LOS ANGELES — As environmentalists celebrate the 50th anniversary of Earth Day this week, a new documentary poses a sobering question.What if wind farms, solar panels and other green energy projects are not enough to save the planet and humanity simply cannot sustain life as we know it?“Planet of the Humans,” executive produced by Oscar-winning filmmaker Michael Moore and written and directed by Jeff Gibbs, asks hard questions about what it sees as the failure of well-meaning efforts to halt climate change.“It seems like we have been losing the battle,” Moore told Reuters. “We are in deep, deep trouble.”“Planet of the Humans,” which will be released on YouTube on Tuesday free of charge to the public, argues that the mainstream environmental