It is heartening to see the Guardian giving considered coverage to the issue of human population and its impacts upon our planet and the threat that continued population growth and excessive consumption pose to the wellbeing and indeed survival of future generations (Best solution to climate change? Fewer children, 12 July). For too long population has been a taboo subject avoided by those normally courageous and outspoken in publicising inconvenient truths about the consequences of ongoing environmental damage.

The new study from Lund University showing that the most effective solution to curbing climate change is for people to have fewer children and smaller families confirms research we highlighted back in 2012, when seeking to persuade the likes of Friends of the Earth, Greenpeace and the World Wildlife Fund to talk openly and honestly about population issues (with little success!). That earlier study by Oregon State University concluded that, over a lifetime, a family that chose to have one less child would reduce their greenhouse gas emissions by 20 times the amount saved from undertaking all other obvious “eco-friendly” lifestyle changes.

Considering having one less child in developed countries and enabling women in developing countries to have the opportunities and means to choose their family size are “no-brainers” that will benefit both people and planet.

Robin Maynard Director, Population Matters

Jonathon Porritt Former chair, Sustainable Development Commission

• Using words like “unsustainable population” and “rampant population growth in Africa”, your article (US funding cuts fuel fears of missing global contraception targets, 10 July) exemplifies a dangerous and persistent species of population alarmism that sees family planning not as a right but as a way to prevent terrorism and stem rising tides of migration. If you’re concerned about refugees escaping environmental crises, blame the west, not poor women and girls who lack the information, resources, and power to determine whether and when to have children, and how many to have.

It would be convenient for the global north not to have to face its life-threatening consumption patterns, but reducing the number of poor people in the global south is not going to solve that problem. Overconsumption of carbon-intensive products, largely by industrialised nations, drives climate change and its effects, not high fertility rates in developing countries.

Casting family planning in the global south as a solution to resource stress, migration, terrorism or rising carbon emissions not only unfairly pins blame for these crises on poor women, it also misdiagnoses the problem. Entrenched inequalities, not population numbers, are the problem.

So, instead of wringing our hands about “unsustainable population”, let’s attack the inequalities that sustain poverty and drive migration, climate change and high fertility. But let’s do it without shifting responsibility to the poor, and without undermining women’s rights to reproductive self-determination.

Let’s work together to expand equality and freedom for women and girls no matter where they live, and to rid the planet of the injustices that are the true threat to all of our futures.

Christine Galavotti

Senior director of sexual, reproductive and maternal health, Care International

• It has long been apparent to people working in environmental science that overpopulation is one of the two key factors in the destruction of the non-human environment – the other being overconsumption by the wealthy world (‘Biological annihilation’: Earth faces sixth mass extinction, 11 July). The impact of the reproductive rate of African women, for example (seven children per female, on average, in many parts), is making itself apparent on the high seas of the Mediterranean, but much more destructively, and less visibly to western eyes, on the wildlife of the African continent. Yet, compared with how much debate goes on about plastic bags and electric cars, constructive discussion about overpopulation is studiously avoided. Climate change is indeed an additional stressor to wild populations already suffering from human-induced habitat loss, but it is humans that will suffer most from it, and in this way it is much the red herring. How ironic that Italy bears the brunt of the surge of ecological migrants, while the pontiff continues to deny that population is a problem, and so inhibits many women of the developing world from accessing birth control. It may be just this issue, however, that forces debate on a humane reduction in human populations, while we still have the resources to do it. Elon Musk and his Teslas are all very flash, but the technological items most required now, globally, environmentally, are condoms and the pill.

Chris Brausch

Whakatete Bay, New Zealand

• The National Academy of Sciences study on which you report is an urgent wake-up call about the eradication of wildlife, but I doubt it will be heeded. Sadly our ever increasingly urban populations are so divorced from the countryside and wildlife that the apocalyptic changes taking place go largely unnoticed. The green fields and neatly manicured hedges of our countryside appear to the untrained and fleeting eye to be in pristine condition.

When I return to the country lanes around Coventry where I enjoyed an idyllic childhood, it is like wandering through a cemetery. As a boy, I used to find robins’, yellowhammers’ and whitethroats’ nests every few metres; bullfinches, linnets and song thrushes twittered and sang everywhere from the trees and bushes, lapwings and yellow wagtails nested in the fields, and grass snakes sunned themselves on the banks of the myriad small ponds; wildflowers turned the lanes into riotous impressionist paintings. But no longer. These memories will be lost in a generation and few will be aware of what has gone missing. If it were dinosaurs instead of small animals and plants that were disappearing, more notice would be taken perhaps, but this loss is just as drastic and with far-reaching consequences that few of our fellow citizens are aware of.

If we don’t drastically curb our population growth and adopt nature-friendly farming methods as a matter of urgency, we could experience not just a continued steady eradication but a cliff-edge phenomenon. But then it will be too late.

John Green

London

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