A different kind of environmental radical

FORTUNE — Mark Tercek, the head of the Nature Conservancy, America’s largest environmental group, is not your usual green-minded crusader. As a former partner and head of corporate finance at Goldman Sachs, Tercek is someone who has lived in both worlds. While at Goldman, then-CEO Hank Paulson had asked him to head up the investment bank’s new Environmental Strategy Group. The idea was that Goldman could do well by doing good — backing renewable energy companies and using sustainability as a screen when investing in and advising big corporations. Because Tercek had been a big-time player at Goldman, his colleagues listened when he talked about the importance of the ecosystem when making investment decisions. How much Goldman’s new green approach has paid off isn’t clear — solar and other renewable stocks have been clobbered over the last few years — but it undoubtedly left the bank a more enlightened place.

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By the time Tercek left Goldman (GS) to run The Nature Conservancy (TNC) in 2008, he had developed a strong belief that nature — clean water, vast tracts of timber, and healthy fish stocks — could be better protected if only the corporations exploiting these resources would become aware of their economic value. So instead of protecting nature for nature’s sake — the traditional approach of the environmental movement — businesses and government should view our global ecosystem as a kind of natural capital that, if developed sustainably, could provide a significant return on investment. Tercek spoke last night at Fortune‘s Brainstorm Green conference.

This is the major theme of Tercek’s new thought-provoking and smartly argued book, Nature’s Fortune: How Business and Society Thrive by Protecting Nature. Co-authored by Jonathan Adams, a science writer and conservation biologist, Nature’s Fortune contends that despite the best efforts of environmental groups, nature remains at risk because of fast population growth with billions now headed toward a middle-class lifestyle. True enough. The question then is, Will Tercek’s radical approach of working hand-in-hand with big business be enough, soon enough?

Some provocative examples in the pages of this book suggest that Tercek may be onto something. In one case, TNC is working closely with Dow Chemical in a five-year partnership launched about a year ago to help the industrial giant put a value on its land and water assets around the world. The goal: to figure out how to develop these valuable resources sustainably. TNC scientists are working with Dow (DOW) employees at the company’s Freeport, Texas production facilities, which has abut 5,000 acres of land and coastal marsh. Worried about the increasing frequency and strength of hurricanes, Dow has been considering building flood walls through the marsh. TNC is trying to determine whether marsh enhancement would provide a better (and cheaper) storm buffer. Dow has still not decided and may indeed choose the concrete wall approach, but at least the company is thinking about its decisions in new terms. Writes Tercek: “Seizing the opportunity to work with companies as they pursue environmental strategies to strengthen their business provides the chance to create significant conservation gains.”

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As Tercek acknowledges, putting a price on nature is a tricky and controversial task. It’s not yet clear whether these partnerships will bear significant fruit. On top of that, TNC is under attack in some quarters for working so closely with business. Greenpeace categorizes TNC as a right-wing environmental organization. Even so, this radical experiment certainly seems worth a try. What’s there to lose?