Plate Tectonics explained by a geologist in simple terms

Environmental Science provides an integrated, quantitative, and interdisciplinary approach to the study of environmental systems. The magnitude and complexity of environmental problems are creating a growing need for scientists with rigorous, interdisciplinary training in environmental science. Environmental Science graduates gain have a foundation in biological and physical natural sciences and the specialized training necessary for integrated analysis of environmental systems.

What is Environmental Science?

Environmental science is an academic field that integrates physical, biological and information sciences (including ecology, biology, physics, chemistry, plant science, zoology, mineralogy, oceanography, limnology, soil science, geology and physical geography, and atmospheric science) to the study of the environment, and the solution of environmental problems.

Environmental Science vs. Environmental Studies

Environmental studies is a multidisciplinary academic field which systematically studies human interaction with the environment. Environmental studies connects principles from the physical sciences, commerce/economics, the humanities, and social sciences to address complex contemporary environmental issues. It is a broad field of study that includes the natural environment, the built environment, and the relationship between them. The field encompasses study in basic principles of ecology and environmental science, as well as associated subjects such as ethics, geography, anthropology, policy, politics, urban planning, law, economics, philosophy, sociology and social justice, planning, pollution control and natural resource management.

Environmental Science vs. Environmentalism

Environmentalism is a broad philosophy, ideology, and social movement regarding concerns for environmental protection and improvement of the health of the environment. Environmentalism advocates the preservation, restoration and improvement of the natural environment and critical earth system elements or processes such as the climate. Environmentalism prioritizes sustainability, pollution control and preservation of biodiversity. The exact strategies to accomplish these goals are often controversial.

Environmental Science vs. Ecology

Ecology refers only to the study of organisms and their interactions with each other as well as how they interrelate with environment. Ecology could be considered a subset of environmental science, which also could involve purely chemical or public health issues (for example) ecologists would be unlikely to study. In practice, there are considerable similarities between the work of ecologists and other environmental scientists. There is substantial overlap between ecology and environmental science with the disciplines of fisheries, forestry, and wildlife

What are Ethical Perspectives?

As many cultures have progressed, intrinsic value and consideration has been granted to more people and things. Care and concern for pets is expanding to include domesticated animals. Whole natural communities are being recognized for their collective value. Science has played a major role in this by demonstrating that people are a part of nature.

What are the Three Ethical Perspectives?

Current attitudes toward the natural world tend to fall within three ethical perspectives. Anthropocentrism is a human-centered view; nonhuman things are given little or no intrinsic value. Costs and benefits of actions are evaluated solely on the positive and negative impacts on people. Biocentrism ascribes intrinsic value to both human and nonhuman life. Biocentrists may oppose clearing a forest, even if it would increase food production for people. Ecocentrism judges actions based on their effects on ecological systems, including nonliving elements. The belief is that preserving systems also preserves their components, including life, water quality, etc.

When Did Environmental Ethics Develop?

Environmental ethics has ancient roots. Although environmental ethics as an academic discipline began in the 1970s, we have considered our ethical relationship with nature for thousands of years. Plato wrote, “The land is our ancestral home and we must cherish it even more than children cherish their mother.” The directive, “You shall not defile the land in which you live.” is found in the book of Numbers, 35:34.

What was the Role of the Industrial Revolution?

The industrial revolution inspired reaction. During the industrial revolution in the 19th century, agricultural economies became industrial ones. Machines replaced human and animal labor and people moved from farms to cities. As populations rose, resource consumption increased, and pollution intensified. A philosophical movement called transcendentalism flourished, rejecting materialism and beginning the ideals of preserving nature as a priority to industrial modernization. Conservation and preservation arose with the 20th century.

Who are Important Contributors to Environmental Ethics?

John Muir was a believer in transcendentalism and became politically active by promoting the preservation ethic, that we should protect nature in its pristine, unaltered state. Muir’s ethic included ecocentrist (nature has intrinsic value) and anthropocentrist (nature promotes human happiness) ideals. Gifford Pinchot, the founder of the U.S. Forest Service, had a somewhat more anthropogenic view than Muir. His conservation ethic held that people should use natural resources, but in a wise, careful manner. Provide the greatest good for the greatest number of people for the longest time. Muir and Pinchot represented different branches of the environmental movement, but both opposed the development ethic, which held that people should be masters of nature and promote economic development as a priority.

What are Natural Resources?

Natural resources are any substances including energy sources that are sourced from the environment. Without natural resources, our way of living would not be possible. The cars we drive, the phones we rely on, the homes that shelter us, the food we eat, even the toothbrush we use everyday would not exist without natural resources.

