Chapter 7: Land and Water Use

In this chapter, we’ll review Unit 5 of the AP Environmental Science Course, Land and Water Use. According to the College Board, about 10–15% of the test is based directly on the ideas covered in this chapter. If you are unfamiliar with a topic presented here, consult your textbook for more in-depth information.

As we’ll see in this chapter, humans use the land and water for countless reasons. We will begin our discussion with a description of the resources of the world—including what happens if people don’t get enough resources and who has too few. We’ll then go through the ways land and water are used for agriculture, forest resources, water use, mining, and urban development. We’ll end with a (short!) discussion of the economics behind our resource use and an introduction to the idea of sustainability.

SHARE AND SHARE ALIKE?

When people talk about managing common property resources such as air, water, and land, the “Tragedy of the Commons” often comes to mind.
This is an important concept introduced by the English economist William Forster Lloyd in 1833 and later applied to the field of natural resource management by Garrett Hardin in a 1968 paper published in Science magazine. In his paper, Hardin referenced the example used by Lloyd, in which a piece of open land, a commons, was to be used collectively by the townspeople for grazing their cattle.
Each townsperson who used the land continued to add one cow or ox at a time until the commons was overgrazed. Hardin eloquently says, “Each [person] is locked into a system that compels him to increase his herd without limit—in a world that is limited.
Ruin is the destination toward which all [people] rush, each pursuing his own best interest in a society that believes in the freedom of the commons. Freedom in a commons brings ruin to all.”
The tragedy of the commons serves as a foundation for modern conservation. Conservation is the management or regulation of a resource so that its use does not exceed the capacity of the resource to regenerate itself. This is different from preservation, which is the maintenance of a species or ecosystem in order to ensure their perpetuation, with no concern as to their potential monetary value.

In this chapter, we’ll continue to show how human economics influence how we interact with the Earth’s resources. Bear in mind that natural resources are drawn from the biotic and abiotic components of functioning ecosystems, and so our exploitation of those resources necessarily affects the functioning of those ecosystems.

Human impact in turn affects the ability of those ecosystems to continue providing the resources. When we humans exploit a resource for the functioning of society or for economic gain, we are placing an economic value on it; therefore, natural resources are described in terms of their value as ecosystem capital or natural capital.
Let’s start by discussing in turn affects the ability of those ecosystems to continue providing the resources. When we humans exploit a resource for the functioning of society or for economic gain, we are placing an economic value on it; therefore, natural resources are described in terms of their value as ecosystem capital or natural capital.

Let’s start by discussing the two main types of resources.

