Climate Changes in the Mediterranean Region: Physical Aspects and Effects on Agriculture
III
predict Egypt's future under a changed climate, but rather to examine the combined
effects on agriculture of different natural factors and the adaptability of the economic
system. This Box summarizes only the agricultural component of the study.
Methods: A physically-based water balance model of the Nile Basin was used to
evaluate river runoff and thus enable inferences to be drawn concerning water supply
for agriculture. Process-based agronomic models were used to estimate crop yields
and crop water requirements.
External factors such as world food prices were introduced from a study of
climate change which used a global food model to assess climate-change impacts on
world food supply and demand. Supply and demand at the national level were then
input to a national agricultural sector model to determine effects on land use, water
use, agricultural employment, etc.
Testing of methods: Each of the sub-models used in the study was validated
against local data.
Scenarios: The current baseline adopted for the socio-economic projections was
1990 and the climatological baseline, 1951-1980. The time horizon of the study,
1990-2060, was largely dictated by the climate change projections.
Impacts: An agricultural water productivity index was used to measure impacts
on agriculture: total agricultural production (tonnes) divided by total agricultural
water use (cubic meters). Under these 2 x C02 GCM-derived scenarios the index
declined between 13 and 45 percent.
Adaptive responses: Adaptations in water resources (major river diversion
schemes), irrigation (improved water delivery systems), agriculture (altered crop
varieties and crop management) and coastal protection against sea-level rise were all
tested. They achieve a modest 7-8 per cent increase in agricultural sector
performance compared to no adaptation, but together would be extremely expensive
to implement. However, investment in improving irrigation efficiency appears to be
a robust, 'no regrets' policy that would be beneficial whether or not the climate
changes.
III
predict Egypt's future under a changed climate, but rather to examine the combined
effects on agriculture of different natural factors and the adaptability of the economic
system. This Box summarizes only the agricultural component of the study.
Methods: A physically-based water balance model of the Nile Basin was used to
evaluate river runoff and thus enable inferences to be drawn concerning water supply
for agriculture. Process-based agronomic models were used to estimate crop yields
and crop water requirements.
External factors such as world food prices were introduced from a study of
climate change which used a global food model to assess climate-change impacts on
world food supply and demand. Supply and demand at the national level were then
input to a national agricultural sector model to determine effects on land use, water
use, agricultural employment, etc.
Testing of methods: Each of the sub-models used in the study was validated
against local data.
Scenarios: The current baseline adopted for the socio-economic projections was
1990 and the climatological baseline, 1951-1980. The time horizon of the study,
1990-2060, was largely dictated by the climate change projections.
Impacts: An agricultural water productivity index was used to measure impacts
on agriculture: total agricultural production (tonnes) divided by total agricultural
water use (cubic meters). Under these 2 x C02 GCM-derived scenarios the index
declined between 13 and 45 percent.
Adaptive responses: Adaptations in water resources (major river diversion
schemes), irrigation (improved water delivery systems), agriculture (altered crop
varieties and crop management) and coastal protection against sea-level rise were all
tested. They achieve a modest 7-8 per cent increase in agricultural sector
performance compared to no adaptation, but together would be extremely expensive
to implement. However, investment in improving irrigation efficiency appears to be
a robust, 'no regrets' policy that would be beneficial whether or not the climate
changes.