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The Simon Abundance Index 2023

Blog Post | Energy & Natural Resources

The Simon Abundance Index 2023

The Earth was 420.1 percent more abundant in 2022 than it was in 1980.

Does population growth lead to greater resource scarcity, as argued by the English scholar Thomas Malthus and, more recently, by the Stanford University biologist Paul Ehrlich? Or does population growth coincide with—and even contribute to—greater resource abundance, as the University of Maryland economist and Cato Institute senior fellow Julian Simon has argued? The Simon Abundance Index (SAI) measures the relationship between population growth and the abundance of 50 basic commodities, including food, energy, materials, minerals, and metals.

Main Findings

Global resource abundance fell by 3.55 percent in 2022, according to the sixth annual Simon Abundance Index. The base year of the index is 1980, and the base value of the index is 100. In 2022, the index stood at 520.1. In other words, the index rose by 420.1 percent over the last 42 years, implying a compound annual growth rate in global resource abundance of 4 percent and a doubling of global resource abundance every 17.65 years.

Figure 1: The Simon Abundance Index (1980–2022)

The graph shows resource abundance increasing since 1980.

Analysis

The SAI is measured in time prices. To calculate a commodity’s time price, the nominal price of a commodity is divided by the average global nominal income per hour worked. Over the last 42 years, the average of the nominal prices of the Basic 50 commodities rose by 150 percent, while the average global nominal income per hour worked rose by 439.2 percent. That means that the time price of the Basic 50 commodities fell by a geometric average of 65.5 percent.

The personal resource abundance multiplier is calculated by dividing the average of the time prices of the Basic 50 commodities in 1980 by the average of the time prices of the Basic 50 commodities in 2022. The multiplier tells us how much more of a resource a person can get for the same hours of work between two points in time. Given that the average of the time prices of the Basic 50 commodities fell by 65.5 percent, the same number of hours of work that bought one unit in the basket of the Basic 50 commodities in 1980 bought 2.9 units in the same basket in 2022.

That means that personal resource abundance of the average inhabitant of the planet rose by 190 percent between 1980 and 2022. The compound annual growth rate in personal resource abundance amounted to 2.7 percent, implying that personal resource abundance doubled every 26 years.

While the average of the time prices of the Basic 50 commodities fell by 65.5 percent, the world’s population increased by 79.4 percent. So, for every 1 percent increase in the world’s population, the average of the time prices of the Basic 50 commodities fell by 0.825 percent (-65.5 percent ÷ 79.4 percent = -0.825).

Note that the personal resource abundance analysis looks at resource abundance from the perspective of an individual human being. The question that we aim to answer is: “How much more abundant have resources become for the average inhabitant of the planet?”

Population resource abundance analysis, in contrast, allows us to quantify the relationship between the overall (or global) resource abundance and the overall (or global) population growth. You can use a pizza analogy to consider the difference between the two levels of analysis. Personal resource abundance measures the size of a slice of pizza per person, while population resource abundance adds up all the slices to measure the size of the entire pizza pie.

Population resource abundance is calculated by multiplying the growth in personal resource abundance by the growth in global population ([1 + percentage change in personal resource abundance] x [1 + percentage change in population]). The resulting product of 5.201 (2.9 x 1.794) corresponds to the 520.1 value in the SAI 2023. Consequently, we can also say that population resource abundance increased at a compound annual growth rate of 4 percent, thus doubling every 17.65 years.

Figure 2: Visualization of the Relationship between Global Population Growth and Personal Resource Abundance of the 50 Basic Commodities (1980–2022)

The figure shows the increase in personal resource abundance for 50 basic commodities since 1980.

Let us also say a few words about the resource abundance elasticity of population. In economics, elasticity measures one variable’s sensitivity to a change in another variable. If variable X changes by 10 percent, while variable Y, because of the change in X, changes by 5 percent, then the elasticity coefficient of X relative to Y is 2 (10 ÷ 5). A coefficient of 2 can be interpreted as a 2 percent change in X corresponding to a 1 percent change in Y.

