本研究探討碳邊境調整機制（Carbon Border Adjustment Mechanism, CBAM）
下，不同碳稅制度對垂直供應鏈廠商決策、市場均衡及社會福利之影響。模型中
包含一家上游獨占中間財廠商，此外，南、北兩國各一家下游廠商生產差異化產
品於北國市場競爭。北國政府與國內上下游廠商進行三階段賽局模型，第一階段
由北國政府決定進口之中間財與最終財產品之邊境碳稅與關稅，第二階段由南國
上游廠商決定污染減排程度及中間財價格，第三階段由兩國下游廠商於北國市場
進行數量競爭。文中分析三種邊境碳稅政策制度：僅課徵上游邊境碳稅之「單一
碳稅」、上下游課徵相同碳稅之「統一碳稅」及上下游課徵不同碳稅之「差異碳
稅」三種政策制度之均衡結果。
結果顯示，當下游產品替代性提高時，最適上下游碳稅與關稅下降，最終財
價格、總產量、廠商利潤、總減排量、環境損害及社會福利皆下降，而消費者剩
餘呈現先上升後下降之變化。針對三種制度作比較，單一碳稅制度效果最差，邊
境碳稅最高、減排量、消費者剩餘、與社會福利最低，且環境損害最高。統一碳
稅制度最能提升環境品質，邊境碳稅最低、總減排量最高、環境損害最低、消費
者剩餘亦最高。然而，差異碳稅制度下，北國政府更有彈性調整上下游碳稅，故
整體社會福利最高。

This paper studies the effects of different carbon taxation regimes under the Carbon
Border Adjustment Mechanism (CBAM) on firms’ decisions, market equilibrium, and
social welfare in a vertically related international supply chain. In the model, there are an
upstream monopolistic intermediate-goods producer and two downstream firms, one
located in the North and the other in the South, competing with differentiated products in
the Northern market. A three-stage game is developed. In the first stage, the Northern
government determines carbon border taxes and tariffs on imported intermediate and final
goods. In the second stage, the Southern polluting upstream firm chooses its abatement
level and intermediate-goods prices. In the third stage, the two downstream firms engage
in Cournot competition. We examine three carbon taxation regimes: a single carbon tax,
in which only an upstream carbon border tax is imposed; a uniform carbon tax, in which
the same carbon border tax is imposed on both upstream and downstream sectors; and a
differentiated carbon tax, in which different carbon border taxes are imposed on upstream
and downstream sectors.
The results show that, as products become more substitutable, optimal upstream and
downstream carbon taxes as well as tariffs decline. Final-goods prices, total output,
abatement efforts, firms’ profits, environmental damage, and social welfare also decrease,
while consumer surplus initially increases and then decreases. Furthermore, we compare
the three policy regimes and find that the single carbon tax performs the worst. It
generates the highest carbon border tax, the lowest level of emission reduction, consumer
surplus, and social welfare, while resulting in the highest environmental damage. The
uniform carbon tax achieves the best environmental performance, producing the highest
quantity of abatement, the lowest environmental damage, and the greatest consumer
surplus. However, under the differentiated carbon tax, the Northern government has
greater flexibility in adjusting upstream and downstream carbon taxes, allowing it to
better balance environmental and economic objectives. As a result, the differentiated
carbon tax regime yields the highest overall social welfare.

論文審定書 ............................................................................................... i
摘要 .......................................................................................................... ii
Abstract ................................................................................................... iii
目錄 ......................................................................................................... iv
圖次 ......................................................................................................... v
表次 ........................................................................................................ vi
第一章 前言 ............................................................................................. 1
第二章 文獻回顧 ..................................................................................... 5
第三章 模型設定 ................................................................................... 10
第四章 均衡結果 ................................................................................... 15
4.1 給定政策下之市場均衡 .................................................... 15
4.2 福利與最適政策 ................................................................ 19
第五章 結論 ........................................................................................... 36
參考文獻 ................................................................................................ 38
附錄 1 ..................................................................................................... 39
附錄 2 ..................................................................................................... 44
附錄 3 ..................................................................................................... 45

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