LCA inventory data based on input-output tables was used to analyze the relationship between the self-sufficiency rate of food and CO
2 emission in Japan. For food item
i with the total consumption
Ci [M\] and self-sufficiency rate
xi, the total amount of CO
2 emission is composed of (1) domestic production of
i, (2) production of industrial product
j to be exported for the import of
i, and (3) transportation to export
j and import
i. According to this model, an effective carbon emission coefficient, σ
eff,
i, j, was calculated for food item
i by assuming the industrial item
j to be exported. Then, σ
eff,
i, jwas averaged among
j proportionally to their amount of annual export statistics and the effective carbon emission coefficient σ
eff,
i was calculated for each food item.
Because of the low self-sufficiency rate of food (-40%), the amount of carbon emission was proved to have substantially increased in Japan. The self-sufficiency rate of food based on C-emission is only 13.6% in Japan. The difference between the present C-emission and that by assuming 100% food self-sufficiency easily reached the goal to reduce CO
2 emission by COP3. This means that an increase in food self-sufficiency rate can be an effective option to reduce CO
2 emission in Japan.
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