Minimizing energy waste is a good place to start, said Thomas Dietz, professor of sociology and environmental science at Michigan State University (MSU). For instance, activities like routine vehicle maintenance and opting for the clothesline instead of the dryer could cut total US carbon emissions by five percent in just five years and 7.4 per cent in 10 years, Dietz said.

That's the equivalent of France's total carbon output, or total emissions by the US petroleum refining, steel and aluminium industries. Household energy consumption accounts for 38 per cent of carbon emissions in the US and eight percent of world emissions, he said. "On the research end of things, we've invested mostly in engineering approaches -- building better technology," said Dietz. "But the best technology we can devise doesn't do any good if people don't use it. We can make great progress with the technologies we already have if we pay attention to behaviour -- how people use the technologies they already have."

Dietz and collaborators didn't base their estimates on a best-case consumer behaviour scenario. Instead, they used the best available information to calculate how many families could reasonably be expected to take such measures if they were provided information, offered financial assistance and could interact with others doing so, an MSU release said.

They excluded potential emission cuts from emerging technologies and from wholesale lifestyle changes, so their estimates are at the low end of potential greenhouse gas reductions, Dietz said.  These results were published in this week's Proceedings of the National Academy of Sciences.