People who have tried to reduce their carbon footprint can relate to the tough choices now facing Congress and the Environmental Protection Agency as they decide how to cut greenhouses gases for a whole nation.
Hearings on climate-change bills open this week on Capitol Hill. And last week the EPA declared CO2 to be a health danger which, under the Clean Air Act, could require rigorous regulation of almost any source.
Whether by law or regulation, will government be able to spread the burden of tackling global warming equitably – from coal-fired plants to autos to henhouses? Or, regionally, from the West to the Midwest to the East?
If energy and car prices must rise for everyone to pay for new technologies, which Americans deserve a rebate based on their income?
And what happens if other nations don't follow the US in making a similar sacrifice to fight off climate change?
These aren't just political or economic questions. They are in the realm of life-boat ethics to save the planet.
No one probably knows all this better than EPA chief Lisa Jackson. She pushed for the EPA ruling on greenhouse gases but then admits she prefers Congress to pass a law dealing with the major issues.
Her ambivalence on now regulating these effluents reflects a natural reluctance not to be the target of public anger as energy prices rise while the benefit of cooling the planet remains decades away. After all, recent polls show the economy now outranks the environment in people's concerns.
Nor does she want to face lawsuits from environmentalists who might demand that the EPA curb emissions even from small sources, such as office buildings or cattle farms.
In 1976, the EPA lost a bid to avoid regulating diverse sources of lead emissions in a lawsuit brought by the Natural Resources Defense Council. Groups like the NRDC profess they prefer regulating only big sources like coal plants for now. But they could easily insist on curbing emissions from backyard barbecues and other small sources later.
"CO2 is CO2" no matter its source, a Sierra Club lawyer told Congress last year.
Even if the EPA tries to limit its authority to emitters that produce more than 250 tons of carbon dioxide a year, that would target about 1.2 million businesses.
The EPA would also need to decide whether to regulate carbon emissions only where they enter the atmosphere and ignore companies that bring carbon into the economy. Should EPA order only a belching coal power plant to cease and desist without going after the coal mine? Does it go after dairy farmers as well as hay growers? Why regulate one but not the other? They all peddle carbon.
And then there's the debate over whether the US should reduce its carbon emissions to preindustrial levels to really take on global warming – even if carbon pollution from China and India still floats over the US.
It is easy, of course, to let the perfect become the enemy of the good and to become paralyzed as a nation into doing nothing or not enough.
Ms. Jackson is probably right to prevaricate. For too long, environmentalists have raised the scare level about global warming while not preparing the public about the costs, the necessary burden sharing, and the ethical dilemmas.
With either the EPA or Congress likely to act on this issue by year's end, Americans need to be more engaged on what size and shape of carbon footprint they want for their nation.