Coordinating climate and trade policies: Pareto efficiency and the role of border tax adjustments

ArticleNOTICE: this is the author’s version of a work that was accepted for publication in Journal of International Economics. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of International Economics, Volume 94, Issue 1, September 2014, Pages 119–128, doi:10.1016/j.jinteco.2014.03.002© 2014, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/This paper explores the role of trade instruments in globally efficient climate policies, focusing on whether or not some form of border tax adjustment (BTA) is warranted when carbon prices differ internationally. The analysis shows that, while there is no case for BTA when all instruments can be freely deployed, Pareto-efficiency does require a form of BTA when carbon taxes in some countries are constrained: its purpose then is to partly counteract the impact on emissions of inappropriate carbon pricing there, or, equivalently, to undo the trade distortions such pricing creates. The required form of BTA is generally complex, but a special case is identified in which it optimally has the simple structure envisaged in practical policy discussions. It is also shown that the efficiency case for BTA depends critically on whether climate policies are pursued by carbon taxation or by cap-and-trade