Charles Ferguson’s latest documentary, “Time to Choose,” is a sobering polemic about global warming that balances familiar predictions of planetary doom with a survey of innovations in renewable energy technology that hold out some hope for the future. Unless the carbon-based energy sources on which we have relied are replaced with solar and wind power (the movie doesn’t address nuclear energy), we are ruined.

Filmed on five continents, “Time to Choose” is divided into three chapters: coal and electricity, oil and gas, and land and food. Hopscotching from country to country, it begins in the United States with scenes of mountaintop removal mining in Appalachia and its destructive environmental effects. Much of the film’s power derives from devastating visual juxtapositions. The glamorous skyline of Shanghai at night is contrasted with daytime images of its smoggy harbor, crowded with ships carrying coal to fuel China’s insatiable energy appetite.