IMAGE - User contributions [en]

Agricultural economy/Data uncertainties limitations

2019-03-07T15:10:51Z

Zeistvw:

{{ComponentDataUncertaintyAndLimitationsTemplate
|Reference=Narayanan et al., 2012; Stehfest et al., 2013; Nelson et al., 2014; Bruinsma, 2003; Hertel, 2011; Woltjer et al., 2011; Alexandratos and Bruinsma, 2012; Woltjer, 2011;
}}
==Data, uncertainty and limitations==
===Data===
The MAGNET model uses the [ REF GTAP9 database ] for sectoral input–output tables and bilateral trade in the reference year 2011 ([[Narayanan et al., 2012]] [Update?]). The model applies all GTAP sectors for agriculture but industrial and service sectors are aggregated into a few groups of sectors. The regional representation of GTAP is aggregated to match the IMAGE regions. For the start year, agricultural land use for both arable land and permanent grassland is based on FAO statistics. In addition, the model also uses a large number of essential coefficients, such as Armington trade elasticities, consumption function parameters, substitution elasticities for all production nests, {{abbrTemplate|CET}} elasticities for land-use transformations, and elasticities in the land supply curve. Some parameters are based on econometric research or economic literature, while others are no more than ‘best guesses’ ([[Woltjer et al., 2011]]). The autonomous technological yield change in is based on FAO projections in both MAGNET and IMAGE ([[Alexandratos and Bruinsma, 2012]]).

===Uncertainties ===
To date, no systematic uncertainty analyses have been carried out for models on the agricultural economy, including the MAGNET model. However, a comparison of the [[MAGNET model|MAGNET]] and [[IMPACT model|IMPACT]] models has revealed large differences in model results, even more in policy scenarios than in baseline projections ([[Stehfest et al., 2013]]).

A recent model comparison within [[AgMIP and ISI-MIP project|AgMIP]] included ten global agro-economic models using harmonised scenario drivers ([[Nelson et al., 2014]]; [[Von Lampe et al., 2014]]). Results indicate that MAGNET is in the upper range of other models, in terms of future land-use expansion. This is probably due to the relatively large land supply in MAGNET, which allows further expansion of agricultural land, particularly in North and South America, and Africa. In contrast, several other models do not explicitly consider agricultural land expansion, but only allow interchanges between, for example, arable land and grassland. In addition to land supply, the most relevant uncertainties in MAGNET are autonomous technological change, relative contribution of intensification or expansion to total production growth, retaining current trade patterns in long-term scenarios, and dynamics in the livestock sector, especially with respect to pasture area and grassland intensification ([[Stehfest et al., 2013]]), and long-term dietary preferences. The empirical basis for many of these parameters in MAGNET and all other agro-economic models needs to be improved ([[Hertel, 2011]]).

===Limitations ===
The MAGNET model provides a complete and internally consistent view of the world economy, covering all economic sectors, and a dynamic modelling of all primary and intermediate production and demand. However, a little known limitation is the uncertainties in constructing the GTAP/MAGNET database because many ad hoc assumptions need to be made to fill the database, for instance, allocating value added across inputs.

Furthermore, volumes in the model are not expressed in physical terms but in monetary values. Likewise, all substitutions in the model are based on monetary values. As a consequence, there is no guarantee that changes in composition are consistent with the physical requirements, such as in livestock feed. Thus, a closer link to physical units is needed ([[Woltjer, 2011]]).

Because of the highly aggregated and general character of MAGNET, most elasticities are kept constant over time. Some improvements have been introduced in the consumption function, by making the income elasticities dependent on income levels. Armington elasticities are also constant, and thus small trade flows in the starting year only increase very slowly in future years.

Although some limitations can be reduced by adding physical units and improving the empirical basis for the main elasticities, many simplifications in agro-economic models will remain. MAGNET provides a consistent system to assess economy-wide effects of policy measures on land use, income, welfare and production, and supports policymakers and scientists in gaining insights into the complex interlinkages in the agricultural system. Nevertheless, simplifications and uncertainties that result from such a broad coverage need to be kept in mind when interpreting results.

Agricultural economy/Policy issues

2019-03-07T15:10:02Z

Zeistvw:

{{ComponentPolicyIssueTemplate
|Reference=Banse et al., 2008; Verburg et al., 2009; PBL, 2010; PBL, 2011; Westhoek et al., in preparation; Overmars et al., 2014;
}}
<div class="page_standard">
==Baseline developments==
In the SSP scenarios, agricultural crop and livestock production increases rapidly driven by population increase and dietary changes ([[Doelman et al., 2018]]). As a consequence of production increases, the total area of cropland and pasture is projected to increase, although this is less certain. Depending on scenario and region, some scenarios may also show decreasing land areas, certainly after 2030 when the population starts to decline in several regions.

{{DisplayPolicyInterventionFigureTemplate|{{#titleparts: {{PAGENAME}}|1}}|Baseline figure}}
==Policy interventions==
Numerous policy interventions can be studied:
* Biofuel policies: Partly as an autonomous process under high oil prices but mainly driven by biofuel policies, the proportion of biofuels (so far, only first generation) in the transport sector is projected to increase ([[Banse et al., 2008]]). The model can be used to estimate direct and indirect land-use change and associated emissions.
* REDD policies: Forest protection leads to a reduction in CO<sub>2</sub> emissions from land-use change. The related opportunity costs can be used to estimate cost curves for the emission abatement that results from REDD policies ([[Overmars et al., 2014]]).
* Agricultural and trade policies can be assessed for their effects on land use, greenhouse gas emissions and biodiversity ([[Verburg et al., 2009]]).
* Measures to reduce biodiversity loss by increasing protected areas, increasing agricultural productivity, dietary changes, and reducing waste ([[PBL, 2010]]). Several biodiversity options, in a stepwise introduction, affect land and commodity prices as well as land-use change (the figure below).
* Consumption changes, dietary preferences, and their effect on global land use, prices and emissions can be studied ([[PBL, 2011]]; [[Stehfest et al., 2013]])
Changes in crop and livestock production systems, such as more efficient production methods, or organic farming can be assessed ([[PBL, 2011]]; [[Westhoek et al., in preparation]]).

{{DisplayPolicyInterventionFigureTemplate|{{#titleparts: {{PAGENAME}}|1}}|Policy intervention figure}}

{{PIEffectOnComponentTemplate }}
</div>

Agricultural economy/Description

2019-03-07T15:09:00Z

Zeistvw:

{{ComponentDescriptionTemplate
|Reference=Hertel, 1997; Britz, 2003; Armington, 1969; Huang et al., 2004; Helming et al., 2010; Banse et al., 2008; Bruinsma, 2003; Woltjer et al., 2011; Van Meijl et al., 2006; Eickhout et al., 2009; Overmars et al., 2014; Alexandratos and Bruinsma, 2012;
}}
<div class="page_standard">
==Model description of {{ROOTPAGENAME}}==
The MAGNET model ([[Woltjer et al., 2011]]; [[Woltjer et al., 2014]]) is based on the standard GTAP model ([[Hertel, 1997]]), which is a multi-regional, static, applied computable general equilibrium ({{abbrTemplate|CGE}}) model based on neoclassical microeconomic theory. Although the model covers the entire economy, there is a special focus on agricultural sectors. It is a further development of GTAP regarding land use, household consumption, livestock, food, feed and energy crop production, and emission reduction from deforestation.

