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climate change and food systems: global assessments and implications for food security and trade
The land endowment shock is brought into the second step of the simulation, as the regional agricultural extent loss to SLR. The scope of agricultural extent includes cropland and grazing land, so the land supply shocks pertain to the corresponding agricultural land-based sectors. All endogenous variables in our model will respond to such shocks and simultaneously reach a new equilibrium where demand equals supply for all commodities in all regions.
We then calculate the percentage of deviation for all endogenous variables (e.g. prices, supplies and demands) in the new equilibrium (point E3
in Figure 1) from those in the old one (point E2 in Figure 1). These deviation percentages measure the economic impacts of the agricultural extent loss due to SLR. We also assume that developing countries do not have coastal protection against SLR. For the five developed regions, given the
lack of information from Dasgupta et al. (2009), we assume there is no agricultural extent loss. One justification for this assumption is that developed countries tend to have sufficient coastal protection (e.g. sea dykes) to ward off storm surges and SLR.
Figure 2 shows the magnitude of agricultural extent loss in percentage changes for the 29 regions, with most of the Asian rice-growing countries disaggregated. Viet Nam is hit the hardest by the 1-metre SLR, losing 7.14 perent of its agricultural extent.9 Other Asian rice-growing countries – for example, China, Indonesia, Myanmar and Taiwan – also lose 0.6-1.5 percent of their agricultural land to SLR. Calculations by Dasgupta et al. also indicate that agricultural activities of Asian developing countries are relatively more vulnerable to SLR than western countries.
parameters would suggest. However, the latter changes require additional modelling improvement and will be reserved for future research.
9 According to the recent FAO (2011) report, the mean sea level along the coastline of Viet Nam rose at a rate of 3 mm per year during 1993-2008, based on observations by tidal gauges in marine hydrometeorological stations. The IPCC AR4 projections are SLR of 65 to 100 cm into the end of the twenty-first century, relative to the 1980-1999 levels under the A1F1 scenario.
This is consistent with IPCC AR4 projections, which call for capacity enhancement to disaster risk reduction actions and adaptation in agriculture to climate change in Asian developing countries (particularly those in lower latitudes).10
4. Simulation results
Given the multitude of the numerical results
from our simulation, we selected Viet Nam as
an example in order to discuss and explain the results in detail, and refer to the relevant charts that show the impact magnitude of simulation results. Output of the land-based crop sectors (e.g., paddy rice, wheat and other grains) will be affected first. In the case of Viet Nam, paddy rice is grown in the low-lying river delta areas, such
as the Mekong Delta region. SLR could easily diminish the paddy rice production capacity of Viet Nam; Table 3 shows rice production in Viet Nam reduced by 4.54 percent. However, given strong demand for Vietnamese rice—both domestically and from abroad—the SLR-inflicted shortfall in
the Vietnamese rice supply would drive up the price of Vietnamese rice; Table 4 shows the price of Vietnamese paddy rice rising by 5.74 percent. The sugar cane price also rises, partly due to production loss from SLR as well as the fact that consumption is growing faster than production. This drives up land rents so that more land can be converted into sugar cane production to meet the market demand.11
The percentage change in land rent and land supply are shown in in Tables 5 and 6, respectively. The other land-based crop sectors would not be
10 Our main purpose is to highlight the cross-border impact of regionalized land endowment loss in the low-lying zones in Asia. This study does not take into account the crop yield responses to climate-induced temperature and precipitation changes. However, the simulation results would reveal the far-reaching spill- over effects of the localized loss of land availability on the global staple market.
11 Sugar cane can be grown in all provinces of Viet Nam, including the drier regions of the south-central coast and Mekong Delta without irrigation, and the Red River Delta area in the north.
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