Renewable resources are resources that can be regenerated quickly, such as plants and animals. Water is an abiotic substance that’s renewable because it can be used over and over again and because sources of water are replenished naturally through the water cycle. Certain natural sources of energy—such as the sun, the wind, and the tides—are also considered renewable because their occurrence in nature is perpetual and not depleted with use. The time necessary for hardwood trees to mature (about 50 years) is widely considered the crossover point from renewable resources to nonrenewable resources. But, in purely practical terms, a resource is renewable if it can be replenished within the time it takes to draw down its supply. Bear in mind that even renewable resources must be carefully managed in order to conserve their sources and insure an ongoing supply.
Nonrenewable resources are resources that do not regenerate quickly, such as minerals and fossil fuels. Nonrenewable resources are typically formed by very slow geologic processes, so we consider them incapable of being regenerated within the realm of human existence.
There are a couple more terms you should know before we dive into our review of the major resources available to humans on Earth; these are consumption and production.
The consumption of natural resources refers to the day-to-day use of environmental resources such as food, clothing, and housing. On the other hand, production refers to the use of environmental resources for profit. An example of this might be a fisherman who sells his fish in a market.
AGRICULTURE
How do resources relate to your dinner? Well, 77 percent of the world’s food comes from croplands, 16 percent comes from grazing lands, and 7 percent comes from ocean resources. Despite the importance of our ever-increasing population, fewer people than ever in the history of the United States now farm the land. Why is this? The short answer is that it has a lot to do with increasing urbanization and industrialization. Now that machines are readily available to work the land and harvest crops, farms have become more like factories—currently only 2 percent of the United States population is directly employed in agriculture.
Farms in the United States today are quite a bit larger than farms of the past. The average farm is 434 acres, or a little less than an American football field, while in the early 20th century the average farm size was about 100 acres.
The use of machinery in farming has allowed farmers to work more land more efficiently; however, one of the drawbacks of the machinery is the amount of fossil fuel needed to power it. As the cost of fuel rises, the cost of food will also rise.
This rise in agricultural productivity can be tied to new pesticides and fertilizers, expanded irrigation, and the development of new high-yield seed types. However, it has also resulted in a significant decrease in the genetic variability of crop plants and led to huge problems in erosion.
Traditional Agriculture and the Green Revolution
Throughout most of history, agriculture all over the world was such that each family grew crops for itself, and families relied primarily on animal and human labor to plant and harvest crops. This process is called traditional subsistence agriculture, and it provides enough food for one family’s survival.
Traditional subsistence agriculture is currently practiced by about 42 percent of the world’s population, predominantly in developing nations. Such intensive mixed farming allows people to settle permanently and subsist without having to migrate seasonally.
Extensive subsistence agriculture results in low amounts of labor inputs per unit of land.
One form of traditional agriculture that’s still practiced in many developing countries today is a method called slash-and-burn, a practice that dates back to early humankind and is especially common in the tropics.
In slash-and-burn, an area of vegetation is cut down and burned before being planted with crops. Tropical soils are typically thin and poor, and whatever fertility they hold is rapidly depleted by the deforestation and subsequent farming. Therefore, the farmer must leave the area after a relatively short time and find another location to clear. Practiced indiscriminately on a broad scale, slash-and-burn agriculture has led to rapid deforestation of the tropical rainforest.

The Green Revolution, which occurred in the 1950s and 1960s, is generally thought of as the time after the Industrial Revolution when farming became mechanized and crop yields in industrialized nations boomed.

Monotonous Monoculture

Believe it or not, three grains provide more than half of the total calories that are consumed worldwide!

These three crops are rice, wheat, and corn, and the phenomenal increase in the yield of these crops was a result of genetic engineering. Genetic engineers discovered a way to cause plants to divert more of their photosynthetic products (called photosynthate) to grain biomass rather than plant body biomass.
It’s estimated that of the roughly 30,000 plant species that could possibly be used for food, only 10,000 have been used historically with any regularity.
Today, 90 percent of the caloric intake worldwide is supplied by just fourteen plant species and eight terrestrial animal species! In other words, today’s agriculture represents a major reduction in agricultural biodiversity.

Much of the farming that occurs today is characterized by monoculture. In a monoculture, just one type of plant is planted in a large area. Monocultures became common in the era of early political civilizations, when farms produced a staple crop in order to feed whole societies and armies.

As we discussed earlier, this has proved to be an unwise practice for numerous reasons. Plantation farming, which is practiced mainly in tropical developing nations, is a type of industrialized agriculture in which a monoculture cash crop such as bananas, coffee, or vegetables, is grown and then exported to developed nations.

Soil Problems for (and Caused by) Humans

In order to be able to grow all of the foods that humans consume, we must have enough arable—suitable for plant growth—soil to meet our agricultural needs. Soil fertility refers to soil’s ability to provide essential nutrients, like nitrogen (N), potassium (K), and phosphorus (P), to plants. Humus (remember, it’s in the O layer!) is also an extremely important component of soil because it is rich in organic matter.

