第２章 ＣＧＥモデル

１. 研究要旨

１.１ はじめに 「経済・環境の相互作用の総合的分析」のための分析モデルとしてのひとつの候補と

しての CGEモデルの研究計画について述べる。 CGE という用語についての注釈から始める。CGE（Computable General

Equilibrium）と AGE （Applied General Equilibrium）とは、同義であるかのように使われることが多い。しかし、それらは、別の研究系譜を示す呼称であると考えた方が

よい。 1950 年代に一般均衡の存在証明がアロー、ドゥブルー、マッケンジー、二階堂らによって盛んに研究されたことは周知の通りであるが、それは一般均衡がどこに存在する

かをつきとめようとするものではなかった。しかし、一般均衡の位置を具体的に計算で

きれば、政策分析等への幅広い応用の可能性が期待できる。実際、スカーフとその研究

を受け継ぐひとびとは、不動点アルゴリズムの開発・改良に取り組みながら財政政策へ

の応用を中心に多くの成果をあげてきた。この研究系譜は AGEと呼ばれる。 それに対して、世界銀行等の国際機関を中心に開発政策の形成・分析の用具として発

展してきたもうひとつの研究系譜がある。それが（AGEとは区別された意味での）CGEである。それは、開発政策の分析用具として 1970 年前後からまず ILO（「世界雇用プログラム」）で、そして世界銀行で活発に使われた社会会計行列（SAM: Social Accounting Matrix）の研究の自然な発展であったこと、したがってSAMベースのCGEであったことにその最大の特色があるだろう。 本来、SAM の「社会」という語の意義は、都市－農村、富裕層－貧困層といった社

会経済的背景に沿って制度部門分類、とくに家計部門の内訳部門分類を行なうことにあ

る1。生産構造（投入産出構造）だけに基づくレオンチェフ逆行列（行列乗数）は、生

産構造と所得分配とを同時に考慮した SAM乗数分析に拡張され、世界銀行の「分配に配慮した成長戦略」を支える重要な道具立てとなった。そうした SAMの発展としてのCGE分析は、SAM乗数分析のもつ、線形性制約や固定価格制約から自由な分析を可能にするものとして位置づけられた。その整合性を確保しながらデータを格納するフレー

ムワークとして、また、モデルを提示する手段として、そこでも SAMが最大限に利用されたことは当然のことであった。 今回、われわれが目指す分析は、後者、すなわち、世界銀行の伝統に沿った SAMベースの CGE 分析である。ただし、アン・クルーガーの登場により、世界銀行は IMF 1 Chowdhury and Kirkpatrick[1994]

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とともに悪名高い構造調整政策の実施機関になる2。われわれの目指す方向は、変質以

前の世銀 SAM派の行なってきた分配重視の CGEである。 １．２ 環境政策の分析にとっての CGE の有効性 たとえば、環境税（炭素税）の景気への影響を分析するのなら、マクロ計量モデルが

適した分析ツールであるかもしれない。しかし、直接規制にしても間接規制にしても、

環境負荷の大幅な低減をめざす環境政策の効果を分析しようとする場合、エコノミー・

ワイドな多種の相互作用を通じて、それが相対価格や当該経済の産業構成に、さらに、

それが所得分配にまで大きな影響を与えることを考慮に入れなければならない。CGEはそのためのひとつの最適な枠組みを与えていると考えられる。また、環境政策を分析

するための CGEには既に十分な研究蓄積がある3。 しかし、CGE 分析には、いつかの弱点も指摘されている。とくに、カリブレーショ

ンについては、改善の余地があるだろう。単年データを使って自動的になされる部分も、

そうでない部分についても、パラメーターの決定に、より実証性がほしいところである。

最近は、計量経済学的手法を取り入れる方向も試みられているが、パラメーターの変更

だけでなく、クロージャーを含むモデル設定の変更に対して、CGE 分析がもつ柔軟さを生かそうとする方向もありえるだろう。動学分析や金融的側面の分析が、今のところ、

未成熟であると批判されることも多いが、今回のプロジェクトにとってのダメージには、

それほど大きくないと考えられる。 １．３ 分析手順 次のようなステップで分析を行った。 (1) 日本版 NAMEA(ハイブリッド勘定)データを、環境技術データを用いて、93SEEAヴァージョン IV.２型のデータに変換する。そうする理由については次節で議論する。

(2) 後者を世界銀行の流れを汲む CGE分析用の SAMに変換する。帰属環境費用を含まない SAMも作成する。

(3) 以上のステップで構築された SAMを使い、次のような SAMベースの CGEを実行する。

(3)―１）維持費用方式で計算されている仮想的費用を実際にかけるとしたら、経済の営みはどのように変わるか。維持費用方式の帰属環境費用が波及効果を含まない、仮想

的な数値であるという批判に答えるためにも、また、環境税のような間接規制と直接規

制とを比較するという目的にとっても有益であろう。 2 80年代の世界銀行の変質については、Stiglitz[2002]で活写されている。その変質の結果、SAM派の多くの有能な研究者が世界銀行を去って、ウォリック大学（グレアム・パイアットの場合）や国際食糧政策研究機構（IFPRI、シャーマン・ロビンソンの場合）などの研究機関に席を置くようになった。 3 Xie[1996]、Conrad[1999]などを見よ。

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(3)―２）環境からの生産要素投入があるという仮説にたった分析を行なう。SAMを構成する際、エコマージン（帰属環境費用）をいわば環境を「搾取」して得られた付加価

値であると考える。所得フローの面では、資本要素への支払いとまったく同様に扱う。

このような仮説のもとで、各種の比較静学分析を実行する。 (3)―３）環境税、排出権のような環境政策手段の検討を行なう。 １．４ SEEA ヴァージョン IV．２とハイブリッド勘定（日本版 NAMEA）の比較・評価 「新しい環境・経済統合勘定について」という文書で発表された、「ハイブリッド勘

