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Northwestern Buffett Institute for Global Affairs

The Day of 8 Billion with John Wilmoth, PhD

The world – and human species – will reach a new milestone in 2022. Scientists estimate that the global population will cross the 8 billion mark on November 15th, 2022, ushering in a new age of potential challenges for countries across the globe. What does this population growth mean for achieving the United Nations Sustainable Development Goals? Specifically, what does this population growth mean for achieving the United Nations Sustainable Development Goal 13: Climate Action? John Wilmoth, PhD, director of the United Nations Population Division, joins Annelise Riles to discuss this issue.

John Wilmoth

You cannot deny development to the rest of the world. And yet, if they develop with these large populations … if they use the same technologies that we've been applying in the richer countries of the world, then … the impact is going to be quite significant.”

– John Wilmoth, PhD, Director of the United Nations Population Division

Background reading:

  • Read the World Population Prospects 2022 Summary of Results
  • Find out more about Wilmoth and the UN Population Division
  • More about UNSDG13

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Read the transcript of this show below

Annelise Riles [00:00:03] Welcome to the Breaking Boundaries podcast. I'm Annalise Riles, executive director of Northwestern University's Roberta Buffett Institute for Global Affairs. The Northwestern Buffett Institute is dedicated to breaking through traditional silos of expertise, geography, culture and language to surface novel solutions to pressing global challenges. The world and the human species will reach a new milestone this month. Scientists estimate that the global population will cross the 8 billion mark on November 15th, ushering in a new age of potential challenges for countries across the globe. What does this population growth mean for achieving the United Nations Sustainable Development Goals and especially addressing U.N., SDG number 13 Climate Action. Here to shed some light on this is John Wilmoth, director of the Population Division of the United Nations Department of Economic and Social Affairs, which leads the monitoring of global demographic indicators and predicted this milestone in its recently released 2022 World Population Prospects report. John took up his position as the 10th director of the Population Division nearly a decade ago after serving as a consultant to the World Bank and chief of the U.N. Population Division's Mortality section. He's also enjoyed a distinguished academic career as a professor in the Department of Demography at the University of California, Berkeley, and member of the editorial boards for leading demographic journals, including Demographic Research and the European Journal of Population. John, thank you so much for being here. Welcome to the show.

John Wilmoth [00:01:50] Thank you for inviting me.

Annelise Riles [00:01:51] So first, tell us a little bit about the population division at the United Nations. What's your mission and what's your mandate?

John Wilmoth [00:01:58] Well, our mandate is to provide information to member states of the United Nations on population trends and the implications of those trends for various aspects of social and economic development. And we support intergovernmental discussions and we produce information that can help inform governments discussions about population and which are of general interest to the world. So, we produce several major datasets. One of which you mentioned earlier, which is the World Population Prospects. It has a complete population series from 1950 to the present and then projections into the future out to 2100 with information about population size by age and sex and levels of fertility, mortality and migration over that entire time period.

Annelise Riles [00:02:42] Help us to understand why this 8 billion matters. Why is this so important? Is it a good thing or a bad thing?

John Wilmoth [00:02:49] That's a good question. And I don't think there's a simple answer. I think the answer is that it's some of both. This is both a day for celebration and a moment for reflection. What population growth really reflects is success in reducing human suffering from disease and from the tragedy of early death deaths that occur at young ages when people are not supposed to die, let's say. Those kinds of deaths, they still happen, but they're much more infrequent. Those early, tragic deaths early in life, premature deaths are sometimes called,  have become much less common. Most people can reliably count on living to 70 years of age and beyond. If you look at things traditionally, how high was mortality? How low was life expectancy? It was not uncommon to have between a quarter and a third of all newborns who would die before they would reach adulthood. So, so a quarter to a third of all people who are ever born, let's say prior to 1700 in most of the world, they would die before adulthood and not even get there. So now how does that compare to how things are today? Just to give you a sense of how much things have changed. Today, more than 99% of newborns in in countries with high levels of life expectancy, the high income countries, more than 99% of babies and newborns survive to age 20 and three quarters survive to age 70. In those countries, basically three quarters of the people can expect to live that long. And even in the countries today, with the lowest levels of life expectancy, more than 90% of newborns survive to age 20 and more than half to age 70. So that's a significant change over where things were in the past. It's not as far as where the high income countries have gone, but it's a sign of the progress that's been made in reducing mortality and with the reduction in mortality that is what brought growth. That's what created population growth. It reflects many of the positive aspects of social and economic development that the whole world is enjoying to one degree or another. But at the same time, I think that there's also a need for caution about this growth. There are many challenges that humanity is facing, and it's probably correct that none of those challenges are caused primarily by human population growth. But nevertheless, the increased size of the population and its speed of increase often magnify the impact of existing problems or complicate their solution. 

