WASHINGTON - Former vice president Al Gore, in an emotional return to Congress Wednesday, declared that the ''planet has a fever" requiring urgent and comprehensive action to reverse global warming, including a freeze on carbon dioxide emission levels and taxing big polluters.

Gore faced strong rebukes from some Republicans who doubt that global warming has become a crisis. But Democrats and many Republicans welcomed him, and some in the GOP agreed that Congress must find ways to counteract the rise of the earth's temperatures.

Sitting next to 12 cardboard boxes filled with petitions and postcards from 516,000 people asking Congress to reduce greenhouse gas emissions, Gore often sounded like a university professor giving a science lecture. And at times he sounded like a revivalist preacher from backcountry Tennessee, arguing that Congress now faces moral choices.

"A day will come when our children and grandchildren will look back and they'll ask one of two questions," he said. "Either they will ask, 'What in God's name were they doing?' ... Or they will say, 'How did they find the uncommon moral courage to rise above politics and redeem the promise of American democracy?' "

He said that the human contribution to global warming constitutes a "planetary emergency."

Several long-term House Republicans, including former speaker J. Dennis Hastert of Illinois, Bob Inglis of South Carolina, and Roscoe Bartlett of Maryland praised Gore for his work on global warming. Bartlett said, "It's possible to be a Republican and not be an idiot" on the issue.

Gore's 10-point plan includes a carbon tax and freeze on carbon dioxide emissions. He also said the United States must be part of a global treaty to dramatically reduce worldwide emissions; place a moratorium on coal-fired U.S. power plants that cannot capture and sequester emissions in the future; build an ''electranet" that allows people to create power from the sun, wind, or other sources and then sell the electricity to the grid; ban incandescent light bulbs; and rapidly increase fuel-efficiency standards for cars and trucks.