Flashcard Lab

The use of knowledge and methods from various scientific disciplines like biology, chemistry, physics, and human population dynamics to study environmental issues.

The variety of life forms, including species, ecosystems, and genetic variation, and the ways these interact and are impacted by human activities.

The study of how living (e.g., organisms) and nonliving components (e.g., water, air, minerals) interact and are organized in nature.

Gases such as carbon dioxide and methane that trap heat in the Earth's atmosphere, contributing to global warming and climate change.

The introduction of harmful substances or products into the environment, affecting air, water, land, and living organisms.

A set of interconnected living and/or nonliving components that interact with each other, where a change in one part of the system can affect other parts.

Large-scale changes to the Earth’s environment, including alterations to climate, ecosystems, and human population dynamics.

The ability to maintain environmental health and resources for future generations by balancing human needs with the preservation of ecosystems and species.

Actions performed by humans that impact the environment, such as deforestation, overfishing, pollution, and the burning of fossil fuels.

Long-term changes in temperature, precipitation, and other atmospheric conditions, often driven by human activities like burning fossil fuels and deforestation.

A community of living organisms interacting with their nonliving environment, such as water, air, and minerals, forming a functional system.

Various methods of generating energy, including fossil fuels, renewables, and nuclear power, each having different environmental impacts.

The effect of human activities on the environment, including negative impacts such as pollution, habitat destruction, and climate change.

Resources found in the natural environment, such as water, minerals, and forests, which are used by humans for survival and economic activities.

The study of how human populations grow, shrink, and move over time, and how these movements affect the environment and resource use.

A systematic approach to investigation in environmental science that involves observation, hypothesis testing, research, and data analysis.

A set of interconnected components that work together, where changes in one part of the system affect other parts. Examples include ecosystems, lakes, and farms.

The clearing or destruction of forests, which reduces biodiversity and contributes to global warming by releasing stored carbon.

The practice of catching fish at a rate that exceeds their ability to reproduce, leading to population declines and ecosystem disruptions.

The negative effects caused by pollutants in the environment, such as the contamination of air, water, and land, which can harm ecosystems and human health.

A measure that reflects the environmental health of a system, such as the amount of new growth on trees, which can indicate the state of a forest or ecosystem.

The variety of genes, species, habitats, and ecosystems on Earth, which is an important measure of the planet's environmental health. The extinction rate of species is a key indicator.

The rate at which species go extinct. Human activities have accelerated extinction rates to up to 100 times higher than natural background rates, posing a threat to biodiversity.

Species that play a critical role in maintaining the structure and function of an ecosystem. The loss of a keystone species can lead to the collapse of entire ecosystems.

The increase in the human population, which has slowed but continues to grow, creating a greater demand on Earth's finite resources, such as food, water, and energy.

A pattern of population growth where the rate of increase is proportional to the existing population. Human population growth was once exponential but is now slowing.

The global production of food, particularly grains like wheat, corn, and rice, which are indicators of agricultural health and sustainability. Agricultural intensity and land quality are key factors.

Refers to how much food is produced per unit area of land (e.g., monoculture vs. polyculture). High-intensity farming can lead to soil degradation and reduced land productivity.

The amount of staple crops like wheat, corn, and rice produced globally, which is impacted by various environmental factors such as soil quality, climate, and agricultural practices.

The removal of soil layers due to factors like deforestation and intensive farming, which can lead to reduced land productivity and environmental degradation.

Harmful substances released into the environment, including air, water, and soil pollution. Increased human population and industrial activity contribute to higher pollution levels.

The use of Earth's natural resources such as energy, water, food, and land. Growing human populations place greater pressure on these limited resources.

Periods in Earth's history when a significant number of species went extinct, often due to large-scale environmental changes. Human impacts are currently contributing to a potential new mass extinction.

The use of resources in a way that meets current needs without compromising the ability of future generations to meet their own needs. Unsustainable use leads to resource depletion.

The total amount of resources (energy, water, land, etc.) used by humans. This consumption is influenced by population size and lifestyle.

The environmental impact increases as the human population grows, with greater consumption of resources and more pollution. Consumption patterns also vary based on lifestyle and region.

Gases like carbon dioxide and methane that trap heat in the Earth's atmosphere, regulating temperature. Human activities, particularly fossil fuel burning, increase these gases.

Over the past 130 years, global temperatures have increased due to higher concentrations of greenhouse gases, largely caused by human activity like burning fossil fuels.

Harmful substances, such as lead or chemicals, released into the environment. This includes air, water, and land pollution, with significant impacts on human health and ecosystems.

Lead is toxic to humans and the environment. It was historically used in gasoline and paints, contributing to pollution. Modern efforts like the switch to unleaded gasoline have reduced lead emissions.

A systematic way to explore the natural world, generate hypotheses, conduct experiments, and report findings. It is based on observation, testing, and repetition to build knowledge.

The initial step of the scientific method where scientists make observations of the natural world and ask questions based on those observations.

A testable and falsifiable statement that explains a phenomenon or answers a question posed from observations. Hypotheses can be revised based on experimental results.

A procedure used to test hypotheses, which may be observational (no interference) or manipulation (changing variables). A control group is compared to an experimental group.

The number of observations or test subjects used in an experiment. Larger sample sizes increase the reliability of results.

Repeating experiments by different scientists to confirm results. If many tests yield the same conclusion, a hypothesis may become a theory, and widely accepted theories become laws.

A widely accepted explanation that has been supported by repeated testing and evidence.

A scientific principle that applies universally without exceptions (e.g., the First Law of Thermodynamics).

A type of scientific experiment aimed at studying the effects of human activity or environmental changes on ecosystems, such as the impact of reducing habitat size on species diversity.

A group in an experiment that is not manipulated and is used as a benchmark to compare with the experimental group.

The factor in an experiment that is deliberately changed to test its effect on the experimental group.

Repeating experiments by different researchers is essential for verifying findings. Results are considered reliable when consistently reproduced, despite occasional disagreements or varying interpretations among scientists.

It's important to critically assess scientific studies, ensuring there is a clear distinction between experimental and control groups, a large enough sample size, and evidence of a cause-and-effect relationship.

Systems are networks of interconnected living and nonliving components. Changes in one part can affect other parts. Environmental science studies the dynamics of these systems, ranging from individual organisms to global ecosystems.

The interactions and changes between components within a system. These dynamics are key to understanding environmental processes and can be applied at various levels, from local ecosystems to global climate systems.

Environmental systems involve the exchange of materials (e.g., water, gases) or energy (e.g., food intake, fossil fuels). The flow of energy, especially from the Sun, is crucial in sustaining life on Earth.

Open systems exchange matter and/or energy with their surroundings (e.g., the ocean). Closed systems only exchange energy, with matter largely contained within (e.g., Earth's overall system with respect to matter).

