The 20-year-old video predated YouTube, yet it has since gone viral, with 20-million views. Its picture is grainy but the words are crystal clear.

"We've come 5,000 miles to tell you adults you must change your ways." A 12-year-old Canadian girl stands before world leaders, expressing the fears and despair of a young generation facing a bleak future for the planet they will inherit.

All listened raptly. Some wept at the starkness of her appeal.

She became known as "the girl who silenced the world for five minutes."

It was 1992, and representatives of world governments were gathered in Rio de Janeiro, Brazil, for the first United Nations Conference on the Environment and Development -- the Earth Summit. The girl was Severn Cullis-Suzuki, daughter of environmentalist David Suzuki. Two decades later, Cullis-Suzuki, with a child of her own, cares even more passionately about the issues now.

As the world prepares for another Earth Summit in Rio, we spoke with her about her recollections of that seminal conference and what in her opinion has -- and has not -- changed in the years since. Cullis-Suzuki remembers the Earth Summit coming at a time of high environmental concern. Two weeks were allotted for the talks. The heads of state from 108 countries attended, including U.S. President George Bush Sr. and Canadian Prime Minister Brian Mulroney. Almost 10,000 journalists were on hand.

Back then, Cullis-Suzuki recalls, addressing the depletion of the ozone layer was high on the environmental agenda, as was a growing awareness of a new environmental issue called climate change. A big concern was bringing on side the developing countries who were worried that being forced to comply with environmental measures would hinder their efforts to develop.

The end of the summit saw the signing of legally-binding agreements, including the UN Convention on Biological Diversity and the Framework Convention on Climate Change, which would pave the way for the Kyoto Protocol. The nations of the world agreed to a global action plan for sustainable development: Agenda 21.

The world emerged from Rio with a sense of hope and promise. "I look back at those documents that came out of Rio, and they were pretty amazing," Cullis-Suzuki says. "Great promises were made at Rio, then it kind of fell off people's agenda."

The hope and promise were short-lived. Cullis-Suzuki recalls that, in the years following the Earth Summit, the global economy slipped into recession and economic constraints meant the environment was no longer a priority.

Cullis-Suzuki notes the parallels to today, as economic woes again displace the environment as a top concern for world leaders. She cites the fact the 2012 Earth Summit will last only three days. President Barack Obama will not be there, and Prime Minister Stephen Harper has not indicated if he will attend. Climate change has risen to a preeminent concern.

"We're in a new reality, living in a time of climate change. We already have climate refugees around the globe and now have to talk about adaptation and mitigation," says Cullis-Suzuki, who holds a Bachelor of Science degree in ecology and evolutionary biology, and a Master of Science degree specializing in ethnoecology.

In an ironic reversal, smaller developing countries like the island nations Grenada and the Maldives, who are already feeling the effects of climate change, are the ones begging industrial nations to address climate change.

However, this time there will be no agreements that legally bind countries to meet environmental targets. Instead countries will be asked to work voluntarily towards targets they set for themselves. Cullis-Suzuki is now coaching young Canadians to represent the interests of the next generation as delegates at Rio 2012. We asked her, if she were to stand before the Rio Summit 20 years after she first held the world's leaders rapt, what would she say now?

"I'm hearing from a lot of people that the same speech I gave then could be given again today. That is a sobering thought," she told us.

"Sometimes it's hard not to feel really negative. I think I would ask why we have not succeeded? Why are we not further along?"

The answer may come from her father. In a recent blog, David Suzuki declared environmentalism a failure. Creating environment ministries and holding environment-focused conferences, he argued, made the environment just "another special interest" like agriculture or education. It was something separate from the economy and so fell to the wayside when recessions struck.

Ironically, Rio's goal in 1992 was to integrate environmental awareness into global development. As Suzuki put it, "The event was meant to signal that economic activity could not proceed without considering ecological consequences."

Twenty years later, world leaders once again need a child to stand up and remind them that, for the next generation, the environment is not a special interest, it's the future.

Craig and Marc Kielburger are authors of the new book Living Me to We: The Guide for Socially Conscious Canadians.

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