Norton opens nicely by setting up a lawn chair on an empty suburban subdivision street reminiscent of '' E.T." and talks into the camera. An intelligent actor, he narrates a smart script, rich in ''wow" factor, with reserve. He is a blessing, given the potential for bloviation from Hollywood environmental arrivistes like Leonardo DiCaprio.
The show succeeds most when it preaches least. This is a challenge because the opportunities for moralistic hectoring are legion. Its four episodes generally avoid the worst of such screeds and let facts speak for themselves. Also effective are interviews with people about how we will be judged by folks 100 years from now on our efforts to arrest the environmental slide. Guess how we did.
The globalization of trade means the globalization of species. Thanks to airports and ships, the scope of this movement is unprecedented in human history. It is an ecological form of Russian roulette. ''When everything moves everywhere," asks Norton, ''what will survive?"
Species without borders, we are told, mean few species. Two-thirds of today's land mammals may face extinction. And, get this: Our ability to predict what's coming remains ''extraordinarily poor," according to ecologist James Carlton.
Consider: At any given time, 7,000 species of creatures are in motion in the world, some crossing oceans and land masses to areas they don't belong. Ninety-nine percent of marine life by weight in much of San Francisco Bay, for example, comes from somewhere else, as millions of gallons of sea water are unleashed at port when a ship empties its ballast tanks.
The series includes four discrete episodes: ''Invaders," exploring alien species; ''The One Degree Factor," covering the effects of a small increase in global warming; ''Predators," reporting the effects of the loss of land and marine predators on the ecosystems; and ''Troubled Waters," about the inexorable pollution of our waters.
''Invaders" is the most compelling because it's the freshest, and its thesis is most bloodcurdling. Others, like ''Troubled Waters," provide engrossing examples of familiar themes.
