The Optimum Population trust today launched a unique project that enables carbon offsets to be made through the support of family planning.

This innovative approach stems from a report that shows meeting the otherwise unmet demand for family planning could be the most cost-effective means of achieving CO2 reductions. For example, we believe every £4 spent on family planning saves one tonne of CO2. A similar reduction would require an £8 investment in tree planting, £15 in wind power, £31 in solar energy and £56 in hybrid vehicle technology.

The initiative is supported by patrons of our trust including Sir David Attenborough, Prof Paul Ehrlich, Prof John Guillebaud, Susan Hampshire, Prof Aubrey Manning, Sara Parkin, Jonathon Porritt, Prof Chris Rapley and Sir Crispin Tickell.

It is the world's first scheme to channel offset funds directly into improving family planning services in developing countries. It will give practical help: both to the poorest women in the world to enable them to control their own fertility and to humanity by tackling the threat posed by human-induced climate change to supplies of food, water and to social stability worldwide.

All environmental and developmental problems become more challenging with ever more people on the planet. Thus population restraint in all countries is a key, but often unacknowledged, component of any world initiative to limit global warming. .

We ask our negotiators at the Copenhagen climate conference this month to recognise the fact that world population growth increases the number both of carbon emitters (especially, indeed, in rich countries with large carbon footprints) and of future victims of climate change.

This project will, for the first time, enable all those who accept the link between population and climate change to make a practical contribution towards resolving the problems it causes, while reducing poverty in the poorest countries.

We are concerned about the focus upon techno-solutions at the expense of the wider environment. For example, a hydroelectric dam can have devastating consequences for the local ecology, whereas reducing population would remove environmental pressures. In addition, the funding of such capital-intensive programmes through donations from carbon offsets simply releases capital elsewhere for other, possibly less benign, projects.

The wider gains by carbon offsetting through family planning include alleviating poverty through improvements in health, nutrition and education for women and children, reducing the scale of all environmental problems including the effects of peak oil; deforestation; freshwater shortages; soil erosion and desertification; the mounting food crisis; declining fisheries; loss of biodiversity; rising waste and pollution; ocean acidification; and depletion of finite resources – all of which would be easier to solve with fewer people, and ultimately impossible to solve with ever more.

In any case, on a finite planet human numbers must stop growing at some point, either earlier through fewer births (contraception backed by sound policy), or later by more deaths (famine, disease, and war). Indefinite growth is simply not an option.

• David Burton is an environmental strategist and member of the Optimum Population Trust