Chapter 1 ~ Introduction

 

Chapter Overview

• Introduction
• The History of Environmental Science
• Biological and Chemical Foundations of Life
• Nature and Process of Science
• Interdisciplinary Nature of Environmental Science
• Biosphere: Lithosphere, Hydrosphere, and Atmosphere
• Preserving Biodiversity and the Six Kingdoms of Life
• Demographics
• Non-renewable and Renewable Energy Sources
• Nutrient Cycles
• Environmental Hazards
• Global Warming
• Environmental Agriculture
• Environmental Ethics, Quality, and Justice
• Chapter Summary

Introduction

Environmental science is a broad, important subject that encompasses all life forms (from microbial organisms to elephants and blue whales), as well as inanimate objects (water, air, soil, rocks, volcanoes) and their interactions. This chapter introduces basic environmental science concepts and perspectives that will be expanded in the remaining ten chapters. This chapter begins with a brief history of environmental science followed by the interdisciplinary nature of environmental science, the biosphere, biodiversity, demographics, environmental hazards, energy sources, nutrient cycling, global warming, environmental impact on agriculture, environmental ethics, quality, and justice and ends with a chapter summary.

The History of Environmental Science

The history of environmental science can be traced back to ancient civilizations where people had to develop techniques for adapting to their environment to survive. However, the modern field of environmental science emerged in the mid-twentieth century, as concerns over pollution and environmental degradation became more prominent. One of the key milestones in the history of environmental science was the publication of Rachel Carson’s book Silent Spring in 1962. This book highlighted the negative effects of pesticides and other chemicals on the environment and helped to spur the environmental movement in the United States and around the world.

During the 1970s, there was a growing recognition of the need for environmental regulation, and many countries passed laws to protect their air, water, and land resources. The Environmental Protection Agency (EPA) was established on December 2, 1970. In 1970, the United States passed the Clean Air Act and the Clean Water Act of 1972, which set standards for air and water quality and established regulatory agencies to enforce these standards.

In the 1980s and 1990s, there was a growing focus on global environmental issues, such as climate change and biodiversity loss. The United Nations (UN) established the Intergovernmental Panel on Climate Change (IPCC) in 1988 to study the causes and impacts of climate change, and in 1992, the UN held the Earth Summit in Rio de Janeiro, where countries pledged to take action to address environmental problems.

Today, environmental science is a multidisciplinary field focused on understanding the interactions between humans and the natural environment and developing solutions to environmental problems.

Biological and Chemical Foundations of Life

Elements in various combinations comprise all matter on Earth, including living things. Some of the most abundant elements in living organisms include carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus. These form the nucleic acids, proteins, carbohydrates, and lipids that are the fundamental components of living matter. Biologists must understand these important building blocks and the unique structures of the atoms that make up molecules, allowing for the formation of cells, tissues, organ systems, and entire organisms.

At its most fundamental level, life is made up of matter. Matter is any substance that occupies space and has mass. Elements are unique forms of matter with specific chemical and physical properties that cannot be broken down into smaller substances by ordinary chemical reactions. There are 118 elements, but only 92 occur naturally. The remaining elements are synthesized in laboratories and are unstable. The five elements common to all living organisms are oxygen (O), carbon (C), hydrogen (H), and nitrogen (N) and phosphorous (P). In the nonliving world, elements are found in different proportions, and some elements common to living organisms are relatively rare on the earth as a whole (Table 1.1). For example, the atmosphere is rich in nitrogen and oxygen but contains little carbon and hydrogen, while the earth’s crust, although it contains oxygen and a small amount of hydrogen, has little nitrogen and carbon. In spite of their differences in abundance, all elements and the chemical reactions between them obey the same chemical and physical laws regardless of whether they are a part of the living or non-living world.

Table 1.1. Approximate percentage of elements in living organisms (from bacteria to humans) compared to the non-living world. Trace represents less than 1%.

	Biosphere	Atmosphere	Lithosphere
Oxygen (O)	65%	21%	46%
Carbon (C)	18%	trace	trace
Hydrogen (H)	10%	trace	trace
Nitrogen (N)	3%	78%	trace
Phosphorus (P)	trace	trace	>30%

The Structure of the Atom

An atom is the smallest unit of matter that retains all of the chemical properties of an element. For example, one gold atom has all of the properties of gold in that it is a solid metal at room temperature. A gold coin is simply a very large number of gold atoms molded into the shape of a coin and containing small amounts of other elements known as impurities. Gold atoms cannot be broken down into anything smaller while still retaining the properties of gold. An atom is composed of two regions: the nucleus, which is in the center of the atom and contains protons and neutrons, and the outermost region of the atom which holds its electrons in orbit around the nucleus, as illustrated in Figure 1.2. Atoms contain protons, electrons, and neutrons, among other subatomic particles. The only exception is hydrogen (H), which is made of one proton and one electron with no neutrons.

Protons and neutrons have approximately the same mass, about 1.67 × 10-24 grams. Scientists arbitrarily define this amount of mass as one atomic mass unit (amu) (Table 1.2). Although similar in mass, protons and neutrons differ in their electric charge. A proton is positively charged whereas a neutron is uncharged. Therefore, the number of neutrons in an atom contributes significantly to its mass, but not to its charge.

Table 1.2. Characteristics of protons, neutrons, and electrons

	Charge	Mass (amu)	Location in atom
Proton	+1	1	Nucleus
Neutron	0	1	Nucleus
Electron	-1	0	Orbi

Electrons are much smaller in mass than protons, weighing only 9.11 × 10-28 grams, or about 1/1800 of an atomic mass unit. Hence, they do not contribute much to an element’s overall atomic mass. Although not significant contributors to mass, electrons do contribute greatly to the atom’s charge, as each electron has a negative charge equal to the positive charge of a proton. In uncharged, neutral atoms, the number of electrons orbiting the nucleus is equal to the number of protons inside the nucleus. In these atoms, the positive and negative charges cancel each other out, leading to an atom with no net charge. Accounting for the sizes of protons, neutrons, and electrons, most of the volume of an atom—greater than 99 percent—is, in fact, empty space. With all this empty space, one might ask why so-called solid objects do not just pass through one another. The reason they do not is that the electrons that surround all atoms are negatively charged and negative charges repel each other. When an atom gains or loses an electron, an ion is formed. Ions are charged forms of atoms. A positively charged ion, such as sodium (Na+), has lost one or more electrons. A negatively charged ion, such as chloride (Cl-), has gained one or more electrons.

