In a city park girding the gray Atlantic ocean, dozens of people stood on line before a giant tent, each toting small bags of garbage. They waited patiently, each one eager to add their bit to the work in progress—plastic artist Vik Muniz’s giant montage of the Rio de Janeiro made of recycled trash. Turning waste into art is Muniz’s specialty and a sorely needed skill set for the occasion.

Across town, in a cavernous convention hall, delegates from 192 nations were putting the finishing flourishes—and their bravest faces—on another piece of work, the final statement of Rio+20. But to hear it from green groups, social activists, and even some conference-goers, global leaders had turned Muniz’s idea on its ear, converting a precious and rare international summit into a squandered opportunity.

For the past three days, heads of state and ministers had gathered at the United Nations Conference on Sustainable Development to hash out a global road map for reversing climate change and achieving economic growth for all without trashing the environment. They congratulated themselves on a job well done. “I have not the slightest doubt that the outcome document you have adopted will provide an enduring legacy,” said Sha Zukang, secretary-general of the Rio+20 conference. “During this conference, you, the world’s leaders, renewed your political commitment for sustainable development.”

Others were not so sure. Optimistically dubbed “The Future We Want,” the conference statement read more like “The To-Do List From Hell.” With marine life in peril, global carbon emissions reaching a record 32 billion tons last year, and emerging market powerhouses led by China adding to the fumes, expectations were bright for concrete action. But by the end, world leaders were as conspicuously short on goals, timetables, and commitments as they were high on rhetoric.

In a speech in Rio, U.S. Secretary of State Hillary Clinton called sustainable development “the only viable development” possible in the 21st century. “The only way to deliver lasting progress for everyone is by preserving our resources and protecting our common environment,” she added.

Part of the problem was the gymnastics of striking a balance among 192 nations, ranging from juggernauts to poorhouses. Brazilian wordsmiths who edited the final-document draft reportedly had to hit the delete button repeatedly to accommodate outliers and to keep talks from derailing. That they produced a document at all was already something of a triumph, an effort hailed by Brazilian President Dilma Rousseff as a “victory for multilateralism.”

Brazilian wordsmiths who edited the final document draft reportedly had to hit the delete button repeatedly to accommodate outliers and to keep talks from derailing.

To others it was a pearl of underachievement. No new targets were set for slashing gases such as carbon dioxide and methane that scientists warn are overheating the atmosphere. When developing nations proposed creating a $30 billion fund to back green jobs and environmentally sustainable initiatives, the richest countries played deaf, distracted perhaps by the euro-zone crisis.

Likewise, specific measures for protecting the high seas and endangered reefs and marine fauna ended up on the cutting-room floor, with further discussion deferred to another environmental parley in 2015. “It is frankly astonishing that world leaders all agreed that this is a major problem needing an international, coordinated solution and then deferred any decision on action for another two and a half years.” Susan Lieberman, international policy director for the Pew Environment Group, said in a statement. The International Union for Conservation of Nature reports that one in 10 natural heritage sites around the globe are endangered.

But while many in Rio despaired, others lobbied. Ivonne A-Baki, the secretary of state for Ecuador, worked the corridors in Rio to drum up support for protecting a 1 million–hectare patch of unspoiled rainforest. Yasuni Natonal Park, where the equator meets the Andes, is famed for its fabulous variety of plants and animals. It also sits on 846 million barrels of oil, fully a fifth of Ecuador’s proven reserves, worth an estimated $7.2 billion, a treasure trove for a poor country. But instead of cashing in that wealth, Ecuador declared the Yasuni off-limits to drilling and wants the world to pitch in.

“By leaving the oil in the ground, we avoid releasing 400 million tons of carbon dioxide into the atmosphere,” says Baki. “That’s about as much as France or Brazil emit in a year.” In exchange for leaving the area intact, Ecuador is looking to raise $3.6 billion from international donors to help protect the park. Though Rio+20 failed to pass the vaunted $30 billion green fund, it was the perfect venue to tout the project.

“Sometimes in a big meeting like this, the good intentions stay on paper,” she said. “But we were in Rio to raise awareness. We have to understand that climate change is going to be a lot more expensive for the world than the current economic crisis.”