[This is an EXCERPT: read the whole article A Big Sum of Small Differences, including informative graphics, at the WSJ site. -Ed.]

By Jeffrey Ball

U.S. consumers have direct or indirect control over 65% of the country's greenhouse-gas emissions, according to new statistics tallied by consultant McKinsey & Co. The figure for consumers in the rest of the world is just 43%. Americans, largely because of how they drive and how they build and use their homes and offices, lead some of the most energy-intensive lives in the world.

Passenger cars account for 17% of U.S. emissions -- something consumers could affect by driving more-efficient cars or by driving less. Residential buildings and appliances contribute another 17% of emissions, underscoring the impact consumers could have if they lived in smaller buildings, or added more insulation, or bought a more energy-efficient model next time they replaced their washing machine.

"The landscape is already laid out in the U.S. Most people live in suburban areas," notes Pankaj Bhatia, a director at the World Resources Institute, a Washington environmental group. Slashing automotive and residential emissions, he says, will require prodding manufacturers to build more-efficient cars and houses. "I would just hope that technologies will come to help us through some of these choices."

One way to overcome this cost barrier would be to tax energy consumption more heavily, making energy inefficiency more expensive. Europe has done this for decades, notably by levying heavy taxes on gasoline. High gas taxes give consumers a strong reason to buy more-fuel-efficient vehicles -- and, in turn, give auto makers a strong reason to build them.

Photo credit: Cindy Seigle