Al Gore's climate film may not change what Americans think on climate change; but that doesn't matter, argues Philip Clapp in the Green Room, because Americans are already concerned - and politicians are following the public's lead.
Al Gore's new global warming movie has been a blockbuster in the United States. At this point, it stands third in box office history among documentaries.
Even Madonna had to yield to Al Gore in the US documentary charts
Gore's film, An Inconvenient Truth, has even beat out Madonna's Truth or Dare; an estimated 2.3 million Americans have seen it.
Unfortunately, that is still less than 1% of the US population.
Many of these movie-goers are probably already in Gore's camp. A significant number undoubtedly bought their tickets more to scratch six years of Bush-induced liberal political itch than to learn anything about global warming.
With audience numbers like these, the former vice president's gripping and beautifully produced video lecture isn't going to cause a tidal shift in American public opinion on global warming in the short run.
In reality, it doesn't need to.
A fog of misinformation is still being generated in the US by an increasingly desperate network of industry-funded think-tanks (a category that includes the Bush White House) and a handful of right-wing ideologues.
Despite the efforts of this shrinking band, the average American already believes pretty much what the rest of the world does about global warming: human-produced pollution is causing it, the potential consequences look more and more devastating, and our governments should act - and act now.
US polls have registered this solidifying consensus for at least five years. The remaining doubts of many Americans were wiped out, along with New Orleans, by Hurricane Katrina.
Even if his impact on the general public is slim, Gore is having an impact where it counts much more - in the media and among politicians, many of whom have been well behind the public on global warming.
He has helped put the issue on the front pages of America's newspapers once again.
Equally important, he has made global warming an inescapable part of the political debate as America prepares to choose new leadership and a new agenda for the post-Bush era.
In many ways, that era has already begun, even though the president has more than two years left in office. This is particularly true on global warming.
Members of the Republican Party in Congress, recognising that international and domestic action is inevitable, are already quietly abandoning the President. They are authoring and supporting legislation to set limits on US emissions.
In June 2005, the Republican-controlled Senate passed a resolution calling for precisely the kind of mandatory global warming emissions reduction law the President so adamantly opposes.
Some senators want the US to move back into the Kyoto fold
Congress has also repeatedly passed resolutions calling on the Bush administration to return to the international negotiating table.
The pressure is now so intense that the White House appears to be planning to make renewable energy development and global warming a centerpiece of its agenda in the president's final two years. Significant new proposals are likely to be unveiled in a major presidential address to Congress in January.
Administration insiders are calling the developing proposals Bush's "Nixon goes to China" moment, after Nixon's startling 1972 reversal of the longtime US refusal to deal with Mao.
Whatever Bush puts forward will probably be weak, but that it is immaterial; the substance of what the president proposes on global warming is likely to have little credibility, given his history on the issue.
But the very fact that Bush would finally reverse his position and call for action will liberate many Republicans to vote for meaningful pollution cuts.
Race to succeed
Equally important, looking forward to the race to succeed Bush in 2008, every serious potential Republican nominee has already abandoned the president's intransigent position.
The most prominent of them, Senator John McCain from Arizona, is actually the Senate's leading crusader on the need for the US to adopt a domestic emissions reduction system. McCain introduced the first such bill several years ago, and has forced Senate votes on it repeatedly, achieving near-majorities.
Gore's own handlers in his 2000 presidential bid found it inconvenient, too, as they sought to shore up labour support in the same states
Al Gore's biggest contribution may be that his movie forces key parts of his own Democratic Party, including some reluctant potential presidential candidates, finally to give more than lip service to the issue.
In Congress, a handful of Democrats from coal and auto-producing states, responding to pressure from those industries' labour unions, has been one of the principal roadblocks to action.
Virtually all of these Democrats - sitting senators and potential presidents - know in their heads and hearts that strong action on global warming is urgent. They are the ones for whom global warming is truly an inconvenient truth - politically inconvenient.
Gore's own handlers in his 2000 presidential bid found it inconvenient, too, as they sought to shore up labour support in the same states. The issue never surfaced seriously in the then-vice president's campaign against George W Bush.
Gore has assured that it cannot be avoided by anyone in 2008, convenient or not.
Philip Clapp is President of the National Environmental Trust in Washington DC
The Green Room is a series of opinion articles on environmental issues running weekly on the BBC News website