定」は、初期の、国連の暫定環境・経済統合勘定マニュアル（93SEEA）のバージョンIV.2に基づいた試算とは異なり、オランダ中央統計局がNAMEA（National Accounting Matrix including Environmental Accounts）という名前で開発した環境統計とほぼ同じものであり、国民勘定行列（NAM）に環境負荷を記録する部分を付け加えたものである。 最新の環境・経済統合勘定（ハイブリッド勘定）で取り上げられている環境負荷項目

の範囲は従来と比べて、格段に拡大しているが、むしろ、SEEAの 90年代における試算と最新の試算との間には、大きな枠組みのちがいがあることに注意すべきであろう。

それは、ごく単純化して言えば、次のように表現することができるであろう。

環境負荷量の測定＋経済活動との関連づけ ＝ ハイブリッド勘定

ハイブリッド勘定＋環境負荷の貨幣評価の帰属（帰属環境費用）＝ 従来の（version4.2の）環境・経済統合勘定

明らかに、統計を作成するうえで必要な情報は、従来型の環境・経済統合勘定のほう

が多い。なお、 グリーン GDP＝GDP－固定資本減耗－帰属環境費用

であるが、ハイブリッド勘定では、グリーン GDPは計算されない。また、帰属環境費用の計算にはいくつかの方式があるが、ヴァージョン IV.2では、既に見たように、「維持費用」と呼ばれる考え方に基づいた帰属環境費用の計算が行なわれる。 環境負荷の貨幣評価は、論争的な話題であり、必ずしも貨幣評価を是としない立場も

ある。しかし、ヴァージョン IV.2の環境・経済統合勘定は、「持続可能性をもった発展」（sustainable development）の見地から支持しうるものと考えられる。ある企業が用いている機械に問題があり、そのため環境を汚染するが、その機械に問題の環境汚染に

対処する装置を組み込むことにより、問題を解決（軽減）させることができるとしよう。

しかし、その企業はそうした努力を怠り、その結果として現実に環境が汚染されている

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状況を考える。この場合、帰属環境費用の計算は以下のように行なわれる1。 第１図 維持費用概念の説明 持続可能性の政策目標の設定

↓ 環境基準の制定（たとえば、ゼロエミッション）

｜ ｜ 汚染量の測定 ｜ ｜←汚染除去技術の想定 ｜ ↓ ｜ 汚染量単位あたり汚染除去費用の算定

｜ ↓ ――→ （汚染量－環境基準にもとづく汚染限界）×単位あたり除去費

用2 ＝帰属環境費用 以上のような帰属環境費用の計算には、「持続可能性をもった発展」を実現するため

に環境政策当局が何をしなければならないか（どのような規制を導入しなければならな

いか）ということについて明確なイメージをもっていなければならない。その点がそう

したコミットメントのないハイブリッド勘定との大きなちがいである。環境問題の解決

のためには、そうした強いコミットメントが必要であると考えられる。 留意すべきことは、グリーン GDPは、いわば、副次的指標であり、帰属環境費用こそが持続的発展のための主要な指標であるという点である。帰属環境費用は、環境を犠

牲にすることによって得た付加価値（エコ付加価値）であり、それをゼロにすることが

持続的発展を実現するための政策目標となるからである。GDP とグリーン GDP の成長率を比較することは有意義だが、GDP の成長率をグリーン GDP の成長率に置き換えれば、後者が持続的発展の指標と考えることは誤解、指標の誤用であり、環境に大き

なダメージを与えることにつながるであろう。 最後に、関連して、国民経済計算調査会議体系整備検討委員会（2005年6月16日）に

おける河野政男委員（中央大学教授）の発言を議事録から引用しておこう3。「サテラ

イト勘定の整備ということで、環境勘定にかかわることです。これから地域版の環境勘

定について、研究を進めたいということでありますが、ぜひＮＡＭＥＡ版ばかりでなく 1 このようなエンド＝オブ＝パイプ方式の技術を想定すること以外にも、より抜本的な技術の変更を想定することもできる。 2 汚染除去費用に非線形性が存在する可能性があるが、単純化する。なお、日本の環境・経済統合勘定の初期の試算では、ゼロエミッションが想定されていた。 3 内閣府経済社会総合研究所[2005]。

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て、ＳＥＥＡヴァージョンIV.２ですか、維持費用評価についても引き続き研究してい