Remember that soils composed of a balanced mixture of the three particle sizes (clay, silt, and sand) are described as loamy, and these types of soil are considered the best for plant growth. Another important characteristic for agricultural purposes is soil structure, or the extent to which it aggregates or clumps. Soil aggregates are formed and held together by such substances as clay particles and organic matter—plants and roots, the root-like filaments of fungi, and sticky substances released by bacteria and fungi. The most fertile soils have good structure.
Soil is considered a non-renewable resource due to the great length of time required to form arable soil. It takes 500 to 1,000 years to form a single inch of soil, and at least 3,000 years to form enough fertile soil to support crop growth.
Unfortunately, certain agricultural activities can change the texture and structure of soil; for example, repeated plowing tends to break down soil aggregates, leaving “plow pan” or “hard pan,” which is hard, unfertile soil.

Soil Erosion

The small rock fragments that result from weathering may be moved to new locations in the process of erosion, and bare soil (upon which no plants are growing) is more susceptible to erosion than soil covered by organic materials.

Because of the constant movement of water and wind on the Earth’s surface, the erosion of soil is a continual and normal process. However, when erosion removes valuable topsoil or deposits soil in undesirable places, it can become a problem for humans.
Eroded topsoil usually ends up in bodies of water, posing a problem for both farmers, who need healthy soil for planting, and people in general, who rely on bodies of water to be uncontaminated with soil runoff.
The most significant portion of erosion caused by humans results from logging and from agriculture—especially slash-and-burn agriculture, which we’ve already discussed. The removal of plants in an area makes the soil much more susceptible to the agents of erosion.
Unfortunately, human activities—unsustainable agricultural practices, overgrazing, urbanization, and development deforestation—have significantly increased the levels of erosion in the upper layers of soil. These processes will continue to create problems for farmers searching for arable land until new techniques that preserve the integrity of soil are introduced and utilized.

Soil Degradation

Much of what we know about soil conservation was established relatively recently. The Soil Conservation Act was passed in 1935 and led to the creation of the Soil Conservation Service.

These developments came in response to the Dust Bowl of the 1930s, which was a period of unprecedented dust storms caused by severe drought and ill-advised farming practices.
The Soil Conservation Service was a federal agency founded by Hugh Hammond Bennett. Its mission was to promote sustainable soil conservation practices among farmers and other landowners and to help restore ecological balance across the nation’s landscape. The agency is now called the Natural Resources Conservation Service.

Soil Conservation

In order to conserve soil resources, several best management practices have been developed. These practices return organic matter to the soil, slow down the effects of wind, and reduce the damage to the soil from tillage (plowing). Here are some of the more common methods.

Use of animal waste (manure), compost, and the residue of plants to increase the amount of organic matter in the soil.
The practice of organic agriculture, a method of farming that utilizes compost, manure, crop rotation, and non-chemical methods to enhance soil fertility and control pests. Organic producers avoid or strictly limit the use of chemical fertilizers and pesticides as well as genetically modified organisms.
Modification of tillage practices to reduce the breakup of soil and to reduce the amount of erosion. These include no-till farming, contour plowing, and strip planting.
Use of trees and other wind barriers to reduce erosion from wind.
The practice of contour plowing, in which rows of crops are plowed across a hillside, prevents the erosion that can occur when rows are cut up and down on a slope.
Terracing also aids in preventing soil erosion on steep slopes. Terraces are flat platforms that are cut into the hillside to provide a level planting surface; this reduces the soil runoff from the slope. Additionally, no-till methods are quite beneficial; in no-till agriculture, farmers plant seeds without using a plow to turn the soil. Soil loses most of its carbon content during plowing.
Plowing accelerates the decomposition of organic matter in the soil, decreasing soil fertility and releasing carbon dioxide gas into the atmosphere. (And as you know, increased levels of CO2 in the atmosphere have been associated with global climate change!)
Perennial crops—crops that grow back without replanting each year—are another way to reduce the need to till (by eliminating replanting) and keep erosion at bay. A windbreak is made up of one or more rows of trees or shrubs planted near crops in such a way as to provide shelter from eroding winds.
Finally, crop rotation can provide soils with nutrients when legumes are part of the cycle of crops in an area. An alternate to crop rotation is intercropping (also called strip cropping), which is the practice of planting bands of different crops in a field.