What are Nonrenewable Natural Resources?

Natural resources that are limited in supply are called nonrenewable natural resources because once they are depleted that’s it, they are gone, they will no longer be available. Minerals that are mined or fossil fuels that are pumped from the ground are examples of nonrenewable resources. Nonrenewable natural resources are created naturally through various processes that take millions of years. The time it takes to make these resources is so so so much greater than the time it take us to deplete it. That is why they are referred to as nonrenewable.

What are Renewable Natural Resources?

Renewable natural resources are the opposite of nonrenewable because they can be replenish over much shorter periods of time. Some renewable resources, like sunlight, wind, and wave energy are inexhaustible, because they are constantly renewed. Others, such as timber, water, or soil, renew over months, years, or decades. They are exhaustible. Renewable natural resources may be sustainably used but they can still be depleted if we consume them faster than they are able to be replenished.

What are Ecosystem Services?

If you think of Earth’s natural resources “goods” then you could also consider some of Earth’s natural processes as “services.” We get tangible things from the Earth, but there are processes that are just as important. For example, Earth’s ecological systems purify the air and water, there are ecological systems that cycle nutrients through water and soil, regulate ocean currents and temperature which directly impacts climate, ecological systems help pollinate plants, and even recycle waste. These functions are called ecosystem services and they are just as important to us as natural resources and like natural resources they can be depleted or degraded. We could not survive on Earth without the gifts of ecosystem services.

How Does Culture Impact Ethics?

What is Culture?

Decisions on how to manipulate the environment involve economics, but are also influenced by our own culture and worldview. Culture is the knowledge, beliefs, values, and learned ways of life shared by a group of people. A person’s perception of the world and his or place within it is their worldview. Among the most influential factors that shape worldview are spiritual beliefs and political ideology. For example, your opinion on the role of government will shape whether you want it to intervene in a market economy to protect the environment. Shared cultural experience is another factor. Early European settlers to the Americas viewed the environment as a hostile force due to inclement weather and wild animals that destroyed their crops and livestock.

Instrumental Value vs. Intrinsic Values

We value things in two ways; if something is valued for the pragmatic beliefs that it brings us, it has instrumental value. If something is believed to have a right to exist and is valuable for its own sake, it has intrinsic value. A forest, for example, has instrumental value due to its timber, game hunting, recreational uses, and water filtration. It also has intrinsic value because it provides homes for other organisms that have a right to live. Market prices can be easily assigned to instrumental values, but not as easily to intrinsic ones.

What are Ethical Standards?

Ethical standards help us judge right from wrong. Ethical standards are the criteria that help to differentiate right from wrong. One example is the “Golden Rule,” which advises us to treat others as we would prefer to be treated. Another is the principle of utility, which holds that something is right when it produces the greatest practical benefits for the most people. Ethics is a set of moral principles or values used to determine right and wrong. Making ethical judgements is grounded in certain values, such as promoting human welfare, protecting individual freedom, or minimizing suffering.

What is Environmental Ethics?

Environmental ethics pertains to people and the environment. The application of ethical standards to the relationship between people and nonhuman entities is environmental ethics. Our interaction with the environment raises many ethical questions. Relativists believe that ethics vary depending on the context of the problem. Universalists define objective notions of right and wrong that hold across many cultures and contexts. Is the present generation obliged to conserve for future generations? This deals with the idea of sustainability. Should some communities be exposed to a disproportionate share of pollution? This is a central question in environmental justice. Are there any circumstances where human-driven extinction of a species is justified? This is a debate between the relative importance of instrumental values and intrinsic values of an ecosystem.

What is an Ecological Footprint?

Population growth has led to a dramatic increase in consumption of Earth’s resources. The material affluence of millions of people has increased across the globe since the industrial revolution. In the process of such progress we have consumed an increasing amount of Earth’s limited resources. One way to quantify resource consumption is to use the concept of the ecological footprint. An ecological footprint expresses the cumulative area of biologically productive land and water required to provide the resources a person or a population consumes and to dispose of or recycle the waste produced.

What is an Overshoot?

The global footprint network estimates that humanity as a whole is using 64% more of the planet’s renewable resources meaning we are depleting renewable resources by using them 64% faster than they are being replenished. This is called an overshoot, because we are surpassing Earth’s capacity to sustainably support us. One way to understand this concept is to think about balancing your bank account… If you have a daily salary of $100 but you spend $164 everyday... You will quickly start cutting into your savings and very soon you’ll be in the negative because you are making less than you are spending. That is precisely our problem. We are spending Earth’s resources faster than Earth can regenerate them.

