Earth's Finite Resources and Human Extraction

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Because Earth is essentially a closed system, there is a finite amount of matter on the planet and in its atmosphere. All of the matter that we have now, is all the matter that there will likely ever be on Earth. There would only be added matter if, for example, the Earth were to be bombarded by meteorites, and their matter was incorporated into Earth.

Figure 18: In this example of the Law of the Conservation of Mass, the two chemical reactants
are mixed to form different products. The chemical form of the matter has changed, but the
total mass has not.1

The Law of Conservation of Mass states that matter cannot be created or destroyed. It can be changed and its composition can be rearranged to form different materials, but the total amount of matter is conserved through these processes (Figure 18). This means that there has always been the same amount of hydrogen, oxygen, carbon, and all of the other elements contained within the Earth and its atmosphere, although the elements change forms and redistribute themselves throughout the different spheres through biogeochemical cycles.

In more recent times, humans have mastered the change and reorganization processes of much of the matter that exists on the surface of the Earth. This means that humans can modify matter for their own purposes. However, there is a danger involved in modifying matter according to human needs and desires. The value, availability, and productivity of the finite matter on Earth can be reduced as a result of pollution and/or over-harvesting. Additionally, any time we industrially transform a natural resource, we risk doing so irreversibly. This means that a natural resource may be altered to such an extent that it does not readily re-enter natural biogeochemical cycles.

The elements used to synthesize plastic are an excellent example of this. Plastics are made of large chains of carbon molecules that are bonded to other chains of carbon. In synthesizing plastics, additional elements are introduced, like hydrogen, oxygen, nitrogen, chlorine, fluorine, or sulfur, causing the carbon chains to take on different properties, resulting in different types of plastics. For example, polyvinyl chloride (PVC), which is used to make plumbing pipes, contains chlorine atoms. Teflon, used as a non-stick surface on the inside of cooking pans, is formed when fluorine is added to the carbon chain matrix.

Figure 19: A Mahi Mahi fish caught in the
Atlantic Ocean off the southeast Florida
coast, U.S.A. The stomach contained a
large plastic aerosol cap. 1

  • 1.

    Image compliments of Captain Joe Dobbin and Michael D. Searle.

Too much altered (non-natural form) matter disrupts the planets’ natural cycles, which are all interconnected. For example, the elements that are bound in plastics remain removed from the natural biogeochemical cycles for decades to hundreds of years because plastic does not decompose. Plastic is a relatively new and human-made material on Earth. As such, no bacterial decomposers have evolved enzymes that can decompose the material, and similarly, no animals have the enzymes to digest it. Therefore, plastic waste is non-biodegradable, and it has accumulated in landfills and in the oceans. Sea creatures of all kinds are ingesting plastic waste (Figure 20), which accumulates in their guts, disrupting their digestion.

While plastic is not biodegradable, it can be mechanically broken apart, weathered, and eroded into finer plastic particles over decades of time.  During this process, the eroding plastic leaks toxic chemicals known as carcinogens into the ocean, which are also consumed by fish, whales, sea birds, seals, and other sea creatures, posing a different kind of health threat to their survival.

The process of transforming matter from its natural state into new human-made material can produce decay-resistant waste as well as hazardous byproducts (as with plastic). If the used materials and the industrial byproducts have no current commercial use, they are both discarded as waste. Waste in general is very disruptive to natural processes. Waste comes in gaseous, liquid, and solid phases, and it contaminates air, water, soil, and living organisms.

All of these environmental challenges linked to resource extraction are intensified by human population growth. Today there are over seven billion people on the planet and our population growth is projected to reach over 9 billion by mid-century. Resource needs and demands are directly proportional to our growing numbers, improving health, and the quality of life. Thus, we are extracting resources from Earth at greater and greater rates. Extraction pressure from the growing human population is greatly exceeding replenishment rates of critical resources, and in some cases, depleting these resources to extremely low levels and converting them into waste. The rest of this section will describe how natural resource extraction, transformation, and waste are impacting Earth’s four spheres.

The Atmosphere

The atmosphere is composed of a mixture of various gases. Those most essential for sustaining life are nitrogen (N2), oxygen (O2), carbon dioxide (CO2), and water vapor (H2O). Oxygen is required by animals and plants for cellular respiration. Nitrogen is required as a structural component of all amino acids, which are the building blocks of proteins in plants and animals. Carbon dioxide is the primary source of carbon for plants, which, in turn, supply organic carbon in the form of carbohydrates, proteins, and lipids to the rest of the food web. Water is critical for all life, and makes up the majority of tissue mass in plants (up to 95%) and animals (approximately 57%).