This type of planting can also prevent some erosion by creating an extensive network of roots. As you might be aware, plant roots hold the soil in place and reduce or prevent soil erosion. Another way to prevent soil degradation is to add nutrients to the soil using green manure or limestone.

Green manure is made by leaving plants (uprooted or simply sown) to wither and then serve as mulch: they are plowed under and incorporated into the soil before they can rot, providing valuable nutrients. Specific cover crops can be grown for this purpose.
Alternatively, pulverized limestone can be used as a soil conditioner to neutralize soils with too much acidity.

FOREST RESOURCES

Many environmentalists are concerned about the deforestation that is taking place in North America. It is interesting to note that the number of trees growing in North America is approximately the same as 100 years ago, but only 5 percent of the original forests are left. The numbers are approximately the same because of the number of trees growing in national parks and tree plantations. What does this mean? It means that most of the trees in North America are young, and that most forests have been harvested and replanted, and have undergone significant succession.

Deforestation, or the removal of trees for agricultural purposes or purposes of exportation, is a major issue for conservationists and environmentalists. Worldwide, industrialized countries have a higher demand for wood and less deforestation, while developing countries exhibit a smaller demand for wood, but more deforestation.
This can be partly explained by the fact that the deforestation that occurs in developing countries primarily takes place because land is being cleared for pastures and farms. Industrialized countries also import lumber from developing countries.
Nearly all of the deforestation that takes place in North America is done in order to create space for homes and agricultural plots. In sites where deforestation is occurring, the impact on resident ecosystems is significant. Take, for instance, Canada’s Vancouver Island. On this island, whole mountainsides have been stripped bare of the centuries-old forests that once existed. While the lumber industry tries to offset this destruction by planting new trees, the saplings, which won’t be harvestable for another 50 years, are no substitute for forests of 300-foot giant redwoods.
Despite the moral questionability of this habitat destruction, the lumber industry will not be asked to leave Vancouver Island. This is because it’s the island’s most important source of income. Fifty cents of every dollar the island earns comes from lumbering—this number easily beats the island’s income from tourism, which is the runner-up. This type of deforestation, also called clear-cutting, has other consequences as well.
The areas affected experience a great deal of runoff due to the loss of root structure, which leads to more erosion. The soil is washed into freshwater streams and rivers and makes the environment less suited for salmon. The loss of shade also leads to higher stream temperatures, which also affect aquatic organisms.
Another environmentally negative by-product of deforestation is seen in countries with tropical forests. In these forests, when trees are removed and farms are placed in the cleared land, the already-poor soil is further degraded, and the area can only support crops for a short time.
Usually, once the soil will no longer support a crop, the land will be used for grazing, but the soil becomes more and more depleted over time until humans have no use for it.
Additionally, any forest is made up of trees, which absorb pollutants and store carbon dioxide. Cutting and burning trees releases carbon dioxide (along with preventing those trees from absorbing it in the future), so deforestation contributes to climate change.

The negative repercussions of clearing tropical rainforests—the losses in biodiversity, and the erosion and depletion of nutrients in the soil, and the release of carbon dioxide—seem to outweigh the economic gains in many people’s opinions. However, for those who would like to take a standby refusing to purchase wood from tropical rainforests, it is often difficult to determine which wood products come from tropical rainforests cleared for slash-and-burn agriculture and which come from sustainable forests.

Various organizations, such as the nonprofit group the Forest Stewardship Council, have developed certifying procedures based on standards that will encourage only the use of wood from sustainable forests.

How Can We Use Forests Sustainably?

There are three major types of forests, which are categorized based on the age and structure of their trees. An old growth forest is one that has never been cut; these forests have not been seriously disturbed for several hundred years. Not surprisingly, the controversies that revolve around the issue of deforestation are primarily centered on instances in which deforestation is occurring in old growth forests. As we mentioned in the last section, old growth forests contain incredible biodiversity, with myriad habitats and highly evolved, intricate niches for a multitude of organisms. Second growth forests are areas where cutting has occurred and a new, younger forest has arisen naturally.

