Modeling climate mitigation and adaptation policies to predict their effectiveness: The limits of randomized controlled trials

Working Paper 120

Abstract

This paper is about some of the serious problems we can expect to face in modelling the effects of climate change policies — in evaluating the effectiveness of policies that have been implemented and in predicting the results of polices that are proposed. The difficulties we will discuss are shared with other kinds of social and economic policies, but they can be particularly problematic for climate change policies, as we will show below. Policies for addressing climate change are commonly divided into two categories, mitigation and adaptation, corresponding to the two levels at which policy makers can address climate change. The Intergovernmental Panel on Climate Change (IPCC) defines a mitigation policy as “A human intervention to reduce the sources or enhance the sinks of greenhouse gases” (IPCC 2007a, 949) and an adaptation policy as an “Adjustment in natural or human systems in response to actual or expected climatic stimuli or their effects, which moderates harm or exploits beneficial opportunities.” (IPCC 2007b, 869) One can put the distinction between mitigation and adaptation in causal terms by saying that while mitigation policies are designed to reduce the causes of global warming, adaptation policies are designed to moderate its harmful effects on natural and human (or social) systems.

Alexandre Marcellesi and Nancy Cartwright