You probably know that the population of planet Earth is growing, but have you ever wondered how fast it's growing? How many people are added to the planet, every second, every minute, every year? Well, it turns out that there's about 2.5 people added to our population every second. About 141 people are roughly a planeload added every minute. And every year, there are 78 million new people on this planet. That's roughly the country of Egypt's population. The question then becomes exactly where are we going to put all these people? I'd like to highlight the growth in human population absolutely drives environmental health issues. You may realize this intuitively, but I'd like to show you some visual examples. What we're looking at here are images of the city of Shanghai in China. Shanghai, perhaps one of the most rapidly developing cities in the history of the world. So this first photo looks at Shanghai in approximately the year 2000 and you can see it's already a fairly built up city with some high-rise construction, and fair amount of density. But then if you look at this next photo of Shanghai in 2015, that's the same Bend in the river that we're looking at here. You can see there's just been explosive growth upward where now we have some exceedingly tall buildings added to what was already a pretty congested skyline. We can also look at this in a slightly different perspective. These are some images from the National Aeronautics and Space Administration, NASA showing Shanghai from overhead via satellite view. So here's an image of hi taken in April of 1984. You can see the city is basically the sort of black gray cluster of buildings and Roads towards the center of the image,, growing towards the banks of the nearby river. If we fast forward just five years to 1989, you can see the city has started to expand it somewhat. Going forward to 1994, again, you can see the city has continued to grow at a relatively modest pace. But if we fast forward to 1999, you can now see the city is really starting to expand its footprint. Going forward to 2004, now you can see that the city has grown to come into contact with the river area, but also expanded in all other directions as well. By 2009,you can see the city has continued to grow now basically spanning the river. And if we fast forward to 2014, you can see what was initially a relatively small city has now sprawled into an enormous metropolis. By 2016 just two years later, the growth has continued in an observable manner. In 2014, there were about seven billion people that lived on planet Earth. And as I've already said, there's another 78 million or so that are added annually. If we project forward by 2025, we're anticipating a population of 8 billion. And by 2050, depending on what predictions you look at. The population could be somewhere between 9.4 billion and 10.2 billion people. Now, that growth is not happening equally around the world. In fact, greater than 90% of the growth is occurring in the world's developing countries. Primarily in sub-Saharan Africa, in the Middle East and in South Asia. There's actually a bit of good news here in that the current population growth rate is actually slower than was projected back in the 1970s. So in fact, in 1970, the projection going forward was that the population would grow by 2% annually. But in fact the annual growth rate in 2014 was only 1.17%. That can sound like a small sort of rounding error. But when you consider we're talking about means of people, even that small percentage change can add up to a huge difference. Here's a photo of Tokyo, which is considered the largest urban area in the world with a population of 38 million. If you haven't been to Tokyo, I can convey to you from my personal experience that this is a very realistic depiction of Tokyo and other incredibly dense highly populated cities. We've got just lots and lots of people. And again, the challenge is how do we accommodate all these people and ensure that they have access to good health. We've got a number of factors that work together here to determine population pressure. The first one I'd like to highlight is fertility rate. And so back in 1970, the average woman on the planet was having 4.8 children over her lifetime contrast that to 2014 where that number had dropped by nearly half to 2.5 children per woman. The graph you're looking at here shows fertility rates by country. And so here, you can see that for most of the world, they're In light brown or darker brown basically at the bottom end of the scale here with the lowest fertility rates. But again, Sub-Saharan Africa, the Middle East and South Asia, we see countries with some of the highest fertility rates on the planet. So that's one factor that's driving population pressure. Another one is average life expectancy. Back in 1970, the average person on the planet was going to live 59 years. If we fast forward to 2014, now the average life expectancy is 72 years. And finally, the third factor to consider is the death rate. So back in 1970, 12 out of every 1,000 people would die on an annual basis. In 2014, that number had dropped, again, almost in half to 7.7 per 1,000 people. So we've got fertility which has been declining, but that's sort of counteracted by people living longer and fewer people dying. All of these things are resulting in our current population pressure. In fact, if we look around the world, there are 65 countries that are now below replacement level fertility. Basically, that means these countries are having fewer than 2.1 children per couple. Why 