About 95 percent of the world’s forests are naturally occurring, and the remaining forests are known as plantations or tree farms. Plantations are planted and managed tracts of trees of the same age (because they were planted by humans at the same time) that are harvested for commercial use.
It makes sense that those in the forestry business would be concerned about finding a way to promote sustainable forestry, because without forests they have no way of perpetuating their income. From an economic viewpoint, the forest must be managed to continually supply humans’ need for wood.
The management of forest plantations for the purpose of harvesting timber is called silviculture. This relatively modern field has a basic tenet to create a sustainable yield; to do this, humans must harvest only as many trees as they can replace through planting. There are two basic management plans that attempt to uphold this tenet.
- Clear-cutting is the removal of all of the trees in an area. This is typically done in areas that support fast growing trees, such as pines. Obviously, this is the most efficient way for humans to harvest the trees, but it has major impacts on the habitat, as in our previous example of Vancouver Island.
- Selective cutting is the removal of select trees in an area. This leaves the majority of the habitat in place and has less of an impact on the ecosystem. When selective cutting is used, it’s quite difficult to remove these trees from the forest, though. This type of uneven-aged management is more common in areas with trees that take longer to grow or if the forester is only interested in one or more specific types of trees that grow in the area. Another type of uneven-aged management occurs in shelter-wood cutting. For shelter-wood cutting, mature trees are cut over a period of time (usually 10–20 years); this leaves some mature trees in place to reseed the forest.

In the case of agroforestry, trees and crops are planted together. This creates a mutualistic symbiotic relationship between the trees and crops—the trees create habitats for animals that prey upon the pests that harm crops, and their roots also stabilize and enrich the soil. Of course, two other options that can also have a great impact in mitigating deforestation are reforestation (planting new forests) and reuse of existing wood.

WATER USE

The following information about human use of water resources is not explicitly tested on the exam, but is helpful to know when you are thinking about water and about resource use. As you know, we all need water in order to live.

In particular, communities need water for many different industries, including fisheries, recreation, transportation, and agriculture.
Agriculture is one of the biggest water-users of all—about 73 percent of the global demand for water is for crop irrigation. Industry accounts for about 21 percent of all water use, and domestic use accounts for about 6 percent.

Since the 1950s, global water use has tripled—mostly due to population growth and improvements in the global standard of living. One way that humans have recently dealt with potential water shortages in communities is through interbasin transfer.

During interbasin transfer, water is transported very long distances from its source, through aqueducts or pipelines. An example of this type of engineering is the pipeline that now exists between the western and eastern slopes of the Rocky Mountains in Colorado.
Known as the Big Thompson Project, 213,000 acre-feet of water is delivered annually to the eastern slope of Colorado. However, this method has several negative effects. It can result in different geographic areas arguing over water rights.
It can also have serious environmental repercussions; interbasin transfer can increase the salinity of the water body being exploited and even change the local climate of an ecosystem.

In North America especially, humans rely on groundwater as a primary source of water for everyday use. Groundwater refers to any water that comes from below the ground—that is, from wells or from aquifers, which are underground beds or layers of earth, gravel, or porous stone that hold water.

Water found in an unconfined aquifer is free to flow both vertically and horizontally. A confined aquifer, however, has boundaries that don’t readily transport water.
Our reliance on and use of groundwater has several detrimental environmental effects; for example, it can result in a depressed water table and the drying up of local groundwater sources. In the late 1990s, a drought in Florida resulted in such a severe reduction in the aquifers that roads collapsed from lack of subterranean structural support. This subsidence (or sinking) of the Earth’s surface is another serious consequence of groundwater withdrawal.

Additionally, aquifers can become compacted—meaning that the mineral grains making up the aquifer collapse on each other and the material is unable to hold as much water. Furthermore, in most urban areas, humans have rendered the groundwater incapable of being replenished by building structures and roads that are impermeable to precipitation.