As already discussed in the previous section on the carbon cycle, the extraction of ancient geological stores of organic C-based fossil fuels and burning them to fuel our world economies has resulted in elevated atmospheric CO2 levels that are driving climate change and ocean acidification. As a result, Earth’s carbon cycle is dangerously out of balance.

Looking Ahead

There will be an in depth discussion of the impact on the carbon cycle of fossil fuel extraction and use for energy in the Climate Change chapter.

Nitrogen is the most abundant gas in the atmosphere, comprising 78% of all molecules in our air. Recall that through microbial nitrogen fixation, the N2 in the atmosphere is converted to a bioavailable form (NH3) for plant uptake. Prior to World War I (1914-1918), the only new nitrogen found in soils came from these naturally occurring nitrogen fixers, and crop production was limited by inadequate concentrations of bioavailable soil nitrogen.

However, in the early 20th century, humans developed a way to fix N2 through an industrial process. The process uses energy to break the two nitrogen atoms apart, and then combines the nitrogen atoms with a source of hydrogen (H2) to form ammonia (NH3). This process, called the Haber-Bosch process (named after the two German chemists who developed it), enabled the production of synthetic crop fertilizers that in turn expanded agricultural production several fold.

Between 1960 and today the amount of biologically available nitrogen on Earth has nearly tripled from the normal base-line level found in natural systems, due to human synthesis of fertilizer. Each year we extract over 120 million tons of inert nitrogen (N2) gas from the atmosphere and transform it into ammonia (NH3) to make fertilizers for use in agriculture. This has been the major contributing factor to pushing the Earth’s nitrogen cycle significantly out of balance.

Closer Look

Learn about the dead zone in the Gulf of Mexico in this short film.

Today, fertilizers are so abundant and inexpensive that they are applied in excess to crops around the world. Since the fertilizer that is applied is not all utilized by the crops, the excess elements are washed off agricultural fields by rain and enter waterways, and eventually end up in oceans.

Nitrogen runoff indirectly causes anoxia and massive die-offs of plants and animals in ocean coastal areas called “dead zones” (Figure 20).  For a detailed explanation of dead zones, refer to the water chapter.

Figure 20: Over 400 coastal dead zones occur globally; eutrophic zones are highly
nutrient enriched and in danger of becoming hypoxic. For additional information
see this interactive map.1

The Hydrosphere

The hydrosphere consists of all the water on Earth, including the water in the atmosphere. As previously mentioned, water is essential for sustaining all forms of life. However, of all the water on Earth, only 2.5% is fresh water, that is, water which is conducive to supporting human life. As you will read in the Water Chapter, the location of much of our precious fresh water is in glacial ice, surface water, and groundwater; three sources that are each dwindling in size.

Humans use water for three primary reasons: drinking, agriculture, and industrial processes, such as mining and manufacturing. The first two uses of water will be discussed in the Water Chapter. Here, we will focus on the impact of mining, manufacturing, and industrial processes on water.

Demand for clean fresh water continues to increase as our human population rises. However, simultaneously, the clean water supply continues to shrink. Freshwater streams, lakes, wetlands, and underground aquifers around the world are impacted by runoff from mining and hydraulic fracturing (fracking), and industrial chemical waste which can be toxic.

Water pollution, when released in high concentrations and/or slowly over long periods, can harm and kill plants and animals. Of course, humans are also impacted. Drinking and bathing in water that is polluted directly harms humans, especially small children and the elderly, and toxic chemicals that accumulate in aquatic top predators (fish and sea mammals) can make some species unsafe to eat. The World Health Organization estimates that 3.4 million people die each year because of contaminated drinking water, most of them under the age of 5.

Feeding and providing water for a growing human population of over 7 billion is both a necessity and a challenge. The extraction of fossil fuels for energy production uses enormous volumes of freshwater--over 52 billion m3/year. Nearly 40% of this is used in extraction, production, and supply of fuel from oil and gas. Fuel in the form of corn-based ethanol accounts for another 15%, coal used for heating accounts for 12%, and electricity from coal-fired power plants uses nearly 16%.

Closer Look

Read more about “the new global water crisis” in this Food and Water Watch report.

