Young people protested at the Earth Summit in Rio last month. (Photo courtesy of Adopt a Negotiator.)

There are two ways to respond when you watch the world’s leaders attempt to solve the planet’s most pressing problems and fail: You can despair or you can raise hell.

After watching the 2009 climate talks in Copenhagen collapse, many bright-eyed young people despaired, suffering through months of what can only be described as a “Hopenhagen” hangover. More recently, when the diplomats at the Rio+20 Earth Summit produced a policy document with all the weight of a fluffy pink cloud, we watched the cloud pass and decided to get down to business.

I attended Rio+20 as the communications coordinator for SustainUS, an entirely youth-run and volunteer-led nonprofit that helps U.S. youth sort through the alphabet soup of the United Nations and push for meaningful change at conferences like Rio+20. It was truly inspiring to be entrusted with the stories of young people across the globe.

For so many of us, sustainability isn’t something we do in our free time; it’s a way of life. It’s an identity that cuts across national boundaries and issue areas, an identity that’s gaining popularity under the term “ecological citizenship.” So it is all the more frustrating when world leaders can’t seem to keep up. On the second-to-last day of Rio+20, young people organized a “people’s plenary” to make our voices heard and then walked out of the conference center after symbolically ripping up the summit’s final “outcome document.”

Unlike many of the gray-haired negotiators, we can’t afford to let our system continue to fail. We’re coming of age in a time of rising inequality, staggering rates of global unemployment [PDF], severe declines in natural resources, and this fun little thing called climate change that even scientists funded by Big Oil can’t seem to deny. Many of my peers and I have come to see this doom and gloom as an incredible opportunity to change the way the world works.

I’ve seen the green economy lift up communities in my own work with Solar Mosaic in Oakland, Calif. Through our crowdfunding platform for solar projects, we’ve managed to save local nonprofits thousands of dollars on their utility bills while creating green jobs and clean energy. We’ll be scaling up the platform even further soon.

And I’m not the only one who has seen the need to change the way the system works. Reverberating through the Occupy movement that encamped in cities worldwide, the Arab Spring that toppled dictatorships, and now even murmuring from the conference halls of the United Nations, is the idea that economic growth — the topic that sucked up most of the energy and air at the official Earth Summit — hasn’t translated into increased well-being for much of the world.

In fact, while the final Earth Summit agreement contains some rainbows and sunshine about “recognizing the need for broader measures of progress,” the push for a new way of thinking about progress dominated discussions at many of the side events run by environmental and social justice groups. As many of the lecturers pointed out, there was a unique combination of factors that led to the formation of gross domestic product, or GDP, as the global indicator of choice: American hegemony after World War II, a strong focus on economic growth as a means of reconstructing Europe, a perceived abundance of natural resources, and the strong belief that economic growth would lift all boats. Clearly, we now live in a different world.

As the old adage goes, “what gets measured, gets managed,” and our sole focus on the production of goods and services has led us to a system that optimizes economic efficiency at the expense of our social and economic values. This isn’t a new idea. Decades ago Sen. Robert F. Kennedy pointed out that GDP (and its corollary GNP) count numerous destructive activities as economic positives:

The Gross National Product includes air pollution and advertising for cigarettes, and ambulances to clear our highways of carnage. It counts special locks for our doors, and jails for the people who break them. GNP includes the destruction of the redwoods and the death of Lake Superior … GNP measures neither our wit nor our courage, neither our wisdom nor our learning, neither our compassion nor our devotion to our country. It measures everything, in short, except that which makes life worthwhile …

Now, people young and old are beginning to push for a new framework for defining progress. The famous economist Jeffery Sachs gathered crowds at Rio when he gave speeches warning that by failing to account for the things that make us well-off and satisfied, our current metrics of progress will lead us over a cliff. Karma Tshiteem, Bhutan’s National Secretary of Happiness, lectured to hundreds of civil society members on how the tiny Himalayan country’s Gross National Happiness indicator can serve as a model for the world.

Surprisingly, even many corporations are jumping on board, recognizing that their sole focus on the economic bottom line is hurting both their reputations and the long-term sustainability of their business. Though we’ll need to stay vigilant for signs of greenwashing, by far the strongest commitments at Rio+20 came from the business community. Over 200 corporations made sustainability pledges through the U.N. Global Compact, which are time-bound, measurable, and are expected to be held accountable through public disclosure and annual reporting.

A few of the most exciting side commitments include: Microsoft’s pledge to become carbon neutral by the end of 2013, Unilever’s pledge to cut greenhouse gas emissions associated with its products in half by 2020, and Bank of America’s pledge of $50 billion by 2022 for clean energy and energy efficiency initiatives. The Consumer Goods Forum — a group of heavyweights like Coca-Cola, General Mills, Kraft, and others — have pledged to have a zero-deforestation footprint by 2020.

And though the commitments from civil society were clearly more exciting than anything the governments could come up with, there are key suggestions in the final Rio+20 text that young people, and civil society in general, must put pressure on world leaders to strengthen. Among them are strengthening the United Nations Environment Programme, which is currently one of the least funded and weakest U.N. bodies, creating clearly defined Sustainable Development Goals to replace the Millennium Development Goals that expire in 2015, and ensuring that the G20 follow up on their commitment to eliminate fossil fuel subsidies.

Though the negotiations might have failed to set ambitious targets for sustainable development, Rio+20 has given us a sense of our common cause and inspired all of us to work harder to put the correct systems into place to create the future we truly want. This time we’re not turning away in despair. We’re walking away determined to lead where our leaders could not.

Editor’s note: The original version of this story attributed the GNP quote incorrectly to President John F. Kennedy.