Introduction

It can be hard to grasp the impacts of climate change. Data sets, complex vocabulary, and confusing political views further complicate our understanding of this long-term, global concern. So how can we make sense of the overwhelming amount of information that’s out there? One way is to look at how environmental changes since 1800 have been intertwined with industrialization and enormous increases in the global population.

The Industrial Revolution changed how we work, where we live, and how many of us there are. Innovations in machinery that propelled industry and improved agriculture produced enough food for a population explosion. Labor underwent massive changes, as more people moved to cities for factory jobs. Human migration changed communities and created new cultural and economic networks of exchange. These new networks connected and further globalized the world.

By the mid-nineteenth century, industrialization had spread throughout the world. It benefitted some a lot more than others. European nations and the US gained the most. These wealthy, industrialized nations extracted resources from Africa, Asia, and Latin America to fuel their own growth. By the end of the nineteenth century, this uneven system of exchange affected everyone on Earth one way or another.

Population Explosion

We know industrial acceleration and globalization caused population growth. In 1803 the global population reached 1 billion for the first time. But that took thousands of years. Then, industrialization took off. And in just 150 years, from 1803 to 1950, the global population more than doubled to reach 2.5 billion. Then, by 1987, it had doubled again, and we were at 5 billion!

To put that in perspective, it took almost seven centuries (900 to 1500 CE) for the population to increase from a quarter billion to half a billion. But it took only two centuries for the world population to jump from one billion to a staggering 8,070,658,700 today—and that number is steadily increasing. And much of that growth can be linked to the effects of industrialization, namely food production.

Table 1: Total Population by Region (in millions, rounded)¹

However, there were also periods when the population fell dramatically in a short period of time. These drops were caused by disasters like the two world wars and global epidemics like the influenza outbreak of 1918. Industrialization played a part as well. Technological breakthroughs and mass production of weapons made war deadlier, and improved transportation helped deadly germs to spread faster and farther. However, innovations in medicine, transportation, and communication—all products of industrialization—let the population recover faster than it ever had in the past.

Increased Urbanization

After 1800, the areas where population increased the most were cities. People were migrating to cities for work long before industrialization. But the urban growth rate really increased after industrialization spread outside of Europe beginning around 1800. For example, in 1800 no region in the world had more than 13 percent of their population living in cities. By 2000, these numbers skyrocketed, as the table below shows. In fact, in 2008, for the first time in human history, the percentage of people living in urban areas was more than those living in rural areas. And by 2017, there were 4.13 billion people living in cities versus 3.4 billion in rural areas. The urbanization trend isn’t showing any signs of slowing down.

Table 2: City Life: Percentage of Urban Population by Region

Urbanization may have been good for employment, but it was generally bad for your health. As more people lived in close proximity, disease and pollution increased accordingly. However, over time, innovations in medicine and sanitation took care of some of these problems.

Advances in medicine also increased life expectancy. In the late nineteenth century, people only lived an average of 30 years! By the early twenty-first century, the global average was up to 71 years. If a 41-year increase in just over a century sounds normal, compare that with the previous hundred years. Life expectancy went from 29 years in 1770 to the ripe old age of 30 for folks in 1870. However, these numbers did vary around the world. Increases in life expectancy have been more pronounced in areas that industrialized first. Developing economies, such as those in Africa and Southeast Asia, have seen more modest climbs.

Environmental Changes

Analyzing rising population and life expectancy may make it seem as though everything got better over this period of time. Unfortunately, that’s not entirely the case. Yes, we have seen tremendous improvements in life expectancy and technological innovations, but industrialization has its downfalls. The industrial world depends on fossil fuels and burning them has hurt the environment.

For 400,000 years, the carbon dioxide level never exceeded 300 parts per million (ppm). Even in the first two centuries of industrialization, CO₂ levels stayed below this threshold. Then as a result of increasing industrialization after World War II, CO₂ levels exceeded 300 ppm for the first time in human history and these levels continued to rise. Current levels of CO₂ are now at 421 ppm. So why does this matter and how does this relate to population growth?

High levels of CO₂ in the atmosphere cause global temperatures to rise. We are already 1.5 degrees Celsius above what’s normal. The rise in CO₂ and global temperatures cause ice at the poles to melt, making sea levels rise. Human communities living near coastal areas are endangered by rising sea levels, and so are animal habitats. Considering nearly half of the human population currently lives within 100 miles of a major body of water, these rising waters will be a major challenge of the future.

But it is not just species on land that are threatened. The US National Oceanic and Atmospheric Administration released a report in 2019 detailing CO₂ increases in Earth’s oceans.

“The global ocean absorbed 34 billion metric tons of carbon from the burning of fossil fuels from 1994 to 2008—a fourfold increase of 2.6 billion metric tons per year when compared to the period starting...1800 to 1994” (NOAA).

These increases make the oceans more acidic, endangering marine life. Shellfish, for example have more difficulty producing their calcium carbonate protection (shell) because of the water’s increased acidity. Luckily, the oceans absorb some of the CO₂ that would otherwise lead to ever-increasing temperatures. However, an important question is whether the oceans can sustain these increases in CO₂ absorption.

Carbon dioxide levels and other pollutants have been increasing since the early nineteenth century. Burning coal to power factories, trains, and ships bathed whole cities in soot with noxious air—a grim image we often associate with the early decades of industrialization. As new engines were developed that relied on oil and gas, more pollutants were then released into the atmosphere and waterways. And as the global population doubled twice in the twentieth century, more resources, more production, and more fuel was needed. More people required electricity, usually generated from the burning of coal. More people required transportation, which led to more oil and gas for cars, buses, trains, and planes. More, more, more.

By the mid-twentieth century, people were feeling the effects of fossil fuel use. In 1948 and 1952, Donora, Pennsylvania and London, England had drastic episodes of toxic air pollution that caused more than 4,000 deaths. In the 1960s, scientists and governments began to call for environmental legislation to help alleviate some of the more dangerous side-effects of industrialization. Many of these actions helped reduce pollution. For example, volatile (dangerous) organic compounds that cause smog decreased by a factor of 50 in Los Angeles from 1960 to 2010, even though the number of gas-powered vehicles went up. However, we still have much more to do. Carbon dioxide levels plateaued (stopped rising) in the early twenty-first century but are now rising again.

Climate scientists around the world warn that if we do not act quickly to reduce emissions, both the Earth and humanity may be doomed.

So now what?

Collectively, humanity must cooperate. If we lower CO₂ levels and curb plastic use, we can, with effort and collaboration, replace these fuels with renewable energy resources like solar, wind, and water power. But what can we do as individuals to help our community and our planet?²

Jane Goodall, a noted primatologist and environmental activist, was recently asked what we can do today to help tomorrow. She said, “Everyday you live you make some impact. So start thinking about the consequences of the little choices you make. What do you buy? Where did it come from? Did it harm the environment?” If the majority of Earth’s 8 billion population took the time to think about these choices on a daily basis, then collectively, we could dramatically change the way we interact with the environment.

1 As of September 4, 2024, the world population according to the US Department of Commerce, Census Bureau was 8 billion. A visit to https://www.census.gov/popclock/ will tell you the current estimate.
2 To explore ways that you can help combat climate change, check out the articles, videos, and activities in Climate Project.