Human activities, such as economics, law, and policy, significantly affect environmental systems, especially when considering issues like climate change, energy use, and resource management.

A method of studying systems by tracking inputs (what enters), outputs (what exits), and flux (the changes). It helps analyze how matter and energy flow and change within a system, similar to personal financial analysis.

The rate of flow or change within a system. For example, the change in the amount of matter or energy entering or leaving a system over time.

A method of assessing the flow of materials within a system by measuring inputs, outputs, and flux. This type of analysis helps understand the environmental impact of substances like pollutants or nutrients.

In scientific studies, it’s important to demonstrate a direct cause-and-effect relationship rather than just a correlation between events. This ensures that findings are scientifically valid and not coincidental.

A condition where the input and output of a system are balanced, so the size of the "pool" does not change over time. Examples include water in the atmosphere or oceans, where the rate of input equals the rate of output, keeping the system stable.

The difference between inputs and outputs in a system. If input equals output, net flux is zero, and the system is in steady state. If input exceeds output, the system will accumulate material; if output exceeds input, the system will deplete material.

The process by which material builds up in a system, often due to greater input than output. This can be problematic in cases like pollutants accumulating in reservoirs.

The process by which material decreases in a system, often due to greater output than input. For example, water resources may be depleted faster than they are replenished during drought conditions.

Mechanisms that regulate a system. They can either amplify or reduce changes within the system. Feedback loops can be negative (restoring balance) or positive (accelerating change). Example: A negative feedback loop in a bank account helps stabilize finances. Positive feedback can lead to a vicious cycle.

A feedback mechanism where changes in the system lead to responses that counteract or reverse the initial change, returning the system to a stable state. Example: Reducing spending when a bank account balance decreases.

A feedback mechanism where changes in the system lead to responses that amplify the initial change, pushing the system further away from its starting point. Example: A gambler betting more money as they lose.

The phenomenon where a system exceeds its stable set point due to delays in feedback responses. In ecology, this occurs when a population grows too large and exceeds the carrying capacity of its environment, leading to a crash.

The maximum population size that an environment can sustainably support, given available resources and conditions. When a population exceeds this capacity, overshoot occurs, often leading to population decline.

Environmental systems that control population sizes based on birth rates, death rates, immigration, and emigration. Population growth can be regulated by both abiotic factors (like food availability) and biotic factors (like predation). Example: Deer populations decreasing due to food shortages.

Nonliving components of an environment that influence the size and behavior of populations. Examples include temperature, water, and food availability.

Living components of an environment, such as other species, that interact with a population. Example: The size of a rabbit population may be regulated by predators like wildcats.

The study of the impacts of human activities on environmental systems. It includes examining various environmental indicators to assess the health of the Earth.

The current human population is around 8 billion, continuing to grow, though the rate of growth has been decreasing since the 1960s.

Human activity has significantly increased the extinction rate, with around 40,000 species possibly going extinct each year, contributing to a sixth mass extinction event.

The increase in atmospheric concentrations of carbon dioxide and other greenhouse gases due to human activities is contributing to global temperature rise and climate change.

Air and water pollution increased in the early 1900s but has decreased in some places like the U.S. due to stricter regulations. Pollution remains a global issue, especially for certain chemicals.

The consumption of resources in the present that does not deplete the ability of future generations to meet their needs. Resource consumption varies worldwide and impacts the environment.

Sets of living and non-living components that interact and influence each other. Changes in one part of the system can affect the entire system.

Open systems exchange matter and energy with their surroundings, while closed systems do not. Human activities often influence these systems.

A method used to calculate inputs and outputs of a system to determine if the system is in a steady state or undergoing change.

Processes that regulate systems. Negative feedback loops restore stability, while positive feedback loops amplify changes, potentially destabilizing the system.

When a system exceeds its capacity due to delayed responses, potentially leading to the depletion of resources or other negative effects.

The process by which genetic changes accumulate over generations, leading to new species. Evolution is driven by natural selection.

The variety of genes, species, and ecosystems on Earth. It includes the diversity of life forms and their interactions with each other and the environment.

The variety of genes within a population, which is the ultimate source of biodiversity. It allows for adaptation and survival in changing environments.

Different forms of a gene that can result in variations in traits. Alleles combine to determine an organism’s phenotype.

The observable characteristics of an organism resulting from the interaction between its genotype and the environment.

The genetic makeup of an organism, consisting of all the genes that influence its traits.

A change in genetic material that can lead to new alleles. Mutations can be neutral, harmful, or beneficial, and those that are beneficial may spread through a population.

A measure of an organism's ability to survive and reproduce. Higher fitness means better chances of passing on genes to the next generation.

A mechanism of evolution where individuals with traits that improve survival and reproduction are more likely to pass those traits on to future generations.

The process by which a species becomes better suited to its environment through evolutionary changes.

The formation of new and distinct species through evolutionary processes such as genetic divergence and adaptation to different environmental pressures.

The variety of species in a given area. It results from both adaptive and nonadaptive processes, such as changes in environment or reduced gene flow between populations.

Changes in the genetic makeup of a population that improve the survival of individuals in specific environmental conditions, driven by natural selection.

A change in the environmental conditions, which can range from gradual shifts to rapid changes, affecting species’ survival and adaptation.

The maximum number of individuals an environment can support without degradation.

Sudden changes in the environment caused by human activity, such as climate change, that may outpace species' ability to adapt and lead to extinction.

Traits that increase an organism’s chances of survival in its environment, passed on to future generations through natural selection.

Evolutionary changes that occur without the influence of natural selection or fitness. These processes can cause genetic changes in populations without providing adaptive advantages.

The movement of alleles from one population to another through migration. Gene flow introduces new genetic variations into a population, potentially leading to changes in phenotypes.

A random process that causes changes in allele frequencies within small populations. Genetic drift can lead to the loss of alleles, which may alter the genetic composition of the population over time.

A type of genetic drift that occurs when a population undergoes a drastic reduction in size due to an event like hunting, habitat loss, or a natural disaster. This reduces genetic diversity within the population.

The variety of alleles and genes present within a population, which provides the raw material for evolution. A loss of genetic variation can lead to problems such as increased susceptibility to disease.

A case study of a population suffering from genetic bottleneck. Due to drastic population reductions, cheetahs now have low genetic diversity, leading to low fertility and higher disease rates.

Evolutionary processes that typically depend on natural selection and genetic variation, where individuals with advantageous traits are more likely to survive and reproduce.

Changes in the environment that force species to adapt. Rapid environmental changes can accelerate evolutionary processes as species must evolve quickly to survive.

The rate at which evolutionary changes occur. Evolution can take from thousands to millions of years for significant changes, but can happen more rapidly in small populations or under specific conditions.

The speed at which environmental conditions change, influencing the pace of evolution. Rapid changes force species to adapt quickly or face extinction.

