based on the HWSD (Harmonised World Soil Database) and on the ISRIC-WISE international soil profile dataset
        Species-area relationships Number of species in relation to the size of an ecosystem.
        Sulphate pattern - grid Patterns of climate change to compute non-linear regional radiative effects of sulphate aerosols.
        Topography - grid Topography and altitude, determining the altitude range within a grid cell.
        Topography, elevation - grid Global high resolution map of topography and elevation from NASA Shuttle Radar Topography Mission. Digital Elevation Model.
        Traditional biomass from non-forest land Fraction of traditional fuelwood from non-forestry sources, such as orchard, assumed to be 50% (low-income countries) and 68% (middle-income countries).
        Water demand other sectors - grid Total annual water demand for non-agricultural sectors (households, industry and electricity production)
        Water temperature - grid water temperature.
        Weighting factors for temperature, precipitation, land use and slope Weighting factors for the contribution of temperature, precipitation, land use and slope on distribution of soil properties.

        Historical datasets

        Historical datasetUseDescription
        Cloudiness - grid Percentage of cloudiness per month; assumed constant after the historical period
        Number of wet days - grid Number of days with a rain event, per month; assumed constant after the historical period

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