Hydraulic fracturing (fracking), a more recent technology for extracting natural gas from the Earth’s crust, may use more water than any other fossil fuel extraction technique. Fracking also mixes freshwater with over 500 different solvents, acids, and toxic chemicals, rendering the water contaminated with carcinogens, and toxic chemicals known to disrupt the nervous, endocrine, immune, cardiovascular, and respiratory systems. The international organization Food and Water Watch (FWW) calls fracking “the new global water crisis”.

Closer Look

Watch this short film which describes fracking and its potential opportunities and dangers.

Fracking impacts both water quantity and quality. As explained in the FWW report, in fracking, a toxic chemical and water solution is injected underground under high pressure in order to open up cracks in the ground and push the natural gas toward the surface. However, sometimes this chemical and water solution will come to the surfaces itself. Along with the chemicals originally put into the solution, this waste water can surface with additional toxic natural elements like heavy metals (chromium, strontium, barium, zinc, lead, arsenic) and radioactive materials like Radium-226, all of which naturally occur deep underground.

Figure 21: Open pit gold mine in Australia.1

Similarly, mining of metals and other minerals from the lithosphere  requires very high volumes of fresh water, and typically produces problematic toxic waste water. Open pit mining (Figure 21) is a common method of natural resource extraction, which exposes toxic substances that naturally occur underground.

Weathering by rain and wind dissolve and move toxic mining chemicals into streams, lakes, wetlands, and ultimately the oceans. Near Silverton, Colorado, in the United States, 3.79 million liters of gold mine operations waste water was accidentally spilled into the nearby waterways in 2015, contaminating water and soils for hundreds of kilometers downstream of the mining site (Figure 22).

Figure 22. Toxic waste water from an abandoned gold mine in southern Colorado, USA. The bright yellow water contains high concentrations of acid and heavy metals including lead, cadmium, aluminum, copper, and arsenic.1

The Biosphere

The biosphere refers to the sum total of all life forms on Earth, and these life forms inhabit the atmosphere (primarily microorganisms drifting in the wind and in clouds), the lithosphere (land organisms are referred to as terrestrial; those belowground are called subterranean), and the hydrosphere (aquatic organisms in fresh and salt waters, surface and subsurface waters).

The biosphere provides critical resources for our biological needs, including all of our food, harvested both from the wild and from domesticated plants/crops and animals/livestock. Plants and animals also serve other important uses for humans, including providing fibers that can be woven into cloth or used to make paper, and fur, horn, and bone that can be used to make clothing, tools, and jewelry. We use wood for building materials and as fuel for heat or cooking. Oils and fats are used to make materials soft and pliable or water proof, and as lubricants. Pigments are used as dyes, fragrant oils for perfumes, essential oils for healing purposes. We also use phytochemicals as medicine. Other unique materials, such as natural rubber are used in multiple commercial products.

Looking Back

The Biodiversity Chapter includes a detailed description of ecosystem services.

The biosphere also provides critical ecosystem services such as oxygen production, water purification, and the decomposition of waste. We often take for granted these and other ecosystem services provided by the biosphere, and yet they are critical to our existence on Earth.

Impacts on Terrestrial Ecosystems

Different types of ecosystems provide humans with different types of necessary resources. For example, forests, which occupy 31% of the land on Earth, are home to many unique species of plants and animals. They provide numerous natural resources to people as well, and are important in mitigating global climate change by sequestering great volumes of atmospheric carbon dioxide into their biomass.

Deforestation is the practice of clear-cutting forests for timber and/or burning forests for conversion to agricultural land or for urban development. Deforestation and over-harvesting of forest organisms pose acute threats to biodiversity in many tropical regions including the Amazon, Indonesia, the Congo, and Sumatra (Figure 23).

Figure 23: Deforestation in Borneo, Malaysia. The tropical rain forest is cut and burned
to make way for access roads and terraces fields for palm oil production.1

Looking Ahead

In the upcoming Action Section you will learn about the IECA, an international organization which is addressing the global problem of soil erosion.

Around 130,000 square kilometers of tropical rain forest are lost each year to deforestation and over-harvesting. In the Amazon alone, 17% of the species-rich tropical rain forest has been lost over the last 50 years through slash-and- burn techniques which convert the forest into cattle pastureland, and from mining for valuable resources like mahogany, gold, and oil. Removing trees at rates faster than the cycles of healthy re-growth reduces the biodiversity of these regions, which, in turn, threatens our food sources, sources of medicines, ecosystem services, and materials for building shelter. Furthermore, clearcutting and slash-and-burn techniques expose the nutrient-poor soils to erosion by wind and rain, reducing the likelihood that the forests might recover.

