"Management is responsible for what is prepared and presented, and it is our opinions or conclusions that can express inherent limitations, such as measurement uncertainty, that just plain cannot be overcome or adequately disclosed," he said. 

Coville said that sometimes it can be a challenge to convince corporate leaders of the importance of even compiling a sustainability report, let alone getting assurance. In his own experience, what he has found works with boards of directors is to emphasize how it fits into the concept of risk management. There can be real financial gains or losses based on ESG metrics, whether due to reputational damage, regulatory action or even litigation, and so it behooves businesses to take these things seriously. 

"When you point out that some of these things come with financial consequences, it opens up a more full dialogue, [with clients realizing,] 'OK, this isn't about being some tree hugger; this is about risk management for the firm and needing to take these things into consideration,'" he said.