We are facing (and causing) an environmental crisis. Wild animal populations have plummeted in recent years, global temperatures are rising, our forests are disappearing and the seas are polluted.

10,000 years ago the Earth had to sustain just a few million people. Today, 7 ½ billion people live on this planet. By 2050, that figure is expected to reach 10 billion. This situation is not sustainable and serious discussions about population sustainability need to be had.

Please note that when I talk about population sustainability, I mean on the individual level. I am not speaking in favour here of force by law or government. China’s historic one child policy had lasting negative consequences and is not something we should emulate. Nor do I speak as someone who dislikes children or from not wanting children myself.

Every women, worldwide, should have access to the information, rights and freedom of choice and medical services to allow them to make their own decision about whether they want to have a family, and then whether or not they want a small or large family. Naturally, planning and what actually happens are not always the same thing. As someone who is married to a twin and who has experienced miscarriage, I know that you can easily find yourself with fewer or more children than expected.

Population Matters (www.populationmatters.org) is a charity that today encourages people everywhere to consider not having children. If a child free life is not for you, they urge people to consider adoption first, caring for children already living and in need of a loving home. If you decide you do want your own biological children, they encourage people to limit their family to one or two children.

Not having children is the most environmentally friendly thing a person can do. In an article published in the Guardian last year, Damian Carrington argued that the most effective way to reduce your carbon footprint over your lifetime is to avoid having children. Having one fewer child saves an estimated 58.6 tonnes of CO2-equivalent per year, whilst living car free saves as estimated 2.4 tonnes.

It’s not wrong to have children. However, when family planning, thought and consideration needs to go to whether and why you want children, whether adoption is something you can consider, and then to the size of the family.