Nature and Process of Science

Biology is a science, but what exactly is science? What does the study of biology share with other scientific disciplines? Science (from the Latin scientia, meaning “knowledge”) can be defined as knowledge about the natural world.

Science is a very specific way of learning, or knowing, about the world. The history of the past 500 years demonstrates that science is a very powerful way of knowing about the world; it is largely responsible for the technological revolutions that have taken place during this time. There are however, areas of knowledge and human experience that the methods of science cannot be applied to. These include such things as answering purely moral questions, aesthetic questions, or what can be generally categorized as spiritual questions. Science cannot investigate these areas because they are outside the realm of material phenomena, the phenomena of matter and energy, and cannot be observed and measured.

The scientific method is a method of research with defined steps that include experiments and careful observation. The steps of the scientific method will be examined in detail later, but one of the most important aspects of this method is the testing of hypotheses. A hypothesis is a suggested explanation for an event, which can be tested. Hypotheses, or tentative explanations, are generally produced within the context of a scientific theory. A generally accepted scientific theory is thoroughly tested and confirmed explanation for a set of observations or phenomena. Scientific theory is the foundation of scientific knowledge. In addition, in many scientific disciplines (less so in biology) there are scientific laws, often expressed in mathematical formulas, which describe how elements of nature will behave under certain specific conditions. There is not an evolution of hypotheses through theories to laws as if they represented some increase in certainty about the world. Hypotheses are the day-to-day material that scientists work with and they are developed within the context of theories. Laws are concise descriptions of parts of the world that are amenable to formulaic or mathematical description.

Interdisciplinary Nature of Environmental Science

As an interdisciplinary field, environmental science involves the study of interactions between humans and the natural environment. It draws upon knowledge and techniques from a variety of scientific disciplines, including biology, chemistry, geology, physics, and ecology, among others. For example, environmental scientists may use their knowledge of biology to study the effects of pollution on plant and animal populations, or they may use chemistry to analyze the composition of air, water, and soil samples. Geology is also important in understanding how natural processes like erosion and volcanic activity impact the environment, and physics is used to study climate change and its effects on the environment.

In addition to the natural sciences, environmental science also incorporates knowledge from social sciences such as economics, politics, and sociology. Environmental economists, for example, study the costs and benefits of different environmental policies, while environmental sociologists may investigate how social factors influence people’s attitudes toward the environment.

This interdisciplinary approach is necessary because environmental problems are often complex and interconnected and require a holistic understanding of the underlying causes and potential solutions. By bringing together knowledge from multiple disciplines, environmental scientists are better able to identify and address these complex problems. Figure 1.4 displays a broader list of academic disciplines that can contribute to environmental studies, a field like environmental science that looks at human interactions and the natural environment.

Biosphere: Lithosphere, Hydrosphere, and Atmosphere

The biosphere is the region of the earth that encompasses all living organisms: plants, animals, and bacteria. It is a feature that distinguishes the Earth from the other planets in the solar system. “Bio” means life, and the term biosphere was first coined by a Russian scientist (Vladimir Vernadsky) in the 1920s. Another term sometimes used is ecosphere (“eco” meaning home). The biosphere includes the outer region of the earth (the lithosphere) and the lower region of the atmosphere (the troposphere). It also includes the hydrosphere, the region of lakes, oceans, streams, ice, and clouds comprising the earth’s water resources.

Lithosphere

The lithosphere is the outer crust of the Earth, which is composed of the upper mantle and crust and arranged in concentric layers like an onion. Below the lithosphere are three layers: the lower mantle, outer core, and inner core.

The massive core has a diameter of about 3,500 km and is composed of hot, molten metals, particularly iron and nickel. The internal heat of Earth is thought to be generated by the slow, radioactive decay of unstable isotopes of certain elements, such as uranium.

The mantle is a less dense region that encloses the core. It is about 2,800 kilometers thick and composed of minerals in a plastic, semi-liquid state known as magma. The mantle contains relatively light elements, notably silicon, oxygen, and magnesium, occurring as various mineral compounds. Magma from the upper mantle sometimes erupts to the surface at mountainous vents known as volcanoes and is usually spewed to the surface as lava, which cools to form basaltic rock.

The lithosphere is only about 80 kilometers thick. It is composed of rigid, relatively light rocks, especially basaltic, granitic, and sedimentary ones. These rocks contain elements found in the mantle as well as enriched quantities of aluminum, carbon, calcium, potassium, sodium, sulfur, and other lighter elements, because of weathering and other forces. Living organisms change the lithosphere slowly by using non-biodegradable substances.

The outermost layer is known as the crust. The oceanic crust is relatively thin, averaging 10–15 kilometers, while the continental crust is 20–60 kilometers thick.

Hydrosphere

The hydrosphere is the portion of Earth that contains water (H₂O), including in the oceans, atmosphere, land surface, and underground. The hydrologic cycle (or water cycle) refers to the rates of movement (fluxes) of water among these various reservoirs (compartments). The hydrologic cycle functions at all scales, ranging from local to global. The major elements of the global hydrologic cycle are illustrated in Figure 1.6.

