the green lantern

Which sex is more eco-friendly?

(Michael Sloan For The Washington Post)
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By Nina Shen Rastogi
Tuesday, November 16, 2010

Lantern, help me settle a bet with my girlfriend. Who's greener, men or women? She says women, because they're not so car-obsessed, but I say guys, because we shop so much less. So who's right?

Sociologists would probably call this one for your lady friend: There's a long history of research that indicates women are the greener sex, at least when it comes to their attitudes and preferences.

Since the 1980s, most studies have found that women are somewhat more likely to express concern about environmental issues than men are, particularly when the issues are local and seem to threaten people's health and safety. A recent analysis of Gallup Poll data from 2001 to 2008 also found that women take climate change more seriously: They were more likely to say that they worried about global warming "a great deal," that they believed it would threaten their way of life during their lifetimes, and that the news media underestimate the seriousness of the problem.

But before my sisters start doing a victory lap, note that women outpaced men by only six to nine percentage points on any given Gallup question. Plus, greater concern doesn't necessarily translate into greater knowledge: Another recent survey found that American men and women were equally (and woefully) misguided about the amount of energy used or saved by various activities.

So women might have greener hearts, but which sex is eco-friendlier in practice? There have been fewer studies on that topic, but they give a slight edge to women, largely based on driving habits.

When Norwegian researchers examined the data from a 10-country survey on environmental behavior, for example, they found that sex didn't have a strong effect on the number of measures a person took to save energy and water or on their recycling habits. Single and married men, however, did drive much more than their female counterparts. (In married households, men may be shuttling their wives around, making those allocations more complicated.)

Swedish researchers recently corroborated these findings by analyzing household expenditures in four European countries - how much each sex spent on everything from gasoline and electricity to food and clothing - and how those expenditures contribute to energy use. They found that single men used more energy than single women in Greece and Sweden, while sex had a statistically insignificant effect in Norway and Germany.

Men used more energy in part because they spent more money overall, but their buying patterns mattered, too. Again, transportation was key. Men consistently used much more energy than women did on vehicles and fuel - 23 to 32 gigajoules more per year. (Total energy consumption ranged from 105 gigajoules for Swedish women to 313 gigajoules for Norwegian men.) In the categories where women outspent men, such as food, hygiene and health, the differences in energy consumption were much smaller. In an expanded report, the researchers calculated that single men in Sweden were each responsible for about 2.2 metric tons more carbon dioxide emissions than their single Swedish sisters. That's about as much as the average American car emits in five months.

The Lantern was curious to see if the same patterns applied to American men and women, so she enlisted the help of Christopher Weber, an adjunct professor of civil and environmental engineering at Carnegie Mellon University who specializes in this kind of economics-based environmental analysis. Weber ran some quick-and-dirty spreadsheet calculations using data from the Bureau of Labor Statistics' most recent Consumer Expenditure Survey and greenhouse gas figures from Carnegie Mellon's 2002 Economic Input-Output Life Cycle Assessment model.

The final result: The average single woman in this country is responsible for 30 metric tons of carbon dioxide equivalent (CO2e); the average single man, 32 tons. (The average American - including children and married adults - generates 23 tons of CO2e, according to earlier estimates by Weber.) As with the European study, the most significant difference between the sexes came in the transport category: When looking just at driving habits, single men have a carbon footprint of 13 metric tons of CO2e, compared with women at 9.4 tons. After that, the most important differences, from a greenhouse gas perspective, were that single women spent more on home utilities and health care, and single men spent more on alcohol, tobacco and education.

As Weber is quick to point out, the differences between American men and women pale in comparison to our similarities. After all, even if American men were at the level of American women, the United States would still have the biggest carbon footprint in the world - by a long shot.

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