By Paulo Prada and Valerie Volcovici
RIO DE JANEIRO (Reuters) - Brazilian President Dilma Rousseff welcomed world leaders to a rainy Rio de Janeiro on Wednesday under a cloud of criticism that a three-day summit is falling far short of its promise to establish clear goals for sustainable development.
Before the official start of the event, known as Rio+20 because of the landmark Earth Summit in the city two decades ago, Brazil convinced visiting delegations to finalize a draft declaration for their leaders. But many delegations and summit organizers - as well as outraged environmentalists and activist groups - are lambasting the document as weak.
"Let me be frank: Our efforts have not lived up to the measure of the challenge," Ban Ki-moon, the U.N. secretary-general, said in opening remarks. "Nature does not wait," he added later. "Nature does not negotiate with human beings."
The draft document, finalized on Tuesday, laid out aspirations, rather than mandatory goals, on issues like food security, water and energy. It also called for countries to pursue "sustainable development goals," a vague set of U.N. objectives built around the environment, economic growth and social inclusion.
Many of those who agreed on the draft said it was stripped of vital specifics. "I was disappointed that we did not go further," Nick Clegg, Britain's deputy prime minister, said in prepared comments.
French President Francois Hollande criticized "shortcomings" in the document, especially a failure by U.N. members to fortify its existing environmental program and transform it into a full-fledged agency. He also criticized the omission of a French proposal to help fund development programs through a tax on financial transactions.
Expectations have long been low for the gathering, which is expected to include nearly 100 heads of state and government by the time it concludes on Friday. Overall, 193 state delegations are at the event.
Many leaders are more focused on the global economic slowdown and the debt crisis in Europe. Rousseff herself, visibly tired during her welcome speech, had just returned from a meeting in Mexico of the Group of 20 major economies.
Despite the presence of the French president and the Russian and Chinese prime ministers, several other high-profile leaders are missing, including U.S. President Barack Obama and German Chancellor Angela Merkel.
Compared with the original Earth Summit, which led to historic decisions on biodiversity and greenhouse gas emissions, organizers say this week's summit is only the beginning of a new goal-setting process for global development. The 1992 event, they noted, was the culmination of years of negotiations.
Speakers sought on Wednesday to highlight the issues most pressing for their nations in the global debate over development. While many spoke of their need for sustainable sources of energy, food and water, Iranian President Mahmoud Ahmadinejad pressed rich countries to eschew "materialistic" desires and pursue "spiritual" development.
"The collapse of the current atheistic order is reaching its time," he predicted, citing wars, turmoil in the Middle East, and disasters that shaped the world.
BRAZIL WANT TO SHOWCASE RIO
Rio authorities, gearing up to host the World Cup and Olympics later this decade, have been working to put a friendly face on the gathering. The city's famous Christ the Redeemer statue is illuminated green, its glow shining nightly on traffic jams and motorcades below.
Demonstrators have made their displeasure known.
Outside the summit in the Rio suburbs, environmental and political activists and others marched through steady drizzle and called for bold action.
At a parallel event nearby, an activist interrupted a speech by Clegg. "This is the great nature sale," shouted the demonstrator, wearing a mask with Clegg's likeness.
Earlier this week, bare-breasted feminists marched through the city center, and Amazonian tribesmen, donning war paint and arrows, descended on Brazil's national development bank, which is financing dams and other controversial infrastructure projects in the Amazon rain forest.
Diplomats said Brazil's push for a draft document had forced delegations to focus and come to an agreement, but it may have shut the door on bolder action by leaders when they arrive.
They added that left little leeway for the draft to improve before a final pronouncement on Friday. "Everybody has things that they have given up in the document in one way or the other," said Todd Stern, U.S. special envoy on climate change. "This is the thread that once you start pulling on it, it unravels quickly."
Brazilian officials said the text that was drafted represented "what was possible" among so many different delegations and interests. Noting the protests, Foreign Minister Antonio Patriota said, "If you put 193 (of them) together, they would have difficulty finding a common denominator, too."
Even some environmentalists agreed, stressing that local and domestic initiatives, by governments and the private sector, were more likely to improve the environment than slow-moving global diplomacy.
"The agreement is fine, but global agreements aren't going to solve anything," said Peter Seligmann, chief executive of Conservation International, a U.S. based environmental group. "The solutions will only come through the enlightened self-interest of countries, companies and individuals."
(Additional reporting by Nina Chestney, Jeb Blount, and Rodrigo Viga Gaier; Editing by Todd Benson and Peter Cooney)