Annelise Riles [00:05:16] So where do we see population growth continuing to rise the fastest in the world? 

John Wilmoth [00:05:22] The growth rate remains much faster in sub-Saharan Africa in particular, and that's where we're expecting that most of the future growth will take place over the next several decades until we think global population growth will eventually come to an end. Toward the end of this century.

Annelise Riles [00:05:39] So, let's talk about the implications of this. What does the report say about the link between population and climate?

John Wilmoth [00:05:48] It says that population growth is one of the important factors that's been driving, helping to drive the increase in human consumption and production over time. So, population growth is clearly an important factor that needs to be taken into account when we try to understand what has happened. However, if you think about what's the total impact on the environment of human activities, the total impact is a product of the impact per person and the number of people. And if you break it down that way and you ask over time, which has been more important, changes in the impact per person or changes in the number of people? The answer in general terms is the increasing impact per person has been much more important than the increase in the number of people. If you look at it historically, the problem is not primarily due to population growth. It's one factor. It's not the major factor. It's human behavior and human choices about how to live and how to organize the economy that make the biggest difference. And if you think about moving forward and which of those can you control or affect in a positive way through government policies? I think it's clear that there's the greatest potential to intervene on the side of human behavior and how the economy is organized rather than in the bedroom, let's say, on the side of how many people will be born in the future. And there there are issues of privacy, obviously, and protecting people's reproductive rights. But there's also just the practical side. If governments want to enact policies, where are they likely to be more successful in the public sphere or in the private sphere? And since the economic activities per person have are the greater factor in all this? That combined with the fact, I think the argument about rights and for public versus private space where you want to regulate is a pretty strong argument for focusing on human activities and choices that we make about economic consumption and production, the impact that has on the environment on a per capita basis, and really aggressively changing that, changing the per capita impact of human activities on the environment. 

Annelise Riles [00:07:43] So, as I understand it, what you're telling us then is that while population growth is relevant to climate change, we can't blame climate change on population growth. And we should focus our energies more on thinking about how to change each of our individual behaviors, particularly in countries or economic environments in which we use a lot of energy. Is that right?

John Wilmoth [00:08:10] That's absolutely right. And if you look at which countries are responsible for climate change, which countries emit the most greenhouse gasses into the atmosphere every year, it's countries with relatively high incomes where the population is not growing and where the population is possibly declining. And yet these are the countries that make the greatest contribution to climate change on a year to year basis. And the countries that are not making much of an impact on the global environment because they're not consuming very much, are poorer countries where the population is growing rapidly. The growth, of course, affects the number of potential consumers in the future. So we cannot ignore the impact of that growth on the eventual impacts of those countries when they begin to consume more, if they develop their economies in a way that's at all similar to what we've seen in other countries, which I think is the aspiration, because the economies need to grow in order for there to be jobs that are needed to keep people employed. So,  there needs to be economic growth and that will require energy, that will require things, activities that are potentially polluting. This is not an easy problem to solve because you cannot deny development to the rest of the world. And yet if they develop with these large populations, if they follow, if they use the same technologies that we've been applying in the richer countries of the world, then, you know, the impact is going to be quite significant. And so it's very important that the richer countries of the world and the international community provide the kind of technical assistance and financial assistance to help poorer countries develop in ways that kind of move immediately toward greener technologies, and that they basically leapfrog in terms of technologies, that they move immediately toward greener energy sources and build an infrastructure that will be much greener as they continue to develop economically and socially.

