Climate Change Mitigation as an Obligation under Customary International Law
88 Pages Posted: 6 May 2022
Date Written: April 18, 2022
Climate treaties impose few substantive obligations on the mitigation of climate change. This article explores customary law as an alternative source of such obligations. The task faces considerable methodological difficulties due to the tension between ascending and descending reasoning in the identification of customary law. The methodology that international courts tend to follow, this article argues, would likely lead to the identification of a customary obligation on climate change mitigation, but one that only requires states to comply with the standard of care that most of them generally follow—even if that points to significantly less ambition than what global mitigation objectives suggest. It could be difficult to assess a state’s requisite level of mitigation action, but compliance with customary law could be tested by breaking down the customary mitigation obligation into implied duties reflecting the measures that states would generally be expected to take when exercising due diligence.
Keywords: climate change, customary international law
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