We found that every 1 percent increase in population corresponded to an increase in personal resource abundance (the size of the slice of pizza) of 2.39 percent (190 ÷ 79.4). We also found that every 1 percent increase in population corresponded to an increase in population resource abundance (the size of the pizza pie) of 5.29 percent (420 ÷ 79.4).

Changes between 2021 and 2022

Over the last 12 months, the SAI declined from 539.3 to 520.1 or by 3.55 percent. While regrettable, last year’s decline was much smaller than the 22 percent drop in 2021, which was caused by the COVID-19 pandemic and pandemic-related policies. That said, note that the index increased by an average 4.46 percent per year between 1980 and 2022.

Figure 3: The Simon Abundance Index, Annual Percentage Change (1980–2022)

The graph shows the average annual change in the Simon abundance index between 1980 and 2022.

Going forward we expect the SAI to start growing again in 2023. Humanity has witnessed shocks like those caused by the pandemic and experienced accompanying reductions in resource abundance before. Mercifully, history suggests that growth in the abundance of resources can be restored. The SAI, for example, grew by 28.4 percent, 20.0 percent, and 19.3 percent in 1986, 1985, and 2009, respectively.

Figure 4: The Simon Abundance Index, Percentage Change in Time Prices of Individual Resources (2021–2022)

The figure shows the percentage change in the time price of individual resources between 2021 and 2022.

Conclusion

Despite the recent decline in SAI, resource abundance is still increasing at a faster rate than the population is growing. We call that relationship superabundance. We explore this topic in our book Superabundance: The Story of Population Growth, Innovation, and Human Flourishing on an Infinitely Bountiful Planet.

Additional Information

Appendix A: Alternative Figure 1 with a Regression Line, Equation, and R-Square.

The graph shows the Simon Abundance Index from 1980 to 2022 with a regression line.

Appendix B: The Basic 50 Commodities Analysis (1980–2022)

The figure gives more detail on the abundance of fifty commodities that compose the Simon Abundance Index.

Appendix C: The Basic 50 Commodities, Percentage Change in Personal Resource Abundance (1980–2022)

The figure shows the percentage change in personal resource abundance for fifty commodities

Blog Post | Population Growth

No, Prosperity Doesn’t Cause Population Collapse

Wealth doesn’t have to mean demographic decline.

Summary: For decades, experts assumed that rising prosperity inevitably led to falling birth rates, fueling concerns about population collapse in wealthy societies. But new data show that this link is weakening or even reversing, with many high-income countries now seeing higher fertility than some middle-income nations. As research reveals that wealth and fertility can rise together, policymakers have an opportunity to rethink outdated assumptions about tradeoffs between prosperity and demographic decline.


For years, it was treated as a demographic law: as countries grow wealthier, they have fewer children. Prosperity, it was believed, inevitably drove birth rates down. This assumption shaped countless forecasts about the future of the global population.

And in many wealthy countries, such as South Korea and Italy, very low fertility rates persist. But a growing body of research is challenging the idea that rising prosperity always suppresses fertility.

University of Pennsylvania economist Jesús Fernández-Villaverde recently observed that middle-income countries are now experiencing lower total fertility rates than many advanced economies ever have. His latest work shows that Thailand and Colombia each have fertility rates around 1.0 births per woman, which is even lower than rates in well-known low-fertility advanced economies such as Japan, Spain and Italy.

“My conjecture is that by 2060 or so, we might see rich economies as a group with higher [total fertility rates] than emerging economies,” Fernández-Villaverde predicts.

This changing relationship between prosperity and fertility is already apparent in Europe. For many years, wealthier European countries tended to have lower birth rates than poorer ones. That pattern weakened around 2017, and by 2021 it had flipped.

This change fits a broader historical pattern. Before the Industrial Revolution, wealthier families generally had more children. The idea that prosperity leads to smaller families is a modern development. Now, in many advanced economies, that trend is weakening or reversing. The way that prosperity influences fertility is changing yet again. Wealth and family size are no longer pulling in opposite directions.