Atmosphere

The atmosphere is an envelope of gasses that surrounds the Earth and is held in place by the attractive forces of gravity. The density of the atmospheric mass is much greater close to the surface and decreases rapidly with increasing altitude. The atmosphere consists of four layers, whose boundaries are inexact because they may vary over time and space:

• The troposphere (or lower atmosphere) contains 85–90% of the atmospheric mass and extends from the surface to an altitude of 8–20 kilometers. It is thinner at high latitudes, and thicker at equatorial latitudes, but also varies seasonally, at any place being thicker during the summer than in the winter. It is typical for air temperature to decrease with increasing altitude within the troposphere, and convective air currents (winds) are common. Consequently, the troposphere is sometimes referred to as the “weather layer.”
• The stratosphere extends from the troposphere to as high as about 50 kilometers above the earth, depending on the season and latitude. Air temperature varies little with altitude within the stratosphere, and there are few convective air currents.
• The mesosphere extends beyond the stratosphere to about 75 kilometers.
• The thermosphere extends to 450 kilometers or more.

Preserving Biodiversity and the Six Kingdoms of Life

Preserving the biodiversity of life forms within each of the six kingdoms of life is essential to maintaining the health and ecological balance of our planet and its inhabitants.

The six kingdoms of life are separated into two groups: prokaryotic and eukaryotic organisms. Prokaryotic organisms lack a true nucleus and other membrane-bound organelles and include Domains Archaea and Bacteria. Archaea includes one kingdom, archaebacteria. Archaea is a group of single-celled microorganisms that are distinct from both bacteria and eukaryotes. Archaea are found in a wide range of environments, including extreme environments such as hot springs, deep-sea hydrothermal vents, and highly saline lakes.

Kingdom Bacteria is also known as Eubacteria, which means “true bacteria.” This kingdom includes a diverse group of prokaryotic organisms that are found in virtually every habitat on Earth. They are characterized by their generally small size (usually ranging from 0.2 to 5 micrometers). Eubacteria are responsible for many important processes, such as nitrogen fixation (the conversion of atmospheric nitrogen into a form usable by plants), decomposition, and fermentation.

Eukaryotic organisms have a true nucleus and other membrane-bound organelles and include the Domain Eukarya. Domain Eukarya includes four kingdoms: Protista, Fungi, Plants, and Animals. Protista is a biological kingdom that includes a diverse group of eukaryotic microorganisms. The classification of Protista is somewhat outdated and is no longer recognized as a formal taxonomic group in many modern classifications. Protista are typically unicellular or simple multicellular organisms, and they exhibit a wide range of characteristics and lifestyles.

Fungi are a diverse group of organisms that include yeasts, molds, and mushrooms.  Fungi play important roles in nutrient cycling and the decomposition of organic matter. To preserve biodiversity in this kingdom, we can protect forests and other habitats where fungi are abundant, limit the use of fungicides, and promote pollutionable farming practices that incorporate the use of mycorrhizal fungi to enhance soil health.

Plants are critical to the survival of many animal species and play a key role in maintaining the health of ecosystems. To preserve biodiversity in this kingdom, we can work to protect and restore natural habitats, reduce deforestation and habitat destruction, and promote the use of sustainable agricultural practices.

Animals play vital roles in maintaining ecological balance and are also important sources of food and medicine for humans. To preserve biodiversity in this kingdom, we can work to protect and restore natural habitats, reduce overfishing and hunting, and promote sustainable tourism practices that do not harm wildlife.

Demographics

Human Demography

Demography applies the principles of population ecology to the human population. Demographers study how human populations grow, shrink, and change in terms of age and gender composition using vital statistics about people such as births, deaths, population size, and where people live. Demographers also compare populations in different countries or regions. Currently, there are two disparate demographic worlds. On one end is an old, rich, and relatively stable world often referred to as an “industrialized” or “developed” world and includes many European nations, the United States, Canada, Japan, and Australia among others. On the other end is a young, poor, and rapidly growing world often referred to as “less-industrialized,” “less-developed,” or “developing” and includes many countries in Asia, Africa, and Latin America. In between these two extremes are countries such as China, India, Brazil, Mexico, South Africa, Russia, and many others that have not quite attained the developed status but have outpaced the so-called developing countries. These nations are sometimes referred to as “newly industrialized” or “emerging market economies.”

Geographical Distribution of Habitats

The geographical distribution of habitats is determined by the global habitable environment. This distribution affects the natural habitats and their biota. The major population growth remains constant in the areas based on habitable environments from which human populations can acquire food.

Human Population and Interference

Humans can alter their environment to increase their carrying capacity sometimes to the detriment of other species (e.g., via artificial selection for crops that have a higher yield). Earth’s human population is growing rapidly, to the extent that some worry about the ability of the earth’s environment to sustain this population, as long-term exponential growth carries the potential risks of famine, disease, and large-scale death. Although humans have increased the carrying capacity of their environment, the technologies used to achieve this transformation have caused unprecedented changes to Earth’s environment, altering ecosystems to the point where some may be in danger of collapse. The depletion of the ozone layer, erosion due to acid rain, and damage from global climate change are caused by human activities. The ultimate effect of these changes on our carrying capacity is unknown. As some point out, it is likely that the negative effects of increasing carrying capacity will outweigh the positive ones—the carrying capacity of the world for human beings might decrease. The world’s human population is currently experiencing exponential growth even though human reproduction is far below its biotic potential. To reach its biotic potential, all females would have to become pregnant every nine months or so during their reproductive years. Also, resources would have to be such that the environment would support such growth. Neither of these two conditions exists. Despite this fact, the human population is still growing exponentially.

Non-renewable and Renewable Energy Sources

Non-renewable Energy Sources

Non-renewable energy resources are those that cannot be easily replenished in a short time, making them finite and unsustainable in the long run. Fossil fuels are generally the remains of plants and animals that died millions of years ago and are found deep underground. These fuels may include coal, oil, and natural gas. Tar sands and shale gas are also considered non-renewable energy resources.

Nuclear energy produced by splitting atoms of uranium or plutonium is a process called nuclear fission. From such an exothermic process, the liberated heat is used to generate electricity. Figure 1.11 shows examples of non-renewable energy sources.

