On horseback, host Lynn Redgrave gallops at a fierce pace down a steep hill; she reins in her mighty steed and shouts, ”I’m Lynn Redgrave, and I’m one of 5 billion people in the world.” Well, so am I, Lynn; what the heck is your point?

Redgrave’s point is that the human race will be in for big trouble unless we do something about protecting the environment, and One Second Before Sunrise details a number of projects to do just that.

For example, Redgrave goes to the Amazon Basin, where Peruvian agriculturalist Juan Guevara is managing to stave off further destruction of the rain forest and improve the standard of living by introducing the ideas of fish-farming and the purification of river water for drinking. The actress moves on to a ghetto in the Bronx, where Gary Waldron, a former executive at IBM, currently spends his time cultivating gardens and building greenhouses on that barren landscape.

Redgrave globe-hops, locating and celebrating other such noble efforts.

But ultimately, the stories Redgrave has to tell are more depressing than inspiring,because they imply that governments all over the world care so little about major environmental and economic problems that it’s left to a few hardy souls to do something — and their efforts are necessarily limited.

Redgrave is chipper, her questions more pointed and more intelligent than most of what passes for television reporting. But in the end, ”One Second Before Sunrise” is one dismaying little bummer. C