This shift also calls into question long-standing assumptions about women’s income and fertility. For years, many economists thought that higher salaries discouraged women from having children by raising the opportunity cost of taking time off work. That no longer seems to hold in many countries.

In several high-income nations, rising female earnings are now associated with higher fertility. Studies in Italy and the Netherlands show that couples where both partners earn well are more likely to have children, while low-income couples are the least likely to do so. Similar findings have emerged from Sweden as well. In Norway, too, higher-earning women now tend to have more babies.

This trend is not limited to Europe. In the United States, richer families are also beginning to have more babies than poorer ones, reversing patterns observed in previous decades. A study of seven countries — including the United States, the United Kingdom, Germany and Australia — found that in every case, higher incomes for both men and women increased the chances of having a child.

This growing body of evidence challenges the assumption that prosperity causes people to have fewer children. 

Still, birth rates are falling across much of the world, with many countries now below replacement level. While this trend raises serious concerns, such as the risk of an aging and less innovative population and widening gaps in public pension solvency, it is heartening that it is not driven by prosperity itself. Wealth does not automatically lead to fewer children, and theories blaming consumerism or rising living standards no longer hold up.

Although the recent shift in the relationship between prosperity and fertility is welcome, it is not yet enough to raise fertility to the replacement rate of around 2.1 children per woman — a challenging threshold to reach.

But the growing number of policymakers around the world concerned about falling fertility can consider many simple, freedom-enhancing reforms that lower barriers to raising a family, including reforms to education, housing and childcare. Still, it’s important to challenge the common assumption that prosperity inevitably leads to lower birth rates: Wealth does not always mean fewer children.

This article was published at The Hill on 6/16/2025.

Blog Post | Food Production

More People, More Food: Why Ehrlich and Thanos Got It Wrong

Compared to 1900, we have 8.28 million fewer farmers today with 263.7 million more people. And we live 30 years longer.

In 1900, the U.S. Census recorded a total population of 76.3 million, including 11 million farmers. Today, with a population nearing 340 million, the number of farmers has dropped to just 2.72 million.

At the turn of the century, each farmer fed 6.94 people. Today, that number has risen to 125. While the U.S. population grew by 346 percent, farmer productivity soared by 1,702 percent. Each one percent increase in population corresponded to a 4.92 percent increase in farmer productivity.

In 1900, life expectancy was just 47 years. Today, it’s around 77. Medicine and sanitation played a role, but the abundance of food made possible by farmers discovering and applying new knowledge was a foundational driver of that gain.

So, who’s going to tell Ehrlich and Thanos they had it backwards? More life discovers more knowledge, which leads to better tools and more abundant resources.

Find more of Gale’s work at his Substack, Gale Winds.

Blog Post | Population Growth

Promoting Parenthood in a Free Society | Podcast Highlights

Stephanie Murray joins Chelsea Follett to discuss discourse around falling birth rates, the tension between pro-natalism and classical liberal values, and how it might be resolved.

Listen to the podcast or read the full transcript here.

In many places, fertility rates are hitting record lows. Practically all rich countries and many developing countries are now below the replacement fertility rate. Some countries are already seeing their populations age and decline, and if this continues for long enough, the global population will begin to shrink.

Your piece discusses an aspect of this topic that I find really interesting. So, let’s walk through it. You begin with an anecdote about how, a little over a year ago, you were conducting an interview about the possible causes of fertility decline. Tell me what happened.

I write on this topic with some frequency, and I follow research on it very closely, so I often interview people who research fertility, economists, sociologists, demographers, and so on. And so I was interviewing somebody, a demographer, about a certain cause of fertility decline. At one point in the interview, she kind of stopped and wanted to clarify that the issue here is that people are having fewer kids than they want. She wanted to make it clear that she wasn’t saying we should raise the birth rate for any kind of national interest.

My piece pushes back on that way of thinking.

Why do you think people tend to characterize the falling birth rate issue this way?

