2019 was a pivotal year for the green, social and sustainability bond market. The value of issuance for all three markets combined rose to $321 billion in 2019, up 52% on the previous year. Cumulative issuance is set to pass the $1 trillion mark in 2020. An online poll conducted by Environmental Finance suggested that the market is expected to continue to grow this year. Most respondents thought the value of issuance is likely to exceed $350 billion. But it is not the growth of the market that made 2019 a pivotal year. To my mind, what was noteworthy in 2019 was the change in the tone of discourse in the market. There has been a vigorous – and in my view very healthy – debate in the market, asking: “What is the market trying to achieve, and what is the best way to achieve it?”