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Contraception is “greenest” technology

Family planning cheapest way to combat climate change

Contraception is almost five times cheaper  than conventional green technologies as a means of combating climate change (please see addendum below for reanalysis of this figure), according to research published today.

Each $7 (£4) spent on basic family planning over the next four decades would reduce global CO2 emissions by more than a tonne. To achieve the same result with low-carbon technologies would cost a minimum of $32 (£19). The UN estimates that 40 per cent of all pregnancies worldwide are unintended.

The report, Fewer Emitters, Lower Emissions, Less Cost, commissioned by the Optimum Population Trust from the London School of Economics*, concludes that “considered purely as a method of reducing future CO2 emissions”, family planning is more cost-effective than leading low-carbon technologies. It says family planning should be seen as one of the primary methods of emissions reduction.

Meeting basic family planning needs along the lines suggested would save 34 gigatonnes (billion tonnes) of CO2 between now and 2050 – equivalent to nearly six times the annual emissions of the US and almost 60 times the UK’s annual total.

Roger Martin, chair of OPT, said the findings vindicated OPT’s stance that population growth must be included in the climate change debate. “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. The taboo on mentioning this fact has made the whole climate change debate so far somewhat unreal. Stabilising population levels has always been essential ecologically, and this study shows it’s economically sensible too.

“The population issue must now be added into the negotiations for the Copenhagen climate change summit in December.** This part of the solution is so easy, and so cheap, and would bring so many other social and economic benefits, from health and education to the empowerment of women. It would also ease all the other environmental problems we face – the rapid shrinkage of soil, fresh water, forests, fisheries, wildlife and oil reserves and the looming food crisis.

“All of these would be easier to solve with fewer people, and ultimately impossible to solve with ever more. Meanwhile each additional person, especially each rich person in the OECD countries, reduces everyone’s share of the planet’s dwindling resources even faster. Non-coercive population policies are urgently needed in all countries. The taboo on discussing this is no longer defensible.”

The study, based on the principle that “fewer people will emit fewer tonnes of carbon dioxide”, models the consequences of meeting all “unmet need” for family planning, defined as the number of women who wish to delay or terminate childbearing but who are not using contraception.*** One recent estimate put this figure at 200 million. UN data suggest that meeting unmet need for family planning would reduce unintended births by 72 per cent, reducing projected world population in 2050 by half a billion to 8.64 billion. Between 2010 and 2050 12 billion fewer “people-years” would be lived – 326 billion against 338 billion under current projections.

The 34 gigatonnes of CO2 saved in this way would cost $220 billion – roughly $7 a tonne. However, the same CO2 saving would cost over $1trillion if low-carbon technologies were used.

The $7 cost of abating a tonne of CO2 using family planning compares with $24 (£15) for wind power, $51 (£31) for solar, $57-83 (£35-51) for coal plants with carbon capture and storage, $92 (£56) for plug-in hybrid vehicles and $131 (£80) for electric vehicles.

However, the study may understate the CO2 savings available because the estimates of unmet need are based on married women alone, yet some studies suggest up to 40 per cent of young unmarried women have had unwanted pregnancies.

Mr. Martin added: “The potential for tackling climate change by addressing population growth through better family planning, alongside the conventional approach, is clearly enormous and we shall be urging all those involved in the Copenhagen process to take it fully on board.”


*Available at

**In a statement issued last month, OPT called on climate change negotiators to ensure that population restraint policies are adopted by every state worldwide to combat climate change. Family planning programmes in poorer countries should be treated as legitimate candidates for climate change funding. The statement was endorsed by OPT patrons including Sir David Attenborough, Dr. James Lovelock and Jonathon Porritt. See:

***A recent study by Oregon State University concluded: “A person’s reproductive choices must be considered along with [their] day-to-day activities when assessing [their] ultimate impact on the global environment.” See Reproduction and the carbon legacies of individuals, by Paul Murtaugh and Michael Schlax, College of Oceanic and Atmospheric Sciences/Department of Statistics, available on The authors calculate that in the US each child adds 9,441 tonnes of carbon dioxide to the carbon legacy of an average female, equivalent to 5.7 times her lifetime emissions. See also: A Population-Based Climate Strategy (OPT Research Briefing) at


Since publication of this report, a flaw has been pointed out in an assumption relating to the calculation of the cost of preventing unwanted births worldwide. This cost was derived from the only figures available, from research in developing countries. In developed countries, however, almost everyone has access to and some knowledge of family planning, though many people who do not want children do not use it. This gives rise to many unintended births with much higher per capita carbon emissions; while the (unknown) cost of preventing such births through programmes to achieve the necessary “culture shift” is probably considerably higher than in developing countries. OPT therefore accepts that the figure of $7 per tonne of carbon abated by investment in family planning is unreliable, and should not be quoted. The true figure worldwide remains unknown, since no-one else has attempted to quantify it. OPT is confident, however, that the cost/benefit remains positive, especially taking account of all the unquantified additional benefits listed in Annex B – notably the one-off, low-carbon cost of contraception, with carbon savings multiplying in perpetuity through all the unborn descendants. Furthermore, if the aid industry succeeds in achieving its aim of making all poor people much richer, as we all hope, the carbon savings from low-cost family planning in developing countries will multiply much faster, and make it even more cost-effective.