Human pressures on the global environment

Now that you've had a chance to look at your country’s population, country’s population growth, and maybe some other things that you were interested in, let’s talk about how we got to where we are today. And so just for the next five, eight minutes, we’ll talk about human pressures on the global environment, and what’s led to this, what’s led to where we are today with human population. And I think it’s worth starting off with looking at a sort of long view of world human population and that for the vast majority of, sort of what we would consider modern human society, we’ve been very few people scattered over the earth. So if we sort of think about the…

Let’s just go back to 7,000 BC or what we call the Common Era, before the Common Era. So today we, instead of using BC and AD, we use Common Era and before Common Era. So before the Common Era, there’s just really not a lot of people, always less than 500 million people on earth, and it slowly started to grow, but really high death rates, low infant mortality, sorry, high infant mortality. So you’d have high birth rates, but lots of people would die all the time. And people just couldn’t, really couldn’t grow as societies because it was always sort of an even birth/death rate.

Now you can see even little bits and pieces down here, the plague, a significant decrease in human population. And then something happened in the 18th century that allowed our population to just grow fantastically. And you can sort of, this is the future. We don’t quite know what’s going to happen in the future. But basically by 1800, we’re approaching 1 billion people, 1900, 1950, 1975, 2000 and 2100, you can see that we’re on this really steep up-slope in human population.

Why is that? What changed in the 18th and 19th centuries?

And so the agricultural revolution allowed population to grow from 10,000 BCE forward. And that’s basically the development of agriculture, right? And crops in one place and movement from, sort of a bigger movement from hunter gatherer to crops. Although people, there’s a lot of evidence out there now that people have been using crops for much longer than the last 12,000 years. So probably the big thing though is in the 18th and 19th centuries, we experienced the industrial revolution. And during that time between 1760 and 1840, we learn about sort of germ theory. We learn about using fossil fuels and coal, steam power, electricity, all sorts of new and amazing things.

And we’ve sort of unlocked the energetic potential of the earth, and we’ve unlocked the wonders of human medicine. And when we do that, what happens is all of a sudden death rates decline and birth rates increase. People can feed all the kids they have. Modern medicine prevents those children they have from dying, and you get a huge population boom, all right? It’s quite extraordinary. Not only are we getting more births than deaths, but all of a sudden people, not all of a sudden, but over time, people start to live longer.

So because of medicine, because of knowledge and increase in knowledge around medicine, and because of our ability to not only grow more food, but to transport that food to cities and to move it around the surface of the earth, life expectancy increases. And life expectancy is simply the average number of years that an individual is likely to live. So you can measure global human life expectancy. You can measure life expectancy in a country. You can measure life expectancy in a state or a territory. I mean, you can measure life expectancy in different neighborhoods of a city. So just depends on which population you want to look at. But urbanization, industrialization and personal wealth reduced mortality rates.

And that was through the quality of life, access to education, and healthcare. And the oldest person who’s lived on this earth was Jeanne Calment. I’m sure I’m brutally slaughtering that French pronunciation. This is a picture of her at 70 years old in 1945. And she lived to 1997. She lived to 121 years. She was born in 1875. This is a woman who saw huge changes in her lifetime from not ever seeing a car, or an airplane to watching people walk on the moon. Really incredible. Who knows maybe she even had a MySpace page. Look, so life expectancy is increased. And that’s part of why population’s increased.

Now here on the bottom, you can see that world life expectancy is about 69 years old.

In more developed regions of the world: Europe, North America, you see longer lifespans associated with better healthcare, education and quality of life. In less developed regions, 67 years. And in the least developed countries, with the least access to healthcare, education and the like, life expectancy is quite short at 56 years old.

Now, that quality of life comes with some caveats. Look affluence, wealth, they take resources. And don’t call it the accumulation of wealth for nothing. You’re accumulating resources. The amount of resources it takes to build a house like this on the left-hand side is orders of magnitude greater than it takes to build a house like this on the right hand side. So with human populations, you’re not only looking at how many people there are, you’re looking at the number of resources that they require, or that they use, you know. It’s not necessarily what they need or want, but what they actually use.

And the person who lives in this home uses far fewer resources than the person who lives in this home. And so when we look at human population growth, we have to consider not only how many people there are, but how many resources they’re using. I like this graph. This is how many, what year it was when we added each billions of people to the world populations. For example, the first billion of people took all of human history until 1800, to add 1 billion people to the earth. It only took 130 years after 1800 to add the second billion people to earth. And then only another 30 years to add another billion people to earth.

And then I was born in 19, you know, before 1974, don’t want to be too specific. I was born before 1974. So when I was born, there were four billion people on earth. When I was just in my last couple of years of high school, there were five billion people on earth. After I graduated from university, there were six billion people on earth. And when my child turned 10, there were seven billion people on earth. And now next year, when my child graduates in 2024, about when my child graduates, there’ll be eight billion people on earth. I’ve been alive long enough to see one, two, three, four billion people added to earth. I’ve lived through the doubling of Earth’s population.

Oh God! So it is impressive. Now, remember when we were talking about growth rates and we may see, and we’re already seeing an increase in the amount of time it takes to add the next billion people. And so that’s something to think about when we think about human population growth, cheers.