As world leaders in Bali strive for agreement on a successor to the Kyoto Protocol, a new study in the U.S. has given the climate-change struggle a domestic perspective.

The escalating number of divorces leads to greater use of energy, researchers say, and governments should take this into account when formulating environmental policies.

Divorce is bad for the environment as it leads to more households with fewer people and greater consumption of water and energy, says a study published in this week’s online edition of the Proceedings of the National Academy of Sciences.

Researchers said housing units require space, construction materials and fuel to heat and cool, regardless of the number of inhabitants.

In the U.S. in 2005, divorced households consumed an extra 73 billion kilowatt hours of electricity and 627 billion gallons of water. Thirty-eight million extra rooms required heating and lighting that same year, costing $6.9 billion in additional utility costs, plus a further $3.6 billion for water, and other costs such as land use.

The study concluded that a married household uses resources more efficiently than a divorced household because people watch the same television, share air conditioning and heat, and use the same refrigerator.