===Demand and supply===
Household demand for agricultural products is calculated based on changes in income, income elasticities, preference shift, price elasticities, cross-price elasticities, and the commodity prices arising from changes in the supply side. Demand and supply are balanced via prices to reach equilibrium. Income elasticities for agricultural commodities are consistent with FAO estimates ([[Britz, 2003]]), and dynamically depend on purchasing power parity ({{abbrTemplate|PPP}}) corrected GDP per capita. The supply of all commodities is modelled by an input–output structure that explicitly links the production of goods and services for final consumption via different processing stages back to primary products (crops and livestock products) and resources. At each production level, input of labour, capital, and intermediate input or resources (e.g., land) can be substituted for one another. For example, labour, capital and land are input factors in crop production, and substitution of these production factors is driven by changes in their relative prices. If the price of one input factor increases, it is substituted by other factors, following the price elasticity of substitution.

===Regional aggregation and trade===
MAGNET is flexible in its regional aggregation (129 regions). In linking with IMAGE, MAGNET closely matches the regions in IMAGE (Figure [[Region classification map|IMAGE regions]]). Similar to most other {{abbrTemplate|CGE}} models, MAGNET assumes that products traded internationally are differentiated according to country of origin. Thus, domestic and foreign products are not identical, but are imperfect substitutes (Armington assumption; [[Armington, 1969]]).

===Land use===
In addition to the standard [[GTAP database|GTAP model]], MAGNET includes a dynamic land-supply function ([[Van Meijl et al., 2006]]) that accounts for the availability and suitability of land for agricultural use, based on information from IMAGE (see below). A nested land-use structure accounts for the differences in substitutability of the various types of land use ([[Huang et al., 2004]]; [[Van Meijl et al., 2006]]). In addition, MAGNET includes international and EU agricultural policies, such as production quota and export/import tariffs ([[Helming et al., 2010]]).

===Biofuel crops===
MAGNET includes ethanol and biodiesel as first-generation biofuels made from wheat, sugar cane, maize, and oilseeds ([[Banse et al., 2008]]) and the use of by-products ({{abbrTemplate|DDGS}}, oilcakes) from biofuel production in the livestock sector.

===Livestock===
MAGNET distinguishes the livestock commodities of beef cattle, dairy cattle, other cattle (sheep & goats), dairy cattle, poultry, and pig and other animal products. The first three are the ruminant sectors which are grass and crop fed, while the poultry and pigs sectors are crop fed. Modelling the livestock sector includes different feedstuffs, such as feed crops, co-products from biofuels (oil cakes from rapeseed-based biofuel, or distillers grain from wheat-based biofuels), and grass ([[Woltjer, 2011]]). Grass may be substituted by feed from crops for ruminants.

===Land supply===
In MAGNET, land supply is calculated using a land-supply curve that relates the area in use for agriculture to the land price. Total land supply includes all land that is potentially available for agriculture, where crop production is possible under soil and climatic conditions, and where no other restrictions apply such as urban or protected area designations (see also Component Land-use allocation). In the IMAGE model, total land supply for each region is obtained from potential crop productivity and land availability on a resolution of 5x5 arcminutes. The supply curve depends on total land supply, current agricultural area, current land price, and estimated price elasticity of land supply in the starting year. Recently, the earlier land supply curve ([[Eickhout et al., 2009]]) has been updated with a more detailed assessment of land resources and total land supply in IMAGE ([[Mandryk et al., 2015]]), and with literature data on current price elasticities. Regions differ with regard to the proportion of land in use, and with regard to change in land prices in relation to changes in agricultural land use.

===Reduced land availability===
By restricting land supply in IMAGE and MAGNET, the models can assess scenarios with additional protected areas, or reduced emissions from deforestation and forest degradation ({{abbrTemplate|REDD}}). These areas are excluded from the land supply curve in MAGNET, leading to lower elasticities, less land-use change and higher prices, and are also excluded from the allocation of agricultural land in IMAGE (e.g., [[Overmars et al., 2014]]).

===Intensification of crop and pasture production===
Crop and pasture yields in MAGNET may change as a result of the following four processes:
# autonomous technological change (external scenario assumption);
# intensification due to the substitution of production factors (endogenous);
# climate change (from IMAGE);
# change in agricultural area affecting crop yields (such as, decreasing average yields due to expansion into less suitable regions; from IMAGE).

Biophysical yield effects due to climate and area changes are calculated by the IMAGE crop model and communicated to MAGNET. Likewise, also the potential yields and thus the yield gap can be assessed with the crop model in IMAGE. External assumptions on autonomous technological changes are mostly based on FAO projections ([[Alexandratos and Bruinsma, 2012]]) [ Update REF FAO 2018 ], which describe per region and commodity, the assumed future changes in yields for a wide range of crop types. In MAGNET, the biophysical yield changes are combined with the autonomous technological change to give the total exogenous yield change. In addition, during the simulation period, MAGNET calculates an endogenous intensification as a result of price-driven substitution between labour, land and capital. In IMAGE, regional yield changes due to autonomous technological change and endogenous intensification according to MAGNET are used in the spatially explicit allocation of land use (Component [[Land-use allocation]]).
</div>

Agricultural economy

2019-03-07T15:06:33Z

Zeistvw:

{{ComponentTemplate2
|Application=Eururalis (2007) project; Millennium Ecosystem Assessment - MA (2005) project; AgMIP and ISI-MIP project; The Protein Puzzle (2011) project; Rethinking Biodiversity Strategies (2010) project; Roads from Rio+20 (2012) project;
|IMAGEComponent=Drivers; Land-use allocation;
|Model-Database=EFIGTM model;
|KeyReference=Stehfest et al., 2013; Woltjer et al., 2014; Von Lampe et al., 2014; Bijl et al., 2017;
|Reference=Woltjer et al., 2011; Kallio et al., 2004; Carpenter et al., 2006; Van Vuuren et al., 2018;
|InputVar=Population; GDP per capita; Capital supply; Labour supply; Trade policy; Biofuel policy; Land supply; Potential crop and grass yield - grid; Technological change (crops and livestocks);
|Parameter=Income and price elasticities;
|OutputVar=Management intensity crops; Management intensity livestock; Food availability per capita; Commodity price; Livestock production; Crop production; Demand (all commodities); Trade (all commodities);
|ComponentCode=AEF
|AggregatedComponent=Agriculture and land use
|FrameworkElementType=pressure component
}}
<div class="page_standard">
==Introduction==
As a result of the growing world population and higher per capita consumption, production of food, feed, fibres and other products, such as bioenergy and timber, will need to increase rapidly in the coming decades. Even with the expected improvements in agricultural yields and efficiency, there will be increasing demand for more agricultural land. However, expansion of agricultural land will lead to deforestation and increases in greenhouse gas emissions, loss of biodiversity and ecosystem services, and nutrient imbalances. To reduce these environmental impacts, a further increase in agricultural yields is needed, together with other options such as reduced food losses, dietary changes, improved livestock systems, and better nutrient management.

