Have you noticed that houses are getting bigger, with more bathrooms, and more, bigger cars out front, and fewer people in them? Of course you have. I grew up (back in the Pleistocene) in a family of eight that had a single car for most of my childhood, and two to three kids per room — and one TV!
What’s going on here? Obviously, there are many reasons for these changes. But a new paper by Yu and Liu published in the Proceedings of the National Academy of Sciences, discovers an intriguing connection: the increasing divorce rate is reducing average household size (i.e., the number of people living in a house) and increasing the number of houses. As a result, a whole range of measures of energy and materials-use efficiency are declining.
And this is not a peculiarly American thing, it’s happening worldwide.
Using international census data, the authors first quantified the trend that conventional wisdom has recognized for some time, that divorce rates worldwide have been rising steadily in recent decades (see graph at left). Based on the simple observation that divorce splits households, and therefore both increases the number of households and reduces the average number of people living in them, they then asked how divorce influences per capita impact on the environment, specifically in terms of housing.
First they found that, between 1998 and 2002, in the 12 countries studied, divorce was estimated to result in the addition of 7.4 million households above what would have existed in the absence of divorce. This adds to society’s environmental footprint because any house (or apartment, etc.) requires a certain amount of resources to construct, and takes up a certain amount of space, fuel, and so on to maintain regardless of how many people are in it. For example, it costs the same to heat your house in winter whether there are two or ten people living in it. Every housing unit has to have a refrigerator, a shower, a plasma TV (well, maybe not that) whether it’s just you or the whole family. You get the picture.
So when the consequences of divorce for increased housing construction, utlility use and so on were tallied up, the authors found several striking results (see graphs at right). First, the number of rooms per person in divorced households was 33-95% greater than in married households. For example, in the USA in 2005, 38 million additional rooms were required to house separately family members separated by divorce. This resulted in addditional costs for heating, lighting and so forth. The divorced households also used an additional 73 billion kilowatt-hours of electricity and 627 billion gallons of water above what would have been used had the marriages remained intact.
Now, many other changes have been happening in society over recent decades that might influence these trends. So, as an additional check on their findings, Yu and Liu were able to obtain data on that subset of divorced people that remarried. When the remarried households were compared with their previously divorced incarnations, the environmental impacts fell back to those of households that had remained married all along. In a nutshell, divorced households in the USA used 42-61% more resources per person than they did before the break-up.
So what’s the message? I’m not touching the social implications of this one. If a marriage goes bad, it’s hard to imagine that environmental impact would carry much weight in attempting to save it. But these data do provide a sobering illustration of the impact left by our changing lifestyles.
Perhaps this opens a new door to engaging social conservatives in the cause of environmental conservation (indeed it’s already being used as ammo by Christian conservatives, ironically enough since most such commentators have little interest or sympathy for other, less politically strategic news about the environment). On the other hand, I’m also reminded of the cheeky bumper stickers from the old days saying “Save water — shower with a friend!” In other words, shacking up (or whatever it’s called these days) should, by the same token, reduce environmental impact. So, in terms of social policy, it’s a two-edged sword . . .