Companies striving to prove their green credibility and compliance often rely on assurance auditing. And according to Steve Starbuck, the Americas leader of climate change and sustainability services for Ernst & Young, this need is only growing. To do assurance right, he says, it's important to embrace a holistic approach. "It's to the benefit of the client if we combine the expertise of financial assurance auditing with the auditing of non-financial and sustainability auditors," he said during a Studio C chat at GreenBiz Forum 2014. "So we team very closely to give the client the best possible service."