In the IMAGE framework, future development of the agricultural economy can be calculated using the agro-economic model [[MAGNET model|MAGNET]] (Woltjer et al. ([[Woltjer et al., 2011|2011]]); Woltjer et al. ([[Woltjer et al., 2014|2014]])). MAGNET is a computable general equilibrium ({{abbrTemplate|CGE}}) model that is connected via a soft link to the core model of IMAGE. Demographic changes and rising incomes are the primary driving factors of the MAGNET model, and lead to increasing and changing demand for all commodities including agricultural commodities. In response to changing demand, agricultural production is increasing, and the model also takes into account changing prices of production factors, resource availability and technological progress. In MAGNET, agricultural production supplies domestic markets, and other countries and regions are supplied via international trade, depending on historical trade balances, competitiveness (relative price developments), transport costs and trade policies. MAGNET uses information from IMAGE on land availability and suitability, and on changes in crop yields due to climate change and agricultural expansion on inhomogeneous land areas. The results from MAGNET on agricultural production, grassland area, and endogenous yield efficiency (management factor) changes are used in IMAGE to calculate spatially explicit land-use change, and the environmental impacts on carbon, nutrient and water cycles, biodiversity, and climate.

Although MAGNET is the standard agro-economic model used with IMAGE, other models can be linked with IMAGE. For example, the [[IMPACT model]] was used with IMAGE in the [[Millennium Ecosystem Assessment - MA (2005) project|Millennium Ecosystem Assessment]] ([[Carpenter et al., 2006]]), and in a [[The Protein Puzzle (2011) project|PBL study on protein supply]], both the [[MAGNET model|MAGNET]] and the [[IMPACT model|IMPACT]] model were used to study the same set of scenarios. This allowed a systematic comparison between IMPACT and MAGNET ([[Stehfest et al., 2013]]). In a more recent study [[van Vuuren et al., 2018]] the Food Demand Model [[Bijl et al., 2017]], which is implemented as an integrated part of the IMAGE framework, was used for projections of food demand with various diets.

Other land-use changes, such as infrastructure expansion, which do not require interregional links, are described in the [[Land-use allocation|land-use allocation]] model). Demand for timber is described in the [[Forest management|forest management]] page.

{{InputOutputParameterTemplate}}
</div>

Agricultural economy

2019-03-07T15:05:34Z

Zeistvw:

{{ComponentTemplate2
|Application=Eururalis (2007) project; Millennium Ecosystem Assessment - MA (2005) project; AgMIP and ISI-MIP project; The Protein Puzzle (2011) project; Rethinking Biodiversity Strategies (2010) project; Roads from Rio+20 (2012) project;
|IMAGEComponent=Drivers; Land-use allocation;
|Model-Database=EFIGTM model;
|KeyReference=Stehfest et al., 2013; Woltjer et al., 2014; Von Lampe et al., 2014; Bijl et al., 2017;
|Reference=Woltjer et al., 2011; Kallio et al., 2004; Carpenter et al., 2006; Van Vuuren et al., 2018;
|InputVar=Population; GDP per capita; Capital supply; Labour supply; Trade policy; Biofuel policy; Land supply; Potential crop and grass yield - grid; Technological change (crops and livestocks);
|Parameter=Income and price elasticities;
|OutputVar=Management intensity crops; Management intensity livestock; Food availability per capita; Commodity price; Livestock production; Crop production; Demand (all commodities); Trade (all commodities);
|ComponentCode=AEF
|AggregatedComponent=Agriculture and land use
|FrameworkElementType=pressure component
}}
<div class="page_standard">
==Introduction==
As a result of the growing world population and higher per capita consumption, production of food, feed, fibres and other products, such as bioenergy and timber, will need to increase rapidly in the coming decades. Even with the expected improvements in agricultural yields and efficiency, there will be increasing demand for more agricultural land. However, expansion of agricultural land will lead to deforestation and increases in greenhouse gas emissions, loss of biodiversity and ecosystem services, and nutrient imbalances. To reduce these environmental impacts, a further increase in agricultural yields is needed, together with other options such as reduced food losses, dietary changes, improved livestock systems, and better nutrient management.

In the IMAGE framework, future development of the agricultural economy can be calculated using the agro-economic model [[MAGNET model|MAGNET]] (Woltjer et al. ([[Woltjer et al., 2011|2011]]); Woltjer et al. ([[Woltjer et al., 2014|2014]])). MAGNET is a computable general equilibrium ({{abbrTemplate|CGE}}) model that is connected via a soft link to the core model of IMAGE. Demographic changes and rising incomes are the primary driving factors of the MAGNET model, and lead to increasing and changing demand for all commodities including agricultural commodities. In response to changing demand, agricultural production is increasing, and the model also takes into account changing prices of production factors, resource availability and technological progress. In MAGNET, agricultural production supplies domestic markets, and other countries and regions are supplied via international trade, depending on historical trade balances, competitiveness (relative price developments), transport costs and trade policies. MAGNET uses information from IMAGE on land availability and suitability, and on changes in crop yields due to climate change and agricultural expansion on inhomogeneous land areas. The results from MAGNET on agricultural production, grassland area, and endogenous yield efficiency (management factor) changes are used in IMAGE to calculate spatially explicit land-use change, and the environmental impacts on carbon, nutrient and water cycles, biodiversity, and climate.

Although MAGNET is the standard agro-economic model used with IMAGE, other models can be linked with IMAGE. For example, the [[IMPACT model]] was used with IMAGE in the [[Millennium Ecosystem Assessment - MA (2005) project|Millennium Ecosystem Assessment]] ([[Carpenter et al., 2006]]), and in a [[The Protein Puzzle (2011) project|PBL study on protein supply]], both the [[MAGNET model|MAGNET]] and the [[IMPACT model|IMPACT]] model were used to study the same set of scenarios. This allowed a systematic comparison between IMPACT and MAGNET ([[Stehfest et al., 2013]]). In a more recent study [ REF 1.5 graden paper ] the Food Demand Model [ Bijl 2017 ], which is implemented as an integrated part of the IMAGE framework, was used for projections of food demand with various diets.

Other land-use changes, such as infrastructure expansion, which do not require interregional links, are described in the [[Land-use allocation|land-use allocation]] model). Demand for timber is described in the [[Forest management|forest management]] page.

