Aron Cramer, President and CEO, BSR

The Rio+20 Summit on sustainable development is still weeks away, and yet many already have proclaimed the event a failure. That verdict is based on outdated assumptions about the nature of change. In fact, a 21st century success in Rio remains possible.

Long gone are the days when a small number of governments shaped the future through lengthy communiqués delivered at global summits. In contrast, the tens of thousands of people who will descend on Rio next month reflect the way the world works today. Ian Bremmer's smart new book, Every Nation for Itself, accurately depicts today's world: a complex system lacking über-powerful mega-states that set the stage for us all. In the "G-Zero world" that Bremmer describes, many have power—and no one has control.

And yet, a world without clearly defined leaders is not a leaderless world. Rio+20 certainly won't be a green version of the Reagan-Gorbachev summits of decades past, where success was defined by the dynamics and agreements between two men and two nations. Achieving the Millennium Development Goals or the new Sustainable Development Goals, which will be debated at Rio, depends upon the engagement of a wide array of nations, businesses, and citizens and on the effective use of technologies that place power in the hands of individuals rather than institutions.

Judging Rio+20 based on the world that existed at the time of the first Earth Summit is unwise. Twenty years ago, the internet was largely unknown. The Cold War had just ended, and BRICS were used to build houses, not the world's most dynamic economies. Few companies attended the original Earth Summit, and examples of company-NGO collaboration were few and far between.

It is disconcerting that President Obama, Prime Minister Cameron, and Chancellor Merkel, among other world leaders, are skipping Rio. Their absence reflects and accentuates a lack of government commitment to prioritize sustainable economic development. But political declarations are not the only—or the best—way to measure progress.

In Rio, we will see hundreds of companies, NGOs, and issue experts calling for action, exploring new partnerships, and debating the best way forward. Rio will serve as an opportunity to take stock of the imperfect but real progress since 1992, to renew commitments, and to focus the world's attention on sustainability. Unlike most political leaders, these institutions have by and large maintained their commitment to sustainable prosperity despite the global financial crisis. They know something that governments seem to have overlooked: successfully meeting the world's need for food, water, fuel, and dignified lives is the mother of all innovation challenges, and this kind of innovation can unlock a new generation of economic vitality that policy debates have failed to deliver.

There is no doubt that Rio will appear chaotic: 21st century solutions to our global challenges are messier than 20th century models. But the old models are no longer relevant. We need to get used to our new reality and shape our actions accordingly. We may live in a G-Zero world when it comes to nation states. But when it comes to leadership, we are living in a G-Everybody world. We all have the ability to shape a more sustainable future at Rio. Let's get on with it.

This post first appeared on the Harvard Business Review blog.