Indigenous people attend a protest against the Belo Monte dam during the People's Summit at Rio+20 for Social and Environmental Justice in Rio de Janeiro. REUTERS

Rio de Janeiro is known for its terrible traffic, but on Wednesday during the official start of the Rio+20 Summit, the United Nations Conference on Sustainable Development, an array of protesters from Amazonian tribesmen to topless feminists filled the streets creating green gridlock -- a traffic jam to save the planet.

Among those in Rio in search of a soap box was Davi Kipenawa Yanomami, the so-called Dalai Lama of the rain forest. Davi is a shaman and spokesperson for the Yanomami tribe who has led a long-running international campaign to secure indigenous land rights.

His quest gained him recognition in Brazil and around the world, and now he is attending Rio+20 to help save another tribe: the Awa.

Awa: Earth's Most Threatened Tribe

London-based indigenous rights group Survival International launched a major international campaign to help save the Awa in April, calling them earth's most threatened tribe. Oscar-winning actor Colin Firth used his star power to highlight the campaign, narrating a short film urging supporters to act now.

The Awa's forest is being illegally cut for timber, Firth said in his appeal. When the loggers see them, they kill them ... At any other time in history, that's where it would end: another people wiped off the face of the earth forever. But we're going to make sure the world doesn't let that happen.

Moving as the appeal may be, Brazilian farm groups have little impetus to protect the indigenous population when the land is ideal for producing soy, beef and other agricultural products that have helped fuel rising fortunes and a growing middle class.

Sen. Katia Abreu, president of Brazil's National Agriculture and Livestock Federation, wrote in a recent opinion article for the newspaper Folha de S. Paulo, that the tribes of the Amazon don't need more physical space, but sanitation, education and an efficient health system.

Who benefits from this? Not our country, which today enjoys the best and cheapest food in the world and boasts of being the globe's second-largest food exporter.

Already, the Senator argues, 11 percent of Brazilian territory and 22 percent of the Amazon have been handed over to indigenous groups, though they represent less than one percent of Brazil's 192 million people.

But according to Survival International, the situation has reached crisis point for groups like the Awa, one of the world's last remaining nomadic hunter-gatherer tribes. Some 30 percent of the partially-contacted community's legally-protected reserves in the Brazilian state of Maranhão have been destroyed. The tribal rights organization claims the Awa's forests are disappearing faster than any other indigenous area in Brazil.

They're surrounded, Survival's research director, Fiona Watson, said. They are now occupying an island in a sea of deforestation.

Beyond the Awa: The People's Summit

At Rio+20, Davi will meet with several politicians and policy-makers to urge them to ask the Brazilian President when she will take action.

How much longer will the government wait before it acts to evict the illegal settlers, ranchers, and loggers, Davi said Tuesday.

Brazil, for its part, has made progress in tackling the issue of illegal logging. The country's National Institute for Space Research estimates 2,410 square miles were lost between 2010 and 2011, down from a peak of 10,695 square miles in 2004.

But how much can federal agencies responsible for protecting indigenous land in Brazil do with limited powers, limited means, and an area larger then Sweden to patrol? That's the heart of the debate in Rio.

If we learned anything from the Earth Summit of 1992, it's that well-meaning promises are worthless when not backed up by concrete action, Survival's director Stephen Corry said. Brazilian authorities must be held to their word: If the Awa's land isn't protected, they won't be around in another 20 years' time.

But the Awa are hardly alone in the fight. Watchdog groups say more conflict is inevitable as new hydroelectric projects and roads draw thousands of settlers deeper into the Amazon. Two bills now working their way through Brazil's Congress could open up indigenous territory to even further development.

The appeal for protection of land rights and compensation for ecological services are only briefly mentioned in the official negotiating text of the Rio+20 Summit, but the issue is at the forefront of the People's Summit, an event that has attracted thousands of environmentalists, unions and indigenous tribes and is running parallel to the Rio+20 meeting.

Some 400 representatives of 20 indigenous groups in Brazil joined forces with a variety of ecological groups and social movements from around the world to denounce the green economy concept being debated by 115 world leaders at the official June 20-22 meeting.

As indigenous groups made their voices heard, the challenge was underscored by simultaneous protests over the weekend in a far corner of Brazil. Hundreds of indigenous people occupied the site of the future Belo Monte Dam -- a project that will displace up to 20,000 people and flood as much as 230 square miles of rainforest. Belo Monte, on schedule to become the world's third-largest dam, is one of roughly 60 hydroelectric projects Brazil has planned for the Amazon.

Be it logging, damming, or agriculture, the problems that face Brazil's indigenous populations are many, but Survival's Fiona Watson said people like Davi are proof that global activism can make a difference in the fate of tribes.

During the 1980s, the Yanomami suffered immensely when up to 40,000 Brazilian gold-miners invaded their land, she said. The miners shot them, destroyed many villages and exposed them to diseases to which they had no immunity. Twenty percent of the Yanomami died in just seven years.

After a long international campaign led by Davi, Survival and the CCPY (Pro Yanomami Commission), Yanomami land in Brazil was finally demarcated as the Yanomami Park in 1992 and the miners expelled. During the landmark trial that followed, five miners were charged with genocide. Today, Yanomami land is the largest indigenous territory in Brazil.

Some people might think: 'Isn't it too late?' But it's not, Watson said. The Brazilian government has the authority and legal obligation [to act]. They can do it if they have enough political will and enough pressure.