{{InputOutputParameterTemplate}}
</div>

Agricultural economy

2019-03-07T15:03:01Z

Zeistvw:

{{ComponentTemplate2
|Application=Eururalis (2007) project; Millennium Ecosystem Assessment - MA (2005) project; AgMIP and ISI-MIP project; The Protein Puzzle (2011) project; Rethinking Biodiversity Strategies (2010) project; Roads from Rio+20 (2012) project;
|IMAGEComponent=Drivers; Land-use allocation;
|Model-Database=EFIGTM model;
|KeyReference=Stehfest et al., 2013; Woltjer et al., 2014; Von Lampe et al., 2014; Bijl et al., 2017;
|Reference=Woltjer et al., 2011; Kallio et al., 2004; Carpenter et al., 2006;
|InputVar=Population; GDP per capita; Capital supply; Labour supply; Trade policy; Biofuel policy; Land supply; Potential crop and grass yield - grid; Technological change (crops and livestocks);
|Parameter=Income and price elasticities;
|OutputVar=Management intensity crops; Management intensity livestock; Food availability per capita; Commodity price; Livestock production; Crop production; Demand (all commodities); Trade (all commodities);
|ComponentCode=AEF
|AggregatedComponent=Agriculture and land use
|FrameworkElementType=pressure component
}}
<div class="page_standard">
==Introduction==
As a result of the growing world population and higher per capita consumption, production of food, feed, fibres and other products, such as bioenergy and timber, will need to increase rapidly in the coming decades. Even with the expected improvements in agricultural yields and efficiency, there will be increasing demand for more agricultural land. However, expansion of agricultural land will lead to deforestation and increases in greenhouse gas emissions, loss of biodiversity and ecosystem services, and nutrient imbalances. To reduce these environmental impacts, a further increase in agricultural yields is needed, together with other options such as reduced food losses, dietary changes, improved livestock systems, and better nutrient management.

In the IMAGE framework, future development of the agricultural economy can be calculated using the agro-economic model [[MAGNET model|MAGNET]] (Woltjer et al. ([[Woltjer et al., 2011|2011]]); Woltjer et al. ([[Woltjer et al., 2014|2014]])). MAGNET is a computable general equilibrium ({{abbrTemplate|CGE}}) model that is connected via a soft link to the core model of IMAGE. Demographic changes and rising incomes are the primary driving factors of the MAGNET model, and lead to increasing and changing demand for all commodities including agricultural commodities. In response to changing demand, agricultural production is increasing, and the model also takes into account changing prices of production factors, resource availability and technological progress. In MAGNET, agricultural production supplies domestic markets, and other countries and regions are supplied via international trade, depending on historical trade balances, competitiveness (relative price developments), transport costs and trade policies. MAGNET uses information from IMAGE on land availability and suitability, and on changes in crop yields due to climate change and agricultural expansion on inhomogeneous land areas. The results from MAGNET on agricultural production, grassland area, and endogenous yield efficiency (management factor) changes are used in IMAGE to calculate spatially explicit land-use change, and the environmental impacts on carbon, nutrient and water cycles, biodiversity, and climate.

Although MAGNET is the standard agro-economic model used with IMAGE, other models can be linked with IMAGE. For example, the [[IMPACT model]] was used with IMAGE in the [[Millennium Ecosystem Assessment - MA (2005) project|Millennium Ecosystem Assessment]] ([[Carpenter et al., 2006]]), and in a [[The Protein Puzzle (2011) project|PBL study on protein supply]], both the [[MAGNET model|MAGNET]] and the [[IMPACT model|IMPACT]] model were used to study the same set of scenarios. This allowed a systematic comparison between IMPACT and MAGNET ([[Stehfest et al., 2013]]). In a more recent study [ REF 1.5 graden paper ] the Food Demand Model [ Bijl 2017 ], which is implemented as an integrated part of the IMAGE framework, was used for projections of food demand with various diets.

Other land-use changes, such as infrastructure expansion, which do not require interregional links, are described in the [[Land-use allocation|land-use allocation]] model). Demand for timber is described in the [[Forest management|forest management]] page.

{{InputOutputParameterTemplate}}
</div>

Livestock systems/Data uncertainties limitations

2019-02-28T13:23:55Z

Zeistvw: Removed some older text, will further update after getting feedback on pigs & poultry from Luis

{{ComponentDataUncertaintyAndLimitationsTemplate
|Reference=FAO, 2012a; Beusen et al., 2008; Bouwman et al., 2005; Seré and Steinfeld, 1996;
}}<div class="page_standard">
==Data, uncertainty and limitations==
===Data===
Historical livestock numbers, milk production per animal, off-take rates and carcass weights were obtained from [[FAO]] ([[FAO, 2012a]]) [ New FAO ref? ]. For ruminants, the production systems have been aggregated to two systems: pastoral, and mixed & landless production systems ([[Bouwman et al., 2005]]). For pigs and poultry ... [ add ref Luis ].

==Uncertainties==
There are several uncertainties in the calculation of livestock production in the different systems for historical years and scenarios. The first uncertainty is the aggregation level on the scale of country or world region, which does not take account of underlying heterogeneity. The second uncertainty concerns the use of average data for carcass weight, off-take rate, and milk production for total livestock populations. In reality, livestock populations cover different age classes, and not all animals in a population are productive. Calculations, such as energy requirement for maintenance, are a non-linear function of body weight, and thus use of average values, may lead to distortion. The third uncertainty is associated with livestock numbers. Methodology and frequency of data collection (for example, by census) vary between countries, and are probably less certain for some developing countries than for industrialised countries. This uncertainty on livestock numbers affects not only the livestock module, but also all impact IMAGE modules that depend on livestock numbers, such as ammonia emissions ([[Beusen et al., 2008]]).

The main uncertainties in construction scenarios concern agricultural demand ([[Agricultural economy]]), the distribution of production over the two systems, and production characteristics per system, including feed requirements and feed types.

