On May 20, the shareholders of Bunge, one of the biggest farm commodity businesses in the world, will walk into some well-appointed meeting room at the Sofitel in midtown Manhattan to vote on five proposals. The first four votes will be utterly boring to anyone who isn’t deeply absorbed with Bunge’s corporate governance (e.g., appoint Deloitte & Touche as auditor?). But the fifth is unusual: It’s a proposal from shareholders suggesting that the company act decisively to curb deforestation. And so in addition to conducting pro-forma votes on new board members and executive compensation, Bunge shareholders will also hold a referendum on global sustainability.

This proposal asks for the company to “set quantitative, time-bound goals for reducing its supply chain impacts on deforestation and related human rights, and report annually against key performance indicators and metrics that demonstrate progress against these goals.” It suggests that, by failing to adequately account for the problem of deforestation, Bunge is putting its stock value at risk. Bunge’s board recommends that shareholders vote no.

Usually, shareholder activism doesn’t overlap with environmental activism. Usually, activist shareholders launch campaigns when they think a CEO is skimming off too much money for his own compensation, or when they think the corporation would be more successful if it was split in two. But environmental activists have also tried to influence corporations by participating in financial governance. In the early days, activists would just buy a couple shares to gain entrance to a shareholder meeting and urge the company to change from the inside. This tactic didn’t accomplish much: It was clear to everyone involved that the activists were focused on something other than shareholder value, so most other investors didn’t listen.

The activists wanted to stop companies from despoiling nature. The shareholders wanted the company to make money. If capitalism and environmentalism were irreconcilable, the whole story would have simply stopped there. But activists found they could often demonstrate that environmental destruction would, in the long term, undermine profitability. They stopped making moral arguments and started making financial arguments. When they did that, some shareholders started paying attention — especially long-term shareholders. If a business is just looking at the next three months, it makes rational sense for it adopt a smash-and-grab approach. But when a business is focused on the next 20 to 100 years, it has to take care of the place where it does business.

And it turned out that were investors who wanted companies to stop chasing quarterly profits and instead provide the best return on investment over the long run. These investors frequently had power because they were managing massive pension funds. “There are a lot of large asset owners looking at long-term risks instead of just looking at quarter by quarter profits,” said Lucia von Reusner, a shareholder advocate for Green Century Funds, the firm that made the shareholder proposal for Bunge to act more aggressively on deforestation.

Inquiries from shareholders about environmental risks helped spur Kellogg’s, ConAgra, Smuckers, Safeway, General Mills, and Target to set deforestation policies. Early this year, Green Century began working with Archer Daniels Midland, and that got the attention of the New York State comptroller’s office, which manages the third largest public pension fund in the nation. The New York State Common Retirement Fund and Green Century filed a shareholder proposal with ADM. But, to the surprise of many (including, I hear, many at ADM Bunge), the company cut off any potential shareholder action at the pass by setting what is perhaps the most sweeping deforestation commitment on record.

Bunge has responded in a different way. Its board said that it was already working on deforestation: “The Board believes that the Company’s existing and planned efforts provide a more focused and effective path forward than that outlined in the proposal,” it wrote in a proxy statement. Bunge already has no-deforestation policies for palm oil, and for soy in the Brazilian Amazon. But what about soy outside the Brazilian Amazon? And what about every other crop besides palm oil and soy?

In an email response to my questions, Stewart Lindsay, Bunge’s director of global corporate affairs, wrote:

We believe in the principle that deforestation should be reduced and ultimately eliminated from agricultural supply chains. Adopting a policy that goes beyond our commitment to zero deforestation in the Amazon and our zero deforestation palm oil policy is really a question of the how and when of implementation. These are challenging issues, but we’re tackling them actively and at the highest levels of the company, so stay tuned. In the meantime, we’re working to map our palm supply chain, with the help of third parties, so we can establish a realistic timeline for 100% implementation of our policy. We hope to have a clear picture on this soon.

Lindsay is saying, look, we’re on board, we just need time to find a realistic path. There is a real danger that these commitments will fall apart if companies don’t fully understand the difficulty in making good on their pledges. It’s important that companies make commitments that they can actually achieve. But this shouldn’t stop them from setting benchmarks. To get anything done in a large organization, you need to set a goal.

“Most companies set policy first, then devote resources to it,” von Reusner said. These things take money, along with teams of employees working full time. Companies are a lot more likely to devote real resources to sustainability after their leaders set a goal and a deadline.

In the last few years, a slew of international agribusiness corporations have made commitments that — if realized — would slam the brakes on humanity’s sprawl into wild lands. The new challenge is to ensure that companies live up to their promises.

Shareholder activism is well positioned to do this because, instead of exacting concessions through battle, it’s a strategy of ongoing engagement. In this upcoming Bunge vote, for instance, Green Capital doesn’t have a partner like the New York Pension Fund pushing things forward. But von Reusner told me she has had conversations with several of Bunge’s large shareholders, and they are interested in seeing the company move forward quickly to stop deforestation. Regardless of which way the vote goes on May 20, if the sustainability push isn’t progressing as planned, the shareholders will be there to ask why.

Correction: A previous version of the story suggested that many at ADM were surprised by ADM’s commitment to fight deforestation. It has been corrected to say many at Bunge were surprised by ADM’s commitment. The reporter will drink a liter of palm oil in penance. Twice.