Populations with more genetic variation can evolve faster due to a larger pool of potential adaptive traits. Limited genetic variation slows down evolutionary processes.

Smaller populations can evolve more quickly through nonadaptive processes like genetic drift, but they are also more vulnerable to the loss of genetic diversity.

Natural selection promotes adaptive evolution based on fitness, whereas nonadaptive processes like genetic drift occur randomly and do not directly enhance survival or reproductive success.

The slow process by which new genetic variations are introduced into a population through mutations. This slow pace of mutation accumulation can delay evolutionary changes, especially in large populations.

When environmental changes occur, species that are no longer adapted to the new conditions may experience a decrease in population size, eventually leading to extinction unless they adapt or migrate.

Fossils provide evidence of past life, showing the history of species over millions of years. The fossil record helps scientists track the evolution of species and the timing of extinctions.

A system used to divide Earth's history into various time intervals based on significant events like the evolution of life forms or mass extinctions.

A period when a large percentage of Earth's species go extinct in a relatively short period. This can be caused by environmental changes, such as volcanic eruptions or asteroid impacts.

The largest known mass extinction, occurring at the end of the Paleozoic Era, wiping out 90-95% of marine species and 70% of land vertebrates, possibly due to volcanic eruptions and ocean circulation changes.

A mass extinction event that occurred 65 million years ago at the boundary between the Cretaceous and Tertiary Periods, famous for the extinction of the dinosaurs.

The idea that human activities, such as habitat destruction, overexploitation, and pollution, are currently driving a mass extinction event, potentially as severe as past extinction events.

After mass extinctions, biodiversity typically recovers over long periods (10 to 100 million years), but current biodiversity loss may take similar amounts of time to recover, requiring restoration of natural habitats.

The excessive use or harvesting of species by humans, leading to their depletion or extinction. Examples include overhunting and overfishing.

The process by which large, continuous habitats are divided into smaller, isolated patches due to human activities, such as urbanization and construction, which can disrupt species movement and reduce biodiversity.

When humans introduce species to new environments where they are not native, these species can outcompete local species, leading to declines in biodiversity.

Human activities that change natural habitats, such as deforestation, agriculture, or urban development, which can result in the loss of biodiversity.

Extinction is the end of a species, often due to environmental changes, whereas evolution is the process by which species adapt over time to their environments. Some extinct species gave rise to new species before disappearing.

Scientists study the impact of environmental changes and human activities on biodiversity and advocate for policies to mitigate the loss of species.

The process by which large, continuous habitats are broken into smaller, isolated patches due to human activity, such as urbanization. This can disrupt species' movement, affect biodiversity, and create more "edge" habitats.

Areas along the boundary between different ecosystems, such as a forest edge near a clearing. Increased edge habitat can change the species composition, as some species thrive at edges, while others may be displaced.

When habitat fragmentation divides a population into smaller populations with reduced gene flow, leading to genetic isolation. Over time, this can result in genetic drift and loss of genetic variation.

Species that are introduced to areas where they are not native, either intentionally or accidentally, by humans. These species can often thrive in their new environment and disrupt local ecosystems, as seen with the zebra mussel.

An exotic species native to the Caspian Sea, which spread to the Great Lakes in the 1980s through ballast water. They have caused significant ecological and economic damage by outcompeting local species and clogging water systems.

The role of an organism within its community, including how it interacts with other species and its environment. Species with overlapping niches may compete for limited resources, potentially leading to competitive exclusion.

A principle stating that two species with the same niche cannot coexist indefinitely, as one species will outcompete the other for resources, leading to the extinction of the less competitive species.

A biological interaction where one species (the predator) feeds on another (the prey). It includes herbivory (animals eating plants) and parasitism (organisms benefiting at the expense of their host).

The fluctuations in predator and prey populations, where an increase in prey may lead to an increase in predators, and vice versa. Without balance, this can lead to the extinction of both populations.

A type of population interaction in which both species benefit. It often involves reciprocal exploitation, where each species gains from the relationship, such as pollination between plants and animals.

A specific type of mutualism where one animal species pollinates only one plant species, and that plant is only pollinated by that specific animal species, like the relationship between fig trees and fig wasps.

The division of resources between species to minimize competition. For example, different species of warblers may feed in different parts of the same tree to reduce direct competition for food.

Non-living physical and chemical factors that influence life, such as temperature, light, and oxygen levels, which determine which species can survive and thrive in a particular environment.

The range of environmental conditions within which a species can survive, grow, and reproduce. Extreme conditions outside this range will prevent survival, while optimal conditions lead to thriving populations.

Environmental elements that organisms consume to survive, grow, and reproduce, such as food, water, and oxygen. Resources are consumed and become unavailable to others, and the availability of resources influences population and community dynamics.

A resource that is in short supply and limits the growth or reproduction of a population. Species must compete for these resources, and competition can lead to changes in population sizes.

Coastal ecosystems with high levels of biomass and nutrients. Despite being nutrient-rich, the vegetation in salt marshes is not diverse, as only a few plant species can survive the harsh environmental conditions like high salt concentrations.

An ecological community is any assemblage of populations of different species living in the same area or habitat. Community ecology studies how these populations interact.

A food web is a complex model that represents the interconnections of species within a community and the pathways of energy flow through predator-prey relationships. Unlike a food chain, it includes multiple feeding relationships.

A food chain is a simple, linear sequence of organisms where each organism serves as food for the next level in the chain. It shows how energy flows from producers to consumers.

Trophic levels refer to the feeding positions in a food chain or web. These levels include primary producers, primary consumers, secondary consumers, and tertiary consumers.

Primary producers, such as plants and algae, are organisms that make their own food through photosynthesis. They form the base of the food web.

Primary consumers are herbivores that feed directly on primary producers (plants or algae). Examples include grasshoppers and caterpillars.

Secondary consumers are organisms that feed on primary consumers (herbivores). Examples include robins (feeding on earthworms) and frogs (feeding on insects).

Tertiary consumers are predators that feed on secondary consumers. Examples include snakes and owls, which feed on other carnivores.

An energy pyramid shows the decrease in energy as you move up from one trophic level to the next. It typically shows that only about 10% of the energy from one level is passed on to the next.

Biomass refers to the total weight or amount of biological material present in an ecosystem at each trophic level. It decreases as energy moves upward through trophic levels.

A keystone species is an organism whose impact on its community is disproportionately large compared to its abundance. Keystone species can be predators, ecosystem engineers, or mutualists.

Ecosystem engineers are species that create or modify habitats for other organisms. A prime example is the North American beaver, which creates ponds and wetlands.

Mutualists are species that interact for each other's benefit. An example is mycorrhizal fungi, which help trees absorb nutrients while trees provide fungi with sugars.

Resilience is the ability of an ecosystem to recover to its original state after a disturbance, such as a drought or a fire. Highly resilient ecosystems can recover quickly.