Today, non-renewable energy sources are still widely used despite the environmental, climate change and social impacts associated with their extraction, production, refining, and final use and applications. As we move toward a more sustainable and environmentally viable and preserving energy future, there is a growing need by energy consumers to shift toward cleaner, renewable energy sources such as solar, wind, geothermal, and hydroelectric power.

Renewable Energy Sources

Renewable energy sources are those that can be refilled naturally and in a relatively short time or at continuous bases (solar, wind). These energy resources are sustainable and reusable, environmentally friendly, and carbon footprint-reducing agents. They may be used as alternatives to non-renewable energy sources.

Solar energy is generated by capturing solar radiation from the sun using solar panels. This can be used to generate electricity, water heating, or provide energy for various other applications. Wind turbines generate electricity by harnessing the power of the wind. This is a widely used form of renewable energy that is growing rapidly around the world. Hydroelectric power is generated by capturing the energy of falling water to turn turbines and generate electricity. This can be done using large-scale dams or smaller-scale run-of-the-river systems. Geothermal energy is generated by capturing the heat of the Earth’s interior to generate electricity or heat buildings. This can be done by using geothermal power plants or ground-source heat pumps. Biomass energy is generated by burning organic materials such as wood, agricultural waste, and other plant-based substances. This technology can be used to generate heat or electricity or to produce biofuels for transportation.

Renewable energy sources are becoming increasingly important to humanity, as we seek to transition to a more sustainable, replenishable energy future with fewer emissions. In addition to being less harmful to the environment than non-renewable energy sources, renewable energy also offers a range of economic and social benefits, including job creation, energy independence, and reduced greenhouse gas emissions. Chapter 4 concentrates more on the effects of energy and sustainability across the nation and the state of Louisiana. The chapter will also address best practices of energy preservation within our environment.

Nutrient Cycles

The existence of organisms in the environment depends on recycling valuable nutrients including nitrogen, phosphorus, oxygen, and carbon, which are all necessary for life. Nutrients are vital for the metabolism of living things and the survival of ecosystems.

Yet, these nutrients can travel from the Hawaiian Islands to Louisiana’s Gulf of Mexico. This happens as nutrients cyclically move through the environment and travel through the atmosphere, hydrosphere, and lithosphere.

The movement of nutrients through the environment is known as nutrient cycles or biogeochemical cycles as seen in Figure 1.14. Carbon is recycled and moves through the environment when animals release CO₂ into the atmosphere to be absorbed by plant leaves. This occurrence is seen in aquatic and terrestrial plants that capture CO₂ from the atmosphere to use in the production of food through photosynthesis. The atmosphere contains 78% of gaseous nitrogen (N₂). However, nitrogen changes into various forms when it enters the soil from the atmosphere. Soil bacteria must convert N₂ to usable forms for plant uptake. This process is known as nitrogen fixation. After this process, N₂ is released from the soil into the atmosphere, and the nitrogen cycle starts again.

A limited amount of phosphorus can be found in the atmosphere as aerosol particles from the ocean and wind-blown dust particulates. However, the majority of the phosphorus in the environment is bonded to subterranean rocks and is only released during weathering processes. Plants can absorb phosphorus through their root systems when phosphate is dissolved in water. Organisms referred to as decomposers recycle phosphorus back into the soil. Decomposers also recycle nutrients in the ecosystem by dissolving decayed organic materials.

The existence of water dates back millions of years. Water is constantly being recycled through the hydrologic cycle, also known as the water cycle. The recycling of water involves four major processes: evaporation, condensation, precipitation, and infiltration. Evaporation occurs when water is heated by the ambient temperature (temperature in the environment) and turns into a gaseous vapor. When the warm water vapor rises and meets the cold air in the atmosphere, condensation occurs, and clouds are formed. Clouds are composed of water droplets from the condensation. The cycle is repeated when the water droplets get too heavy and fall out of the cloud back to the Earth as precipitation. Precipitation may exist in the form of ice, rain, sleet, and snow.

Environmental Hazards

A wide range of environmental hazards come across in almost all habitats and public and private properties including, but not limited to, the workplace, construction areas, parks and recreational areas, industries, and living beings.

• Biological hazards are caused by a variety of organisms belonging to the six kingdoms of life. The effect of biological hazards such as physiological changes, responses to stimuli, reproductive behavior, and diseases, could cause short (acute) and or long-term (chronic) damage to life forms. Their environmental abiotic factors are also affected depending on the causative agent, dose, length of interaction or exposure, and geographical distribution of the hazard.
• Chemical hazards are mainly two kinds—inorganic such as toxic metals (Lead, Pb; Copper, Cu; Iron, Fe; Mercury, Hg; Aluminum, Al; Cadmium, Cd, etc.) and organic chemicals such as Methyl Mercury (CH₃Hg); Polychlorinated biphenyls; Benzene; Polycyclic aromatic hydrocarbons, etc. The chemical hazards are toxic, which affects the living organisms and their habitats, including the water, air, and soil quality. They will have long-term consequences for living beings. Radiation will have devastating long-term and generational consequences in life forms due to its mutagenic and carcinogenic properties.
• Physical hazards ranging from a wet floor in buildings, foul odor in the air, depth in water bodies, and extreme temperatures cause thermal pollution. War zones, heavy machinery use in construction areas, and ball games in indoor stadiums cause noise pollution. Excessive rainfall and flooding cause loss of property and life especially in low-lying areas and flood-prone zones. Forest fires cause loss of life, biomass of ecosystems, and toxic gas release.
• Natural disasters, such as hurricanes, tornadoes, earthquakes, and volcano eruptions, cause loss of life and biodiversity, disrupt the harmony in ecosystems, reduce the productivity of food chains and food webs, and damage the environmental quality.

The details of various hazards and their impact on humans and biodiversity will be presented in chapters 5 and 6.

