Twenty-seven years ago, US teacher Ronald Sakolsky saw a Chinese woman on TV planting trees in the desert. He sent her $5,000 to buy saplings – and that changed both their lives.

Now, he's returning to China to reunite with Yin Yuzhen, whose fight against desertification he helped support from half a world away. The trees she planted have grown into a forest. And Sakolsky says the journey still feels like a dream.

"It's literally becoming a reality," he says. "It's been like a dream for the last three months."

When he sees Yin again, he knows he'll cry. "I'll give her a big hug, and then I'll cry."

His time in China changed him forever. "I am Lao Nei, not Lao Wai," Sakolsky says. "China will always be a part of me. I became a better person because of my life in China."