Climate Risk and Stock Markets: Implications for Market Efficiency and Return Predictability

In this study, we set out to construct a daily frequency climate risk index with the aim to explore the impacts of climate risk on the stock markets of advanced and emerging countries and green stocks. We adopt an approach similar to the Sharpe ratio to demonstrate the pricing of climate risk into stocks and therefore reexamine the (in)efficiency of these markets. We specify an econometric model to evaluate the predictive content of the climate risk index for stock returns. We find compelling evidence of market efficiency when climate risk is priced into the stocks and market inefficiency otherwise. Results from the predictability analyses indicate that about 85% of advanced stock markets, 17% of emerging stock markets, and 100% of green stocks have the capacity to protect investors against climate risk. Forecast evaluations reveal that the climate risk index is a good predictor of the stock returns only after controlling for the macroeconomic environment. We explore several robustness checks and highlight both investment and policy implications.