ただきたいというふうに思っております。と言いますのは、実は企業会計の方で、イギ

リスの貿易産業省支援のもとに、シグマ計画という計画がありまして、そのもとでは環

境に優しい企業のいろいろな経営のためのガイドをつくっているんですが、その中にエ

ンバイロメンタル・アカウンティング・ガイドラインというのがあります。そこでは企

業が持続可能なためには、税引き後利益から維持費用を引く、企業が排出する負荷物質

について、それをゼロエミッションしたときのコスト、ゼロエミッションまでいかなく

ても、持続可能な排出量というのがあって、そこまで減らすのにかかるコストを引いた

ものが持続可能利益だということで、そういう会計決算書を示した上で単位当たりの負

荷物質の削減のための計算レートなんかをみんな載せたものがあるのです。既にこうい

うことを実施している企業も幾つかあります。私も環境省の環境会計の２００５年版の

ガイドライン、企業向けのガイドラインの作成にかかわっていましたけれども、そこで

はシグマ計画の会計計算書も参考表として載せているのですね。企業レベルでも維持費

用ということには関心を持っているところが出てきたということでありますので、ぜひ

地域版についてもヴァージョンIV.２をお忘れなくやっていただければというふうに思

っています」。

参考文献 Chowdhury, Anis and Colin Kirkpatrick[1994] Development Policy and Planning: an introduction to models and techniques, Routledge, 1994.（嶋田晴行・瀬戸健太・不破雅実・三重野文晴訳『発展途上国の開発政策と計画』古今書院、1997年。） Conrad, Klaus[1999] “Computable general equilibrium models for environmental economics and policy analysis,” Jeroen C.J. M. van den Bergh(ed.), Handbook of Environmental and Resource Economics, Edward Elgar. Stiglitz, Jeseph E. [2002] Globalization and Its Discontents, 2002.（鈴木主税訳『世界を不幸にしたグローバリズムの正体』、徳間書店、2002年。） Xie, Jian[1996] Environmental Policy Analysis: A General Equilibrium Approach, Ashgate. 内閣府経済社会総合研究所[2005]「国民経済計算調査会議第２回体系整備委員会議事録：2005年 6月 16日」、http://www.esri.cao.go.jp/jp/sna/050616/gijiroku.pdf

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２. 研究成果と今後の課題

２．１ 研究成果 ・維持費用概念の帰属環境費用の明確な意義づけのもとに、それを従来の日本総研推計

の範囲、方法で、若干の加除のもとに推計することによって、NAMEAデータを SEEAヴァージョン 4.2型のデータに変換した SAMを構築した。その際、CO２、SPMについて、新たに帰属環境費用を推計した。さらに、その SAMに基づいた CGEモデルを実行して、試験的な結果を得ることが出来た。

・NAMEA をベースとしたことにより、従来の SEEA ベースのモデル(2003 年地域学会発表)とは異なり、モデル上の産業分類を格段にふやすことができ、モデルの内容も充実してきた。

・帰属環境費用データを用い、環境を生産要素とみなすという Main Model では、Closureの意味づけを明瞭にし、排出権市場とモデルとを関係づけることができたと考えている。一方、Alternative Modelでは、いわゆる Greened Economy集計量をモデル上計測し、統計上の Green GDPとの比較をすることができ、後者が対応する前者の下限値を与えると見られることを示すことができた。

２．２ 今後の課題 ・データの面では、帰属環境費用の推計対象の範囲が依然狭いので、それをさらに拡大

する必要がある。 ・環境負荷項目を一括して取り扱うのではなく、少なくとも CO２とその他というように、環境負荷項目の細分化された取り扱いを試みる必要があるだろう。

・Main Modelの経済主体の行動想定に関して、環境コンシャスネス（ペーパーにおける記述を参照のこと）の想定を様々に変更してみる必要がある。

・モデルの生産構造を変更して、比較静学実験結果のロバストネスを検証してみる必要

がある。 ・同モデルに排出権市場を明示的に取り入れることは興味深い。そのうえで、比較静学

実験の種類を拡大する必要がある。たとえば、排出権の海外からの購入など。 ・さらに、技術のスイッチを含むモデルを工夫し、間接規制・直接規制という政策上の

課題に答えられるようなモデル構築をめざす必要があるだろう。 ・Alternative Modelでは、投入係数変更の実験をより現実的なものにするために、環境技術情報の収集が必要であろう。

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An Environmental SAM and SAM-based CGE Modelling

for Environmental Policy Problems

Paper prepared for International Workshop for Interactive Analysis on Economy and Environment,

Cabinet Office, the Government of Japan, 4th March 2006

Noritoshi Ariyoshi Faculty of Environmental Studies

Nagasaki University

Itsuo Sakuma School of Economics Senshu University

Akihiko Taniguchi

Graduate School of Economics Senshu University

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1. Introduction The purpose of this paper is twofold. First, concerning data aspects, it attempts to construct a data matrix (DATA SAM) from Japanese NAMEA1 (or hybrid accounts) compiled by ESRI. The data matrix which the authors will formulate contains national accounts data as well as SEEA2 (ver.IV.2) type economic-environmental data. In doing so, imputed environmental cost, one of the main features of SEEA verIV.2, will be estimated for each industry. It should be stressed that the estimation of imputed environmental cost or maintenance cost is highly important because by doing so what the government should do for the environment will be clarified and obliged at least logically. NAMEA as such, on the contrary, dose not contain any information of this sort. This DATA SAM will be called “DATA ENVIRONMENTAL SAM”.

Second, concerning modelling aspects, it attempts to conduct SAM-based CGE analyses. To do this, the second version of “Environmental SAMs” must be created. This second version of environmental SAM will be called “MODEL ENVIRONMENTAL SAM” in which environmental and national accounts data are arranged to accommodate a specific general equilibrium modelling structure. The authors attempt to conduct a computable general equilibrium (CGE) analysis with this model environmental SAM as a base. Finally, some (policy or other) simulation results will be presented and commented.

2. A general explanation of Japanese NAMEA (Hybrid Accounts) In this section, the authors would like to give a very condensed account of Japanese NAMEA or Hybrid Accounts recently compiled by the ESRI (Economic and Social Research Institute), Cabinet Office of Japan. A sketch and a summary of Japanese NAMEA are given in Figure 2.1 and Table 2.1. the simplest utline of Japanese NAMEA is as follows.

1) It is based on the original NAMEA by the Netherlands, and estimates for 90, 95, and 00

2) It has twofold parallel structure: national accounting matrix (NAM) at monetary term and environmental accounts (EA) at physical term.

3) It has twofold structure of EA : substance accounts and environmental problem accounts.

Because further explanation of Japanese NAMEA is given in Ariyoshi (2006), it is omitted in this paper.

1 “NAMEA” is an acronym for National Accounting Matrix including Environmental Accounts. See de Haan, M. and S. J. Keuning [1996], Department of National Accounts[2004], and Ariyoshi[2006]. 2 “SEEA” is an acronym for System for Integrated Environmental and Economic Accounting. See United Nations [1993].

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47.9

0.07.