In general, the types of hazards and levels of their toxic intensity and interaction with species in diversified habitats could cause the following changes in life forms (biota):

• Anthropogenic: Toxins and their distribution in the environment and among the biota are due to human activities, which eventually damage the natural resources and human health. Most commonly, anthropogenic (man-made) toxins are associated with numerous activities. One example is the accidental emissions of chemicals into the environment. Another example is the release of substances that react in the environment to synthesize chemicals of greater toxicity. The release of excessive heat from factories and industrial sites into the nearby water bodies increases the water temperature. The discharges of nutrient-rich sewage or fertilizer into water bodies cause eutrophication.

Environmental hazards and toxins may have serious effects:

• Human illness, diseases, and death due to the excessive release of toxic gases such as carbon dioxide (CO₂), carbon monoxide (CO), and sulfur dioxide (SO₂).
• Loss of habitats, life forms, and biodiversity.
• Chronic respiratory and heart diseases.
• Auto exhaust fumes, smoking, secondhand smoke, laboratory solvents, and particulate matter released into the air from the mining industry will cause health severe and chronic problems to humans.
• Indoor pollution and toxins released from space heaters, furnaces, fireplaces burning wood, kerosene, nitric oxide, and organic vapors cause health problems and loss of man-hours and productivity.
• Smog causes a significant number of problems and toxicity to vegetation, erodes building surfaces and metal sculptures due to acid rain, and causes heart and lung problems such as asthma, bronchitis, and emphysema, in vulnerable populations.

Global Warming

An increase in the Earth’s surface temperature is referred to as global warming, also known as climate change. To be more precise, global warming is the cause of the Earth’s climate change. Natural occurrences on the Earth and anthropogenic activities are responsible for increased surface temperatures. Rising sea levels, sporadic flooding, melting glaciers, wildfires, storms, and the loss of wildlife habitats are just a few of the damaging effects of heightened warming trends. The culprit for extreme weather and climate events can be traced to greenhouse gas emissions in the environment. Greenhouse gases are a product of man-made activities such as agricultural activities, combustion of fossil fuels, deforestation, and industrial manufacturing of products.

Major greenhouse gasses include carbon dioxide, chlorofluorocarbons, methane, ozone, nitrous oxide, and water vapor as shown in Figure 1.15. The greenhouse effect occurs when a layer of greenhouse gasses from man-made activities hovers in the Earth’s atmosphere. Because of this, solar radiation strikes the surface of the Earth and bounces back into the atmosphere. The rays from the sunlight are blocked by the layer of greenhouse gasses. The surface temperature of the Earth increases as a result of this activity. It is important to note that without greenhouses, the Earth would be too cold for life to exist. Nonetheless, the amount of emissions caused by human activity is excessive and has become globally problematic. Once in the atmosphere, greenhouse gasses can linger there for a few years to thousands of years.

The persistent altering of Earth’s climate and weather patterns is evidence of the unsettling impacts of global warming. About 2% of global warming is caused by natural events such as variations in solar radiation levels, tectonic shifts, and the suspension of volcanic ash in the atmosphere. However, on a larger scale, global warming is caused by the human usage of petroleum-based fuels, coal, electricity, fertilizers, and industrial manufactured products. The intensity of storms, the rise in sea levels, and the expansion of the ocean are all signs of climate change.

All around the world, but notably at the Earth’s poles, ice is melting. This global imbalance has affected various wildlife species and their habitats. In some cases, the melting ice has led to the collapse of sections of the landscape because rising sea levels often flood coastal regions. Unusual warm temperatures in the ocean can damage aquatic species, fuel tropical cyclones and hurricanes, and cause the ocean to expand.

Most of the extra heat from global warming is absorbed in the upper crust of the ocean, which is about 700 meters down. Unfortunately, this area of the ocean is home to a diverse population of aquatic species such as fish, plankton, and whales. Scientists believe that increased temperatures cause stress in marine environments. Due to their extreme sensitivity, corals will expel their internal algae in the presence of heated temperatures. This event is known as bleaching in which corals frequently fail to recover as shown in Figure 1.17.

To support healthy ecosystems, we must engage in sustainable practices, as these actions can reduce the effects of global warming. Using renewable energy sources, consuming less water, walking instead of driving, and recycling plastic and aluminum products, among other things, are some practical ways to lessen the impact of global warming and climate change. Advocates for local initiatives addressing global warming have grown in popularity, and many of the environmental projects they support have an impactful transformation on the environment and our planet. On a larger scale, some environmental groups support projects that protect our forest landscape. This is a notable effort because CO₂ is a key greenhouse gas. Protecting our forest ecosystems will sequester significant amounts of CO₂.

Environmental Agriculture

Agriculture can be defined as the science, and art, of cultivating the soil, producing crops, and raising livestock. Even relatively simple agricultural practices can greatly increase food production compared with the hunting and gathering of wild animals and plants. Before the development of agriculture, which first appeared around 10,500 years ago, perhaps 5–10 million people were able to subsist through a hunter-and-gatherer lifestyle.

Today, the world supports an enormous population (more than 7.3 billion in 2015 and 7.9 billion in 2023), and almost all depend on the agricultural production of food (fishing and hunting also provide some food). The development of agricultural practices and technologies, and their improvements over time, are among the most crucial of the “revolutions” that have marked the socio-cultural evolution of Homo sapiens.

In any event, beginning with the cultivation and then domestication of a few useful plants and animals, agricultural technology has advanced to the point where it can support enormous populations of humans and our mutualist species.

Modern agriculture involves several distinct management practices that impact crop plants, production of crops, cultivation practices, and livestock, to name a few. In the case of crop plants, they include selective breeding, tillage, the use of fertilizer and pesticides, irrigation, and reaping. Each practice helps to increase the yield of biomass that can be harvested for food or other uses. The practices are typically used in various combinations, which are undertaken as an integrated system of the ecosystem and species management to achieve a large production of crops. However, the management practices also cause important environmental damage.

Chapter 10 will investigate environmental damages associated with agriculture, with particular attention to effects that occur in the United States.

Environmental impacts on agriculture include declining site capability, nutrient loss, organic matter, soil erosion, compaction, salinization, and desertification.