What is Sustainability?

One of the biggest challenges in environmental science is sustainability; a way of living so that the Earth’s resources can sustain us well into the future. Living sustainably means to not take more of the Earth’s renewable resources than can be replenished. If we continue our banking analogy then you can think of sustainability as living off the interest produced by your savings account. Environmental scientists aim to study and develop solutions to the problems caused by depleting resources and degrading ecosystems. But as an informed global citizen, you can be a part of the solution.

What are Feedback Loops?

What are Systems?

A system is a network of relationships among parts that influence each other through the exchange of energy, matter. Systems are not isolated—they may exchange energy, matter, and information with other systems. How a system is defined may depend on what you are studying. Scientists divide the Earth’s components into structural “spheres”. The lithosphere is the rock and sediment in the upper mantle and crust. The atmosphere is the air surrounding the planet. The hydrosphere includes all surface, underground, and atmospheric water. The biosphere consists of all the planet’s organisms and the abiotic portions they interact with. All the interactions between each sphere are an important part of understanding each sphere or system itself.

What are Feedback Loops?

To be stable, all systems need to be self-regulating. A system’s output may serve as input back into the same system, a process called a feedback loop. Feedback loops permit systems to adjust their response to change (forcing factors) to return to stable conditions. A feedback loop is essentially a cause and effect cycle. Feedback loops come in two flavors: positive and negative. the positive and negative naming of the loops do not indicate whether the feedback is good or bad.

What are Positive Feedback Loops?

A positive feedback loop increases the effect of the change and produces instability. Positive feedback loops occur when increased output in a system leads to increased input, which further stimulates output. The melting of glaciers and sea ice in the Arctic is an example. Heat warms the surface, causing further melting, which exposes more dark surface area. a positive feedback loop moves a system further away from the target of equilibrium

What are Negative Feedback Loops?

A negative feedback loop reduces the effect of change and helps maintain balance. A negative feedback loop results when the system moving in one direction acts as an input that cause the system to move in the opposite direction. Negative feedback enhances stability in a system. When processes in a negative feedback system move in opposing directions at equivalent rates then the system is in dynamic equilibrium. This contributes to homeostasis, the tendency of a system to maintain stable internal conditions. An example of this is your body's ability to control temperature. The condition of the body's temperature is the information fed back to the brain, which is the controller. If the temperature is high, the body sweats in order to cool down. Since the process of sweating is done to stop the temperature change, this is a negative feedback.

Why do Systems & Feedback Loops Matter?

Systems are not isolated—they may exchange energy, matter, and information with other systems. How a system is defined may depend on what you are studying. Scientists divide the Earth’s components into structural “spheres”. The lithosphere is the rock and sediment in the upper mantle and crust. The atmosphere is the air surrounding the planet. The hydrosphere includes all surface, underground, and atmospheric water. The biosphere consists of all the planet’s organisms and the abiotic portions they interact with. The interactions between each sphere is an important part of understanding ecology.

How Do Nutrient Cycles Impact Ecosystems?

What is an Ecosystem?

An ecosystem consists of all organisms and nonliving entities that occur and interact in a particular area at the same time. Ecological communities only include living organisms. In ecosystems, energy flows and matter cycles between the living and nonliving components. An estuary for example is an ecosystem where rivers flow into the ocean, mixing salt and fresh water. Organisms are affected by the flow of water, nutrients, and sediment from the rivers. The chemical and physical conditions of the bay’s waters are affected by the photosynthesis, respiration, and decomposition of its life. Ecosystems interact with one another. The term ecosystem is most often used to describe somewhat self-contained geographic areas. Adjacent ecosystems may interact and share resources extensively. Areas where ecosystems meet in a transitional zone are called ecotones.

How is Energy Distributed in an Ecosystem?

Energy is converted into biomass. The conversion of solar energy into chemical bonds in sugars is called primary production. The total chemical energy produced by autotrophs is called gross primary production. The energy that remains after respiration is used to generate biomass (leaves, stems, and roots) is net primary production. Energy used by consumers to generate their own biomass is secondary production. The rate at which energy is converted to biomass is termed productivity. Freshwater wetlands, tropical forests, coral, reefs, and algal beds tend to have the highest net primary productivities. Deserts, tundra, and open ocean have the lowest.

What are Nutrients in an Ecosystem?