411

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--

--

CO2

10a

1,238

,699

1,238

,699

CO2

Othe

rs(5)

10b

36,6

9394

,246

SO2

10c

-82

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Agric

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CA2,8

29.3

--

--

-21

,172

--

-4,

910

25,38

0-

1,000tonnes-CO2

1,000 t-N2O

1,000 t-NOX1,000t-SO2

1,000 ｔ

1,000 ｔ

1,000 ｔ

PJ

1,000ｍ3

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Unit

Unit

1,000tonnes-CO21,000t-SO2

1,000 ｔ-PO4

3-.

1,000 ｔ-PO4

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1,000ｍ3

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Final consumption (purpose)

Acco

unt

(clas

sifica

tion)

Goods & services (products)

Non-financial assets (kinds)

Production (activities)

Final

cons

umpt

ion (p

urpo

ses)

Prod

uctio

n (ac

tivitie

s)Go

ods &

servi

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prod

ucts)

Open

ing st

ocks

Value

add

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ateg

ories

)

Gree

n-ho

use

Rest

of th

e wor

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Taxe

s (tax

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)Ca

pital

(secto

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l ass

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kinds

)

Ener

gy(3

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Fishe

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sour

ces

(mar

ine p

rodu

cts)

Land useFo

rest

(volum

e)

Natural resources Wate

r res

ource

s(w

ateru

se)

Was

te(2)

Pollutions

Distr

ibutio

n &

use (

secto

rs)

Billio

n Yen

Reco

ncilia

tion/

indica

tors

Clos

ing S

tock

s

Substances

Air Quali

tyof

wate

r

Acidi

fi-ca

tion

Accumulation of substancesto the environment

Changes of natural resourcesin ROW caused by import

Substances

Quali

tyof

water

Hidden material flows

Pollutants

Natural resources

Waste (2)

Land use

Air

Gree

nhou

se e

ffects

Acidi

ficat

ion

Othrs (5)

Agricultural lamd

Water (water use)

Fishery resources(marine products)

Energy (3)

Water

Fish

Greenhouse effects

Regional

Acidification

Eutrophication

Tabl

e 2.

1 J

apan

ese

NA

ME

A (2

000)

- Su

mm

ary

Tabl

e -

Rest of the world

Forests (volume)

Environmental problems

Hidden material flows

Changes in

land uses

Wastewater

Waste

Forests

Not

e) T

his

is a

sum

mar

y ta

ble

of th

e at

tach

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New

Sys

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of I

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ocia

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(htt

p://w

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.go.

jp

Value added (categories)

Distribution & use (sectors)

Taxes (tax categories)

Capital (sectors)

Accumu. To env.

Land for housing

Other lands

Changes in natural resources

Energy resources

Final

dispo

sition

ofwa

steW

astew

ate

Agric

ultur

al lan

d

Chan

ges i

nfis

hery

reso

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Proc

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recy

cleof

pollu

tants

Explo

itatio

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dom

estic

natu

ral

reso

urce

s

The potential contributions to Global warming, acidification and

Eutrophication are expressed in GWP, AEQ and EEQ, respectively.

Global Warming Potencials (GWP) CO2 ： 1, N2O：310, CH4：21

Acid Equivalents (AEQ) Nox ： 0.7, So2：１, NH3

Eutrophication Equivalents (EEQ) P ： 3.06, N：0.42

Proc

essin

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pol

luta

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ploi

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atur

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Pres

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water

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Cont

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glob

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al iss

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Contr

ibutio

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regio

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envir

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Ｂ

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Natio

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ROW

Ｃ

Explo

itatio

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OW's

natur

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caus

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impo

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Hidd

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ateria

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sin

dome

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rea

Hidd

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ateria

l flow

s in

ROW

caus

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ports

汚染物質の排出

Chan

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Emiss

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poll

utant

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Resto

ratio

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atur

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Ａ－Ｂ

Makin

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Pres

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Othe

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Deple

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Othe

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Hidden material flows

Envir

onm

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Clos

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Open

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Envir

onm

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indic

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Mon

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: Cel

ls fo

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enta

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icat

or

-46-

3. From NAMEA to a SEEA-type SAM with Monetary Valuation of Environmental Pressure

Table 3.1 is a summary version of a SEEA-type SAM with monetary valuation of environmental pressure. In order to obtain this table, the two processes are needed. To begin with, imputed environmental costs are calculated by maintenance cost methods using the estimates of environmental pressure in Japanese NAMEA for 1995 and the additional pollutants (SPM). Then, table 3.1 is obtained by incorporating these imputed environmental costs into Japanese NAMEA.

Table 3.2 shows imputed environmental cost (eco-margins) by origin of industries calculated by the maintenance cost method. According to the table, the largest eco-margin is found in non-metallic mineral products.

Table 3.3 shows imputed environmental cost by type of environmental pressure. According to the table, CO2 has the largest eco-margin.

The most notable difference between the two statistical efforts made by the Government of Japan (new NAMEA and old SEEA) might be that in their positions on monetary valuation of environmental pressure. However, it is no use listing up pros and cons on monetary valuation of environmental pressure in general. Thus, the authors are pro the maintenance cost concept, but con the concept of green GDP. If green GDP were used as a substitute for GDP in the ordinary sense, it might justify inappropriate growth-accelerating policies which may worsen the environment.

In this section, the authors will attempt to construct a SEEA-ver.IV.2-type matrix from Japanese NAMEA. In doing so, imputed environmental cost must be estimated by using the maintenance cost concept.

