When agriculture was introduced about 8000 to 12000 years ago, the population was small, roughly about 8 million.
In the first century (C.E) it was below 300 million.
Causes of Population Explosion
World trade expanded during the 16th and 17th centuries, setting the stage for rapid population growth.
During, the dawn of the Industrial revolution around 1750, the World population was around 550 Million.
The world population exploded in the 18th after the Industrial Revolution.
Technological advancement reduced the death rate and provided the stage for accelerated population growth.
As per the current trends of the world, the population is expected to reach 8.6 billion in 2030, 9.8 billion in 2050, and 11.2 billion in 2100, as per the UN report.
The current world population is 7.6 billion.
Approximately 83 million people are added to the world population every year, and this upward trend will continue and even assuming that the fertility level will continue to decline.
The current world population, according to the UN Department of Economic and Social Affairs, in Feb 2019, the population is 7,685,036,620.
The new projections include some notable findings at the country level. China (with 1.4 billion inhabitants) and India (1.3 billion inhabitants) remain the two most populous countries,
comprising 19% and 18% of the total global population respectively. In roughly seven years, or around 2024, the population of India is expected to surpass that of China.
Among the ten largest countries worldwide, Nigeria is growing the most rapidly.
Consequently, the population of Nigeria, currently the world’s 7th largest, is projected to surpass that of the United States and become the third-largest country in the world shortly before 2050.
Most of the global increase is attributable to a small number of countries.
From 2017 to 2050, it is expected that half of the world’s population growth will be concentrated in just nine countries: India, Nigeria, Congo, Pakistan, Ethiopia, the United Republic of Tanzania, the United States of America, Uganda and Indonesia (ordered by their expected contribution to total growth).
The group of 47 least developed countries (LDCs) continues to have a relatively high level of fertility, which stood at 4.3 births per woman in 2010-2015.
As a result, the population of these countries has been growing rapidly, at around 2.4 % per year.
Although this rate of increase is expected to slow significantly over the coming decades, the combined population of the LDCs, roughly one billion in 2017, is projected to increase by 33 % between 2017 and 2030, the world population will reach 9.7 billion in 2050.
Similarly, Africa continues to experience high rates of population growth. Between 2017 and 2050, the populations of 26 African countries are projected to expand to at least double their current size.
The concentration of global population growth in the poorest countries presents a considerable challenge to governments in implementing the 2030 Agenda for Sustainable Development, which seeks to end poverty and hunger, expand and update health and education systems, achieve gender equality and women’s empowerment, reduce inequality and ensure that no one is left behind.
Population in the world is currently ( 2019) growing at a rate of around 1.09% per year (down from 1.12% in 2017 and 1.14% in 2016).
It is estimated to reach 1% by 2023, less than 0.5% by 2052, and 0.25% in 2076.
In 2100, it should be only 0.09% or addition of only 10 million people to a total population of 11.2 billion. The world population will, therefore, continue to grow in the 21st century.
Doubling Time of population
Doubling time is the amount of time it takes for a given quantity of population to double in size at a constant growth rate.
We can find the doubling time for a population undergoing exponential growth by using the Rule of 70.
It is because the population of a country becomes double in 70 years if the growth rate is 1%.
Thus, we divide 70 by the growth rate and we get the doubling time of population growth rate.
For example, if the growth rate is 2.08, divide 70 by 2.08 and we get 33.6 years as the doubling time of population.
World population has doubled in 40 years from 1959 ( 3 billion) to 1999 ( 6 billion).
It is now estimated that it will take another nearly 40 years to increase by another 50% to become 9 billion by 2037.
The latest world population projections indicate that the world population will reach 10 billion persons in the year 2055 and 11 billion in the year 2088.
World Population Milestones
According to the United Nations, the 6 billion figure was reached on October 12, 1999 (celebrated as the Day of 6 Billion).
The world population reached 7 Billion on October 31, 2011.
The current world population is 7.7 billion as of Feb 2019 according to the most recent United Nations estimates.
The United Nations projects the world population to reach 8 billion in 2023 and 10 billion in the year 2056.