Nutrients influence productivity. Nutrients are elements and compounds that organisms require for survival. Elements and compounds (nitrogen, carbon phosphorus) needed in large amounts are called macronutrients. Nutrients needed in smaller amounts (zinc, copper, iron) are micronutrients. Nitrogen tends to be the limiting nutrient in marine systems and phosphorus in freshwater systems like this lake in Ontario. Dead zones are found mostly in coastal areas with the greatest human ecological footprints.

What are Biogeochemical Cycles?

Nutrients move through ecosystems in nutrient cycles, also known as biogeochemical cycles. Elements or molecules travel through the atmosphere, hydrosphere, lithosphere, and biosphere in dynamic equilibrium. Nutrients move from one reservoir, or pool, to another for varying amounts of time, called the residence time. You, a cow, grass, sedimentary rocks, and the atmosphere are all reservoirs for carbon. When a reservoir releases more materials than it accepts, it is called a source. When a reservoir accepts more materials than it releases, it is called a sink. Flux is the rate at which materials move between reservoirs.

What is the Water Cycle?

The water cycle affects all other biogeochemical cycles. Water is the medium for all biochemical reactions, and it plays key roles in nearly every environmental system. Water carries nutrients, sediments, and pollution, and returns atmospheric pollutants to the surface through rain or snow. The hydrologic cycle summarizes how water flows as a solid, liquid, and gas, through our environment. The oceans are the main reservoir (97%) for water. Only about 3% is fresh water, and two-thirds of that is frozen in glaciers, ice caps, and snowfields.

How Does Water Move Through the Water Cycle?

Evaporation converts water from a liquid to gaseous form, taking it to the atmosphere. Increased by warmth, wind, and a high degree of exposure. Transpiration is the release of water vapor by plants through their leaves. Transpiration and evaporation both leave any substances dissolved in water behind. Water returns to the Earth’s surface as precipitation when it condenses into rain or snow. Some may be taken up into plants, some precipitation and surface water soaks down through soil and rock, becoming groundwater. Groundwater recharges aquifers, which are regions of rock and soil that are underground reservoirs of water. The upper limit of groundwater in an aquifer is called the water table. Groundwater becomes surface water when it emerges in springs or flows into surface waters.

Our Impact on the Water Cycle

Our impacts on the water cycle are extensive. Human activity impacts every aspect of the water cycle. Damming rivers slows the movement of water and increases evaporation from reservoirs. Removing vegetation increases runoff and decreases infiltration and transpiration. Withdrawal of groundwater lowers water tables. Air pollution can change the chemical nature of precipitation.

What is the Carbon Cycle?

The carbon cycle circulates a vital organic nutrient. Carbon is found in all organic molecules—carbohydrates, fats, and proteins, which make up living organisms. The carbon cycle describes the routes that carbon takes through the environment.

How Does Carbon Move Through the Carbon Cycle?

Producers (plants, algae, and cyanobacteria) pull carbon dioxide (CO2) out of the air and use it to produce sugars like glucose (C6H12O6). Autotrophs, consumers, and decomposers consume organic molecules and release some of the carbon as carbon dioxide. The remainder is used for structural growth of the organisms. As aquatic organisms die, their remains may settle in sediments in ocean basins or freshwater wetlands. With burial and pressure over long periods of time can oil can form within the sedimentary rock that forms.

What are the Carbon Reservoirs?

Sedimentary rock is the largest reservoir in the carbon cycle. Carbon can be released during uplift, erosion, volcanic eruptions, or the burning of fossil fuels. The oceans are the second-largest reservoir of carbon, dissolving carbon dioxide, carbonate ions (CO32−), and bicarbonate ions (HCO3−), which are incorporated into the shells of marine organisms. Some of the excess CO2 is being absorbed by the oceans from the atmosphere, causing it to become more acidic. Today’s atmospheric carbon dioxide reservoir is estimated to be the largest in the past 800,000 years. Combustion of fossil fuels and a decrease of surface vegetation have a major impact.

What is the Nitrogen Cycle?

The nitrogen cycle involves specialized bacteria. Nitrogen is an essential ingredient in DNA, RNA, and proteins. Nitrogen gas (N2) makes up 78% of the atmosphere, but is chemically inert and cannot leave the atmosphere without assistance. Under the right conditions, nitrogen can become biologically active and enter the biosphere and lithosphere, a process called the nitrogen cycle.

How is Nitrogen Transported?