I think there’s a sense that catastrophizing low fertility could justify taking really drastic and coercive steps. And I think that is a major and legitimate concern. Getting the state involved in getting people to have children or stop having children could be a legitimate threat to civil liberties.

People also sometimes acknowledge that falling fertility is a problem, but they redefine it. They’ll say something like, “There are going to be economic challenges because of low fertility, but the problem is with our economic system, so let’s just change the economic system.”

I am sympathetic to people who want to talk about economic reforms, especially if pension systems, for example, are unsustainable. But as you say, there is no reason you can’t discuss both of those things.

There are definitely ways that we can adapt our economic system to low fertility, but there are limitations to that approach. You get this sense that people think that the need for children is just a byproduct of capitalism, and if we just changed our economic system, then we wouldn’t need endless growth propped up by a high birth rate. Maybe we can tweak our pension system, or become less reliant on GDP growth, but it’s a fact of human existence that you need new people to take over as the rest of us get older.

Now, some demographers and economists push back on the idea that anything below replacement-level fertility is going to cause massive issues. Some think that we could have anything above 1.5 births per woman, and with immigration, technological advancement, and education, we’ll be fine. One demographer that I spoke to said that since we are becoming more productive per capita as time goes on, each generation has “broader shoulders,” to stand on. So, maybe we can do more or as much as we are currently doing with fewer people.

That said, you can’t have a society without kids. We don’t know exactly when the falling birth rate becomes a big problem or how long we have before it’s a big problem. Lots of room for disagreement there. But eventually, it becomes a problem.

Let’s talk about some of the reasons that people are choosing to have fewer children. You make a very good point that in the past, parents captured more of the fruits of their children’s labor, while today, most of us are raising kids who will spend most of their lives working for someone else.

Yeah, for a lot of human history, parents were employers who grew their own laborers. There were steep economic incentives to raise kids. It could be brutal on a personal level. If you couldn’t bear children, your husband might put you aside and find somebody else who can. Today, parents still do a lot of the work of raising children, but they’re raising kids who are going to work for somebody else.

Of course, there are still practical reasons to have children. Basically everywhere in the world, lots of elder care is done informally by family members, especially adult children. However, even still, that care is not reliable in a liberal society. This is how liberalism works: when you grow up, nobody can tell you what to do, including your parents. So, I think capitalism, labor markets, and liberal values in general have altered the relationship between parents and children in a way that fundamentally changes the economics of child-rearing.

I do think it is easy to oversell the importance of economic considerations and downplay the psychological or cultural factors. It’s notable that, to date, no amount of government spending anywhere in the world has successfully restored sub-replacement birth rates to replacement levels.

You spend a lot of your piece talking about another factor in people’s decisions about having children: the feeling that having children is good for your society’s future. Could you tell me a bit about that?

People often pitch parenthood as simply an experience that makes the parents feel good without acknowledging the important role parents play in society.

I think that undermines the case for parenthood. If we pretend that parenthood is just about you being happy, we rob parents of a source of satisfaction. Imagine if we tried to recruit people to the army by saying, “It doesn’t really matter how many people sign up. This is about you getting the experience of holding a gun and riding in a tank.” I really don’t think anybody would join. People are motivated to serve their communities. So why are we downplaying that? Why are we so scared of saying, “you should consider having kids because we need parents”?

How do you think that relates to this view that the world is overpopulated and having kids is essentially selfish? Do you think that kind of messaging might affect people’s decision-making?

Absolutely.

A couple of years ago, I signed up for this half-marathon hike and ended up hiking it with this woman who was a total stranger, and we were talking about fertility rates. You can’t go on a half-marathon hike with me without me talking about fertility; that’s pretty much inevitable.

So, we were chatting, and she, at one point, said that she felt like she was harming the planet by having kids, and since she had to take maternity leave, she was also slowing down work. She felt like she was doing a selfish thing and drawing resources away from the planet and from her workplace in order for her to have the experience of parenthood.

