A novelty in the C-suite not so long ago, the chief sustainability officer (CSO) is fast becoming a fixture in companies of note as climate change and inequality increasingly dominate global attention.

During the past year alone Citigroup, General Motors, and International Paper have each appointed their first CSO. They join Diageo, P&G, Mastercard, and Tyson Foods on the growing list of firms that have added a CSO to their top management team in recent years. Yet these firms are hardly trailblazers. Between 2004 and 2014, the number of S&P 500 companies that have a CSO increased from 25 to 90.

 …