2.1 children? Well, we need 2 children to replace the 2 parents and the 0.1 basically accounts for childhood mortality. So of these 65 countries whose populations are declining, because they're no longer replacing their population through fertility, 56 of those countries are developed. So we see At these countries that have stabilized or whose population is started to stagnate or even shrink our well-over-represented among developed countries and there are very few developing countries on this list around the world. The fastest population growth is happening in regions that unfortunately are also facing the greatest environmental health hazards. So these are things like air pollution and water pollution, and injuries. The graph we're looking at here shows levels and trends of the world's population broken out by different regions. And so you can see there's estimates going back to 1975 all the way forward to 2015 and then projections forward from 2015 to 2050. So I'd like to draw your attention to a few of the trend lines on this graph. You can see the lines clustered around the bottom of the graph are for places like Europe and Latin America, and North America, and Oceania. So basically, we're seeing essentially a perfectly flat trend there no real increase in population, but the two lines that goes swooping upwards out of the bottom of this graph correspond to Africa in blue and Asia in dark red and you can see there. We see tremendous population growth with Asia in the lead through 2015 and maintaining that lead or greatest population through 2050, but Africa has sort of rapidly increasing and potentially converging with Asia around the year 2100. So we know that environmental health hazards are present around the world, but we do know that Asia and Africa and particularly the developing countries. There are facing greater environmental health hazards than some other countries around the world. All this leads to a natural question, which is what is Earth's carrying capacity. In other words, what's the maximum supportable human population? Well, we currently have about 3.5 billion acres of arable land that we can use for food production. If everybody on the planet wanted to live like a vegetarian, it's anticipated that we could have a population of as many as 10 billion. But if everyone wants to live like a citizen in the US and be an omnivore with, for example, a lot of consumption of meat, the sustainable population is more like 2.5 billion which is a problem, of course, because we've already got 7 billion plus living on the planet. What we're hoping to avoid here is something called Thomas Malthus's catastrophe. So this was an idea put forth by Thomas Malthus in 1798. You can see Illustrated in the chart on the right here. So basically, what Thomas Malthus predicted is that if we look over time and time is our x-axis with increasing time, we expect our production of food to increase. So you'll see a straight line on that graph labeled production of food. So as there's more of us, more of us are able to work the land and create food. So we have that very linear growth in food production. The problem is population doesn't grow linearly. You can see their swooping upward line labeled population on this graph. The population growth is relatively linear at the start, but then starts to exponentially accelerate. What we're trying to avoid here is what's labeled as the Malthusian catastrophe. We're basically our population has exceeded the ability. We have to feed that population. That's going to lead to collapse and catastrophe. Now, there's consensus on three things that we need to do to come up with a sustainable population. One is to protect the environment. Two is to increase living standards and achieve health equity for everyone, and three is to slow population growth. So we have these three needs. We need to protect the environment. We need to increase living standards and we need to slow population growth fortunately. These things are mutually reinforcing. And if we can accomplish all three we should be able to achieve a see the animal population on the planet. Now, I want to wrap up by highlighting that pressure on resources from population is absolutely not equitably distributed around the world. In the US and everywhere around the world, we have in equitable distribution of resources and that tends to lead to poverty. We see that in the United States. But when we look globally, we see more extreme poverty. So for example, about 10% of Earth's population earns less than $1.90 per day. That sounds terrible. It's actually good news. That number is down by more than a third since 1990. We know that more than half of the extremely poor population in the world lives in Sub-Saharan Africa. We also know that 11% of the world's population can't satisfy their basic daily food needs and that the global poor who are making these extremely small amounts of money, and facing food insecurity tend to live in rural areas. They're poorly educated. They're employed in agriculture typically and their children less than 18 years old. So all of that information is tragic and troubling. The good news is again, we have tools available to us to deal with this in environmental health. So once we identify these populations with the correct political will and resources, we have ways to address these challenges of environmental health threats and nutrition. We simply need the will to do so and we absolutely have to find that will in order to ensure that people around the world have good health, and health equity.