If that is how you view parenthood, it becomes a lot harder to justify the decision. And if you already have personal reservations like, “would I be a good mother?”, it could easily tip the scales toward not having children.

This topic is very tricky for those of us who are devoted to a free society. I really love the last paragraph of your piece. You say:

Those of us who want to reverse falling fertility while preserving the values of a liberal society have a tricky task ahead. We’ve got to hold two truths at once: that no one ought to be coerced into parenthood, and that we will all suffer if no one raises kids. That may seem like an impossible line to walk—and yet, we walk versions of it all the time. I don’t think there’s anyone in the world that would hesitate to admit that we need doctors. And yet, most of us agree no one should be coerced into medical school. In other words, acknowledging the necessity of parents while respecting individuals’ right not to become one is really just a matter of applying the same logic to parenting that we do to every other path in life.

Could you expound on that?

I think most people can agree that we don’t want people to be coerced into parenthood, but we can’t allow that concern to make us overlook the fact that we need parents. They provide an essential service in society. So we have to be willing to hold both of them at the same time. I think people just have this impulse that that’s not possible, but we do this all the time with other types of work.

If we go with the military example, most people think that national security is important, but most people also oppose conscription. They want a volunteer army. It’s the same with basically any line of work. We don’t like forcing people to do things, but that doesn’t stop us from acknowledging that society can’t function without doctors or teachers.

You’re basically just suggesting that people voluntarily give more social recognition to parents. And you write that all around you, you can see that parents, and mothers in particular, are desperate for recognition that the work they are undertaking is valuable for the world. Do you think that more social recognition could shift the culture toward higher birth rates?

I do. I’ve always thought that parenthood is really important, but I constantly felt like the culture was telling me otherwise. There is this assumption that you shouldn’t get married and have kids right after college, right? That you should do something with your life. But having kids is doing something. And there are lots of ways that we denigrate parenthood and treat it as a waste of somebody’s skills and talents.

If we thought more about the work of parenthood in the way that we think about other work, if we treated it like a really cool way of contributing to society, maybe people would be more motivated to go into that line of work.

If you look at the few populations in wealthy countries that do have high birth rates, religious communities, for example, those populations give people a lot of positive messaging about how raising children is a good thing for society.

I just remembered that the woman I went on that half marathon hike with, who seemed to believe she had done a selfish thing by having children, told me about a time she visited Jordan. She was so struck by what it was like to have a child there. In the UK, where I live, sometimes when you go into a coffee shop, people almost groan if they see you brought your kids. But in Jordan, she said that when she would walk into a coffee shop or a restaurant, it felt like she had gifted them this child. She felt an overwhelming sense that people were delighted that she had this child there, and she didn’t even live in Jordan. I think this kind of social recognition changes how you think about having children.

Another other thing to remember about social recognition is that it’s free. It doesn’t cost taxpayers a single dime, and there’s not really any downside to people just voluntarily giving this kind of recognition to the parents in their lives.

One of the reasons that people are hesitant to talk about birth rates is that, as you wrote in your piece, it can feel icky to have a strong opinion on such a personal decision. You don’t want to try to make everyone follow the same path and become a parent.

I think we need to use other types of work as a model for how we think about parenthood. There are a lot of roles that need to be filled in society, and just because you are not filling all of them doesn’t mean that you’re failing society. You can appreciate the existence of doctors and nurses without feeling bad that you are not a healthcare worker.

We usually end this podcast with an optimistic note. What trends, if any, make you feel optimistic about the future of birth rates?

I think that people are becoming more receptive to the idea that parenthood, motherhood, and caregiving are valuable and often overlooked. It feels like we’re on the cusp of being willing to admit that we need parents. Not in a catastrophizing way, but in a “hey, this is important” way. So, I think we’re moving in the right direction.

The Human Progress Podcast | Ep. 60

Stephanie Murray: Promoting Parenthood in a Free Society

Stephanie Murray joins Chelsea Follett to discuss discourse around falling birth rates, the tension between pro-natalism and classical liberal values, and how it might be resolved.