A disturbance is a sudden event that causes significant changes in an ecosystem, including physical, chemical, or biological damage. Natural disturbances include hurricanes and wildfires.

Perturbation refers to any gradual change or fluctuation in an ecosystem that shifts it from its equilibrium state, such as gradual temperature increases.

An ecosystem boundary defines the limits of an ecosystem and separates it from others. Boundaries can be identified by the range of species or particular ecological processes.

Abiotic components of an ecosystem are the non-living physical and chemical factors, such as temperature, water, and soil nutrients, that influence living organisms.

Biotic components are the living organisms in an ecosystem, including plants, animals, and microorganisms, that interact with each other and with abiotic components.

Ecosystem-level processes are subject to change, which can be caused by disturbances or perturbations.

A disturbance refers to a sudden, often rapid event that causes injury or death to organisms, or damage to the biotic component of the ecosystem. Examples include natural events like hurricanes, ice storms, and forest fires, as well as anthropogenic events like clearcutting, agriculture, and air pollution.

Perturbation is a broader term referring to any gradual change in a system, especially one that shifts the system from its equilibrium state. An example is the slow increase in global temperatures due to climate change.

Resilience is the ability of an ecosystem to return to its original state after a disturbance. Highly resilient ecosystems recover quickly, while less resilient ecosystems may take much longer or may not return to their pre-disturbance conditions at all.

Biomes are large geographic regions characterized by particular types of vegetation and wildlife, influenced by the area's climate, specifically temperature and precipitation.

Global biodiversity refers to the variety of life on Earth, and it is closely tied to the different types of biomes, as well as the temperature and precipitation patterns that influence these biomes.

Terrestrial biomes are land-based ecosystems, each with distinct types of vegetation and wildlife, which are shaped by temperature and precipitation. There are ten major types of terrestrial biomes.

The wettest and warmest biome is the tropical rainforest, such as those in the Amazon and in western and central Africa.

High plant and animal diversity. Ecosystem productivity is high, but much of the ecosystem’s energy and nutrients are tied up in the vegetation, and the soils are often extremely poor in mineral nutrients.

Some forests in the tropics experience a pronounced dry season

Deciduous trees, which drop their leaves and flower during the dry season, are common. Productivity and diversity of both plant and animal species per meter are less than in tropical rainforests

Tall coniferous trees are the dominant form in temperate zone rainforests such as the U.S. Pacific Northwest

Mild winters, heavy rain, and frequent fog are the main factors creating optimal conditions for trees that are frequently 60−70 meters high. Productivity is roughly half that found in tropical rainforests. Soils tend to be rich in organic matter.

These forests occur in regions of moderate rainfall and high seasonal temperature variation and include deciduous-dominated forests in the eastern U.S., southern Canada, Europe, and eastern Asia.

Productivity is similar to that of temperate rainforests. Because most plants shed their leaves, a thick leaf litter will decompose into a rich soil. Both plant and animal diversity are much lower than in the tropics.

As temperature decreases, the dominant deciduous vegetation in areas of moderate to high rainfall are forests almost exclusively of conifers, primarily spruces and firs that are 10−20 meters high.

Several large mammal species, such as moose, bear, wolf, and Siberian tiger are found in these forests. Productivity is roughly one-third that of tropical rainforests, with low plant species diversity. Yearly weather variation results in dramatic yearly variation in seed production, which causes dramatic fluctuations in bird and other animal populations. Low temperatures and chemicals in foliage result in low leaf litter decomposition and relatively poor soils.

When precipitation decreases to the point that there is not enough water to support dense forests, vegetation shifts to grasslands.

Portions of this biome contain scrub vegetation, which is small and stunted due to limited nutrients and a short growing season. Migrating herds of herbivores, such as wildebeests, follow the rain and move across this biome. Fire and grazing are responsible for generating and maintaining the savanna biome. Productivity and species diversity per square meter are significantly less than in tropical rainforests.

Found in countries bordering the Mediterranean Sea, as well as California (where it is known as chaparral), this biome comprises dry areas that receive most of their rain in the winter, before the temperatures rise enough to permit plant growth.

Vegetation is made up mostly of dense, woody shrubs and small trees. Leaves tend to be small, leathery, and waxy—adaptations that help retain water. Fires are frequent, and many trees and shrubs have evolved fireresistant bark to protect themselves. Several bird species and small mammals such as jackrabbits, kangaroo rats, and chipmunks can be found, along with mule deer and several species of lizards

Usually defined as areas receiving less than 25 cm of precipitation per year, desert biomes cover a fairly broad temperature and latitude range.

Although commonly considered hot, there are cold deserts in places such as Mongolia and Montana. Because of its low precipitation, Antarctica is classified as a desert. Most deserts are characterized by sandy or rocky soil. Sparsely spaced shrubs and grasses are common. Desert productivity ranges from 0 to roughly 5 percent of that found in tropical rainforests. Many desert species have evolved adaptations to the lack of water.

Tundra occurs in the arctic region beyond the tree line, the upper limit of tree growth at high latitude or elevation.

Vegetation consists primarily of grasses and grass-like sedges, lichens, and dwarf forms of trees. The soil (permafrost) is frozen all year round, though it thaws to a depth of 0.5−1 meters during the brief summer growing season. Mean productivity in the tundra regions is low, normally between 5 percent and 10 percent of what is found in tropical rainforests. Rodent species, such as lemmings, can be abundant, but their populations undergo dramatic fluctuations correlated with variation in resources. Though bird populations can be abundant in summer, most species will migrate south during the long winters.

Divided into two major types: freshwater (low salt concentration) and marine (saltwater).

Includes flowing waters (rivers and streams) and standing waters (ponds and lakes).

Organisms living on or near the bottom of rivers, streams, ponds, and lakes.

Single-celled algae, primary energy producers in open-water freshwater systems requiring light for photosynthesis.

Primary consumers feeding on phytoplankton; mostly small crustaceans.

Abrupt changes in water temperature with depth, preventing mixing of water layers in lakes and ponds.

Covers 71% of Earth; varied communities due to light, nutrients, depth, and other environmental factors.

Unique deep-water ecosystems on the ocean bottom, independent of sunlight for energy.

Nutrient-rich waters rising to the surface due to winds, increasing productivity and species diversity.

Transitional areas between terrestrial and aquatic environments, including salt marshes, bogs, swamps, and intertidal regions.

Intertidal regions affected by ocean tides.

Transitional areas where rivers meet the sea, combining freshwater and saltwater.

Include bogs, marshes, swamps, and peatlands; water is at or near the soil surface for most of the year.

Examples include salt marshes, which are highly productive and critical for nesting and feeding of migratory birds.

The cycling of elements (e.g., nitrogen, phosphorus) within the biosphere and between the biosphere, soils, and water.