This imputation is considered to be highly important because it can clarify what the government should do for the environment as noted before. In this paper, however, only imputed environmental cost the origin of which is industries (=market producers in 93SNA) are considered, because it is necessary to take the extension of production boundary into consideration in order to deal with consumption-related imputed environmental costs.3

Except for CO2 , the assumption of “zero-emission” is posited in order to calculate imputed environmental cost about each environmental pressure category. Concerning CO2, the 94% of the emission level of CO2 in 1990 is assumed, according to the Kyoto Protocol. Two tables below summarise imputed environmental costs (=eco-margins) by sources and by environmental pressure types (matters). More detailed tables including a table for description of the method of calculation are attached at the end of the paper.

3 “Shifting” was a device in 93SEEA to deal with imputed environmental cost originated in non-producers.

-47-

Environment

al protection

facilities

(types)

Other

produced

assets

Airpollutions

Quality ofwater

Waste

12

34

56

78

910

1112

1314

1431040.2

349633.1

6105.5

134225.8

45230.1

2922938.0

3349633.2

4458525.0

-204.2

-88912.7

108.7

5973.133372.6

369345.0

19372.2

64051.6

57549.1

-214.4

Environmental protection

facilities(types)

75901.3

Other produced assets

(types)

845313.1

9Discharge of residuals

(CO2,SOX,NOX,SPM

etc)

1068568.0

-68568.0

Quality of water

(T-P,T-N,waste water)11

6969.8

-6969.8

Waste

(final disposition)

1211428.0

-11428.0

13-86965.8

86965.8

1438272.4

171.8

15880.6

10171.8

Rest of the world

Capital accounts

accumulation

(institutional sectors)

Imputed environmentalcosts

Environmentalimpacts

Eco-margin((-)sum of imputed

environmental costs)

producedassets

Non-produced assets(types)

Production(activities)

Final consumption(purpose)

Incomeaccounts

Generation of income

(items of value added)

Use and distribution of income

(institutional sector)

Non-produced

assets

(types)

Goods ＆ services(products)

Environmental impacts

Eco-margin

Generation

of income

(items of

value added)

Use and

distribution

of income

(institutional

sector)

accumulatio

n(institution

al sectors)

Table 3.1 a SEEA-type SAM with Monetary Valuation of Environmental Pressures (1995)

Rest of

the

world

Ａｃｃｏｕｎｔ

（Classification）

Goods ＆

services

(products)

Productio

n(activitie

s)

Final

consumptio

n(purpose)

Income accounts

Capital accounts

Imputed environmental costs

produced assets

Imputed environmental cost

valuated by maintenance cost

approach (-) sum of imputed environmental costs

valuated by maintenance cost approach

Deterioration of non-produced

assets by production activities

(-) sum of deterioration of

non-produced assets by

production activities

-48-

Table 3.2 Imputed Environmental Cost by origin of industries

Eco-margins

Industries

(Billion yen)

Distribution

of

Eco-margin

(%)

Distribution

of Value

Added (%)

Agriculture ,forestry and fishing 2295.4 2.6 2.0

Mining 91.8 0.1 0.2

Food products and beverages 940.4 1.1 2.8

Textiles 1947.8 2.2 0.3

Pulp, paper and paper products 237.0 0.3 0.7

Chemicals 1521.7 1.7 2.1

Petroleum and coal products 255.9 0.3 1.2

Non-metallic mineral products 29863.3 34.3 1.0

Iron and steel 11573.6 13.3 1.3

Non-ferrous metals 443.7 0.5 0.4

Fabricated metal products and Machinery 2260.8 2.6 10.7

Other Manufacturing 5560.7 6.4 4.1

Construction 3531.9 4.1 8.7

Electricity, gas and water supply 8035.8 9.2 2.9

Wholesale and retail trade 2829.0 3.3 16.3

Finance and insurance 1150.7 1.3 6.3

Real estate 2229.8 2.6 12.8

Transport and communications 8786.8 10.1 7.6

Service activities 3409.6 3.9 18.8

Total Industries 86965.8 100.0 100.2

-49-

Table 3.3 Imputed Environmental Cost by type of environmental pressure

Types of Environmental Pressure Eco-margins

CO2 61033.4

N2O 11.7

CH4 4.5

HFCs 88.2

PFCs 50.7

Green House Effects

SF6 73.7

NOX 4984.7 Acidification

SO2 2261.6

Discharges

SPM 59.4

T-P 3390.2

T-N 2552.2 Quality of Water

Waste Water 1027.4

Wastes Final Disposition 11428.0

Total 86965.8

4. A CGE Analysis The authors will attempt to conduct a CGE analysis in this section. A few words may be necessary about the terminology before going into the subject. 4-1.AGE and CGE

Although the term CGE (Computable General Equilibrium) is often used as a synonym for AGE (Applied General Equilibrium), these two terms are considered to be reflecting different genealogy of a sort. The latter term suggests that the study in question lies in the tradition of Scarf and his successors. The former term would identify the study as being in the World Bank’s tradition of development modelling. As is well known, Scarf and his colleagues attempted to find the exact location of a general equilibrium not just its existence. They developed and improved algorithms for finding a fixed point so that they could conduct various policy simulations.

On the other hand, the modellers in the World Bank who had used SAM multiplier analyses to draw up development policies felt that their tool should be more flexible. In fact, the SAM multiplier analyses confine their application only in the cases where the prices are constant and production functions and consumption functions are linear. The computation of general equilibrium has made it possible for them to generalise SAM

-50-

multiplier analyses to SAM-based CGE analyses. The CGE models in this tradition have several common features. Of course, one

common formal feature is that they are SAM-based. SAMs (Social Accounting Matrices) are in the centre of World Bank’s modelling attempts. As is well known, Professor Graham Pyatt played a leading role in development of SAM-based CGE modelling, in which much use was made of SAMs both as a framework of data housing and model presentation, whence consistency of modelling as well as data set was assured.4

It is often said that S (social) in “SAM” suggests something “social” is involved in the data set. For example, the sub-sectoring of the “households” may be done so that the incomes of the sub-sectors of household sector may be analysed and forecast. In fact, the development strategy of the World Bank until the middle of 80’s was characterised by its emphasis on income distribution. Thus, one more common feature of the CGE models, substantive rather than formal, may their focus on income distribution. In our modelling, however, this feature (detailed institutional distribution rather than factorial distribution) does not appear so explicitly because necessary sub-sectoring is not done in our modelling due to lack of data. A seemingly closely related feature may be that they do not often rely upon utility-function-based welfare measures to evaluate alternative economic situations which alternative policy schemes would lead to. Instead, distribution measures like the Gini coefficient or others are often used.

