The growth in investment funds that claim to be sustainable is eye-catching — not just in their investment mandates, but also in their recent growth of assets under management.

According to the Global Sustainable Investment Alliance, a global club of sustainable investment organisations, environmental, social and governance (ESG) investing now accounts for more than $30-trillion of assets under management, with expectations of further growth to $50-trillion within the next two decades. To put that into perspective, the entire S&P 500, an index of the top 500 companies in the US by market capitalisation, is a little over $24-trillion...