Impacts on Aquatic Ecosystems

Closer Look

View this video where rangers protect the endangered Irrawaddy Dolphins in the Mekong River between Cambodia and Laos from being caught in fishing nets.

Aquatic ecosystems including oceans, wetlands, freshwater lakes, and rivers, are home to a high diversity of plants and animals which supply the major source of protein in the diets of billions of people each day. In addition, millions of people worldwide make their livelihood from fishing the oceans, lakes, and rivers. However, in the past 50 years, the ocean’s fisheries have experienced increased pressures from new technologies and fishing equipment that extract higher yields, severely stressing the world’s fisheries.

According to the World Wildlife Fund, over 85% of the world’s fisheries have been depleted beyond their biological ability to recover, and are in need of strict regulation and management strategies for survival.

Figure 24. Marine turtle bycatch. In addition to threatening many species of sea turtles and sea birds, the World Wildlife Fund estimates that 300,000 small whales, dolphins and porpoises become entangled in fishing nets that are set for other fish. These sea mammals die when caught in fish nets because they cannot surface for air. This unintended snaring is the single greatest
cause of death for small whales, dolphins and porpoises.1

Bycatch poses a serious threat to fish, sea turtles, dolphins, small whales, sea birds, and other marine life (Figure 24). More often than not, unintentionally caught animals are severely injured or die in the nets, and are thrown overboard after fishermen haul in their nets.

Looking Ahead

In the upcoming Action Section you are invited to visit overfishing.org and discover what you can do about the global problem of overfishing.

New technologies have exacerbated the problem of bycatch, producing fishing nets that are stronger, thinner, and much harder for marine life to detect ans avoid. Thousands of miles of fishing nets are crisscrossing the oceans, threatening all forms of sea life.

The Lithosphere

The lithosphere, which is comprised of solid soils, sediments, and rocks of the Earth’s crust and upper mantle, provides resources that are essential for supporting life, such as nutrients and minerals that are metabolically necessary. Additionally, the lithosphere provides many important construction materials (rock, minerals, and metals), as well as sources of energy (fossil fuels and uranium). Lithospheric resources have been used to advance technology and build prosperous societies. Below we will explore minerals, rock, metals, and energy sources.

Minerals and Rock

Figure 25: Learn more about these various minerals.1

Mineral resources and rock are foundational components for modern society. They provide raw materials that we use to construct buildings, bridges, machines, and medical equipment. These raw materials are also used to produce items that are crucial to the advancement of the economy and commerce, such as automobiles, computers, and mobile devices. Generally, we rely on rock and mineral resources for many of the raw materials that we need to make life safe, organized, and comfortable.

Closer Look

See this informative poster from the U.S. Geological Survey on how we use minerals in our everyday lives.

Minerals are defined as naturally occurring crystalline substances that have a specific chemical composition and are generally nonliving (see Figure 25). Minerals are present in rock, where they can mix with other minerals. In order for human society to use minerals, they must be removed from the earth, which is done using mechanical and chemical techniques.

Rocks can be categorized into three groups depending on the geologic processes and environments in which they were formed: igneous, sedimentary, and metamorphic (Figure 26). Igneous rocks are formed by the crystallization or solidification of Earth’s core magma or volcanic lava. Sedimentary rocks are produced through the processes of deposition, burial, and lithification – the transformation of sediment into solid rock. Metamorphic rocks are formed by the transformation of pre-existing solid rocks under high pressure and temperature. These forces can cause any kind of rock—igneous, sedimentary, or other metamorphic rock—to change its mineral composition, texture, or chemical composition, while retaining its solid form.

Figure 26 - How rock is formed through the forces of heat, pressure, weathering and erosion. For more information about rocks click here.1

We extract building stone, crushed stone, sand, gravel, and lightweight aggregates (e.g. pumice) from these various types of rock. We also modify and chemically treat some of these rock materials in order to form additional building products such as cement, plaster, brick, ceramics, and glass.

Metals

Closer Look

Read more about rare Earth metals and mobile devices in this article.