Among other features is a distinctive production structure used in the models, in which wide use is made of the so-called Armington assumption and CET (Constant Elasticity of Transformation) production functions. See Figure4.1 below. 4-2. Features of the modelling in the present paper The main purpose of estimating imputed environmental cost is to make clear what the environmental policy target should be. The policy makers should use whatever regulation measures are necessary to make the eco-margin measure reduce to zero. The policy measures should be those designed to reduce the emission by the amount that is indicated through the measurement of the imputed environmental cost. The policy measures may be direct policy instruments or indirect ones to reduce the emission. Thus, naturally, the environmental SAM modelling is strongly policy-oriented.

The authors attempt to construct two alternative models. They are both SAM-based CGE models for environmental policy analyses.

In the main model, certain policy measures are incorporated into the model from the very first. They could be interpreted as emission permits of a sort that should be paid for by the producers who want to use the environment. The environment may be treated as 4 See Pyatt[1988].

-51-

one of the three production factors the remaining two of which are capital and labour as usual.5 The environment may be considered to function as a sink of a sort. The authors introduce a “fixed price” closure rule for the production factor instead of “fixed quantity” closure rules for the other two production factors. There is a thought behind this treatment. The domestic equilibrium price of the permit will be determined at the level of imputed environmental cost, estimated according to the concept of “maintenance cost.” Because the firms will not pay for the permit if they can reduce the emission by spending actual environmental protection cost which equals to maintenance cost and is less than the value of the permit. The alternative model may be called “Ordinary Economy” model because the environment does not play any role of a production factor in this model. In other words, the economy is an ordinary (or actual) one without any environmental imputation. By using this model, the consequence of a certain regulation measure which is designed to reduce the emission by the amount designated by the policy target can be projected. For example, the consequence of direct regulation of the production processes of the firms discharging residuals in an inappropriate manner might be analysed. In the main models, the payment flow (for the environment as a factor of production) is received as if it is owned by the capital owners, who are characterised as those who take any surplus gain in the production process. The government in turn takes up the sum as a kind of transfer payment. But in a base equilibrium, it will be transferred back to the owners of capital to reproduce the actual data in 1995.

This needs some excuse actually. Thus, imputed environmental cost is the part of value added of the producers which they get through exploiting the environment, so to speak. Firms doing so may not be so aware of the environmental pressure they have made. At the same time, however, it is also the case that the present state of the economy is not the result of “zero environmental awareness.” In fact, there is, at present, so much pressure on the firms that are responsible to any ill-usage of the environment in the society. For example, the possibility of damage payment in the future may cause the firms to act in a more deliberate manner. Any new system for environmental protection will force the firms to adjust to it. Thus, the models assume that the firms are just ready for the introduction of a national tradable permit system although in reality they do not make any net payment about it.

But, this hypothesis may be considered to assume too “environment-conscious” firms

5 Rather than treating the environment as a production factor, a possible alternative model that we might suggest (but not fully developed here) will be the model where the emission of residuals are treated as a joint production of a sort which might be formulated in terms of “CET” technologies. This treatment seems to fit quite well with the logical framework of NAMEA.

-52-

- 53 -

in the model. It may be better to think that the present size of eco-margin may be the result of the behaviour of the firms which respond to not full but a half or even one third of the domestic equilibrium price of tradable permits. Thus, it might be more plausible to assume less “environment-conscious” behaviour of firms in the model. In any case, it will be easy to adapt or reinterpret the model in the way suggested here. However, it should be careful about the implementation and interpretation of the simulation results Production part of the model, which is one of typical World-Bank-type models except for the treatment of the environment, may be schematised in Fig. 4.1.

A few comments should be in order. (1) The environmental production factor is combined with mixed production factors by using CES production function form. Aside from a parameter automatically calibrated, the modeller(s) need(s) to set one parameter of the CES production function, namely, the elasticity of substitution. The authors set it to be 1.5.1 (2) Domestic goods (and services) stage 1 are domestically produced goods some of which may be further transformed to exports, the rest being (transformed into) domestic goods (and services) stage 2. The CET transformation function indicates the process. (3) Domestic goods (and services) stage 2 combined with imports are transformed into composite goods (and services) that are to be used for the final uses and intermediate consumption.

A sketch of the model SAM as a whole is illustrated below in Table 4.1

6 If the elasticity parameter is set otherwise, the results will change, but only slightly.

Factors Institutions including Company a/c

Savings.- Investment.

Com. Activities. ROW

Factors Factor

Payment to

Capital,

Labour,, and

Environment

Factor

Payment

From the

ROW

Institutions including Company account

Primary

Distribution

Income Generation

on the Assumption

that payment to

the environment

goes as if it is

owned by the

capital owners

Transfer

payments

between

Institutions

including

those related

with

emission

permits

Transfer

from

ROW

Savings- Investment

Savings

Commodities Final

Consumption

Capital

Formation

Intermediate

Input (U)

Exports

Activities Output

(V)

Rest of the World

Factor payment to

the ROW

Transfer to

ROW

Current

Balance

Imports

Table 4.1 Model SAM sketched

-54-

4-3. Results for the main model The increase in the endowments of capital or labour leads to the decrease in imputed environmental cost (eco-margin). In one sense, the environment is ill-used just to save other factors. But size of pressure of the 10% increase in each factor endowment to the industries is different industry by industry. Concerning labour, a large decrease in eco-margin is found in construction, transport and communication, service, etc. Concerning 10% increase in capital, a large decrease in eco-margin is found in real estate, agriculture, wholesale and retail trade, etc.

