This article is part of a series of excerpts from the fifth annual State of Green Business Report, looking at trends in corporate sustainability. Download the free report from GreenBiz.com, and see all of our trends here.

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The Big Four accounting firms have taken notice. They see new opportunities in helping CFOs bring the same level of diligence to sustainability reporting that they bring to financial reporting.

"Making the business case" has long been a mantra of sustainability advocates. After all, if sustainability doesn't create business value, why bother? For years, the business case focused on growing sales and cutting costs. But there are other aspects of sustainability -- transparency, disclosure, compensation, and risk -- that garner the attention of shareholders and others near and dear to the boardroom.

Enter the chief financial officer, historically an outsider to most corporate conversations about sustainability, which was viewed as "too soft" to be relevant to hard-nosed bean counters.

That's changing. According to a study conducted by Ernst & Young and GreenBiz.com, one in six (13 percent) respondents said their CFO was "very involved" with sustainability while 52 percent said the CFO was "somewhat" involved. The survey was conducted for a forthcoming report from the two organizations, looking at trends in corporate sustainability reporting.

How to account for this? A variety of issues -- among them, greenhouse gas emissions, toxic ingredients in products, and reliable access to water, energy, and raw materials -- are increasingly seen as material risk factors that warrant scrutiny by shareholders, customers, and regulators.

Growing calls for transparency and disclosure of sustainability impacts are requiring more, and more reliable, information about increasingly deeper levels of company operations and supply chains. Ratings and stock indices, such as those from Newsweek and Dow Jones, are being taken ever more seriously by companies, elevating the collection and dissemination of key data to the C-suite.

Shareholder resolutions focusing on social and environmental issues made up the largest portion of all shareholder proposals in 2010 and 2011. That further bonds sustainability with board-level interest.

Shareholders aren't the only ones concerned about the impact of sustainability issues on stock price. In 2010, the U.S. Securities & Exchange Commission issued guidance to companies regarding their responsibility to disclose material risks related to climate change.

The guidance notes that a company's CEO and CFO must certify that the company has installed "controls and procedures" enabling it to discharge its climate change disclosure responsibilities. That placed sustainability directly into the realm of controllership and financial risk management.

The Big Four accounting firms have taken notice. During 2011, two of them -- Ernst & Young and Deloitte -- published reports on CFOs and sustainability, while the other two -- PricewaterhouseCoopers and KPMG -- have taken a keen interest in the topic. They see new opportunities in helping CFOs bring the same level of diligence to sustainability reporting that they bring to financial reporting.

In its report, Ernst & Young pointed to the growth of corporate sustainability reports, but especially to the growing wave of integrated reports that combine sustainability metrics and conventional financial reporting.

A handful of CFOs are starting to be heard on the topic. In 2011, Kurt Kuehn, CFO of UPS and a 33-year veteran of the company, gave a speech at the Boston College Center for Corporate Citizenship on "Five Reasons the CFO Should Care About Sustainability" (a subject he wrote about on GreenBiz.com in 2010).

He cited cutting costs, mitigating risks, generating revenue, driving innovation, and improving employee development and retention. "The one thing Wall Street hates the most is surprise," he told the audience. "So when a company confidently talks about how it will reduce risks and be successful for the long-term, Wall Street listens."

_{Businessman photo via Shutterstock.}