Goodall, who rose to fame in the 1960s through her ground-breaking study of chimpanzees in East Africa, now spends 300 days a year on the road using her personal story and rock star status among young people to inspire them to act on critical issues in their communities.

She said her goal has been to build a critical mass of young activists to carry on her life's work for a more humane world, acting through youth organizations such as her own Roots & Shoots which started on her front porch in Tanzania in 1991.

"I was determined not to die until Roots & Shoots could survive. Now I know it will. It's got its own life without me," Goodall said.

The 100 young people at the summit in Orlando, Florida, came from 28 countries, and all were selected personally by Goodall based on their work in their communities.

Among them, Chih-Chung Lin, 21, advocates for the use of reusable chopsticks by restaurants in Taiwan where around 2.8 million disposable wooden utensils are discarded each day.

Another, Weldon Korir, 23, founded a youth group in Kenya for HIV and malaria prevention. And Manoj Gautam, 22, runs what he calls a restaurant for vultures in a pasture in Nepal where birds, who have been dying in large numbers from tainted food, can feed on clean carcasses.

Karoline McMullen, 17, of the United States, who published a textbook on the threatened native Ohio brook trout, said she had been inspired by listening to the stories and seeing the determination of her peers from around the world.

"It makes me hopeful for what I can do and reassures me that it's possible do what seems impossible," she said.

Speaking at the summit, Henri Landwirth, 81, a Holocaust survivor and long-time philanthropist behind such foundations as Give Kids the World, reminded the young people that his work and the work of his generation was nearly over.

"I am one of a dying generation. You youth have to do it," he said.