Activities like fertilizer use release excess nutrients, leading to over-fertilization of natural ecosystems.

The movement of water through the atmosphere and Earth's surface, driving biogeochemical cycling.

Combined process of evaporation and transpiration, returning water to the atmosphere.

Water penetrates the soil, entering the spaces in rocks and sediments below the surface.

Rainfall drains into rivers, streams, or other waterbodies, or sinks into the soil.

Ultimate reservoir of water on Earth; water evaporates to form clouds, continuing the water cycle.

Solar energy drives evaporation, making it the main energy source for the water cycle.

Driven by four processes: photosynthesis, respiration, decomposition, and combustion.

Conversion of carbon dioxide into organic compounds by plants (on land) and phytoplankton (in oceans).

Formed from buried organic matter over millions of years; includes coal, oil, and natural gas.

Releases carbon into the environment, occurring during forest fires or burning of fossil fuels.

Largest reservoir of carbon on Earth; includes limestone and organic matter in sedimentary rocks.

Oceans hold significant carbon but show little annual net gain; extra atmospheric CO₂ is causing acidification.

Activities like burning fossil fuels and deforestation disrupt the carbon balance, adding CO₂ to the atmosphere.

Practice of clearing forests by cutting and burning, often without replacement, adding carbon to the atmosphere.

The process by which nitrogen is converted into various forms as it cycles through the atmosphere, soil, and organisms.

Conversion of atmospheric nitrogen (N₂) into ammonium (NH₄⁺) by bacteria, fungi, cyanobacteria, or through lightning.

The decomposition process where organic nitrogen is converted into ammonium (NH₄⁺) by microorganisms.

Two-step process where ammonium (NH₄⁺) is converted to nitrite (NO₂⁻), and then to nitrate (NO₃⁻), which plants can use.

The conversion of nitrate (NO₃⁻) into nitrogen gas (N₂) or nitrous oxide (N₂O), releasing it back into the atmosphere.

The process where nutrients like nitrate are washed out of soil by water, often affecting rivers and streams.

Nitrous oxide (N₂O), produced during denitrification, is a potent greenhouse gas impacting global warming.

Nitrogen often limits plant growth; its availability directly affects primary productivity and ecosystem dynamics.

The variety of genes, species, and habitats on Earth, derived from genetic diversity and measured across scales.

Genotype refers to an organism's genetic makeup, while phenotype is its observable traits, influenced by genotype and environment.

Process where individuals with advantageous traits are more likely to survive, reproduce, and pass on their genes.

Periods in Earth's history with widespread species loss; current rates suggest a human-driven mass extinction is underway.

A species whose loss can lead to the collapse of an entire ecosystem or community.

Interacting living (populations) and nonliving (climate, minerals, etc.) components in a specific area.

Cycles such as the water, carbon, and nitrogen cycles, driving interactions between living and nonliving components.

Movement of water through evaporation, precipitation, and runoff, powered by solar energy.

Movement of carbon through photosynthesis, respiration, decomposition, and combustion.

Land ecosystems defined by temperature and precipitation, including rainforests, tundras, and deserts.

Includes freshwater systems like lakes, rivers, and wetlands, and marine environments like oceans and coral reefs.

Includes air and water pollution, energy production, and global climate change, significantly affecting ecosystems.

Pollution from distinct, identifiable locations like factories or sewage treatment plants.

Pollution from diffuse areas, such as agricultural runoff, suburban areas, or urban parking lots.

Disease-causing organisms (bacteria, viruses, parasites) that contaminate water and can cause illnesses like cholera and hepatitis.

Organic matter that decomposes in water, consuming oxygen needed by aquatic life; includes food scraps and animal waste.

Non-organic substances like nitrogen and phosphorus, which can lead to eutrophication and harm aquatic ecosystems.

Overgrowth of algae due to excessive nutrients, leading to oxygen depletion and declines in fish populations.

Toxic metals like lead, mercury, and arsenic can contaminate water from industrial and sewage sources, posing health risks.

Rainfall containing nitrate and sulfate from air pollution, contributing to water and soil contamination.

Excess nitrogen and phosphorus from agriculture or fertilizers entering waterways, promoting harmful algae blooms.

Toxic human-made chemicals (e.g., PCBs) that persist in the environment, bioaccumulate, and are harmful to organisms.

Toxic, carcinogenic compounds used in plastics and electrical transformers; banned in 1979 but still persist.

Sand, silt, and clay mobilized from disturbed soil, clogging fish gills and reducing sunlight penetration in water.

Increase in water temperature due to human activity, reducing dissolved oxygen and stressing aquatic organisms.

Pollution from crude oil, petroleum products, and solid waste harming marine life and ecosystems; includes major spills like Deepwater Horizon.

Toxic oil leaks (e.g., Deepwater Horizon, 2010) that contaminate oceans and coastlines, requiring extensive cleanup efforts.

Garbage like bottles, plastic bags, and cigarette butts washed into oceans or left on beaches, harming wildlife.

Tiny plastic particles (<5 mm) from degrading waste, posing risks to marine life and human health through the food chain.

Water from homes/buildings requiring treatment to remove harmful contaminants before reintroduction into the environment.

Wastewater from non-toilet sources (e.g., sinks, showers) that is less harmful and sometimes reused without treatment.

Process where bacteria decompose organic matter, reducing biological oxygen demand (BOD) and pollutants in water.

The amount of oxygen required for microorganisms to break down organic material in water; high BOD can deplete oxygen.

Removes 40–50% of solid waste material from wastewater; solids settle as sludge, often containing metals.

Breaks down organic matter with microorganisms, removing 85–90% of pollutants. Water is disinfected before release.

Solid material from primary treatment, often containing metals, requiring careful disposal or treatment.

U.S. legislation regulating water pollution by setting water quality standards and limits on pollutant discharges.

The maximum allowable amount of a pollutant in a waterbody, including contributions from point and non-point sources.

Emission of harmful compounds into the atmosphere, causing damage to ecosystems, human health, and buildings.

Six regulated pollutants: sulfur dioxide, nitrogen oxides, carbon monoxide, lead, particulate matter, and ozone.

Emitted by burning fossil fuels; causes respiratory issues and forms acid rain (sulfuric acid).

Emitted by combustion; contributes to smog, acid rain (nitric acid), and respiratory harm.

Colorless, odorless gas from incomplete combustion; impairs oxygen transport, causing severe health effects.

Once common in gasoline; affects blood production and neurological function, especially in children.

Solid or liquid particles suspended in air; causes lung issues and reduces photosynthesis by blocking sunlight.

Harmful oxidant formed by sunlight reacting with NOₓ and SO₂; contributes to smog and damages plants and lungs.

A haze of pollutants, including ozone, trapped in urban areas by geography and sunlight (e.g., Los Angeles).