Agricultural site capability (or site quality) refers to the ability of an ecosystem to sustain the productivity of crops. As plants grow, they take up nutrients from the soil. When a crop is harvested, the nutrients contained in its biomass are removed from the site, resulting in nutrient loss. Soil organic matter is a crucial factor that affects fertility and site capability, since the organic matter has a strong influence on the capacity of soil to hold water and nutrients and on its aeration, drainage, and tilth. Soil is eroded by wind and by the runoff of rain and melted snow. Although erosion is a natural process, its rate can be greatly increased by agricultural practices, and this may be a serious environmental problem. Compaction occurs when the air spaces in the soil are compressed, resulting in waterlogging, oxygen-poor conditions, impaired nutrient cycling, poor root growth, and decreased crop productivity. Salinization is a buildup of soluble minerals in the surface soil that can be a major problem in drier regions. Desertification, the increasing aridity of drylands, is a complex problem, caused by both climate change and other anthropogenic influences. Ultimately, these aforementioned environmental factors interweave and can negatively impact agricultural outcomes.

Pollution caused by agriculture includes groundwater and surface waters, which can become polluted by runoff containing fertilizer, pesticides, and livestock sewage. Inputs of nutrients and organic matter from fertilizer and sewage can cause severe ecological damage to surface waters through eutrophication and oxygen depletion. These changes, coupled with the presence of pathogenic and parasitic organisms, can result in waters becoming unsuitable for drinking by people, perhaps even by livestock, or for use in irrigation. Chapter 10 will explore these impacts on human behaviors.

Environmental Impact of Human Behavior

Human behaviors can positively or negatively impact environmental outcomes. For instance, food supply and nutrition, malnutrition, and starvation. In 2014, more than 7.3 billion people were alive, and almost all were reliant on crops as their prime source of food. There are also relatively minor amounts of food that are harvested from the wild, such as by fisheries, but agricultural production is responsible for the great bulk of the modern human diet. Staple food crops are the main source of dietary energy in the human diet and include rice, wheat, sweet potatoes, maize, and cassava.

However, food security plagues one in nine individuals in the world with more individuals living in poverty, which is defined as living on less than $1.25 per day. Poverty is the major driver of food insecurity. The lack of social and physical economic access to food at national and household levels and inadequate nutrition (or hidden hunger) are major issues for impoverished communities. Food security is built on four pillars: availability, access, utilization, and stability. Individuals lacking food stability may suffer from a lack of essential nutrients or malnutrition.

As a means to counteract crop loss, which could further impact food security, plant physiologists have genetically engineered crops through agricultural biotechnology. The field of agricultural biotechnology uses a range of tools that include both traditional breeding and modernized lab-based methods, which include genetically modified organisms (GMOs) and transgenic crops. Creating GMOs introduces new traits to crops that can allow protection from pests, enhanced nutrition to humans and animals, reduced costs to farmers, and more manageable production. However, there are factors to consider with the cultivation of GMOs such as hybridization with native species, ecological impacts on the pollinating organisms, and human health.

Another recent innovation in agriculture is the use of transgenic crops, which have been genetically modified by the introduction of genetic material (DNA or RNA) from another species. This bioengineering intends to confer some advantage to the crop that cannot be developed through selective breeding, which relies only on the intrinsic genetic information (the genome) that is naturally present in the species. Chapter 10 will further investigate the impacts of the four pillars of food security along with the impacts of agricultural biotechnology on human health.

Environmental Ethics, Quality, and Justice

Environmental Ethics

The choices that people make can influence environmental quality in many ways—by affecting the availability of resources, causing pollution, and causing species and natural ecosystems to become endangered. Decisions influencing environmental quality are influenced by two types of considerations: knowledge and ethics.

In this context, knowledge refers to information and understanding about the natural world, and ethics refers to the perception of right and wrong and the appropriate behavior of people toward each other, other species, and nature. Ethical behaviors are typically associated with social interactions with other members of society. Environmental ethics centers around the responsibility of our society to make ethical and moral decisions in response to the world around us. Of course, people may choose to interact with the environment and ecosystems in various ways. On the one hand, knowledge guides the consequences of choices, including damage that might be caused and actions that could be taken to avoid that effect. On the other hand, ethics provides guidance about which alternative actions should be favored or even allowed to occur.

Because modern humans have enormous power to utilize and damage the environment, the influence of knowledge and ethics on choices is a vital consideration. And we can choose among various alternatives. For example, individual people can decide whether to have children, purchase an automobile, or eat meat, while society can choose whether to allow the hunting of whales, clear-cutting of forests, or construction of nuclear power plants. All of these options have implications for environmental quality.

Perceptions of value (of merit or importance) also profoundly influence how the consequences of human actions are interpreted. Environmental values can be divided into two broad classes: utilitarian and intrinsic.

Utilitarian value (also known as instrumental value) is based on the known importance of something to the welfare of people (see also the discussion of the anthropocentric world view, below).

Intrinsic value is based on the belief that components of the natural environment (such as species and natural ecosystems) have inherent value and a right to exist, regardless of any positive, negative, or neutral relationships with humans.

The environmental values described above underlie this system of ethics. Applying environmental ethics often means analyzing and balancing standards that may conflict, because aesthetic, ecological, intrinsic, and utilitarian values rarely coincide.

Values and ethics, in turn, support larger systems known as worldviews. A worldview is a comprehensive philosophy of human life and the universe and of the relationship between people and the natural world. World views include traditional religions, philosophies, and science, as well as other belief systems. In an environmental context, generally important worldviews are known as anthropocentric, biocentric, and ecocentric, while the frontier and sustainability worldviews are more related to the use of resources. These worldviews will be further explored in chapter 11.

Environmental Quality

Environmental quality deals with anthropogenic pollution and disturbances and their effects on people, their economies, other species, and natural ecosystems. Pollution may be caused by gases emitted by power plants and vehicles, pesticides, or heated water discharged into lakes. Examples of disturbance include clear-cutting, fishing, and forest fires. The consequences of pollution and disturbance for biodiversity, climate change, resource availability, risks to human health, and other aspects of environmental quality are examined in chapters 3, 8, 9, 10, and 11.

