Big business is now free to blitz the airwaves to attack politicians who support action against climate change, which could smother messages from environmentalists.

But it is not yet clear whether corporations have the will or the budgets to use the advertising weapon the climate change wars that emerged in January when the U.S. Supreme Court ruled that corporations have the same right as individuals to free political speech, including spending on advertising.

The decision could affect every issue and every political race in this congressional election year, but those pushing for a federal law to limit greenhouse gas emissions say it will hit them harder because business interests have much more money to spend on these campaigns.

Environmental voices are already far outspent by voices of all sorts of polluting interests, but the Supreme Court decision has really now opened the floodgates for big oil and dirty coal to spend ... much, much more money in the electoral arena, said Gene Karpinski, president of the League of Conservation Voters.

Green groups -- including even the powerful Service Employees International Union, which has pushed for cap-and-trade measures as a spur to clean-energy jobs -- are at a disadvantage.

What will happen now is corporate CEOs will be able to freely raid their corporate till and spend their shareholders' money to advance this political agenda ... to give an even larger voice to corporations and their profit margins, said Lori Lodes of the employees union.

Legislation to battle global warming is stalled in the U.S. Senate and there is growing pessimism that a law can be passed before November's elections. A defeat of pro-green candidates could doom the initiative for some time.

Another factor working against those seeking a global warming law is the shrinking of traditional media, according to Bob Deans of the Natural Resources Defense Council.

Environmental groups used to be able to get free media coverage by pitching stories to reporters. Now many journalists who wrote about those issues are gone, and the space available for coverage of the environment is shrinking.

When you combine that with this ruling ... it just makes it harder and harder for the real interest of the public to be expressed in that way, Deans said.

TAKING AIM AT CANDIDATES?

The Supreme Court ruling makes it possible for businesses, unions and interest groups to take aim at political candidates because of their stance on a specific issue.

It is impossible to predict spending on candidate-specific climate change ads, but energy interests spent about 10 times as much as environmental interests in the last election year, according to the non-partisan Center for Responsive Politics.

In 2008, corporations in the broad energy sector made $77.7 million in political contributions, with $35.5 million coming from the oil and gas industries. Republican candidates, most of whom oppose carbon-capping legislation, received 66 percent of the total.

By contrast, environmental groups spent $5.5 million on political contributions in 2008, with 87 percent of that going to Democrats.

In addition, the Service Employees International Union contributed $2.7 million, with 95 percent given to Democrats. The union and environmental groups together donated $8.2 million, a bit more than one-tenth the energy sector's tally.

But this is more than a simple financial contest. One energy lobbyist noted that many big corporations, including energy firms and automakers, have joined the push for a bill to cap greenhouse emissions and trade allowances for them.

Nobody wants to not be green, said Josh Zeib, a lawyer and lobbyist with the firm Bracewell and Giuliani, which handles energy industry clients.

Nobody wants to wander out alienating the public and legislators and making things worse, and that risk is out there for companies who move too aggressively in political advertising, Zeib said in a telephone interview.

This year, neither he nor other corporate sources saw a big influx of advertising money targeting climate change.

One oil industry source who spoke on condition of anonymity said the impact of the Supreme Court's decision would be minimal.

At this time we don't plan on using corporate funds for this purpose, the source said. Everybody's tightening their belts and looking where they can be economical in their spending. (Editing by Russell Blinch and Chris Wilson)

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