PRINCE.EDWARD.ISLAND (CBC) - Nobel Prize-winner Al Gore issued an audacious challenge to the United States on Thursday, calling on the nation to produce every kilowatt of electricity through wind, sun and other Earth-friendly energy sources within 10 years.

The former vice-president also said fellow Democrat Barack Obama and Republican rival John McCain, who will run for president, are "way ahead" of most politicians in the fight against global climate change.

Rising fuel costs, climate change and the national security threats posed by U.S. dependence on foreign oil are conspiring to create "a new political environment" that will sustain bold and expensive steps to wean the nation off fossil fuels, Gore said.

"The survival of the United States of America as we know it is at risk," he told an energy conference in Washington. "The future of human civilization is at stake."

Gore also warned the continued rise of greenhouse gas emissions posed "dangerous national security implications" for the U.S., citing studies predicting what he said would be "hundreds of millions" of climate-change refugees in the wake of their homelands being rendered uninhabitable.

He pointed to such bold programs as the Marshall plan to rebuild post-Second World War Europe and the U.S. social security system as examples of some of the nation's greatest achievements that were successful long after being proposed.

"A political promise to do something 40 years from now is universally ignored because everyone knows that's meaningless," he said. "Ten years is about the maximum time that we as a nation can hold a steady aim and hit the target."

Investment 'will pay itself back many times over'

Called an alarmist by conservatives and skeptics, Gore has made global warming his signature issue. He portrayed Thursday's speech as the latest and most important phase in his effort to build public opinion in favour of alternative fuels.

He said the single most important policy change would be placing a carbon tax on burning oil and coal.

The Alliance for Climate Protection, a bipartisan group he leads, estimates the cost of transforming the U.S. to clean electricity sources at $1.5 trillion to $3 trillion over 30 years in public and private money. But he says it would cost about as much to build greenhouse gas-polluting coal plants to satisfy current demand.

"This is an investment that will pay itself back many times over," Gore said. "It's an expensive investment, but not compared to the rising cost of continuing to invest in fossil fuels."

Gore narrowly lost the presidential race in 2000 to George W. Bush after a campaign in which his prescient views on climate change took a back seat to other issues. In the 2008 presidential race, both the Republican and Democrat candidates support action to curb the gases blamed for global warming.

With files from the Associated Press

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