The 10% increase in labour endowment has a larger effect on the reduction of eco-margin than the same proportional increase in capital endowment.

The result of the experiment about 10% increase in the price of environment as a production factor may not seem to be so definite. Eco-margins decrease in some industries but increase in other industries.

The results of selected experiments will be summarised as follows

Industries

% changes in

eco-margin due to

10% increase in

Labour

% changes in

eco-margin due

to 10% increase

in Capital

% changes in

eco-margin due to

10% increase in

environmental factor

price

Agriculture, forestry and fishing -5.4 -7.9 1.3

Manufacturing -5.4 -2.9 3.9

Construction -13.5 -3.3 -0.3

Electricity, gas and water supply -6.2 0.6 0.0

Wholesale and retail trade -9.2 -5.5 -1.5

Finance and insurance -7.7 -4.2 -1.5

Real estate -3.5 -8.4 -1.2

Transport and communications -10.7 -1.0 1.2

Service activities -10.5 -5.1 -0.5

Table 4.2 Selected Results of the Main Model

-55-

4-4. Results for the ordinary economy model In addition to the main model, an alternative model is formulated to analyse an

ordinary or actual economy without environmental imputation. Policy makers may be inclined to think that it is necessary to introduce direct rather than indirect regulation measures in order to reduce the imputed environmental cost known quite immediately to zero. In other words, the imputed cost in the main model needs to be borne actually by the producers of the alternative model. Thus, they must spend some additional cost for the environmental protection instead of discharging residuals.

On this assumption, the working of the economy will be simulated by using this model. Additionally, so-called “Greened GDP” or more adequately “Greened Economy GDP” in the terminology of SEEA2003 draft manual will be calculated although “greened economy SAM” may be more meaningful.

According to the authors’ model, Greened Economy GDP seems to be greater than Green GDP by the amount depending on the assumptions made.

Some words may be necessary here to compare the two concepts, “Green GDP” (GDP minus Fixed Capital Consumption minus Imputed Environmental Cost) and “Greened Economy GDP.” One typical criticism on the former concept may be that it does not take into account various percussion and repercussion of employing one or other residual reduction measures. Some authors advocated “Greened Economy GDP” instead of Green GDP to respond to the criticism. Numerical comparisons between the two are found in the table below.

Table4.3 Green GDP and Greened Economy GDP （Billion yen）

CASE 1: Imputed environmental cost replaced by INTERMEDIATE INPUT CASE 2: Imputed environmental cost replaced by FACTOR INPUT CASE 3: Imputed environmental cost replaced by Mixed INTERMEDIATE and FACTOR INPUT

GDP AT FACTOR COST 469,870.3 GDP AT MARKET PRICES 509,969.1 FIXED CAPITAL CONSUMPTION 89,116.9 NDP AT MARKET PRICES 420,852.2 ECO‐MARGIN in the model 86,025.0 GREEN GDP 334,827.2 GREENED ECONOMY GDP (CASE 1) 407,862.4 at constant pricesGREENED ECONOMY GDP (CASE 2) 392,774.6 at constant pricesGREENED ECONOMY GDP (CASE 3) 400,739.7 at constant prices

-56-

5. Closing Remarks Firstly, a controversial problem over “direct” vs. “indirect” regulations will be spotlighted by the modeling of this sort. Both types of regulations use “market mechanisms.” The latter induces the economic agents to change their behaviors by using the mechanisms to achieve the policy targets. The former regulates discharging of residuals directly and the market mechanisms work afterwards to achieve a new equilibrium position in which the policy targets are met.

The modelling seems to be insufficient to get to any decisive conclusion about the problem raised. Because the key to the problem may be whether any switch of techniques as well as shift in industrial structure is triggered by the policy change. The main model excludes any switch of techniques from consideration. However, plausibly, indirect regulations may bring about insufficient, if not nil, switch of techniques for the accomplishment of the policy target. If this is the case, direct regulation may be better way to achieve the target, for additional consequences brought about by indirect regulations may not necessarily be desirable from the viewpoint of income distribution.

Secondly, needless to say, more disaggregated treatment for the environmental pressure categories should be necessary. Green house gases such as CO2 and other residuals cause different environmental problems that need to be solved differently.

Lastly, it should be stressed again that monetary valuation of environmental pressure according to the concept of maintenance cost is important in that it not merely gives an estimate of the equilibrium price of an emission permit but clarifies the responsibility of the government for the environment. For, the estimation of imputed environmental costs clearly has an implication that they need to be reduced to zero.

References Ariyoshi, N. (2006), "The Development of Japanese NAMEA" the paper prepared for

International Workshop for Interactive Analysis on Economy and Environment, Cabinet Office, the Government of Japan, 4th March 2006.

De Haan, M. and S. J. Keuning (1996), "Taking the Environment into Account：The NAMEA Approach," The Review of Income and Wealth, Series 42, No.2, pp.131-148.

Department of National Accounts, Economic and Social Research Institute (ESRI), Cabinet Office of Japan (2004), “New System of Integrated Environment and Economic Accounting: Trial Calculation on Hybrid Accounting System

-57-

Integrating Environmental Pressures and Economic Activities, http://www.esri.cao.go.jp/en/sna/menu.html.

. Pyatt, G. (1985), " A SAM Approach to Modeling,” Journal of Policy Modeling, vol.10, pp.

327-352. United Nations (1993), Handbook of National Accounting: Integrated Environmental and

Economic Accounting, Interim version, United Nations (ST/ESA/STAT/SER.F/61).

