U.S. Secretary of State Hillary Rodham Clinton called for pragmatic steps to solve global environmental problems and promote sustainable development on Friday, urging leaders attending the Rio+20 summit to partner with private-sector groups to make progress on a wide range of issues.

Clinton's address came during the final day of the development summit, the largest meeting the United Nations has yet organized. The gathering has come under withering criticism from activists for what they say is the unambitious final document all nations agreed upon to put the globe on a sustainable path, promoting economic growth that doesn't devour natural resources.

"In the 21st century, the only viable development is sustainable development. The only way to deliver lasting progress for everyone is by preserving our resources and protecting our common environment," Clinton said during a speech before delegates from 192 other nations.

She added later in the speech: "We know that we will be judged not by what we say nor even by what we intend to do, but by whether we deliver results for people alive today, and whether we keep faith with future generations."

Upward of 50,000 people participated in the Rio+20 event. Beyond official government delegations, there were thousands of people from every sector imaginable, from Latin American indigenous groups to Asian women rights' proponents to corporations teaming up with celebrities to tout their environmentally friendly proposals.

Additionally, Rio hosted a parallel "People's Summit" of non-governmental organizations and others who called for more radical and progressive action on the environment and development issues.

Despite the numbers, there was little energy around this year's summit. Going in, expectations were extremely low for any major advances, to the point that delegates' ability to agree on what critics called a watered-down final document that mostly reaffirmed what was agreed to in 1992 was viewed as a successful outcome by governments.

Activists were not impressed.

"Rio will go down as the hoax summit. They came, they talked, but they failed to act," said Barbara Stocking, chief executive of Oxfam. "We elect governments to tackle the issues that we can't tackle alone. But they are not providing the leadership the world desperately needs."

Jim Leape, director of WWF, said that the "formal negotiations were by any measure a huge disappointment."

"Governments didn't find a way to come together. There is a lot in the text about `acknowledging problems' and `encouraging countries to act,' but very little commitments. That falls way short of what is needed," he said.

Brazil's Environment Minister Izabella Teixeira defended the work of governments and like many officials said that any multilateral process involving 193 nations is going to be a grinding negotiation that will leave most parties equally unsatisfied.

"The ending document doesn't meet all of Brazil's ambitions ... but I'm certain that it's the best agreement we could come to," she said.

During her brief stop in Rio, Clinton on Friday announced some U.S. initiatives, including an agreement to partner with more than 400 companies to support their efforts to eliminate deforestation from their supply chains by 2020, and $20 million in government grants to jumpstart clean energy projects in Africa and support private investment.