A Warning on Warming

The polar ice caps are melting, the ozone layer is shot, the rain forests have been reduced to twigs and shreds. The year is 2050, and the long-term forecast isn't pretty. In After the Warming, a new two-hour PBS documentary (originally broadcast Nov. 21, with repeats all this week; check local listings), British journalist James Burke (Connections, The Day the Universe Changed) issues mankind an environmental warning: Clean up your act or face potential disaster. Set 60 years in the future, Warming looks back at the ''past'' — our present — and speculates on what might happen if the ''greenhouse effect'' is left unchecked. It also offers some possible solutions to the world's imminent ecological meltdown: fossil fuel taxes, new solar energy technologies, and international exchanges of ''carbon credits'' to cut back on toxic emissions. But don't get your hopes too high. ''I personally feel it's going to take a major catastrophe before governments wake up and actually do something,'' Burke predicts. ''Say, three years of severe drought and starvation. That ought to start the ball rolling.''