==Limitations==
The key limitation in the current livestock module is that the ruminant livestock system have a soft linkage to the agricultural economy model MAGNET ([[Agricultural economy]]). Although [[MAGNET model|MAGNET]] has some representation of feed substitution and intensification as a result of land scarcity, and mimics the dynamics described here, there is no explicit representation of livestock systems and physically based feed compositions.
</div>

Livestock systems

2019-02-28T13:00:37Z

Zeistvw:

{{ComponentTemplate2
|Application=Roads from Rio+20 (2012) project; Global Environmental Outlook - GEO4 (2007) project; Millennium Ecosystem Assessment - MA (2005) project; OECD Environmental Outlook to 2030 (2008) project; OECD Environmental Outlook to 2050 (2012) project; Global Environmental Outlook - GEO3 (2002) project; EU Resource efficiency (2011) project
|IMAGEComponent=Drivers; Agricultural economy; Land-use allocation; Agriculture and land use; Atmospheric composition and climate; Crops and grass;
|Model-Database=MAGNET model;
|KeyReference=Bouwman et al., 2005;
|Reference=Bruinsma, 2003; Bouwman et al., 2006; Bouwman et al., 2005; Delgado et al., 1999; Seré and Steinfeld, 1996; FAO, 2012a;
|InputVar=Production system mix; Feed conversion; Livestock rations; Livestock production; Management intensity livestock; Animal productivity;
|OutputVar=Animal stocks; Feed crop requirement; Grass requirement;
}}<div class="page_standard">
==Introduction==
Food production will have to increase in order to feed the world’s growing population. However, with increasing prosperity and falling production costs, dietary patterns are shifting to include a higher proportion of meat and milk. In the last few decades, traditional mixed farming systems have not been able to raise production levels sufficiently to meet increasing demand. Consequently, modern livestock production systems are expanding rapidly particularly for poultry and pork, creating growing demand for feed crops. This trend started in high-income countries and is now observed in emerging and developing countries ([[Alexandratos and Bruinsma, 2012]]) [ Add FAO 2018 Ref? ].

Interactions between crop and livestock production are described in the livestock systems module of IMAGE, and also the consequences of changing practices in livestock farming for production of food crops and grass. For this purpose, IMAGE distinguishes pastoral livestock systems, and mixed and landless (industrial) production systems. Pastoral systems are based on grazing ruminants, while mixed and landless systems integrate crop and livestock production in which livestock are fed a mix of crops, crop by-products, grass, fodder and crop residues ([[Bouwman et al., 2005]]; [[Bouwman et al., 2006]]). [ To do, update for pig & poultry module ]

Livestock production is related to a wide range of the environmental issues, and the consequences of changes in the livestock system can be studied in the IMAGE framework:
#Expansion of grazing land and particularly arable land for feed crop production, is required to support increasing livestock numbers. According to Bouwman et al. (2005) most arable land expansion is to increase feed production;
#Large amounts of methane (CH<sub>4</sub>) emitted by ruminants during enteric fermentation are the second major source of greenhouse gas emissions after CO2;
#Excreta from all livestock categories is a source of ammonia, methane, nitrous oxide and nitric oxide;
#Odour nuisance and nitrate leaching to groundwater are major local-scale problems;
#A significant amount of land used for ruminants grazing is marginal, low productive grassland with low carrying capacity and high risk of degradation due to overgrazing, especially in arid and semi-arid regions ([[Seré and Steinfeld, 1996]]; [[Delgado et al., 1999]]). To compensate for productivity losses in these areas, forests may be cleared to expand agricultural land areas.
|ComponentCode=LS
|AggregatedComponent=Agriculture and land use
|FrameworkElementType=pressure component
|LeadText=What are the impacts on land-use, greenhouse gases and other emissions to air, land and surface water of increasing livestock production? And how may use of marginal lands for grazing increase the risk of degradation and loss of productivity, inducing more forest clearing.

{{InputOutputParameterTemplate}}
</div>

Livestock systems/Description

2019-02-28T12:58:40Z

Zeistvw: Minor edit, generalized the grazing intensity vs grass area a bit.

{{ComponentDescriptionTemplate
|Reference=Seré and Steinfeld, 1996;
}}<div class="page_standard">
==Model description of {{ROOTPAGENAME}}==
===Livestock production===
IMAGE distinguishes two livestock production systems, namely pastoral systems, and mixed and industrial systems, based on FAO ([[Seré and Steinfeld, 1996]]). Pastoral systems are mostly dominated by extensive ruminant production, while mixed and industrial systems are more intensive with animal husbandry comprising grazing ruminants and monogastrics. The distribution of livestock production in the two systems is constructed from historical data for the years up to the present, and for future years will depend on the scenario selected.

===Livestock===
IMAGE distinguishes five types of livestock: beef, dairy cattle (large ruminants), the category sheep & goats (small ruminants), pigs, and poultry (monogastrics). The numbers of animals and the proportion per production system are calculated from data on domestic livestock production per region provided by the agro-economic model MAGNET ([[Agricultural economy]]). The number of animals in each of the five livestock types is calculated from the total production per region and the characteristics of the livestock systems in that region.
Stocks of dairy cows (POP) per country and world region are obtained from total milk production (PROD) and milk production per animal (MPH).
<math> POP = PROD / MPH </math>

Animal stocks per region of beef cattle, pigs, and sheep and goats are obtained from production and carcass weight (CW) and off-take rate (OR):
<math>POP = PROD/(OR*CW)</math>

Historical data on milk production per cow, off-take rate, and carcass weight are obtained from statistics, and values for future years will depend on the scenario selected.

===Energy requirements===
For dairy cattle, the energy requirements are calculated for maintenance (based on body weight), feeding (based on the proportion of grass in feed rations), lactation (based on milk production per cow) and pregnancy (based on the number of calves per year). The amount of feed dry matter is calculated on the basis of the proportion of digestible energy in the total energy intake, and the energy content of biomass.

Energy requirements for cattle are based on animal activity and production, and for pigs, poultry, sheep and goats on Feed Conversion Ratios (FCR). This is the amount of feed (kg dry matter) required to produce one kilogram of milk or meat. The {{AbbrTemplate|FCR}} values are based on historical data and values for future years will depend on the scenario selected.

===Cropland and grassland required===
Areas for feed crop production and grass are calculated on the basis of feed crop and grass requirements ([[Land-use allocation]]), which are calculated from total feed requirement and diet composition (feed rations, see below).
Composition of animal feed
IMAGE distinguishes five feed categories:
#grass, including hay and grass silage;
#food crops and processing by-products;
#crop residues in the field after harvesting, and fodder crops;
#animal products;
#foraging including roadside grazing, scavenging household waste, and feedstuffs from backyard farming.

In pastoral ruminant production systems, the feed is almost entirely grass except in developing regions where foraging constitutes a larger but variable proportion of the total feed. Pigs and poultry are fed feed crops and by-products, crop residues and fodder. Since these animals are mainly farmed in mixed systems, the contribution of feed crops and residues to the total feed in these systems is much higher than in pastoral systems.

The required feed crop production per animal is calculated from feed rations, and this information is incorporated into the agro-economic model ([[Agricultural economy]]). The proportion of grass in feed rations determines total grass consumption. The amount of grassland area required, and the corresponding grazing intensity are based on the[[Agricultural economy]] module.