Pollutants like mercury, primarily from coal burning, regulated under specific sections of the Clean Air Act

Pollutants emitted directly from a source, such as sulfur dioxide (SO₂), nitrogen oxides (NOₓ), and carbon monoxide (CO).

Pollutants formed through chemical reactions in the atmosphere, including smog, sulfuric acid, and nitric acid.

A secondary pollutant formed by reactions between primary pollutants, water vapor, and sunlight.

A secondary pollutant formed when sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) react with water vapor to produce acidic precipitation.

Includes volcanoes (SO₂, particulates, CO, NOₓ), forest fires (particulates, CO, NOₓ), and plants (organic compounds).

Canadian wildfires caused severe air quality issues globally, with extreme particulate matter and doubled CO₂ emissions.

Human-induced climate change has increased the likelihood of extreme weather conditions fueling wildfires.

Occurs when a warm air layer traps cooler air below it, causing pollutants to accumulate near the ground, worsening air quality.

Electricity is a secondary energy source generated by converting primary sources (coal, oil, natural gas, etc.).

Fuel produces steam that drives a turbine, turning a generator to produce electricity, which is then distributed for use.

Wind, water flow, and other renewable sources can also drive turbines to generate electricity, reducing reliance on fossil fuels.

Fossil fuel formed from ancient plant material, used for electricity and steel production. Mined via deep shaft or surface mining.

Classified by energy content: peat (lowest), lignite, bituminous coal, anthracite (highest).

Emits sulfur dioxide, particulates, and mercury; causes acid mine drainage and degrades nearby water quality.

Fossil fuel formed from ocean-dwelling plankton; extracted via wells on land or offshore. Refined into gasoline, diesel, kerosene, and more.

Unrefined liquid petroleum separated into various fuels and products based on weight.

Emits carbon dioxide when burned; oil spills pollute water and harm ecosystems.

Composed mainly of methane (CH₄), emits fewer pollutants than coal and oil, but methane leaks contribute to greenhouse gases.

High-pressure water, sand, and chemicals injected into bedrock to extract oil and gas. Increases access to reserves but raises environmental concerns.

High water usage, chemical contamination risks, and potential depletion of aquifers in drought-prone areas.

Potent greenhouse gas, 25 times more effective than CO₂ in trapping heat; leaks during extraction increase pollution.

Generates electricity with low emissions but produces radioactive waste requiring safe long-term storage.

Uses uranium to generate electricity through the fission of uranium atoms in reactors, producing heat that creates steam to drive turbines.

Uranium, found in rocks like shale and sandstone, is mined through surface mining. It requires large amounts of ore to produce usable uranium oxide.

Uranium ore is enriched by removing impurities, resulting in uranium oxide containing 2−3% uranium for use in fuel rods.

Uranium oxide is processed into pellets, which are bundled into fuel rods. Each fuel rod can contain multiple pellets and is placed into a reactor.

Uranium atoms split during fission, releasing heat. This heat is used to produce steam, which powers turbines to generate electricity.

A pound of enriched uranium contains the energy equivalent of a million gallons of gasoline, or 26,000 times more energy than coal.

Nuclear power plants produce no air pollution during operation, making them a "clean" energy source compared to fossil fuels.

Fossil fuels are used in the construction, uranium mining, processing, transportation, and decommissioning of nuclear plants.

Nuclear plants emit 60 grams of CO₂ per kilowatt-hour, far less than coal plants (800-1,100 grams per kilowatt-hour).

Human error caused a cooling valve failure, leading to overheating and a small release of radiation. This incident fueled widespread public concern.

The Three Mile Island accident, combined with fears stirred by the film The China Syndrome, led to protests against nuclear power and increased scrutiny of plant safety.

A "runaway" reactor incident in Ukraine caused by safety violations, resulting in an explosion, fire, and acute radiation exposure. Over 31 immediate deaths and long-term health impacts occurred.

An earthquake and tsunami flooded Japan’s Fukushima nuclear reactors, causing radioactive leaks, the evacuation of 150,000 people, and long-term contamination.

Dangerous byproduct of nuclear energy requiring secure, long-term storage to prevent harm to humans and ecosystems.

Fuel rods that can no longer efficiently generate electricity but remain highly radioactive, requiring storage in water pools or dry cask storage.

Proposed U.S. site for long-term nuclear waste storage; plans stalled due to political, cultural, and geological concerns.

Energy sources like solar, wind, and hydroelectric that are sustainable and cannot be depleted over human timescales.

Renewable energy from organic materials (e.g., wood, crop waste) that can be sustainable if managed responsibly (e.g., balancing logging with reforestation).

Focus on renewable resources and reducing energy use through efficiency improvements and conservation practices.

Fossil fuels are finite resources that take millions of years to form, making them unsustainable for long-term energy needs.

Energy directly harnessed from the Sun's rays, such as through solar panels or passive solar design.

Energy derived from solar-driven processes, including wind (caused by uneven heating) and hydropower (via the water cycle).

The amount of solar energy reaching the Earth's atmosphere (~1,370 watts/m²); about 200 watts/m² reaches the surface.

The available solar energy for human use; varies by location and weather, with the U.S. Southwest having the highest potential.

Uses the Sun's heat directly without mechanical systems, such as south-facing windows, thermal mass materials (e.g., stone), and dark roofs.

The ability of a material to retain heat once warmed (e.g., stone, concrete); important for passive solar design.

Uses mechanical systems like pumps and fans to collect and distribute solar energy, commonly for water heating and electricity generation.

Converts sunlight directly into electricity using ultra-clean silicon dioxide (SiO₂) layers, often with added metals for increased voltage.

Converts wind's kinetic energy into electricity using wind turbines, with an average turbine generating energy for over 940 U.S. homes monthly.

Clusters of wind turbines near coastlines; Europe has over 40 operational farms, while the U.S. has only two but more planned.

Produces no air or water pollution or fossil CO₂ during operation; suitable for remote locations; compatible with agriculture.

Limited by weather and time of day; requires large areas for installation in utility-scale projects.

Can affect local wildlife (e.g., bird collisions), be visually intrusive, and require backup energy sources for periods of low wind.

Renewable energy generated by harnessing the movement of water to turn turbines, producing electricity.

Utilizes the natural flow of rivers without significant storage; energy generation depends on seasonal water flow.

Stores water in reservoirs behind dams, allowing controlled water release for consistent and on-demand electricity generation.

Provides reliable electricity generation regardless of seasonal flow; capable of producing large amounts of power (e.g., Hydro Quebec’s 7,300 MW).

Dams can disrupt ecosystems, block fish migration, and pose safety risks to species and humans.

Energy from sources that are naturally replenished, such as solar, wind, hydropower, and biofuels, making them sustainable over time.

Achieved by balancing energy consumption with renewable inputs and improving energy efficiency and conservation.

Energy harnessed directly from the Sun's rays for heating, cooking, or electricity generation (e.g., photovoltaic cells).

