Revised 28 February 2025


For 10,000 years the world population grew very slowly until 1800. The world population by then had reached almost one billion people. From then onwards, the rate of exponential growth increased. 



Figure 1: Exponential Growth in World Population (Our World in Data 2021) 


Figure 2 below shows that In 1803, the world population was one billion people. By the end of 1927, the world population had grown to 2 billion people, a doubling time of 124 years. By 1975, the world population had grown to 4 billion people, a doubling time of 48 years. The world population in 2025 is almost 8.2 billion, a doubling time of 50 years since 1975.



 Figure 2: Time for global population to increase by one billion (Our World in Data 2021)



Figure 3 below shows that the most rapid growth rate in the world population occurred in the 1950s and 1960s peaking at 2.1% per year in 1971. From 1971 onwards, the world population growth rate started to decline. In recent years, we have been adding about 80 million people to the world population every year. The current world population in 2025 is almost 8.2 billion people (United Nations 2024).  The United Nations expects the world population to level out at 10.2 billion by the end of this century.




Figure 3: World Population Growth 1750-2100 (Our World in Data 2021) 


The increase in the rate of population growth from the 1950s to the 1970s was enabled by the green agricultural revolution when traditional farming practices were replaced by artificial fertilisers, pesticides, and farm machinery. Howard Odum (1971) pointed out that people were effectively eating oil as a result of the green agricultural revolution. This is even more so the case today with subsequent increases in the lengths of supply chains from the farm gate to the plate of each consumer due to the increase in globalisation of food production. 



Figure 4: Industrialisation of food production



Gross DomesticProduct (GDP) is a measure of economic activity in an economy both good or bad, and it has grown exponentially since the start of the industrial revolution and the use of coal in steam engines. Growth in GDP accelerated with the discovery and drilling of oil fields in the late 1800s (Hall & Klitgaard 2018). GDP per capita has also grown exponentially since the start of the industrial revolution.



Figure 5: Exponential growth in GDP (Our World in Data 2021)



Figure 6 below shows that the most rapid rate of growth in GDP per capita shown in green has been in the United States, Canada, Australia, and New Zealand. The rate of growth in the average world GDP per capita shown in black has been much slower.



Figure 6: Exponential growth in GDP per capita (Our World in Data 2021)


Economic growth has been possible due to the exploration, mining, and drilling of fossil fuels (Hall & Klitgaard 2018). As much fossil fuel energy used from 1800 until 1990, a period of 190 years, was used over a 30-year period from 1990 until 2020. Advocates of economic growth currently target a continued economic growth rate of 3% per year. This exponential rate of growth would require the use of as much energy as has been used since 1800 until 2020 over the next 24 years. 



Figure 7: Global Consumption of Fossil Fuels (Our World in Data 2021)