===Scenario definition===
A scenario includes assumptions on milk production per animal for dairy cattle, carcass weight and off-take rate for beef cattle, pigs, poultry, sheep and goats, and feed conversion rates ({{abbrTemplate|FCR}}) for pigs, poultry, sheep and goats. The changes in these parameters are generally based on the scenario, and on the economic growth scenario.
</div>

Agricultural economy/Data uncertainties limitations

2019-02-28T11:54:14Z

Zeistvw:

{{ComponentDataUncertaintyAndLimitationsTemplate
|Reference=Narayanan et al., 2012; Stehfest et al., 2013; Nelson et al., 2014; Bruinsma, 2003; Hertel, 2011; Woltjer et al., 2011; Alexandratos and Bruinsma, 2012; Woltjer, 2011;
}}
==Data, uncertainty and limitations==
===Data===
The MAGNET model uses the [ REF GTAP9 database ] for sectoral input–output tables and bilateral trade in the reference year 2011 ([[Narayanan et al., 2012]] [Update?]). The model applies all GTAP sectors for agriculture but industrial and service sectors are aggregated into a few groups of sectors. The regional representation of GTAP is aggregated to match the IMAGE regions. For the start year, agricultural land use for both arable land and permanent grassland is based on FAO statistics. In addition, the model also uses a large number of essential coefficients, such as Armington trade elasticities, consumption function parameters, substitution elasticities for all production nests, {{abbrTemplate|CET}} elasticities for land-use transformations, and elasticities in the land supply curve. Some parameters are based on econometric research or economic literature, while others are no more than ‘best guesses’ ([[Woltjer et al., 2011]]). The autonomous technological yield change in is based on FAO projections in both MAGNET and IMAGE ([[Alexandratos and Bruinsma, 2012]]) [ Update REF FAO 2018 ].

===Uncertainties ===
To date, no systematic uncertainty analyses have been carried out for models on the agricultural economy, including the MAGNET model. However, a comparison of the [[MAGNET model|MAGNET]] and [[IMPACT model|IMPACT]] models has revealed large differences in model results, even more in policy scenarios than in baseline projections ([[Stehfest et al., 2013]]).

A recent model comparison within [[AgMIP and ISI-MIP project|AgMIP]] included ten global agro-economic models using harmonised scenario drivers ([[Nelson et al., 2014]]; [[Von Lampe et al., 2014]]). Results indicate that MAGNET is in the upper range of other models, in terms of future land-use expansion. This is probably due to the relatively large land supply in MAGNET, which allows further expansion of agricultural land, particularly in North and South America, and Africa. In contrast, several other models do not explicitly consider agricultural land expansion, but only allow interchanges between, for example, arable land and grassland. In addition to land supply, the most relevant uncertainties in MAGNET are autonomous technological change, relative contribution of intensification or expansion to total production growth, retaining current trade patterns in long-term scenarios, and dynamics in the livestock sector, especially with respect to pasture area and grassland intensification ([[Stehfest et al., 2013]]), and long-term dietary preferences. The empirical basis for many of these parameters in MAGNET and all other agro-economic models needs to be improved ([[Hertel, 2011]]).

===Limitations ===
The MAGNET model provides a complete and internally consistent view of the world economy, covering all economic sectors, and a dynamic modelling of all primary and intermediate production and demand. However, a little known limitation is the uncertainties in constructing the GTAP/MAGNET database because many ad hoc assumptions need to be made to fill the database, for instance, allocating value added across inputs.

Furthermore, volumes in the model are not expressed in physical terms but in monetary values. Likewise, all substitutions in the model are based on monetary values. As a consequence, there is no guarantee that changes in composition are consistent with the physical requirements, such as in livestock feed. Thus, a closer link to physical units is needed ([[Woltjer, 2011]]).

Because of the highly aggregated and general character of MAGNET, most elasticities are kept constant over time. Some improvements have been introduced in the consumption function, by making the income elasticities dependent on income levels. Armington elasticities are also constant, and thus small trade flows in the starting year only increase very slowly in future years.

Although some limitations can be reduced by adding physical units and improving the empirical basis for the main elasticities, many simplifications in agro-economic models will remain. MAGNET provides a consistent system to assess economy-wide effects of policy measures on land use, income, welfare and production, and supports policymakers and scientists in gaining insights into the complex interlinkages in the agricultural system. Nevertheless, simplifications and uncertainties that result from such a broad coverage need to be kept in mind when interpreting results.

Agricultural economy/Policy issues

2019-02-28T11:48:35Z

Zeistvw: Removed old reference, should add doelman et al 2018 figures.

{{ComponentPolicyIssueTemplate
|Reference=Banse et al., 2008; Verburg et al., 2009; PBL, 2010; PBL, 2011; Westhoek et al., in preparation; Overmars et al., 2014;
}}
<div class="page_standard">
==Baseline developments==
In the SSP scenarios, agricultural crop and livestock production increases rapidly driven by population increase and dietary changes [ Doelman 2018 ]. As a consequence of production increases, the total area of cropland and pasture is projected to increase, although this is less certain. Depending on scenario and region, some scenarios may also show decreasing land areas, certainly after 2030 when the population starts to decline in several regions.

{{DisplayPolicyInterventionFigureTemplate|{{#titleparts: {{PAGENAME}}|1}}|Baseline figure}}
==Policy interventions==
Numerous policy interventions can be studied:
* Biofuel policies: Partly as an autonomous process under high oil prices but mainly driven by biofuel policies, the proportion of biofuels (so far, only first generation) in the transport sector is projected to increase ([[Banse et al., 2008]]). The model can be used to estimate direct and indirect land-use change and associated emissions.
* REDD policies: Forest protection leads to a reduction in CO<sub>2</sub> emissions from land-use change. The related opportunity costs can be used to estimate cost curves for the emission abatement that results from REDD policies ([[Overmars et al., 2014]]).
* Agricultural and trade policies can be assessed for their effects on land use, greenhouse gas emissions and biodiversity ([[Verburg et al., 2009]]).
* Measures to reduce biodiversity loss by increasing protected areas, increasing agricultural productivity, dietary changes, and reducing waste ([[PBL, 2010]]). Several biodiversity options, in a stepwise introduction, affect land and commodity prices as well as land-use change (the figure below).
* Consumption changes, dietary preferences, and their effect on global land use, prices and emissions can be studied ([[PBL, 2011]]; [[Stehfest et al., 2013]])
Changes in crop and livestock production systems, such as more efficient production methods, or organic farming can be assessed ([[PBL, 2011]]; [[Westhoek et al., in preparation]]).