Global Water Needs

Scientists differentiate between countries that are water-stressed and those that are water-scarce. Countries that are water-stressed have a renewable annual water supply of about 1,000–2,000 m3 per person, but countries that are water-scarce have less than 1,000 m3 per person and lack sufficient freshwater resources to meet demand.
Currently, approximately 4 billion individuals experience severe water scarcity for at least one month a year, and 500–700 million people in 43 countries experience severe water scarcity year-round.
Many of the countries that are currently considered water-scarce are developing countries that have rapidly increasing populations—which means that their water-scarcity problems will grow over time.
Water scarcity is affected by national and regional politics, civil strife, and other issues affecting access and distribution; and lists of water-scarce countries differ by the source reporting.

However, among the countries currently experiencing the most severe water scarcity are Yemen, Libya, Jordan, Western Sahara, and Djibouti. Unfortunately, more and more countries are expected to become water-scarce by the year 2050.

Water Use in the United States

The United States is not considered water-scarce, but certain regions of the United States are considered water-stressed. Additionally, water use in the United States is out of control—we use water more quickly than it can possibly be replenished, so water scarcity is definitely in our future if we continue to use water at our present, furious rate.

What Are We Doing About It

Water is a tricky business. It’s difficult for politicians and lawmakers to put restrictions on water use because many people think that water should be free. After all, it falls from the sky; we can take a bucket from the lake down the street and no one will arrest us for stealing.

For the AP Environmental Science Exam, you should know about certain concepts of human water rights. The first is the idea of riparian right. Riparian means of, on, or relating to the banks of a natural course of flowing water, and riparian right is the right of people who have legal rights to use that area.
Alternately, in prior appropriation, water rights are given to those who have historically used the water in a certain area. In other words, prior appropriation can be thought of as water squatters’ rights!
It has been proposed that, in order to solve current global water crises, we simply take tons of ocean water and desalinate it—this is a fairly simple process physically, but unfortunately it isn’t currently economically viable on a large scale, because it takes a great deal of energy to remove the salt through distillation or reverse osmosis.
As water becomes scarcer globally, it will be important for countries to think of ways to regulate the use of water, as estimated global water consumption is set to continue rising. As global water crises become more common, research into the economic viability of desalination has increased.

Ocean Resources

The term fishery is used in several ways, but it is primarily defined as the industry or occupation devoted to the catching, processing, or selling of fish, shellfish, or other aquatic animals. In the economic sense, a fishery is the sum of all activities on a given marine resource.

Worldwide, about one billion people depend on fish as their main source of food, and about 35 million people are currently employed in the fishing industry.
Incredibly, about 172 million metric tons of fish are harvested each year—approximately 75 percent of this total amount is consumed as food by humans, and the other 25 percent is used for other purposes.
For many years, nations were subject to what is known as the 12-mile limit—this limited each nation’s territorial waters to just 12 miles from shore. However, in the late 1960s, the depletion of a number of offshore fisheries inspired the United Nations to host a series of international conferences to address the problems of fish scarcity.
The result of this conference was that nations were authorized to extend their limits of jurisdiction to 200 miles from shore. The depletion of marine fisheries worldwide came to be seen as a further example of the tragedy of the commons on an international scale. A new term was coined to recognize this shift: the Tragedy of Free Access.
Today, fishermen must go farther and farther out to sea to catch fish and need to rely on more sophisticated methods for finding them. Sonar mapping, thermal sensing, and satellite navigation are just a few of the advances that have aided fishermen as fish become scarcer and harder to locate.

