Ou Hongyi stopped going to school after watching Al Gore in "An Inconvenient Truth,” the documentary on the looming climate catastrophe, on her 16th birthday.

Her parents, both university lecturers, didn’t approve, but she was determined to try to make a difference — all the more challenging in China, where people trying to make a difference often evoke suspicion. Or worse.

In the two years since, she has waged a lonely, often frustrating campaign to raise awareness of the perils of a warming planet. She has joined international "climate strikes,” planted trees in her hometown in southern China, Guilin, and mounted a flurry of one-woman protests.