C - How Does Settlement Affect the Environment?

You probably would have lived with a small community of people. Your settlement would have had little impact on the environment. Today, there is a global population of 8 billion. As every year goes by, more of us are moving to cities. Now more than 450 cities have a population of over 1 million.

Our settlements now affect the environment in significant ways. Growing populations need water, food, land, and other resources, such as electricity and a system of sewage disposal. In both rural and urban areas, these needs can put stresses on the air, water, and soil, and can create different kinds of pollution.

As cities grow, they need to provide clean water for their populations. Cities also need to deal with the waste that their residents produce. This waste can include...

• liquids from baths, toilets, and sinks

• waste liquids from industries or manufacturers

• storm water run off

Wastewater needs to be treated so pollutants are removed before it is returned to any waterways. Solid waste, or garbage, also needs to be disposed of in a way that does not harm waterways or the land.

Not all cities can meet these needs. They may  not have enough money. They may have poor infrastructure, which means they lack the services they need to function. Untreated sewage, which includes human waste, is a major source of water pollution. About 80 percent of sewage around the world is untreated and flushed into waterways. As more people migrate into cities with poor wastewater treatment, the problem will get worse. The sewage systems in many cities are already overloaded.

Landfill sites are places where garbage is buried under the soil. The landfill sites in many cities are full, and they struggle to find new sites for storing waste safely. Many waste materials, especially electronic waste such as computers and televisions contain toxic pollutants. As the waste breaks down, pollutants can be released into the soil and pass into waterways. This can threaten the local freshwater supply. Pollutants from landfills can eventually reach the ocean.

MALE AND ITS ISLAND OF GARBAGE

Many cities have environmental laws in place to protect the air, rivers, and soil by controlling the dumping of waste. Others have created problems by dumping their waste irresponsibly. For example, Male is the capital of the Maldives, an island nation south of India. Male is the most populated city in the Maldives. Ten thousand tourists a week visit the Maldives, creating a huge amount of garbage. There is no space in Male to sotre all of this waste.

In 1991, Male created an artificial island, Thilafushi, to deal with its garbage problem. Built on a coral reef, Thilafushi is used as a dump site. Now there are mountains of garbage on the island. Smoke from the burning waste pollutes the air. Hazardous waste, such as asbestos and lead, is mixed with solid waste. It seeps into the ocean, harming local ecosystems. So much garbage is brought to Thilafushi that the island expands by a square meter every day. Many people worry that "garbage island" will affect tourism in the Maldives, in addition to damaging the environment.

Forests absorb and store carbon. This reduces the effects of carbon dioxide emissions, which cause global warming. However, forests near cities are often cut down to make way for new factories and housing. A 2013 report stated that 2.3 million km2  of forest were lost worldwide between 2000 and 2012. Only 800 000 km2  of forest were added.

Is urbanization having an effect on forests everywhere? According to the UN, it is not. The rate of deforestation may decline when countries become wealthier and when more of their population lives in cities. People rely less on wood for fuel and heat. They use renewable sources instead. They may begin to protect their forests instead of cutting them down for firewood.

This is not always the case, however. Fore example, according to one 2014 report, Canada, a wealthy nation with a high urban population, damaged more hectares of untouched forests than any other country in the world. As well, because urban populations tend to be wealthier than rural populations, they buy and use more animal products, such as meat or dairy products. However, producing animal products requires large amounts of land. Grazing animals need space. As well, it can take 5 to 7 kg of grain to produce every kilogram of beef, and this grain also requires farmland to grow. Often forests are cut down to provide this land. For example, in South America, 70 percent of Amazon forests have been cut down to provide land for grazing.

As populations increase, there is greater stress on the soil. More people are growing crops and raising livestock. As the soil becomes over-farmed, it loses nutrients. The soil dries up and blows away. Eventually the land is no longer arable. As you already know, this process of soil degradation leads to desertification. Half of the world's topsoil has been lost in the last 150 years.

Increasing desertification means that people must migrate to find new land for farming. If they cannot find arable land, farmers may move to urban areas to find other wordk. However, even some cities are feeling the effects of desertification. For example, Nouakchott, Mauritania, is slowly being covered by desert sand. Many people have moved to Mouakchott from more rural areas in teh past few decades because of drought. As the land outside the city becomes desertified, fewer people can survive there.

According to the UN, urbanization is also affecting the amount of arable land. For example, when people build structures, or use land for industry, that land is no longer available for farming. As well, it makes surrounding land less fertile. To fight against the loss of arable land, some urban communities are trying to increase local food production by turning open spaces--including backyards, parks, and even rooftops--into gardens for growing vegetables.