MINING

Mining is the excavation of earth for the purpose of extracting ore or minerals. We can divide mineral resources into two main groups according to how they’re used.
Metallic minerals are mined for their metals (for example, zinc), which can be extracted through smelting and used for various purposes.
Nonmetallic minerals are mined to be used in their natural state—nothing is extracted from them. Examples of nonmetallic minerals are salt and precious gems.
Here are two more terms you should know for the exam, if you don’t already: a mineral deposit is an area in which a particular mineral is concentrated. An ore is a rock or mineral from which a valuable substance can be extracted at a profit.
The cost of extracting minerals depends on numerous factors, including the location and size of the mineral deposit. Additionally, the impetus for mining certain deposits more than others is often purely based on the value of the mineral resource. Understandably, the higher the value of the resource, the more money and effort will be put into mining it.
Environmental concerns about mining do not center on the depletion of mineral resources from the Earth’s surface. Instead, they revolve around the damage that is done during the extraction process. The extraction of a mineral from the Earth generally disrupts the ecosystem and scars the land. Sometimes the extraction leaves pollutants that result from the surface exposure of underground minerals, from transformation of these minerals during mining, from chemicals or other substances introduced during extraction, or even from the machinery used for extraction.
An example of this is the deposition of iron pyrite and sulfur in the mining of coal. The acid forms as water seeps through mines and carries off sulfur-containing compounds.
The chemical conversion of sulfur-bearing minerals occurs through a combination of biological (bacterial) and inorganic chemical reactions, and the result is the buildup of extremely acidic compounds in the soil surrounding the deposit. These compounds create acid mine drainage that can severely harm local stream ecosystems. In mining processes, waste material is called gangue, and piles of gangues are called tailings.

As the more accessible ores are mined to depletion, mining operations are forced to access lower grade ores. Accessing these ores requires increased use of resources that can cause increased waste and pollution.

Surface mining is the removal of large portions of soil and rock (this layer is called overburden, and it is whatever material lies above an area of scientific interest) in order to access the ore underneath. An example is strip mining, which involves removal of the vegetation from an area, which makes the area more susceptible to erosion. This type of mining is only practical when the ore is relatively close to the surface, which is why it’s used mainly for coal mining.
This is the least expensive—and least dangerous—method of mining for coal. However, because strip mining requires removing massive amounts of topsoil, it has a much greater impact on the surrounding environment than underground mining. The most extreme form of strip mining, mountaintop removal, transforms the summits of mountains and destroys ecosystems. This method is mostly associated with coal mining in the Appalachian Mountains.
As coal reserves get smaller, due to a lack of easily accessible reserves, it becomes necessary to access coal through subsurface mining, which is very expensive. With shaft mining, vertical tunnels are built to access and then excavate minerals that are underground and otherwise unreachable.
Another environmental drawback to mining is that the refinement of these minerals often requires extensive energy input. For example, it takes approximately 15.7 kW of electricity to produce one kilogram of pure aluminum from its ore.
On the other hand, recycling aluminum requires only 5 percent of the energy that’s required to smelt it and generates only 5 percent of the greenhouse gases. Recycle those soda cans!
After minerals have been extracted from their ore, they may be used in their rough form or further processed. Aluminum, for example, must be further refined after it is mined. Coal is an exception. After mining, it is transported to a power plant and burned in its original state.
Sometimes two metals are combined to form a product; this is the case with stainless steel, which is a combination of iron and either nickel or chromium, and regular steel, which is 95.5 percent iron and 0.5 percent carbon. Because of the energy expended in mining and extraction, the steel industry is responsible for much of the air pollution that exists today!
Fortunately, air, land, and water harmed by mining can be reclaimed through mine restoration projects. In 1977, Congress passed the Surface Mining Control and Reclamation Act (SMCRA), which created one program to help coal mines manage pollutants and another to guide the reclamation of abandoned mines.

HOUSING AND COMMUNITY

The majority of humans live in some type of community, and the largest percentage of the human population lives in relatively large communities and urban centers.