Annelise Riles [00:09:52] What role do you see for universities globally in helping us to address the huge challenges you've just described? And how can universities collaborate better with international institutions and units like yours in the future.

John Wilmoth [00:10:07] I think the universities are doing mostly what they should in terms of helping us to understand what's really going on. The questions come up more quickly. If you're in an organization like the United Nations, you're immediately asked to respond to things like "What's the impact of the pandemic been on global trends in fertility and mortality and migration?" We immediately had to start coming up with some explanation and some forecasts and numbers associated with all of that. But in academia, they have more time and they can follow up that initial work that's done by international organizations and do it more completely. And so now we're seeing, for example, you know, some of our expectations around levels of fertility in countries during the pandemic were just wrong, actually. And I just recently saw a study which kind of explained why. So, there was a belief that possibly fertility rates would really fall, especially in richer countries where people might be exercising a sort of economic caution like they do in a recession and where they back off on having more children. And so there was a concern that fertility rates might fall. And there is some evidence in some countries that may have happened, but that was mostly in the early days of the pandemic and really too early to have been affected by the pandemic. And it ends up that in the U.S., that effect was probably caused by the fact that you had fewer immigrant women arriving during the pandemic. And immigrant women tend to have more births on average. So it wasn't that there was a decline in fertility or recession like decline in fertility, but rather that the stoppage of immigration flows had a secondary impact on the fertility level in the U.S. And that by the time we got to 2021, when the pandemic had been there for long enough that people could have conceived births that were born in 2021, the fertility rate actually went up. It was the opposite of what people had expected, and it became a story about flexibility in work. And when people have greater flexibility in their working lives, they can better manage and balance the tradeoffs between work and family. And so the pandemic was a moment of discovery for many people when they realized that, wow, it's possible to have more flexibility in our worlds of work and family. And when we do, we might even have another child where we were hesitating before. 

Annelise Riles [00:12:15] Does the report take a position on family planning and the importance of giving women tools to control their own fertility?

John Wilmoth [00:12:24] The report doesn't necessarily take a position, but it echoes the position that has been taken by member states of the United Nations when they've met and made pronouncements on these topics, which the general guidance is that governments should support women and couples in their decisions about how many children to have and when to have them. And that should include providing access to family planning, both the services as well as information about the service. That this is part of health care. This is reproductive health care is a part of health care which is considered a human right.

Annelise Riles [00:12:58] What worries you the most and what are you most hopeful about?

John Wilmoth [00:13:01] I think the climate crisis worries me the most. This is something that we've been learning more and more about over the past few decades. It was clear early on that temperatures were rising around the world, that there was a connection between human activities and the gradual increase of the global temperature. But the evidence about extreme events was not as clear. And over the last few decades, the information and the scientific conclusion about the connections between human activities and extreme weather events has become more and more clear. And the scientists now, we've looked at this very closely rate, that confidence with much greater confidence. That's truly a problem. And we're seeing this all the time in the media. And what I worry about, to be honest, is whether humanity will be able to take the steps that are necessary to avert an even worse crisis, because we continue to consume. There are economic incentives to consume. There's really nothing about our economic system that encourages or requires people to avoid excessive consumption in a manner that pollutes the world in a grave way, which is global in scope, because it's affecting the atmosphere. And so I do worry about whether this will just continue and get worse, continue to get worse and spiral more and more out of control. And whether humanity will really be able to take the difficult steps that will be needed to change fundamentally their behavior. I'm most hopeful about human action and people who get excited about topics enough that they get out there and they try to make a difference. I don't think governments can do this alone. We really need the private sector to step up and to be involved in finding solutions here. And I think we increasingly see that in discussions at the UN certainly the importance of involving the private sector to make the kinds of transitions that we need to make. I'm hopeful about young people and what they can contribute and the ideas that they can bring. I'm always hopeful that there will be a way out of the crisis. 

Annelise Riles [00:14:55] Well, John Wilmoth, thank you so much for all you do to lead science and science based policymaking at the multilateral level. You're an inspiration.

John Wilmoth [00:15:05] Thank you very much, Annelise. It was my pleasure.

Annelise Riles [00:15:10] For more information on this episode and on the Northwestern Buffett Institute for Global Affairs, visit us at