Climate Policy in an Unequal World: Assessing the Cost of Risk on Vulnerable Households

Policy makers concerned with setting optimal values for carbon instruments to address climate change externalities often employ integrated assessment models (IAMs). While these models differ on their assumptions of climate damage impacts, discounting and technology, they conform on their assumption of complete markets and a representative household. In the face of global inequality and significant vulnerability of asset poor households, we relax the complete markets assumption and introduce a realistic degree of global household inequality. In contrast to the representative agent framework, we find that a household’s position on the global wealth distribution predicts the identity of their most-preferred carbon price. Specifically, poor agents prefer strong public action against climate change to mitigate the risk for which they are implicitly more vulnerable. We find the carbon tax fills the role of insurance, reducing the volatility of future welfare. It is this role that drives the wedge between rich and poor households’ policy preferences, even in the absence of redistribution. Taking into account the risk channel, we find an optimal tax value four times larger than standard estimates from representative agent models