To the Editor: Egger makes novel and valid points in his portrayal of individual human effort as a potential contributor to offsetting greenhouse gas emissions by personal carbon trading.1 Of course, there is an even more potent strategy humans should adopt to modify climate change through their own activities — population control.

Anthropogenic greenhouse gases constitute the largest source of pollution, with by far the greatest contribution from humans in the developed world. Every newborn baby in Australia represents a potent source of greenhouse gas emissions for an average of 80 years, not simply by breathing, but by the profligate consumption of resources typical of our society.

What then should we do as environmentally responsible medical practitioners? We should point out the consequences to all who fail to see them, including, if necessary, the ministers for health. Far from showering financial booty on new mothers and thereby rewarding greenhouse-unfriendly behaviour, a “Baby Levy” in the form of a carbon tax should apply, in line with the “polluter pays” principle.2 Every family choosing to have more than a defined number of children (Sustainable Population Australia suggests a maximum of two3) should be charged a carbon tax that would fund the planting of enough trees to offset the carbon cost generated by a new human being. The average annual CO2 emission by an Australian individual is about 17 metric tons,4 including energy usage. As the biomass of trees in a mature forest sequesters about 6 metric tons of CO2 per hectare (104 m2) per year,4,5 each child born should be offset by planting 4 hectares of trees, to allow for the time they take to reach maturity, and attrition through crop losses, bushfires, dieback and so on. This infers a levy per child of at least $5000 at birth (to purchase the land needed and plant trees) and an annual tax of $400–$800 thereafter for the life of the child (for maintenance of the afforestation project) (based on 1990 figures,4 and probably much more now).

By the same reasoning, contraceptives, intrauterine devices, diaphragms, condoms and sterilisation procedures should attract carbon credits for the user and the prescriber that would offset their income taxes, and lead to rewards for family planning clinics and hospitals that provide such greenhouse-friendly services.

As David Attenborough said:

As doctors, I believe we need to think this way. Our responsibility extends further than the patient on the other side of the desk. As Australians, I believe we need to be less arrogant. As citizens of this world, I believe we deserve no more population concessions than those in India and China.

In reply: I agree with Walters. One must wonder why population control, which was such a popular topic during the 1970s, is spoken of today only in whispers. Is this because of the discovery of new oil in the 1980s, taking resource scarcity off the public agenda? Is it because of politicians and economists, so keen on the growth trail that “. . . one for mum, one for dad and one for the country”1 seems an easy solution? Or is it the great religions, intent on outnumbering each other?

Environmental groups have also gone silent on the issue — perhaps afraid to alienate their growing support on other environmental issues.

Population remains crucial to all environmental (and subsequently, health) considerations. The debate needs to be reopened as part of a second ecological revolution (following the failure of the first in the 1960s and 1970s).2 Doctors, as opinion leaders in the community, must be at the forefront of this debate.