Page 270 - Climate Change and Food Systems

climate change and food systems: global assessments and implications for food security and trade
A two-level demand nested structure is identified within the AEZ-specific land demand by the agricultural sectors. We specify a large constant elasticity of substitution (CES) function of 20 between AEZs, so that land rents of
all AEZs would change in the same direction and at very similar magnitude in response
to exogenous shocks. This assumption also implies that production technology is the same across all AEZs, albeit with differentiated output levels.
The land supply is also AEZ-specific,
with a three-level nested structure under
the assumption of weak separability. For
each tier, we specify a Constant Elasticity of Transformation (CET) function to govern the optimal allocation of land according to relative land rents payable by the land-using sectors. The bottom tier allocates the land between agricultural and forestry uses, while the middle
tier allocates agricultural land between livestock husbandry and cropping activities. The top
tier allocates land among alternative cropping activities5.
3. Simulation design
We simulate the impact on global food supply, prices and land use, in combination with estimates by Dasgupta et al. (2009), as exogenous shocks to the GTAP model. Dasgupta et al. conducted
a detailed geographic information system (GIS) analysis and overlaid satellite images of the world
5
table 1
Regions in the model
Note that, in the current version of the model, land transition between agricultural and commercial plantation uses is specified as possible but limited. Conversion of natural lands to crops is possible
in reality. However, there is no such information to benchmark the GTAP model to reflect the reality and so this is omitted in this study
No.
Code
Region description
No.
Code
Region description
1 ANZ_Oceania
2 China
3 Japan
4 SKorea
5 Taiwan
6 OtherEAsia
7 Cambodia
8 Indonesia
9 SouthAsia
10 Myanmar
11 Malay_Singap
12 Philippines
13 Thailand
14 VietNam
15 OtherSEAsia
Australia, New 16 Zealand & Oceania
China and Hong Kong 17
Japan 18
South Korea 19
Taiwan 20
Other East Asia 21
Cambodia 22
Indonesia 23
South Asia 24
Myanmar 25
Malaysia& Singapore 26
Philippines 27
Thailand 28
Viet Nam 29
Other South East Asia
NorthAmerica
Mexico
Argentina
CaribCentrAm
Brazil
Chile
NSAmerica
EU27
OthEurope
Russia_FSU
MiddleEast
NAfrica
NoCstlAfrica
SAfrica
North America
Mexico
Argentina
Central America
Brazil
Chile
Northern South America
European Union
Other Europe
Russian Federation & Former Soviet Union
The Near East
North Africa
No Coastal Line Africa
South Africa
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