{{DisplayPolicyInterventionFigureTemplate|{{#titleparts: {{PAGENAME}}|1}}|Policy intervention figure}}

{{PIEffectOnComponentTemplate }}
</div>

Agricultural economy

2019-02-28T11:38:09Z

Zeistvw: Added sentence on Food Demand Model, still need to add refs

{{ComponentTemplate2
|Application=Eururalis (2007) project; Millennium Ecosystem Assessment - MA (2005) project; AgMIP and ISI-MIP project; The Protein Puzzle (2011) project; Rethinking Biodiversity Strategies (2010) project; Roads from Rio+20 (2012) project;
|IMAGEComponent=Drivers; Land-use allocation;
|Model-Database=EFIGTM model;
|KeyReference=Stehfest et al., 2013; Woltjer et al., 2014; Von Lampe et al., 2014;
|Reference=Woltjer et al., 2011; Kallio et al., 2004; Carpenter et al., 2006;
|InputVar=Population; GDP per capita; Capital supply; Labour supply; Trade policy; Biofuel policy; Land supply; Potential crop and grass yield - grid; Technological change (crops and livestocks);
|Parameter=Income and price elasticities;
|OutputVar=Management intensity crops; Management intensity livestock; Food availability per capita; Commodity price; Livestock production; Crop production; Demand (all commodities); Trade (all commodities);
|ComponentCode=AEF
|AggregatedComponent=Agriculture and land use
|FrameworkElementType=pressure component
}}
<div class="page_standard">
==Introduction==
As a result of the growing world population and higher per capita consumption, production of food, feed, fibres and other products, such as bioenergy and timber, will need to increase rapidly in the coming decades. Even with the expected improvements in agricultural yields and efficiency, there will be increasing demand for more agricultural land. However, expansion of agricultural land will lead to deforestation and increases in greenhouse gas emissions, loss of biodiversity and ecosystem services, and nutrient imbalances. To reduce these environmental impacts, a further increase in agricultural yields is needed, together with other options such as reduced food losses, dietary changes, improved livestock systems, and better nutrient management.

In the IMAGE framework, future development of the agricultural economy can be calculated using the agro-economic model [[MAGNET model|MAGNET]] (Woltjer et al. ([[Woltjer et al., 2011|2011]]); Woltjer et al. ([[Woltjer et al., 2014|2014]])). MAGNET is a computable general equilibrium ({{abbrTemplate|CGE}}) model that is connected via a soft link to the core model of IMAGE. Demographic changes and rising incomes are the primary driving factors of the MAGNET model, and lead to increasing and changing demand for all commodities including agricultural commodities. In response to changing demand, agricultural production is increasing, and the model also takes into account changing prices of production factors, resource availability and technological progress. In MAGNET, agricultural production supplies domestic markets, and other countries and regions are supplied via international trade, depending on historical trade balances, competitiveness (relative price developments), transport costs and trade policies. MAGNET uses information from IMAGE on land availability and suitability, and on changes in crop yields due to climate change and agricultural expansion on inhomogeneous land areas. The results from MAGNET on agricultural production, grassland area, and endogenous yield efficiency (management factor) changes are used in IMAGE to calculate spatially explicit land-use change, and the environmental impacts on carbon, nutrient and water cycles, biodiversity, and climate.

Although MAGNET is the standard agro-economic model used with IMAGE, other models can be linked with IMAGE. For example, the [[IMPACT model]] was used with IMAGE in the [[Millennium Ecosystem Assessment - MA (2005) project|Millennium Ecosystem Assessment]] ([[Carpenter et al., 2006]]), and in a [[The Protein Puzzle (2011) project|PBL study on protein supply]], both the [[MAGNET model|MAGNET]] and the [[IMPACT model|IMPACT]] model were used to study the same set of scenarios. This allowed a systematic comparison between IMPACT and MAGNET ([[Stehfest et al., 2013]]). In a more recent study [ REF 1.5 graden paper ] the Food Demand Model [ Bijl 2017 ], which is implemented as an integrated part of the IMAGE framework, was used for projections of food demand with various diets.

Other land-use changes, such as infrastructure expansion, which do not require interregional links, are described in the [[Land-use allocation|land-use allocation]] model). Demand for timber is described in the [[Forest management|forest management]] page.

{{InputOutputParameterTemplate}}
</div>

Agricultural economy/Description

2019-02-28T11:32:09Z

Zeistvw: Edited the livestock components of manget, some things still to do.

{{ComponentDescriptionTemplate
|Reference=Hertel, 1997; Britz, 2003; Armington, 1969; Huang et al., 2004; Helming et al., 2010; Banse et al., 2008; Bruinsma, 2003; Woltjer et al., 2011; Van Meijl et al., 2006; Eickhout et al., 2009; Overmars et al., 2014; Alexandratos and Bruinsma, 2012;
}}
<div class="page_standard">
==Model description of {{ROOTPAGENAME}}==
The MAGNET model ([[Woltjer et al., 2011]]; [[Woltjer et al., 2014]]) is based on the standard GTAP model ([[Hertel, 1997]]), which is a multi-regional, static, applied computable general equilibrium ({{abbrTemplate|CGE}}) model based on neoclassical microeconomic theory. Although the model covers the entire economy, there is a special focus on agricultural sectors. It is a further development of GTAP regarding land use, household consumption, livestock, food, feed and energy crop production, and emission reduction from deforestation.

===Demand and supply===
Household demand for agricultural products is calculated based on changes in income, income elasticities, preference shift, price elasticities, cross-price elasticities, and the commodity prices arising from changes in the supply side. Demand and supply are balanced via prices to reach equilibrium. Income elasticities for agricultural commodities are consistent with FAO estimates ([[Britz, 2003]]), and dynamically depend on purchasing power parity ({{abbrTemplate|PPP}}) corrected GDP per capita. The supply of all commodities is modelled by an input–output structure that explicitly links the production of goods and services for final consumption via different processing stages back to primary products (crops and livestock products) and resources. At each production level, input of labour, capital, and intermediate input or resources (e.g., land) can be substituted for one another. For example, labour, capital and land are input factors in crop production, and substitution of these production factors is driven by changes in their relative prices. If the price of one input factor increases, it is substituted by other factors, following the price elasticity of substitution.

===Regional aggregation and trade===
MAGNET is flexible in its regional aggregation (129 regions). In linking with IMAGE, MAGNET closely matches the regions in IMAGE (Figure [[Region classification map|IMAGE regions]]). Similar to most other {{abbrTemplate|CGE}} models, MAGNET assumes that products traded internationally are differentiated according to country of origin. Thus, domestic and foreign products are not identical, but are imperfect substitutes (Armington assumption; [[Armington, 1969]]).

===Land use===
In addition to the standard [[GTAP database|GTAP model]], MAGNET includes a dynamic land-supply function ([[Van Meijl et al., 2006]]) that accounts for the availability and suitability of land for agricultural use, based on information from IMAGE (see below). A nested land-use structure accounts for the differences in substitutability of the various types of land use ([[Huang et al., 2004]]; [[Van Meijl et al., 2006]]). In addition, MAGNET includes international and EU agricultural policies, such as production quota and export/import tariffs ([[Helming et al., 2010]]).

===Biofuel crops===
MAGNET includes ethanol and biodiesel as first-generation biofuels made from wheat, sugar cane, maize, and oilseeds ([[Banse et al., 2008]]) and the use of by-products ({{abbrTemplate|DDGS}}, oilcakes) from biofuel production in the livestock sector.