History has marked the discovery and increased use of specific metals by naming certain historical ages after them. For example, there are prehistoric periods of time known as the Copper Age, the Bronze Age, and the Iron Age. Each of these metals was discovered and prominently used in some way in the corresponding period of advancement in human history.

Like their parent components (minerals), metals provide a variety of desirable properties for making things, like cars, bicycles, and cellular phones. Other metals are desired strictly because they are considered precious, beautiful and valuable, such as gold (Au) and silver (Ag).

Some of the more commonly known metals include iron (Fe), aluminum (Al), copper (Cu), zinc (Zn), tin (Sn), lead (Pb), gold (Au), and silver (Ag). The most abundant metals in the Earth are silicon (Si), aluminum (Al), iron (Fe), magnesium (Mg), titanium (Ti), and manganese (Mn). These, and many other metals, have distinctive lusters (or shiny surfaces), and are generally heavy, good conductors of heat and electricity, and malleable under heat and pressure. These properties make them desirable for industrial and commercial use.

Energy Sources

Several primary energy resources come from the lithosphere including fossil fuels and radioactive material, primarily uranium. Today, fossil fuels are the predominate source of electricity and fuel energy for humans on the planet. Worldwide, they make up more than 80% of our fuel and energy sources, but that is changing as new, cleaner energy sources emerge.

Looking Ahead

The use of fossil fuels and uranium as energy sources is addressed in detail in the Energy Chapter.

The dead carcasses of plants and animals that lived and died millions of years ago make up the raw materials for the formation of fossil fuels in the lithosphere. Over geological time spans these materials decay under intense pressures; a process that forms crude oil, coal, and methane gas. The Energy Chapter describes the formation of fossil fuels in greater depth.

Uranium ore extracted from the earth provides a source of radioactive uranium that can be enriched in order to make it usable in nuclear power plants. Though it is not a renewable resource, nuclear energy from fissionable uranium is a much more efficient source of energy than coal – a single enriched uranium pellet (~0.3 grams) can provide the same amount of energy as a ton (~1x106 grams) of coal.

Extraction Methods

The primary methods employed to obtain resources from the lithosphere are through mining. As mentioned in the section about terrestrial ecosystems above, the process of mining has far reaching consequences to the land formations, the health of the surrounding ecosystems and human communities, and the quality of nearby water sources. The extraction of minerals from the earth necessitates the alteration of lands or sea floors. Before any active terrestrial mining occurs, the area must be cleared of vegetation, roads for transporting the materials must be built, and facilities for processing the minerals and for housing the people who work at the mines must be constructed. Table 1 lists the types of mining and their environmental impacts.

Table 1: Types of mining and their impacts

Once the resources are depleted in mining areas, the land itself is left physically damaged and chemically contaminated with by products (heavy metals, radioactive materials, and acid contamination) that may continue to pollute surface and groundwater sources for decades after the mine is abandoned. Efforts to restore mined land vary in their efficacy, methodology, and costs. In some cases, the environmental damage is too severe, making it impossible to restore the land at all.

Mining phosphorus, primarily for use as a fertilizer for crop production and for use in detergents, presents an unusual environmental problem. As mentioned above, all forms of life require phosphorus for metabolic processes, for cellular energy (adenosine tri-phosphate, or ATP), and as a component of many organic molecules (like DNA). Since nearly all of the Earth’s phosphorus resources are located in the lithosphere as apatite in sedimentary rock, it is extracted by open pit mining. Once extracted, the phosphorous is applied to agricultural soils and much of it is sequestered by the crops, which are then consumed by humans. This is how we obtain our source of phosphorus for our body’s metabolic needs.

Closer Look

See this article for a closer look at phosphorus recovery.

Presently, there is an imbalance in the phosphorus cycle. The phosphorus that is mined from lithospheric deposits that ends up in terrestrial and aquatic food webs because of excess fertilization does not enter back into the natural phosphorous cycle to replenish the lithospheric apatite rock deposits. In other words, we are mining the Earth’s concentrated apatite sources of phosphorous that are not being restored through the natural phosphorous-biogeochemical cycle. Since there is a limit to the reserves of apatite that can profitably be recovered on Earth, this imbalance between the amounts of phosphorous extracted and that recovered is causing depletion in the stores of easily recoverable phosphorus rock.

Questions to Consider

Are resources extracted from the lithosphere in the country where you live? If so, what are they? Look again at the Table above that lists various mining types. Which, if any, of these mining methods are used in your country?