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Appendix 1 Estimation Method of Imputed environmental costs: Outline

Inputed

environmental costs

＝Unit costs for maintenance

×(total emission less permissible level of emission)

CO2

Unit cost of

CO2

（Depreciation＋maintenance costs）/(CO2 emission eliminated)

Depreciatin

estimated by PIM method using investment data stated in the environmental reports of selected companies with service life being 7 years

Maintenance costs

maintenance cost stated in the environmental reports

Eliminated CO2

environmental

pressures

environmental pressure eliminated stated in the environmental reports

Unit costs for

maintenance

elimination cost

depreciation

accumulative plant and

equipment investment

for specific category

of environmental

facilities）

ratio of salvage value

0.1

maintenance

costs

plant and equipment

investment for a

specific category of

environmental

facilities

ratio of maintenance

costs to investment

Environmental

pressures

eliminated

processing capacity of each type of environmental ficilities×the removal rate

Note1:The Kyoto Protocol set the permissible emmission level of CO2, while zero emmission is assumed about the other environmental pressure items..

Note2: The estimation method concerning environmental pressures other than CO2, the same method as used in the ESRI's compilation of SEEA accounts is used...

maintenance costs data known for the environmental

facilities for the mitigation of air polltion /capital

formation in the environ,mental facilities for the

mitigation of air polltuion

ohter

environmental

pressures

accumulative plant and equipment investment known for the

mitigation of air pollution × accumulative gross output

of the specific category of environmental facilities

/accumulative gross output of environmental facilities for

the mitigation of air pollution

accumulative plant and equipment investment for a specific category of

environmental facilities）×（１－ratio of salvage value）／service

life(7 years) The amount known concerning the investment in

environmental facilities for the mitigation of air

plollution ×accumulative gross output of the specific

vategory of environmental facilities／accumulative gross

output of environmental facilitie for the mitigation of

air polltion

depreciation + maintenance costs

plant and equipment investment of a specific category of environmental

facilities×ratio of maintenance costs to investment

the relevant costs incurred about the elimination of environmental pressures totalled for all gotegories of environmental

facilities /environmental pressures eliminated totalled for all categories of environmental facilities

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Agriculture ,forestry and fishing

Mining

Food products and beverages

Textiles

Pulp ,paper and paper products

Chemicals

Petroleum and coal products

Non-metallic mineral products

Iron and steel

Non-ferrous metals

Fabricated metal products and Machinery

Other Manufacturing

Construction

Electricity ,gas and water supply

Wholesale and retail trade

Finance and insurance

Real estate

Transport and communications

Service activities

12

34

56

78

910

1112

1314

1516

1718

19

CO21815.00

46.83

409.59

1868.2082.591097.72

50.0329652.7411278.28

332.08

4.07

4716.921683.177472.1356.66

17.77

29.48

331.91

88.27

61033.42

N2O

0.22

0.02

0.47

0.05

0.13

0.36

0.15

0.13

0.27

0.11

1.92

0.64

1.21

0.31

1.47

0.55

0.90

0.74

2.06

11.71

CH4

0.09

0.01

0.18

0.02

0.05

0.14

0.06

0.05

0.10

0.04

0.74

0.25

0.46

0.12

0.56

0.21

0.34

0.28

0.79

4.49

HFCs

1.68

0.17

3.54

0.41

0.98

2.71

1.09

1.00

2.04

0.79

14.47

4.85

9.11

2.37

11.05

4.11

6.74

5.58

15.49

88.18

PFCs

0.97

0.10

2.03

0.23

0.56

1.56

0.63

0.57

1.17

0.46

8.31

2.79

5.24

1.36

6.35

2.36

3.87

3.20

8.90

50.65

SF6

1.41

0.14

2.96

0.34

0.82

2.26

0.91

0.84

1.70

0.66

12.09

4.05

7.62

1.98

9.23

3.44

5.63

4.66

12.95

73.70

NOX

23.00

0.62

2.07

1.24

4.04

7.25

5.59

17.92

9.22

1.35

3.63

1.35

14.40

29.22

1.35

0.10

0.52

4856.99

4.87

4984.73

SO2

5.18

0.04

2.06

0.72

2.15

3.07

1.98

1.39

2.74

0.63

0.76

0.67

0.55

10.32

1.39

0.13

2225.94

1.94

2261.64

SPM

7.09

0.07

0.67

0.36

2.05

1.75

0.81

1.82

2.09

0.27

0.70

0.37

2.58

9.10

0.29

0.02

0.11

28.36

0.92

59.42

T-P

67.81

6.25

93.61

11.27

24.66

70.95

39.08

32.07

42.74

16.62

363.49

137.49

296.33

96.71

549.89

212.58

433.41

255.86

639.43

3390.24

T-N

51.05

4.70

70.47

8.49

18.57

53.41

29.42

24.14

32.17

12.51

273.64

103.51

223.08

72.81

413.96

160.03

326.27

192.62

481.37

2552.22

Waste Water

20.55

1.89

28.37

3.42

7.47

21.50

11.84

9.72

12.95

5.04

110.15

41.67

89.80

29.31

166.64

64.42

131.34

77.54

193.77

1027.39

Wastes

Final Disposituon

301.37

30.95

324.39

53.08

92.89

258.98

114.31

120.91

188.09

73.151466.84546.16

1198.33310.10

1610.20685.09

1291.09

803.12

1958.9011427.96

2295.40

91.81

940.43

1947.83236.95

1521.67255.89

29863.3111573.56

443.69

2260.815560.713531.888035.822829.041150.692229.828786.803409.6586965.75

Appendix 2 Eco-margin

Industries

Total by tyoe of residuals

Eco-Margin

Discharges

Green House

Effect

Acidification

Water Use

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