Gigaworld: Why the Earth should have one billion people, and how to get there from here. This is the title of an imaginary book that I hope someone will write soon. Humanity's predicament comes from things that are good in themselves, like health and wealth, but things that also allow the population to grow and each person to consume more in a way that now threatens our future. Can we or should we do anything to intervene? Gigaworld could provide a hopeful answer.


How many people can the Earth support? This is the title of an actual book (Joel Cohen, 1995), and includes a range of estimates, from less than 1 billion to 1000 billion. Asking "can support" doesn't yield a clear answer, and asking "should support" is more problematic, begging questions of values, ethics, science, and religion. But I don't think we can hope to avoid the question. I hope we (humanity as a whole) can achieve a consensus that people should generally be healthy and happy, sharing fulfilling lives in harmony with the rest of nature. As far as we know, this requires significant use of energy and resources, economic activity which can be measured (crudely) by GDP. Globally this is about $7000 per person per year, and is about 5 times that in the US. Most people are dissatisfied with living at the global average economic level and work hard to better themselves. The Earth's carrying capacity is limited, so there is a trade-off between population and wealth. Our hope is to live well, sharing the world with enough well-off neighbors to create a dynamic and diverse culture, but probably fewer neighbors than the 7 billion living today. This is the case for Gigaworld -- 7 times fewer people, but maybe 7 times richer and with more equitable distribution.


Such thinking has a long and checkered history. The overpopulation catastrophe predicted by Thomas Malthus over 200 years ago didn't happen, and neither did the economic collapse scenarios of The Limits to Growth from 1972. Population control policies by governments can be coercive and affect ethnic groups differently -- "they" are trying to get rid of "us!" Eugenics is blighted by its association with Nazi death camps. Nevertheless, many respected scholars and leaders like those supporting the UK charitable group Population Matters make a strong case, especially for education and voluntary family planning. My wife and I were persuaded in the 1970's, and had only two children who have now followed suit and each have only two of their own. We're not unusual -- most of the affluent societies in the world now have fertility rates less than replacement. So could the subtitle of Gigaworld be easy, could "how to get there from here" be "just wait?"


The hope that population will take care of itself is naive, and the expectation that every country and ethnic group in the world will automatically become like us if we just wait is hubris. Active engagement is required to bring the benefits of science, technology, education, human rights and justice to more people in more places. Humanity's challenge is to share this enlightenment and the good life that it brings with everyone, without domineering coercion. But if my family and I got the message fifty years ago when the population was 3 billion, why do I now have to worry about a population beyond 7 billion? Is it fair to have to share the Earth's resources with others whose presence I didn't invite? Tribal hostility can grow from such questions, and we do need ways to get everyone onboard. I imagine a book like Gigaworld that would make a persuasive case that we are all in this together, and convince not just an educated elite but a commanding consensus of people everywhere. I hope we can do it, and I hope you do too.


Daniel Johnson, Houston, Texas, May 2013, updated 2015