The marginal impact of predicted climate risk scenarios on portfolio credit risk stress testing

This paper adapts the methodology developed by de Oliveira Campino et al. (June 2021) to account for predicted climate risk shocks' impact on a sovereign portfolio's credit quality on a forward-looking basis and in probabilistic terms. In particular, the portfolio stress testing capability is enhanced by adjusting the severity of the credit shocks to account for climate risk-related events on an additive basis. The benefit to risk managers is that it allows understanding of the impact of climate risk in marginal terms in relation to the original credit shock. The recently created NGFS (the Network for Greening the Financial System) database makes this exercise possible. Moreover, the described approach translates the marginal impact of climate risk scenarios on the portfolio's credit risk stress testing into capital adequacy metrics dislocations, which facilitates communicating the marginal impact of climate risk scenarios as capital consumption amounts. The paper presents an overview of the underlying model, and the methodological approach developed to adapt the credit risk stress-testing capabilities to account for climate risk using the NGFS database. Moreover, it applies the methodology to a hypothetical sovereign loan portfolio and discusses the results. Over the period considered, the study finds that the transition aspect of climate risk has a more pronounced marginal impact on a sovereign portfolio's credit risk than the chronic physical aspect of climate risk. Moreover, the results indicate that as the world takes action to transition away from carbon, the credit risk of sovereign portfolios may be exacerbated, especially if there are delays and a lack of coordination across countries and sectors.