Since the development of ancient civilizations, humans have lived together in large, centralized communities, or cities. A couple of ancient cities that you may be familiar with are Rome (in what is now Italy) and Athens (in Greece).
However, never before have the urban centers of the world grown as quickly as they are growing now. If we traced the growth of urban areas in the United States, we would find that before the Civil War (around the 1850s), only about 15 percent of the population lived in cities.
Around the time of World War I (1920), that number grew to encompass about 50 percent of the total population of the United States, and today it hovers around 75 percent.

Globally, almost half of the world’s population today lives in an urban area. In the United States, this is partly due to the fact that our aging population has largely moved into the cities to have greater access to health services, employment opportunities, and cultural activities. When urban areas grow too large and become too dense, distributing water to all citizens becomes increasingly difficult. Coupled with this is the strain on the water supply—more people mean more water use. In many of these newly crowded areas, water shortages have led to the implementation of restrictions on water usage.

Additionally, urbanization impacts the ecosystem in which a city is located rather a lot. The sheer number of people using resources in such a densely packed cluster puts a strain on those resources far more than in any other location—and not just the water supply.
The burning of fossil fuels for industry, transportation, and electric power releases greenhouse gases and affects the carbon cycle.
The sheer weight of buildings and roads compacts the soil. The impervious surfaces that make up so much of a city’s footprint—concrete, pavement, etc.—do not allow water to reach the soil, disrupting the natural flow of water and causing runoff, which can lead to flooding without more infrastructure to redirect flow.
Methods to increase water infiltration (reducing runoff) include replacing traditional pavement with permeable pavement, planting trees (which redistribute water more evenly), increased use of public transportation (to reduce road usage), and building up, not out (decreasing a city’s overall “footprint”).
Runoff matters, because without the normal amount of water flowing into it, soil can become salinized, and saltwater can intrude into the water table.
Even the ubiquitous front lawn is often at complete odds to what the natural ecosystem of an area would look like, and the pesticides used to keep lawns looking up to social standards add to the number of pollutants present.
Another problem that results from the increase in the populations of cities is what to do with all of the waste that’s created. When you think about it, almost all human activities create waste—when you go to your local coffee shop and get a cup of coffee, you probably don’t think much of it.
However, if you get a cup of coffee every morning in a paper cup, five days a week for the 52 weeks of the year, then at the end of the year you’ve accumulated more than 250 cups! That’s a significant pile of garbage. This all has to go somewhere, and with the large populations in cities, landfills continually fill up and new landfills are required to replace them. (Not to mention that landfills also release greenhouse gases!)
Any type of redevelopment of these areas is hindered by the possibility that the soil and water are contaminated.

Building Sustainable Cities

In order for cities to be sustainable, city planners and developers must build and manage cities to work with, and within, their natural settings, instead of merely placing buildings and structures in these settings.

Big Cities in Less-Developed Countries

So far, we’ve made it sound like the cities of the world are dealing well with the boom in their population, but this is not true globally.

Some cities, called megacities, have grown in excess of 10 million people very rapidly. In less-developed countries, this increase in the population size of major cities has many very negative effects.
Among the worst effects is a deficiency of housing or habitable areas for the burgeoning population. As a result, people are homeless, become “squatters,” or make their homes in areas that are completely undeveloped areas that have no water, electricity, or stable, durable housing.
Some of the reasons people in less-developed countries are moving to cities are similar to those of people in developed countries: for example, cities have more opportunities for employment. However, these people often have other motivations that drive them out of the country, such as war, religious or cultural persecution, or the degradation of their environment.

Ecological Footprint

One concept that you should definitely be familiar with for this exam is that of the ecological footprint.

An ecological footprint is used to describe the environmental impact of a population or individual person. It is defined as the amount of the Earth’s surface that’s necessary to supply the needs of, and dispose of the waste of, a particular population or individual.
Americans have one of the largest ecological footprints: we require about 9.7 hectares per capita (per person). One hectare is 10,000 square meters, or about 2.5 acres. America’s amount is comparatively enormous—the ecological footprint of Indonesia is only 1.1 hectares per capita. In general, affluent populations have a much higher ecological footprint than non-affluent ones.