Contraception would be the cheapest and most effective way to reduce carbon emissions worldwide between 2010 and 2050, according to a study by the London School of Economics.
The report, "Fewer Emitters, Lower Emissions, Less Cost," (PDF) determined that if contraception was made widely available between 2010 and 2050 to women and men around the world who wished to use it, the reduction in unwanted births could result in saving 34 gigatonnes (one billion tonnes) of carbon emissions. That's roughly 60 years worth of U.K. emissions or 6 years worth of U.S. emissions.
The cost for supplying, and distributing contraception over those 40 years would cost an estimated $220 billion, or $7 for each tonne of carbon emissions avoided. It's cheaper than the next most efficient low-carbon technology, wind power, which would cost $24 per tonne or $1 trillion to prevent the same amount (one billion tonnes) of carbon emissions from being produced, according to the report.
In its per-tonne cost analysis, the report also calculated $51 for solar, $57 to $83 for coal plants with carbon capture and storage, $92 for plug-in hybrid vehicles, and $131 for electric vehicles.
The contraception as carbon reduction conclusion was based on United Nations statistics that 40 percent of worldwide pregnancies are unintentional. If contraception was made available to people who wanted it, those unintentional births could be reduced by as much as 72 percent. Between 2010 and 2050, that would result in curbing the world population growth by half a billion people, according to the UN statistics.
That is a conservative estimate, according to the report, since the UN figures are based solely on the lack of contraception access for married couples, and did not include unintended pregnancy statistics for unmarried women.
The study was funded by the U.K. environmental group Optimum Population Trust (OPT), which has argued that a more responsible attitude toward reproduction could be the answer to many environmental issues such oil, food, and water shortages.
The group has said that family planning programs in poor countries should qualify for environmental aid, since fewer people result in less energy use and fewer emissions.
"It's always been obvious that total emissions depend on the number of emitters as well as their individual emissions--the carbon tonnage can't shoot down, as we want, while the population keeps shooting up," Roger Martin, chair of OPT, said in a statement.
Is the practical idea too controversial to be considered because of moral reservations, or will countries warm up to it as not only climate change, but world water supplies become an issue?
"The taboo on mentioning this fact has made the whole climate change debate so far somewhat unreal. Stabilising (sic) population levels has always been essential ecologically, and this study shows it's economically sensible too," said Martin.