In a general sense, the cumulative impact of humans on the biosphere is a function of two major factors: (1) the size of the population and (2) the per capita (per-person) environmental impact. The human population varies greatly among and within countries, as does the per capita impact, which depends on the kind and degree of economic development that has occurred. Sustainable economic development requires meeting and sustaining the needs of the current generation without inhibiting future generations from meeting and sustaining their needs. Meeting goals for environmental quality, specifically sustainable economic development, can be measured by applying the IPAT Equation.

Calculations based on this simple IPAT formula show that affluent, technological societies have a much larger per capita environmental impact than poorer ones. This requires a look at ethical decision-making about the environment and principles, such as the Tragedy of the Commons and environmental justice.

The Tragedy of the Commons is an economic principle that focuses on individuals intentionally or unintentionally using resources in excess. This principle stems from the 1968 essay, “The Tragedy of the Commons” written by Garrett Hardin. The essay presents the following scenario:

Imagine a pasture open to all (the ‘commons’). It is to be expected that each herdsman will try to keep as many cattle as possible on the commons. As rational beings, each herdsman seeks to maximize their gain. Adding more cattle increases their profit, and they do not suffer any immediate negative consequence because the commons are shared by all. The rational herdsman concludes that the only sensible course is to add another animal to their herd, and then another, and so forth. However, this same conclusion is reached by each and every rational herdsman sharing the commons. Therein lies the tragedy: each person is locked into a system that compels them to increase their herd, without limit, in a world that is limited. Eventually this leads to the ruination of the commons. In a society that believes in the freedom of the commons, freedom brings ruin to all because each person acts selfishly (Fisher, 23).

Hardin went on to apply the situation to modern commons: overgrazing of public lands, overuse of public forests and parks, depletion of fish populations in the ocean, use of rivers as a common dumping ground for sewage, and fouling the air with pollution.

Environmental Justice

Environmental justice is the fair treatment and inclusion of all individuals independent of their demographic characteristics (race, ethnicity, national origin, and socioeconomic status) in the “development, implementation, and enforcement of environmental laws, regulations, and policies.” Therefore, environmental injustice stems from an imbalance in resource access and systemic issues plaguing society. Chapter 11 will further explore historical and modern instances of environmental injustices exhibited within the United States of America.

Chapter Summary

Environmental science crosses several academic disciplines including atmospheric science, biology, chemistry, ecology, geology, oceanography, physics, and many others. Each discipline can become more specialized and integrated with other disciplines to explain the science of “what is happening in the environment.” Historically, environmental science has been traced to ancient civilizations where people had to learn how to adapt to their environment for survival. Today, the survival of the human population depends on the sustainability and stewardship of natural resources. Environmental science is an interdisciplinary field of study because it allows for the integration of many perspectives on each issue into in-depth analyses of the topic. Anthropology, business, chemistry, law, medical sciences, philosophy, psychology, sociology, and other disciplines can all make contributions to environmental science.

The biosphere is characterized by a substratum of layers that support all living things on the Earth. These layers include the lithosphere, hydrosphere, and atmosphere. The lithosphere is the outer crust of the Earth and exists as one of the concentric layers (crust, core, and mantle) that is stacked in an onion-like pattern. The area of Earth that is covered by water (H2O), including the seas, atmosphere, the surface of the land, and subterranean, is known as the hydrosphere. The atmosphere consists of a layer of gasses that envelops the planet and is kept in place by the gravitational pull of the Earth.

The biosphere sustains six kingdoms, which greatly enhances the diversity of life on Earth. These kingdoms include Eubacteria, Archaea, Protista, Fungi, Plantae, and Animalia. The aquatic and terrestrial environments of the biosphere are home to a wide variety of organisms from the six kingdoms. Our understanding of the biosphere’s limitations has been saturated by the effects of human activity. The manufacturing of global products, agriculture, and new technologies have caused unprecedented changes to the Earth’s ecosystems to the point where some may be in danger of collapsing. However, it is unclear how these persistent changes will ultimately affect the carrying capacity of the planet.

A biological or non-biological substance that poses a risk to human life or health is referred to as a hazard. Human activities or natural processes cause hazards in the environment that exist as a combination of biological, chemical, or physical hazards. Bacteria, mold, fungi, viruses, and natural toxins are organic sources of biological hazards that can adversely affect animal and human health. There are two types of chemical hazards: inorganic and organic. Inorganic substances that contain no carbon are sources of chemical hazards. Organic substances come from chemicals that contain carbon and are sources of chemical hazards as well.

Energy plays a significant and impacting role in the preservation of the environment. Humanity should effectively, responsibly, and efficiently use these energy resources to support current global energy consumption needs. There are two types of energy sources for human consumption: renewable and non-renewable. Renewable energy sources can be replenished. Examples of typical renewable energy sources include wind, solar, hydropower, biomass, and geothermal energy. Non-renewable energy sources are limited and unsustainable over the long term, since they are difficult to quickly replace. Fossil fuels are found deep down in the Earth and are typically the skeletal remnants of plants and animals that perished millions of years ago. Coal, oil, and natural gas are just a few examples of fossil fuels.

Nutrient cycling is the movement of nutrients through a repeated pathway that occurs in the environment. The recycling of nitrogen, phosphorus, oxygen, and carbon is essential for life and allows organisms to exist in the environment. Carbon is recycled when animals release CO₂ into the atmosphere to be absorbed by plant leaves. When nitrogen is moved to the soil from the atmosphere, nitrogen fixation allows soil microorganisms to change N₂ into forms that plants can use. Weathering activities liberate most of the phosphorus that is bound to underground rocks so that plants can absorb it through their root systems. The availability of water for all organisms in the environment depends on the movement of water molecules from lakes, oceans, rivers, and streams to the atmosphere and back to the Earth.

