population 7 billion

PowerPoint Show by Andrew

Just 200 years ago, there were only 1 billion people on the planet, and over the next 150 years, that number grew to 3 billion.

But in the past 50 years, the global population has more than doubled, and the UN projects that it could possibly grow to 15 billion by the year 2100. As the international organization points out, this increasing rate of change brings with it enormous challenges.

Meeting the basic needs of so many will mean growing, shipping, and distributing more food while providing more clean water, health care, and shelter -- all without inflicting too much further damage on our environment.

A street in Mong Kok district in Hong Kong. Mong Kok has the highest population density in the world, with 130,000 in one square kilometer.

Motorists crowd at a junction during rush hour in Taipei. There are more than 8.8 million motorcycles and 4.8 million cars on Taiwan's roads and nearly all motor vehicles and inhabitants are squeezed into a third of the island's area.

According to Honduras' health authorities, about 220,000 babies are born in Honduras each year and the cost of having a baby delivered at the public hospital is $10.

A long abandoned farmhouse sits in open fields near Osoyoos, British Columbia. British Columbia has one of the largest collection of ghost towns or derelict communities in Canada.

Public residential buildings are seen in Po Lam, one of the "satellite towns" in Hong Kong.

A neighborhood in the Sulawesi Sea in Malaysia's state of Sabah. A community of 30 families of the indigenous ethnic group of sea gypsies maintain a nomadic and sea-based life without fresh water supply, TV nor electricity, and only go to land to bury the dead.

In the remote village of Siyani in India, there are 350 unmarried men over the age of 35 - and hundreds more under 35 - because there aren't enough women to marry. Many women have also left to look elsewhere for grooms with more money and better prospects.

Marie and Gabrielle Vaudremer, a pair of 101-year-old Belgian twins, hold hands as they celebrate their birthday at a retirement home.

Men look at the overflowing Sardar Sarovar Narmada Dam on Narmada river at Kevadia Colony, some 200 kms from Ahmedabad, India.

The crowded maternity ward of the government-run Dr. Jose Fabella Memorial Hospital in Manila, Philippines.

Indian laborers are silhouetted after sunset at a construction site of a new apartment building on the outskirts of New Delhi, India.

The Dharavi slum in Mumbai, India, at twilight. Already the second most populous country with 1.2 billion people, India is expected to overtake China around 2030 when its population soars to an estimated 1.6 billion.

The sun sets over the Ifo extension refugee camp in Dadaab, near the Kenya-Somalia border. The whole of drought- and conflict-wracked southern Somalia remains in a serious food crisis.

An aerial view of the island of Out Skerries. It is a tiny, treeless island off the east coast of Scotland where the population is just 65. There are only seven children on the island making the school the smallest in the UK.

Aron Anderson, 6 plays in the playground at Out Skerries school. Aron is one of only seven children on the entire island.

A view of a residential building in Shanghai, China. Shanghai is currently the most populous city in the most populous nation in the world, home to more than 23 million residents.

A traditional Mongolian tent near Zuunkharaa city, Mongolia. Mongolia is the world's least densely populated country, with 2.7 million people spread across an area three times the size of France.

A cargo train on the Kenya-Uganda railway line travels through the sprawling Kibera slum, one of the largest and poorest slums in Africa and home to about 1 million people.

People gather to get water from a huge well in the village of Natwarghad in the western Indian state of Gujarat.

Workers remove floating garbage from Three Gorges reservoir area in Yunyang County, China.

Residents crowd in a swimming pool to escape the summer heat during a hot weather spell in Daying county of Suining, China.

Nurses watch over premature babies in the natal intensive care unit of a public maternity hospital in Gatire on the outskirts of Caracas, Venezuela.

Thousands of Bangladeshi Muslims board overcrowded trains as they try to return home after attending a three-day Islamic Congregation on the banks of the river Turag in Tongi, outskirts of Dhaka, Bangladesh.

A nurse fills in documents minutes after a baby was born inside the childbirth unit at hospital Escuela in Tegucigalpa, Honduras.