===Livestock===
MAGNET distinguishes the livestock commodities of beef cattle, dairy cattle, other cattle (sheep & goats), dairy cattle, poultry, and pig and other animal products. The first three are the ruminant sectors which are grass and crop fed, while the poultry and pigs sectors are crop fed. Modelling the livestock sector includes different feedstuffs, such as feed crops, co-products from biofuels (oil cakes from rapeseed-based biofuel, or distillers grain from wheat-based biofuels), and grass ([[Woltjer, 2011]]). Grass may be substituted by feed from crops for ruminants.

===Land supply===
In MAGNET, land supply is calculated using a land-supply curve that relates the area in use for agriculture to the land price. Total land supply includes all land that is potentially available for agriculture, where crop production is possible under soil and climatic conditions, and where no other restrictions apply such as urban or protected area designations (see also Component Land-use allocation). In the IMAGE model, total land supply for each region is obtained from potential crop productivity and land availability on a resolution of 5x5 arcminutes. The supply curve depends on total land supply, current agricultural area, current land price, and estimated price elasticity of land supply in the starting year. Recently, the earlier land supply curve ([[Eickhout et al., 2009]]) has been updated with a more detailed assessment of land resources and total land supply in IMAGE ([[Mandryk et al., 2015]]), and with literature data on current price elasticities. Regions differ with regard to the proportion of land in use, and with regard to change in land prices in relation to changes in agricultural land use. [ To do WJvZ: add description of land price / substitution elasticies once we finalize the SSP paramter options. ]

===Reduced land availability===
By restricting land supply in IMAGE and MAGNET, the models can assess scenarios with additional protected areas, or reduced emissions from deforestation and forest degradation ({{abbrTemplate|REDD}}). These areas are excluded from the land supply curve in MAGNET, leading to lower elasticities, less land-use change and higher prices, and are also excluded from the allocation of agricultural land in IMAGE (e.g., [[Overmars et al., 2014]]).

===Intensification of crop and pasture production===
Crop and pasture yields in MAGNET may change as a result of the following four processes:
# autonomous technological change (external scenario assumption);
# intensification due to the substitution of production factors (endogenous);
# climate change (from IMAGE);
# change in agricultural area affecting crop yields (such as, decreasing average yields due to expansion into less suitable regions; from IMAGE).

Biophysical yield effects due to climate and area changes are calculated by the IMAGE crop model and communicated to MAGNET. Likewise, also the potential yields and thus the yield gap can be assessed with the crop model in IMAGE. External assumptions on autonomous technological changes are mostly based on FAO projections ([[Alexandratos and Bruinsma, 2012]]) [ Update REF FAO 2018 ], which describe per region and commodity, the assumed future changes in yields for a wide range of crop types. In MAGNET, the biophysical yield changes are combined with the autonomous technological change to give the total exogenous yield change. In addition, during the simulation period, MAGNET calculates an endogenous intensification as a result of price-driven substitution between labour, land and capital. In IMAGE, regional yield changes due to autonomous technological change and endogenous intensification according to MAGNET are used in the spatially explicit allocation of land use (Component [[Land-use allocation]]).
</div>

Agricultural economy

2019-02-28T11:14:50Z

Zeistvw: Removed forestry things and updated a little bit of the description.

{{ComponentTemplate2
|Application=Eururalis (2007) project; Millennium Ecosystem Assessment - MA (2005) project; AgMIP and ISI-MIP project; The Protein Puzzle (2011) project; Rethinking Biodiversity Strategies (2010) project; Roads from Rio+20 (2012) project;
|IMAGEComponent=Drivers; Land-use allocation;
|Model-Database=EFIGTM model;
|KeyReference=Stehfest et al., 2013; Woltjer et al., 2014; Von Lampe et al., 2014;
|Reference=Woltjer et al., 2011; Kallio et al., 2004; Carpenter et al., 2006;
|InputVar=Population; GDP per capita; Capital supply; Labour supply; Trade policy; Biofuel policy; Land supply; Potential crop and grass yield - grid; Technological change (crops and livestocks);
|Parameter=Income and price elasticities;
|OutputVar=Management intensity crops; Management intensity livestock; Food availability per capita; Commodity price; Livestock production; Crop production; Demand (all commodities); Trade (all commodities);
|ComponentCode=AEF
|AggregatedComponent=Agriculture and land use
|FrameworkElementType=pressure component
}}
<div class="page_standard">
==Introduction==
As a result of the growing world population and higher per capita consumption, production of food, feed, fibres and other products, such as bioenergy and timber, will need to increase rapidly in the coming decades. Even with the expected improvements in agricultural yields and efficiency, there will be increasing demand for more agricultural land. However, expansion of agricultural land will lead to deforestation and increases in greenhouse gas emissions, loss of biodiversity and ecosystem services, and nutrient imbalances. To reduce these environmental impacts, a further increase in agricultural yields is needed, together with other options such as reduced food losses, dietary changes, improved livestock systems, and better nutrient management.

In the IMAGE framework, future development of the agricultural economy can be calculated using the agro-economic model [[MAGNET model|MAGNET]] (Woltjer et al. ([[Woltjer et al., 2011|2011]]); Woltjer et al. ([[Woltjer et al., 2014|2014]])). MAGNET is a computable general equilibrium ({{abbrTemplate|CGE}}) model that is connected via a soft link to the core model of IMAGE. Demographic changes and rising incomes are the primary driving factors of the MAGNET model, and lead to increasing and changing demand for all commodities including agricultural commodities. In response to changing demand, agricultural production is increasing, and the model also takes into account changing prices of production factors, resource availability and technological progress. In MAGNET, agricultural production supplies domestic markets, and other countries and regions are supplied via international trade, depending on historical trade balances, competitiveness (relative price developments), transport costs and trade policies. MAGNET uses information from IMAGE on land availability and suitability, and on changes in crop yields due to climate change and agricultural expansion on inhomogeneous land areas. The results from MAGNET on agricultural production, grassland area, and endogenous yield efficiency (management factor) changes are used in IMAGE to calculate spatially explicit land-use change, and the environmental impacts on carbon, nutrient and water cycles, biodiversity, and climate.

Although MAGNET is the standard agro-economic model used with IMAGE, other models can be linked with IMAGE. For example, the [[IMPACT model]] was used with IMAGE in the [[Millennium Ecosystem Assessment - MA (2005) project|Millennium Ecosystem Assessment]] ([[Carpenter et al., 2006]]), and in a [[The Protein Puzzle (2011) project|PBL study on protein supply]], both the [[MAGNET model|MAGNET]] and the [[IMPACT model|IMPACT]] model were used to study the same set of scenarios. This allowed a systematic comparison between IMPACT and MAGNET ([[Stehfest et al., 2013]]). Other land-use changes, such as infrastructure expansion, which do not require interregional links, are described in the [[Land-use allocation|land-use allocation]] model). Demand for timber is described in the [[Forest management|forest management]] page.

{{InputOutputParameterTemplate}}
</div>