The world population is expected to breach seven billion this year, which is more than twice the number of people that lived on the earth just 50 years ago, according to recent projections by the United Nations.

The population is expected to exceed nine billion by 2050 and 10.1 billion by 2100. For the next forty years, an estimated 2.3 billion more people will be added: 97 percent of the growth will be in developing regions.

The numbers are drastically larger than anything the earth has experienced before - and scientists are very concerned about the impact this surplus of humans will have on the world. Namely, they are unsure whether the planet can actually sustain that many people.

The global population growth is expected to be highly uneven geographically.

In Africa alone, the population is expected to grow 1.1 billion, or 49 percent of the global projected growth, by 2050. Population is doubling every 20 years in some parts of Africa, making it impossible for communities to keep up with the growing demand for housing, roads, schools, and health clinics.

In certain developed countries like Japan and Germany, the growth rate is expected to stay flat or even decline. In the coming decades, these countries could face a crisis as society fails to produce enough adults to care for the elderly.

By 2050, the entire developed world is expected to contribute only three percent of the projected global growth.

"Although the issues immediately confronting developing countries are different from those facing the rich countries, in a globalized world, demographic challenges anywhere are demographic challenges everywhere," argues David Bloom of the Harvard School of Public Health.

The population growth began to accelerate with industrialization around 1750. The world reach one billion people in 1800 and two billion in 1925. The numbers grew dramatically in the last 50 years from three million to seven million and peaked in the mid-1960s at a growth rate of two percent per year.

“In the 1960s and 1970s, people expected a population bomb. Now, we have mini-bombs going off in the most fragile parts of the world. Issues of inequality and poverty may spill over from less-developed countries, which will not be good for their neighbors or the rest of the world,” Bloom told Bloomberg.

Meanwhile, global life expectancy is also expected to rise from age 69 this year to 76 in 2050. Nearly a quarter of the world's population is expected to be over 60 by then, which is about double the proportion it is today.

According to researchers, in 2011, nearly 135 million people will be born and 57 million will die. That's a net increase of 78 million people. The longer life spans and lower death rates play a role in explaining population growth; the variable that will make the greatest difference in how many people will live on earth in 100 years is fertility rates.

For example: If every woman had two babies, the world's population would remain as it is.

Yet, the global average is 2.5 births per woman. That's down from five in 1950, but the number varies drastically by geographic location.

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.