A Finance Approach to Climate Stress Testing

There is increasing interest in assessing the impact of climate policies on the value of financial sector assets, and consequently on financial stability. Prior studies either take a "black box" macro-modelling approach to climate stress testing or focus solely on equity instruments - though banks' exposures predominantly consist of debt. We take a more tractable finance (valuation) approach at the industry-level and use a Merton contingent claims model to assess the impact of a carbon tax shock on the market value of corporate debt and residential mortgages. We calibrate the model using detailed, proprietary exposure data for the Dutch banking sector. For a €100 to €200 per tonne carbon tax we find a substantial decline in the market value of banks' assets equivalent to 4-63% of core capital, depending on policy choices.