Global warming, often known as climate change, is the term used to describe an increase in the Earth’s surface temperature. Evidence of the unsettling effects of global warming is the continual alteration of Earth’s climate and weather patterns. Greenhouse gas emissions are to blame for extreme weather and climatic occurrences. Major greenhouse gasses include carbon dioxide, chlorofluorocarbons, methane, nitrous oxide ozone, and water vapor. Human activities including deforestation, fossil fuel combustion, agriculture, and industrial product manufacturing all produce greenhouse gases. Once in the atmosphere, greenhouse gasses can linger there for a few years to thousands of years, trapping radiation from the sun. The rise in the Earth’s surface temperature can be seen in the intensity of storms, the rise in sea levels, and the expansion of the ocean.

Agricultural production is responsible for dietary energy in the modern human diet that comes from staple food crops, such as rice, wheat, sweet potatoes, maize, and cassava. Numerous management techniques are used in modern agriculture practices to influence animal and plant crop productivity, cultivation methods, and livestock production. Environmental issues that are associated with agricultural practices are reduced site capacity, nutrient loss, organic matter loss, soil erosion, compaction, salinization, and desertification. Food security is important and is built on four pillars: availability, access, utilization, and stability. Conversely, poor nutrition (or hidden hunger) and lack of social and economic access to food at the national and household levels are significant problems for impoverished communities. Genetically modified organisms (GMOs) and transgenic plants are two examples of modern lab-based techniques that are used in the field of agricultural biotechnology. Transgenic crops can resist diseases because of their genetic modification. This results in significant reductions in the application of chemical pesticides, which in turn reduces harmful effects on the environment.

The core idea of environmental ethics is that society must act morally and ethically concerning the environment. Although the perceptions of value are influenced by the consequences of human actions, environmental values are divided into two categories: utilitarian and intrinsic. The foundation of utilitarian value is based on the importance of something that is connected with the welfare of people. Intrinsic value is associated with the belief that components of the natural environment have inherent value and a right to exist independently of human perspectives.

The term “environmental quality” refers to the state of the environment, including anthropogenic pollution, disruptions, and their impact on people, their economies, other species, and natural ecosystems. An economic principle known as “The Tragedy of the Commons” focuses on people consuming resources excessively, whether on purpose or accidentally. This rule is applicable in cases when overgrazing, resource overuse, food supply depletion, water, air, and land pollution, as well as other factors that contribute to climate change, are present. Environmental justice is the equitable treatment and participation of all people, regardless of their racial, ethnic, national, and socioeconomic backgrounds, in the “development, implementation, and enforcement of environmental laws, regulations, and policies.” Therefore, unequal access to resources and societal systemic problems are the root causes of environmental injustice.

Links to Discovery

• Measuring Progress: Water-Related Ecosystems and the SDGs (Sustainable Development Goals)
• Restore a River Back to Life 
• Solar Panels on Farms Make Sheep Happier and Healthier

Critical Thinking

1. How do water, air, and soil quality affect agriculture?
2. Explain the relationship between air quality and circular economy.
3. Explain the generation of electrical energy using wind turbines.
4. How does biodiversity impact energy resources?

Key Terms

• Abiotic factors – Non-living factors present in or impacting the environment.
• Biodiversity – The richness of biological variation, including genetic variability as well as species and community richness.
• Biotic factors – living factors present in or impacting the environment.
• Climate change – Long-term changes in air, soil, or water temperature; precipitation regimes; wind speed; or other climate-related factors.
• Environmental hazard – A potential risk factor that negatively impacts the environment.
• Environmental justice – The fair treatment and meaningful involvement of all people regardless of race, color, national origin, or income concerning the development, implementation, and enforcement of environmental laws, regulations, and policies.
• Global warming – The heating of the earth’s surface is believed to be caused by human behaviors that emit fossil fuels and trap gas in the atmosphere.
• Hydrosphere – The parts of the planet that contain water, including the oceans, atmosphere, land, surface water bodies, underground, and organisms.
• Hypothesis – A suggested explanation for an event, which can be tested
• Lithosphere – An approximately 80-km thick region of rigid, relatively light rocks that surround Earth’s plastic mantle.
• Non-renewable energy – Energy sources that are present on Earth in finite quantities, so as it is used, its future stocks are diminished.
• Nutrient cycles – The transfers, chemical transformations, and recycling of nutrients.
• Pollution – The exposure of organisms to chemicals or energy in quantities that exceed their tolerance, causing toxicity or other ecological damages.
• Population growth – When the birth rate plus immigration exceeds the death rate plus emigration.
• Renewable energy – Energy sources that can regenerate after harvesting and potentially can be exploited forever.
• Scientific laws – A description, often in the form of a mathematical formula, for the behavior of some aspect of nature under certain specific conditions.
• Scientific method – A method of research with defined steps that include experiments and careful observation.
• Scientific theory – A thoroughly tested and confirmed explanation for observations or phenomena
• Sustainability – Maintaining the current resources without diminishing the availability of resources for future generations.

References

Fowler, S., Roush, R., & Wise, J. (2013). Concepts of Biology. OpenStax. https://openstax.org/books/concepts-biology/pages/1-introduction

González-González, R. B., Sharma, P., Pratap Singh, S., Pinê Américo-Pinheiro, J. H., Parra-Saldívar, R., Bilal, M., and H. Iqbal. (2022). Persistence, environmental hazards, and mitigation of pharmaceutically active residual contaminants from water matrices. Science of the Total Environment, 821. https://doi.org/10.1016/j.scitotenv.2022.153329

Theis, T., and J. Tomkins (Eds.) Environmental Science. OpenStax. Available via Internet Archive.

Zehnder, C., Manoylov, K., Mutiti, S., Mutiti, C., VandeVoort, A., and D. Bennett. (2018). Introduction to Environmental Science (2nd ed.). University System of Georgia. Available via the Open Textbook Library.

Recommended Reading

Biodiversity Heritage Library

Biosphere: Lithosphere, Hydrosphere, and Atmosphere

Diversity and Biological Balance

Energy and the Environment