The causes and consequences of global warming are still debated. But few still dispute its existence. According to NASA, 2005 was the warmest year since the late 1800s. The next four warmest were 2004, 2003, 2002 and 1998. The last time the Earth was this warm, by many estimates, was 100,000 years ago.
Scientists point to disturbing signs: The melting of glaciers and the polar ice caps. The migration of animals, worldwide, to higher, cooler altitudes. The drop in nighttime temperatures across America during the three-day jet grounding following Sept. 11. The deaths of overheated coral reefs. The documentary film "March of the Penguins" spotlighted how global warming makes it more difficult for penguins and their chicks to survive the trek to nursing grounds.
Whether recent changes to the Earth's climate are the result of naturally occurring climatic cycles is pretty much the only question people are still asking. If the shift is as man-made as Australian scientist Tim Flannery argues, we've gotten ourselves into big trouble.
Flannery is the author of "The Weather Makers: How Man Is Changing the Climate and What It Means for Life on Earth," a new book that explores global warming.
Flannery believes world leaders who decline to take immediate action are fiddling while Rome burns.
The over-reliance on fossil fuels by the industrial world's "weather makers," Flannery says, could set off the eradication of 95% of the Earth's species. Flannery blames fossil fuels for 80% of the Earth's warming, and argues that unless oil, coal and gas are replaced quickly -- by green technology such as solar energy and hybrid cars -- hurricanes and floods could wreak havoc on the East Coast.
"This is no part of any known cycle," said Flannery, a burly Australian scientist who is a professor at the University of Adelaide and likes to be photographed in full bush regalia.
"We know how the cyclical climate works. It's related to the way the Earth moves around the sun. Those cyclical changes are highly predictable. They should be driving the Earth into a new cooling phase. Instead they're doing the opposite."
Flannery's views are likely to resonate in California, which has become a battleground over efforts to curb greenhouse gases. Concerns over greenhouse gases prompted the state to implement a pioneering law in 2002 requiring "feasible and cost-effective" emissions curbs. Since then, Maine, Vermont, Massachusetts, Rhode Island, Connecticut, New York, New Jersey, Pennsylvania, Washington and Oregon have adopted similar curbs.
A California bill introduced by Democrats on Monday would make it the toughest state in limiting emissions from such businesses as refineries and power plants in an effort to curb global warming -- a measure that President Bush has resisted.
California is being sued by the Alliance of Automobile Manufacturers, which argues that the state is usurping powers that belong to the federal government. Some car dealers have also joined the suit.
The people who are still resisting calls for action are leaders of industry who have "set out systematically to deceive the public on this matter," Flannery said.
"I hate the term special interests," he said. "Why don't we call them people who want to make money through continuing to pollute the planet? Why dignify them? To me, they lack the imagination to see how rapidly the world is changing."
Flannery's book details his belief that the Earth is now in an artificially induced warming cycle, Flannery says, one that is far less predictable than natural warming, "because this warming's created by greenhouse gases, so we can't use that as a model."
About 150,000 years ago, Flannery says, the Earth was just slightly warmer than it is now -- and sea level was 12 feet higher.
"Imagine the trillions that will be needed to be spent, worldwide, to secure port facilities against rising sea levels," he said. "We're inflicting this on our children and grandchildren because we want to drive big cars and consume lots of energy, and that is the whole truth of it."
The biggest immediate issue, Flannery said, "is the melting of the north polar ice caps."
"We know that ice cap has been stable for at least a million years and more likely 3 million years," he said. "The north polar ice cap won't be there in summer by 2020 and 2100 if it keeps up. Some people say it won't be there in 15 years time. That polar ice cap reflects sunlight back into space. Instead of reflecting the sun's energy, it is now absorbing the sun's energy, and that is heating the planet more. The ice is much thinner, maybe 40% of its thickness 30 to 40 years ago.
"You don't have to be a Rhodes scholar or a Harvard graduate to see that that's a problem," he said.