External carbon costs and internal carbon pricing

The use of internal carbon prices (ICPs) is a practice by which companies voluntarily attach a hypothetical cost to their carbon emissions to help prioritize low-carbon investment projects. We find that ICP use is driven by external carbon constraints and by firms' exposure to formal carbon pricing systems, next to various firm and society characteristics. The size of the gap between countries' actual and intended emissions alone, without a translation into stringent climate policies, does not play a role. These findings inform policymakers and investors about when and why firms account for future carbon constraints internally. A key societal risk is that corporate investments are not sufficiently directed at a future low-carbon economy. Stringent climate policies that provide predictable pathways appear to help firms mitigate the misalignment of their investments by using ICPs and thereby contribute to a less erratic and less expensive transition of the energy system.