There are carbon calculators galore on the web — including The Nature Conservancy’s very own. These calculators allow you to figure out how your activities and lifestyle contribute to the carbon emissions that are responsible for the climate disruption the world now faces.
Rarely, however, does one see any discussion of what population growth means for our emissions challenge. This is why I took notice of a recently published analysis in the journal Global Environmental Change that combines data on per capita emissions with national patterns of birth and death to calculate the total emissions cost of deciding to have a child.
The scientists get their results via an elegant application of lineage analysis — a branch of mathematics that combines probability theory with demography. The mathematics is only a tool. It is the results that are compelling.
The average lifetime emissions of people living in the United States is 1,644 tons of carbon. If you live in the United States and have a child, the average carbon legacy of that child will be 9,441 tons – that is how much extra carbon you are responsible for because you had that child, and it includes all of the carbon emitted by that child and his or her descendants before that lineage dies out given current birth and death rates in the United States.
To put this another way, suppose you are committed to doing something about climate change and want to do everything possible to reduce emissions. Now assume you do all of the sorts of things we are told to do to cut down, and you do them for your entire life. Specifically:
- You switch from a car that gets 20 mpg to one that gets 30 mpg, and you reduce the miles driven per week from 231 to 155.
- And you replace single-glazed windows with energy efficient double-paned windows in your home.
- And you replace 10 75-watt light bulbs with 10 25-watt energy efficient light bulbs.
- And you replace your old refrigerator with a top-of-the-line new energy-efficient refrigerator.
- And you religiously recycle all newspaper, glass, plastic, and aluminum and steel cans.
If you did all the above, you would be an eco-hero — and over your lifetime, you would reduce your emissions by 388 metric tons. Not bad.
Now suppose you decided to reduce by one the number of children you intend to have. You would save 9,441 metric tons of carbon emissions.
Now I have kids, and I am no eco-hero by any measure. In fact I am likely an eco-disaster. And I realize regulating population growth is not a viable option.
But, especially in high-consumption societies like the United States, even the smallest reductions in birthrates can make a huge difference to carbon scenarios. In contrast, deciding to NOT have a child in Bangladesh saves 56 metric tons of carbon, which is roughly what you get for recycling all of your newspapers and bottles and cans and switching those 10 light bulbs from 75W to 25W energy efficient light bulbs.
So let’s not pick on Bangladesh for its high population growth rate, when our own reproductive decisions have far greater environmental impacts.