Energy from processes driven by the Sun, such as wind (caused by uneven heating) and hydropower (from the water cycle).

The average solar energy received at the top of the Earth's atmosphere (~1,370 watts/m²); only ~200 watts/m² reaches the surface.

The usable solar energy at the Earth's surface, varying by location, time of year, and weather conditions; highest in the U.S. Southwest.

Captures solar heat without mechanical systems, e.g., south-facing windows, dark roofs, and materials with high thermal inertia like stone and concrete.

The ability of a material to retain heat after absorbing it; stone and concrete have high thermal inertia, while wood and glass do not.

Uses mechanical systems (e.g., pumps, fans) to collect and distribute solar energy for heating water or generating electricity.

Devices that convert sunlight directly into electricity using ultra-clean silicon dioxide (SiO₂) layers and trace metals (e.g., arsenic).

Each photovoltaic cell generates 1–2 watts of electricity, with multiple cells combined into panels for greater output.

PV-generated electricity can power appliances directly, be stored in batteries, or be converted to grid voltage for broader use.

Converts wind's kinetic energy into electricity using wind turbines; a renewable and sustainable energy source.

Modern turbines are ~100 meters tall with blades 40–75 meters long, generating an average of 843,000 kWh per month (enough for ~940 U.S. homes).

Clusters of wind turbines located near coastlines; Europe has over 40 farms, while the U.S. has only two but more are planned.

No air or water pollution during operation, free and renewable wind resource, minimal maintenance energy costs, and compatibility with agricultural land use.

Intermittent availability (wind doesn’t always blow), requires energy storage (e.g., batteries), and may cause aesthetic concerns.

Large-scale batteries needed for energy storage are costly, inefficient, and reliant on mining minerals like lithium and cobalt, leading to environmental and ethical concerns.

Wind turbines cause an estimated 10,000–40,000 bird deaths annually in the U.S., though newer designs and better placement have reduced these impacts.

Offshore wind farms may potentially harm migratory and endangered whales, raising objections near New England coastlines.

Collisions with wind turbines kill fewer birds compared to millions lost annually from buildings, communication towers, and windows.

Once installed, wind turbines require no fuel input, relying solely on wind for energy production.

Renewable energy generated by capturing the kinetic energy of flowing or falling water to turn turbines, producing electricity.

Diverts river water through a channel to a turbine; small-scale and dependent on natural water flow, with lower environmental impact.

Stores water in reservoirs behind dams for controlled flow and reliable electricity generation; supports large-scale energy production.

Allows electricity generation on demand and supports high-capacity power plants like Hydro Quebec's 7,300 MW facility.

Floods land, displaces communities, disrupts ecosystems, impedes fish migration, alters natural water flow, and promotes methyl mercury bioaccumulation.

Energy from organic matter such as wood, dung, plant remains, ethanol, and municipal solid waste (MSW).

Includes heating, cooking, electricity generation, and transportation fuel (e.g., ethanol mixed with gasoline).

Roughly 67% from wood, 23% from MSW, and 10% from agricultural waste and landfill methane.

Carbon recently in the atmosphere and absorbed by plants; burning biomass releases this carbon but does not add to net atmospheric CO₂ if regrowth occurs.

Ancient carbon stored in fossil fuels; burning it adds new CO₂ to the atmosphere, increasing global concentrations.

Biomass use can be carbon-neutral if regrowth balances carbon release, whereas fossil fuels cause a net increase in atmospheric CO₂.

A biofuel made from fermented sugars and starches, primarily derived from corn in the U.S. (~1.8 billion gallons/year). Mixed with gasoline to improve combustion and reduce pollutants.

Reduces gasoline use, incorporates modern carbon (less fossil CO₂ emissions), and absorbs moisture to prevent fuel freezing.

Less fuel-efficient than gasoline, requires fossil fuels for production, and reduces agricultural land for food crops.

Renewable energy derived from the Earth’s heat; used to heat water or generate electricity without greenhouse gases.

Relatively inexpensive, sustainable, and emits fewer pollutants; effective in geologically active regions (e.g., Iceland).

Limited to geologically active areas and may emit localized harmful gases.

Renewable energy harnessed from tidal movements; limited by suitable locations with significant differences between high and low tides.

Disrupts coastal ecosystems, reduces recreational/commercial use of affected areas, and alters coastline aesthetics.

A measure of usable energy output relative to total energy input; global efficiency is ~37%, with newer technologies achieving higher rates (e.g., combined cycle gas plants at 60%).

Reducing energy use through consumer actions, such as turning off lights, driving less, or wearing warmer clothing instead of raising the thermostat.

Using less energy for the same work; examples include smaller cars, home insulation, compact fluorescent lights, and EnergyStar appliances.

Shifting high-energy activities to non-peak times to reduce the need for new power plants; utilities incentivize this by charging higher rates during peak periods.

The EPA’s Energy Star Program designates certain appliances as Energy Star compliant if they meet specified efficiency levels, e.g., an air conditioner using <1,000 watts for 10,000 Btus.

Energy Star appliances can reduce electricity usage, e.g., 100,000 households with compliant air conditioners can lower peak demand by 20 megawatts.

Widespread use of Energy Star appliances in residential and business settings could reduce the need for additional power plants.

The Intergovernmental Panel on Climate Change (IPCC) prepares comprehensive reviews on climate change, including its science and impacts.

This assessment reduced scientific uncertainty and confirmed that human activity has unequivocally warmed the atmosphere, ocean, and land.

Includes climate change, global warming, and other large-scale environmental changes like deforestation, biodiversity loss, and chemical pollution.

Refers to variations in average weather patterns (temperature, precipitation, storm intensity) over years or decades.

Refers to the increase in Earth’s global surface temperature relative to pre-industrial levels.

CO2 concentrations have reached their highest levels in millions of years due to human activity, far exceeding natural variations over the past 800,000 years.

Examples include the melting of Arctic and Antarctic ice, increased CO2 and nitrogen compounds in the atmosphere, and rising mercury levels in fish and mammals.

The greenhouse effect is a natural process that warms an area beneath a heat-trapping medium, like glass or Earth's atmosphere, by retaining heat and reducing energy outflow.

Solar energy passes through car windows, heats surfaces inside, and is reradiated as infrared radiation, which is trapped inside, causing the car's temperature to rise.

Similar to a car, Earth absorbs solar energy and radiates it as infrared radiation. Heat-trapping gases in the atmosphere reduce the outflow of infrared radiation, warming Earth.

Earth's energy balance depends on solar radiation input and two outputs: reflection of solar energy and emission of infrared radiation.

If incoming solar energy exceeds reflected solar and emitted infrared energy, Earth warms due to additional heat retained by heat-trapping gases.

Variations in Earth's temperature can result from increased solar radiation (e.g., sunspots) or decreased reflected solar radiation due to surface changes or greenhouse gases.