To become biologically available, nitrogen fixation will combine nitrogen with hydrogen to form ammonia (NH3), whose water-soluble ions of ammonium (NH4+) can be taken up by plants. Nitrogen-fixing bacteria convert nitrogen gas into ammonia. The bacteria form nodules on plant roots, absorbing sugars from the roots in exchange for nitrogen fixation. Some of these bacteria are found in legumes, such as soybeans. Other bacteria perform a process called nitrification, which converts ammonium ions into nitrite ions (NO2−), then into nitrate(NO3−) ions, which plants can directly take up. These ions are also added to the soil through the use of fertilizer. Consumers obtain nitrogen by ingesting plants or other animals. Decomposers obtain and release nitrogen from dead and decaying matter. Denitrifying bacteria will then convert nitrates back into nitrogen gas, releasing it back into the atmosphere and completing the cycle.

What is our Impact on the Nitrogen Cycle?

We have greatly influenced the nitrogen cycle. Nitrogen fixation has historically been a bottleneck, a step that limited the flux of nitrogen out of the atmosphere. The Haber-Bosch process enabled people to artificially fix nitrogen, greatly enhancing agriculture. Humans have effectively doubled the rate of nitrogen fixation on the Earth. Runoff can cause excess nitrogen to enter waterways, causing eutrophication. Burning fossil fuels releases additional nitrogen into the atmosphere.

What is the Phosphorus Cycle?

The phosphorus cycle circulates a limited nutrient. Phosphorus is a key element in many organic molecules, including DNA, RNA, and ATP. The biggest phosphorus sinks are rocks, soil, sediments, and the oceans. There’s very little in the atmosphere. The processes that move phosphorus from these sinks to living matter are called the phosphorus cycle.

How Does Phosphorus Move Through Ecosystems?

Weathering of rocks releases phosphate (PO4−) ions into water. These phosphates precipitate into a solid form, sink to the bottom of bodies of water, and re-enter the lithosphere as sediments. Aquatic organisms take up phosphates directly from surrounding waters. Terrestrial organisms take up phosphates from soil water through their roots. Phosphates are passed through the food chain and eventually returned to the soil by decomposers.

How Do We Impact the Phosphorus Cycle?

We affect the phosphorus cycle in many ways. Like nitrogen, the runoff of phosphorus increases its concentration in surface waters. Wastewater rich in dishwater and clothes detergents is also a contributor. Managing nutrient enrichment requires diverse approaches like reducing farm and lawn fertilizer application, planting vegetation “buffers” or using wetlands around streams to trap nutrient runoff, improving sewage treatment technology, and reducing fossil fuel consumption. The cost of each treatment varies but natural approaches like wetlands and vegetation buffers are the most economical.

What is Evolution?

A species is a classification of organism whose members can interbreed and produce fertile offspring. A population is a group of individuals within a species that live in the same geographic area. Populations change over multiple generations as genetic changes alter their physical and behavioral characteristics, a process called evolution. Evolution originates in genes and often leads to modifications in appearance or behavior. Natural selection shapes organisms. Evolution is driven by natural selection, a process that favors certain inherited characteristics over others, causing them to be passed on more frequently.

What is Natural Selection?

The idea of natural selection is based on three observations:

Organisms face a constant struggle to survive and reproduce.
Organisms tend to produce more offspring than can survive to maturity.
Individuals of a species vary in their attributes.

The concept of natural selection was first proposed in the 1850s by Charles Darwin and, independently by Alfred Russel Wallace, two British naturalists.

Speciation vs. Adaptation

Attributes are passed from parent to offspring through genes. Genes that lead to better reproductive success will eventually evolve through the entire population. This is called adaptation. Speciation produces new types of organisms. Allopatric speciation occurs when populations become physically separated over a geographic distance. When a mutation arises in an organism of one of the populations, it does not spread to the other. Eventually the populations grow so different that they can no longer mate. Selection acts on genetic variation. Accidental changes in DNA, called mutations, give rise to genetic variation in individuals. The mixing of genetic material through sexual reproduction also generates variation.

What is the Influence of Selective Pressures?

Natural selection can drive a feature in a particular direction. An environment with flowers with short nectar tubes would favor short beaks. An environment with flowers with long nectar tubes would favor long beaks. Selective pressures from the environment influence adaptation. Closely related species that live in different environments tend to diverge in their traits. Different selective pressure lead to different adaptations. Unrelated species living in similar environments in separate locations may independently acquire similar traits. Similar selective pressures. This is called convergent evolution.

Why Does Evolution & Natural Selection Matter?

Understanding evolution is vital for modern society. Evidence of selection is all around us. Humans have conducted selection under our own direction, called artificial selection. Domesticated dogs, cats, and livestock for example. Many medical advances have resulted from our knowledge of evolution. How infectious diseases spread and gain or lose potency. Tracking evolving strains of influenza, HIV, and other pathogens. Detection of the evolution of antibiotic resistance in bacteria.