No responsible series discussing finite global resources or long-term sustainability – and certainly not one on the challenges posed by a human-caused warming of the atmosphere – can ignore what many consider the best-left-unmentioned “elephant in the room”: global population. Simply put, it is for many an issue too sensitive to be raised, too divisive to be considered … but yet too important to be ignored.

Family planning

I must mention one more choice some of us can make to reduce the amount of GHGs emitted; the consumption of freshwater; and the further degradation of ecosystems. And that choice really does involve the elephant in the room when it comes to how to deal with global warming and issues contributing to it. The issue involves decisionmaking by women of childbearing age and their partners: whether to have children, and, if so, how many and when?

The authors of a 2017 paper in Environmental Research Letters considered a broad range of individual lifestyle choices and calculated their potential to reduce GHG emissions in developed countries, based on 148 scenarios and 39 sources. Having one fewer child was the lifestyle choice with the greatest potential to reduce annual personal emissions, averaging 58 t CO2 e [tons per carbon dioxide equivalent]. Living car-free was a distant second, at 2.4 t CO2 e. And the average annual saving resulting from eating a plant-based diet was calculated to be 0.8 t CO2 e.

Perhaps no one has more cleverly pointed this out than writer Tamar Haspel.

No amount of bean eating or Prius-driving will compensate for reproducing, and it’s the childless, not the vegetarians, who are more likely to save the planet. Which doesn’t mean that we should ignore the benefits of beans and Prii [plural of Prius] or that we shouldn’t have kids — it just means that we should acknowledge that human survival takes a climatic toll. Our obligation isn’t to minimize our carbon footprint at the expense of all other considerations; it’s to try to be prudent, taking those considerations into account.

The carbon footprint among Americans varies greatly, but even the poorest among us flushes toilets and need food (2,000-3,000 calories of food per day for healthy adults), clothing, and shelter – as do their offspring.

The human desire to reproduce is innate, but there doesn’t appear to be a positive correlation between the number of children we have and happiness. Parents with one or two children tend to be just as happy as parents with more than two.

Also, there is evidence that couples who have their first child when they are in their mid-30s or older tend to be happier than couples who have their first child at a younger age.

Stabilizing and eventually reducing the human population is important for two reasons:

1) Family planning is the most powerful method available for reducing the amount of GHGs emitted; for helping assure continued availability of freshwater; and for avoiding further degradation of ecosystems. Alan Weisman, author of the book Countdown, points out that to build enough clean energy capacity for a large and growing population will likely require the use of additional fossil fuels (e.g., to build more solar arrays and wind machines). In the meantime, he argues, the best hope to keep the planet livable is to reduce the global population making all the demands.

2) The number of full-time, high-paying jobs is likely to continue to decline – as software and robots become more capable and are able to accomplish many tasks traditionally done by both blue and white collar workers. Therefore, most of the high-paying jobs of the future will probably require advanced education, training, and experience. Couples who start their families later and have one or two children will generally be able to spend more time with their child or children and have more money for enrichment activities and education than couples who start their families early and having several children. (See here and here.)

3) This added attention and education could result in a distinct advantage when it comes to qualifying for the best available jobs.

It’s clear that individuals and families can make lots of “drops in the bucket” without having to “go off the grid” or live the lives of monks. And most individuals and families cannot make, or are not willing to make, all of the changes in consumption and lifestyle covered in this series. That’s okay. If most can make “drops” in whatever ways are best for them, these “drops” will fill buckets and these buckets, added together, will create a “river of GHGs” not emitted into the atmosphere.

Author Wendell Berry reminds us that “large problem(s) may be effectively addressed by many small solutions that, after all, are necessary, no matter what the government might (or might not) do.”

Craig K. Chandler is a retired horticulturist and professor at the University of Florida’s Gulf Coast Research and Education Center, where he led the university’s strawberry breeding program from 1987 until 2010.