Over the long term, Earth maintains a steady-state heat balance where energy inputs equal energy outputs.

GHGs trap heat in Earth’s atmosphere, maintaining hospitable temperatures. Without them, Earth’s temperature would be about -18°C (0°F).

Major GHGs include water vapor (H₂O), carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), and chlorofluorocarbons (CFCs).

Human activities, such as fossil fuel combustion and land clearing, increase GHG concentrations, intensifying the greenhouse effect and causing global warming.

The natural greenhouse effect is essential for life; the problem arises when human activities increase GHGs, leading to excessive warming.

Earth's temperature has fluctuated naturally over millennia but generally remained stable over decades or centuries until recent human-induced changes.

Global warming refers to the rise in Earth’s surface and atmospheric temperatures due to increased heat-trapping gases, primarily from human activity.

Direct temperature measurements began around 1880. Data shows a steady increase in global temperatures from 1880 to 2020, confirmed by NASA and other researchers.

June, July, August, and September 2023 were the hottest months on record, further supporting evidence of ongoing global warming.

Establishing precise, long-term global temperature changes is difficult due to limited historical data, but models and records indicate a warming trend.

Indirect measurements, such as tree rings and coral growth, suggest current global temperatures are higher than at any time in the last 150,000 years.

Wider tree rings typically indicate warmer and/or wetter conditions, allowing researchers to estimate historical temperature variations.

Corals add annual calcium carbonate layers that provide geochemical clues to historical ocean temperatures, sometimes spanning hundreds of years.

CO₂ levels have increased by 50% since 1750, and global average temperatures have risen by about 2°F since 1880.

Impacts include decreased Arctic ice, reduced snow cover (by 10% since the 1960s), thawing permafrost, longer growing seasons, and shifts in species' geographic ranges.

Plants, insects, and birds are moving northward or to higher altitudes, blooming earlier, nesting earlier, and emerging earlier in the Northern Hemisphere.

Current observable changes are just the beginning; environmental scientists predict extensive future changes across Earth's systems.

Models predict moderate to worst-case scenarios by the end of the 21st century, suggesting significant and widespread impacts on global systems.

Continental glaciers and the Greenland ice sheet are expected to retreat, contributing to sea level rise.

Global mean sea level is projected to rise by 0.1 to 0.9 meters by 2100 due to melting glaciers and ice sheets.

Maximum temperatures and heat waves will increase, impacting crops and increasing energy demand for cooling.

Minimum temperatures will rise, resulting in fewer cold days, fewer frost events, and expanded ranges of pests and disease vectors.

Rainfall will increase in some regions, leading to flooding, landslides, and soil erosion.

Global warming may alter ocean currents, disrupting the planet's heat distribution and climate patterns.

Ecosystems will be affected, with vegetation types shifting northward, threatening species unable to adapt to rapid changes.

Rising seas threaten coastal and island communities with inundation, erosion, and water contamination.

Warming will expand the range of disease vectors (e.g., mosquitoes), increase heat-related deaths, and extend bacterial and fungal illnesses.

Poorer communities will bear the greatest costs of climate change due to limited resources. Tourism and ecosystems will also be significantly impacted.

Mitigating climate change requires international agreements like the Paris Agreement, which encourages emission reductions and support for vulnerable nations.

Pollution stems from point and non-point sources, including pathogens, oxygen-demanding waste, inorganic compounds, and synthetic chemicals like PCBs.

Wastewater is treated through sewage systems; U.S. laws like the Clean Water Act ensure municipal water safety.

The six criteria pollutants include sulfur dioxide, nitrogen oxides, carbon monoxide, lead, particulate matter, and ozone, stemming from primary pollutants like CO and SO₂.

Primary pollutants (e.g., SO₂, NOₓ) are transformed into secondary pollutants, such as nitric acid, sulfuric acid (acid rain), and ozone, through chemical reactions.

Forms when NOₓ reacts with oxygen and other compounds in sunlight, producing ozone. Common in urban areas and worsened by thermal inversions.

Developed countries have shifted from wood and coal to fossil fuels and nuclear power; developing countries still rely heavily on biomass.

Common sources include coal, oil, natural gas, and nuclear power, with the power grid connecting plants regionally.

Coal is efficient but causes pollution, safety issues in mining, and environmental damage, including toxic slag piles and contaminated waterways.

Oil is primarily used for transportation and produces significant pollution. Natural gas is cleaner but contributes to greenhouse gases (GHGs).

Produces minimal emissions but has risks of accidents and long-term radioactive waste disposal issues.

Sustainable energy minimizes environmental damage and ensures future availability. Renewable energy comes from perpetual sources like solar and wind.

Solar energy powers direct (solar cookers) and indirect systems (winds, hydrologic cycle). Passive and active solar systems harness solar energy differently.

Converts wind's kinetic energy into electricity. Wind farms are clean but face objections due to aesthetics.

Includes wood, dung, and biofuels. Biomass burning doesn't significantly increase CO₂ if managed sustainably.

Hydropower uses water’s kinetic energy; geothermal taps Earth's internal heat. Both are clean but may disrupt ecosystems.

Generated by the movement of water along coastlines.

Human activities, especially fossil fuel combustion and deforestation, are the main contributors, surpassing natural causes.

Based on surrogate indicators like tree rings, ice cores, and rising temperatures, as well as predictive models.

CO₂ is the largest anthropogenic contributor due to its high atmospheric concentration. Other GHGs include CH₄, N₂O, and water vapor.

Describes how GHGs trap heat, altering Earth's energy balance and contributing to warming.

Conservation, efficiency improvements, and renewable energy adoption are essential for sustainable energy systems.

Global warming affects environmental and human systems through three interconnected feedback cycles, amplifying its impacts.

Over the past 100 years, global average temperature has risen enough to significantly impact natural processes.

Changes include more extreme weather events, shifts in climate patterns, and disruptions to natural ecosystem processes.

Global warming leads to habitat destruction, altering ecosystems and causing species extinction.

Rising temperatures cause health issues, economic challenges, and social problems, particularly in vulnerable populations.

Earth consists of natural, human-made, and combined systems of varying scales, all with interacting components where changes in one part affect the whole system.

Studies how systems change when impacted and how to manage them sustainably for the future.

Tools include species number, global temperature, atmospheric CO₂ levels, food production, and land use, used to monitor environmental changes and human impacts.

Industrialization and population growth negatively affect environmental indicators, causing species loss, deforestation, rising temperatures, and extreme weather events.

Current rates of species loss suggest Earth may be heading toward a sixth mass extinction event.

Scientists and policymakers are developing strategies to protect wilderness areas, manage natural resources sustainably, and reduce harmful chemical releases.

Decades of research have led to international agreements to reduce greenhouse gas emissions, aiming to mitigate and potentially reverse climate change impacts.