報告書番号

Y10030

タイトル（和文）

環境税の地域経済影響を評価するための空間一般均衡モデルの開発

タイトル（英文）

Spatial CGE Model for Analyzing Impact of Carbon Tax Imposition on Regional Economies of Japan

概要 （図表や脚注は「報告書全文」に掲載しております）

当所では税制変化が地域経済に与える影響を分析するために47都道府県空間一般均衡モデルの開発を行ってきた．しかし，当モデルは経済変数とエネルギー消費量との対応が考慮されていないため，環境税の影響を詳細に分析することができない．本研究の目的は，経済変数と整合的なエネルギー消費量を取り入れた地域間社会会計行列に基づき，47都道府県空間一般均衡モデルにエネルギー代替構造を導入することによって，環境税導入が地域経済に与える影響を評価するための経済モデルを開発する．開発したモデルは，環境税の導入が生産者，消費者の行動変化に与える影響を考慮した上で，需給が均衡する価格と数量の変化を計測することができる．環境税の導入が生産者のエネルギー需要に与える影響を把握するために生産関数は入れ子型構造をしており，エネルギー投入は「エネルギー－資本・労働」，エネルギーにおける「電力－非電力」，非電力の「石炭系－石油系－ガス系」と多段階で決定される．消費者についても，効用関数が入れ子型構造になっており，エネルギー消費需要は「エネルギー－非エネルギー」，エネルギーにおける「石油系－電力系－ガス系」という多段階で決定される．そして，生産と消費における「エネルギー－非エネルギー」の代替弾性値を変化させる感応度分析からは，1万円/CO2-tの環境税率では，代替弾性値の違いは生産，消費ともに各県におけるCO2削減率の相対的な大きさ（順位）には影響を与えておらず，モデルによる環境税がCO2削減に与える計測結果はロバストであると考えることができる．

概要 （英文）

To apply the conventional CGE model for analyzing the impact of carbon tax imposition on regional economies of Japan, the model must be modified to match the following requirements. Firstly, due to a vast variety in the production structure and consumption preference among regions in the Japanese economy, the model must take into account the linkages between economic systems and the spillover and possible feedback effects that one region may have on another. Namely, the spatial aspect must be explicitly introduced into the modeling framework. This kind of model is called the spatial CGE model. Secondly, it is preferable that the carbon emission is particularly associated with the energy inputs/consumptions, although the existing models usually calculate the emission level on the aggregated level of production outputs. Thirdly, the impact of relative price change resulting from the carbon tax on the interregional regime shift in the consumption of household and the output level of production sectors must be verified.
The first objective is fulfilled by the development of spatial CGE model for evaluating the tax system reform in Japan by CRIEPI (2008). However, the last two necessities still call for a further development. CRIEPI (2011) have compiled the interregional energy social accounting matrix (SAM) database of Japan that consistently reflects all the flows of goods, services and income distribution between all economic agents in the economy. This database also satisfies all the requirements listed above and, hence, can be used as an integral part of the benchmark data set for analyzing environmental tax policies effectively.
The main objective of this report is to develop the spatial CGE model for analyzing impact of carbon tax imposition on regional economies of Japan. To illustrate the potential usefulness of the proposed model, a simple simulation is subsequently conducted under the environment tax scheme as a provision against the global warming under the 2011 tax reform plan proposed by the Ministry of the Environment (2010). According to the increase in energy prices due to the carbon tax imposition, the impacts on the consumption of household, the output level of production sectors both on sectoral and prefectural basis are examined. Finally, the sensitivity analysis on the critical parameter is also carried out to verify the reliability of the proposed model.
Our simulation results reveal that the environment tax scheme proposed by the Ministry of the Environment has only minor effects on the Japanese economy. The level of carbon dioxide emission is reduced by just 1.096% as compared to emission level in 2000, where the decrease in level of gross domestic product (GDP) is 18.30 billion yen or 0.004% of level in 2000.
The sensitivity analysis on the critical parameter of the model - the elasticity of substitution parameter - proofs that the qualitative results from the carbon tax simulation are, to some extent, robust and the reliability of our proposed model is partly approved.

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