The global population is expected to top seven billion in 2011. By 2050, it's expected to exceed nine billion. By 2100, it's expected to rise to 10 billion.
The figures were cited by a Harvard School of Public Health press release about a review article of Professor David Bloom published in Science.
The global population growth is expected to be highly uneven geographically.
In certain developed countries like Japan and Germany, it's expected to stay flat or even decline. In the coming decades, these countries could face a demographics crisis as society fails to produce enough adults to care for the elderly.
Towards 2050, the entire developed world is expected to contribute only three percent of the projected global growth.
In developing countries, populations are expected to explode. In Africa alone, the population is expected to grow 1.1 billion, or 49 percent of the global projected growth, by 2050.
The demographics challenges in these developing countries are supplying food, water, housing and energy for the growing population, said Bloom.
However, contrary to popular belief, the earth isn't running out of resources to accommodate its growing population.
Agricultural scientists almost universally agree that the earth has more than enough arable land to feed people. The following link shows that if the world's population was packed in the same population density as New York City, the entire global population would fit in the state of Texas.
Nevertheless, starvation and overcrowding are common occurrences in developing countries because of technological backwardness, resource mismanagement, corruption, and many other factors.
To help meet the coming global demographics shift in all parts of the world, mankind needs to "tackle some tough issues ranging from the unmet need for contraception among hundreds of millions of women and the huge knowledge-action gaps we see in the area of child survival, to the reform of retirement policy and the development of global immigration policy," said Bloom.