Global warming may be the biggest topic that neither President Barack Obama nor GOP presidential candidate Mitt Romney wants to touch.
Obama devoted all of four sentences to climate change in his speech at the Democratic National Convention last month. Romney rarely mentions it at all.
It's a stark change from the 2008 presidential race, when both Obama and his Republican opponent, John McCain, preached the need to reduce greenhouse gases. And environmentalists are furious the issue is largely ignored.
"The silence of Governor Romney and President Obama on climate change is deafening," said Erich Pica, president of the environmental group Friends of the Earth Action.
His organization has launched a campaign called Climate Silence to inject global warming into the presidential race, working with another group called Forecast the Facts. The campaign's website features photos of Obama and Romney with duct tape over their mouths.
"Voters deserve to know where they stand on the most serious threat to our nation," Pica said in a news release. "Anyone who is elected to lead the country -- or aspires to do so -- should realize that true leadership means a willingness to engage difficult issues, not sweep them under the rug."
Nine environmental groups circulated petitions asking journalist Jim Lehrer, the moderator of last week's debate, to press the candidates on global warming. About 160,000 people signed, but Lehrer didn't mention climate change, or energy.
"It's often true that political speech lags behind public understanding," said Steve Cochran, vice president of climate policy at the Environmental Defense Fund, which participated in the letter-writing campaign. "The population is ahead of the politicians on this."
Each candidate, analysts say, has reasons to avoid discussion of the issue.
Among Republicans, skepticism about climate change has hardened into outright rejection. They tend to view efforts to cap the greenhouse gas emissions that come from burning fossil fuels as heavy-handed government interference in the free market, if not a threat to personal liberty. After the solar firm Solyndra's bankruptcy, they deride government support for clean-energy companies.
A poll conducted last month by Bloomberg found that only 26 percent of Republicans believe human activity is warming the planet. Contrast that with 78 percent of Democrats and 56 percent of independents.
"The GOP is as stony a ground for that issue as you can find today," said Jerry Taylor, a senior fellow at the Cato Institute libertarian think tank and a frequent critic of federal environmental policy.
As governor of Massachusetts, Romney explored ways to fight global warming. But he eventually backed out of a multistate plan to limit greenhouse gas levels through the use of a cap-and-trade system, in which power plants buy and sell permits to emit those gases.
Now Romney says he is uncertain about the extent of warming and people's role in it, and he supports more research into the issue. He does not back climate change policies that could boost energy prices.
"What I'm not willing to do is spend trillions of dollars on something I don't know the answer to," Romney said last year at a campaign appearance in New Hampshire.
For Obama, the political calculus of global warming is far more complex than it is for his challenger.
Obama placed climate change at the heart of his 2008 campaign. His economic stimulus package in 2009 steered billions of dollars to companies building solar power plants or wind farms that generate electricity without greenhouse gases. And he set new car mileage standards that will double fuel economy to 54.5 miles per gallon by 2025, slashing oil use.
But he let die in Congress a bill to create a federal cap-and-trade system in 2010, bitterly disappointing many environmentalists. Now he may be worried about alienating independent voters, whose concern about climate change isn't as strong as it is among Democrats.
His official campaign website still calls for fighting climate change and touts the rapid growth of renewable power on his watch. But it doesn't mention cap and trade or setting hard limits on the country's production of greenhouse gases.
"Obama probably feels that with bringing up the issue, there are potential losses and not too many gains," said Lester Brown, president of the Earth Policy Institute. "A real response (to global warming) would include a lot of substantial changes -- in the forms of energy we use and the way we use it -- and that makes people uncomfortable."
- David R. Baker, San Francisco Chronicle