Environmental Science Glossary

The nonliving physical and chemical components of an ecosystem that influence living organisms, including temperature, light, water, soil composition, pH, humidity, wind, and atmospheric gases.

A proposed geological epoch dating from the start of significant human impact on Earth's geology and ecosystems, characterized by unprecedented changes to climate, biodiversity, and biogeochemical cycles driven by human activity.

An underground layer of permeable rock, sediment, or soil that contains and transmits groundwater. Aquifers are critical freshwater sources for drinking, irrigation, and industry, and can be depleted faster than they recharge.

The gradual accumulation of a substance, such as a pesticide or heavy metal, in the tissues of a living organism over time, occurring when the rate of intake exceeds the rate of excretion or metabolic breakdown.

The variety of life on Earth at all levels, from genes to ecosystems, encompassing genetic diversity within species, species diversity within communities, and the diversity of ecosystems across landscapes and regions.

A large-scale ecological community classified by its dominant vegetation and characterized by adaptations of organisms to that particular environment, such as tropical rainforest, desert, tundra, or temperate grassland.

The total amount of greenhouse gases, expressed in carbon dioxide equivalents (CO2e), emitted directly and indirectly by an individual, organization, event, or product throughout its life cycle.

The process of capturing and storing atmospheric carbon dioxide, either through natural processes (forests, oceans, soil) or technological methods (carbon capture and storage), to mitigate climate change.

The permanent removal or clearing of forests for non-forest uses such as agriculture, urban development, or mining. It is a major driver of biodiversity loss, carbon emissions, soil erosion, and hydrological disruption.

The scientific study of the interactions between organisms and their environment, including relationships among organisms and between organisms and their physical surroundings at multiple scales from individuals to the biosphere.

A species facing a very high risk of extinction in the wild in the near future, as classified by organizations such as the IUCN Red List. Causes include habitat loss, overexploitation, pollution, invasive species, and climate change.

Hydrocarbon-based energy sources formed from the remains of ancient organisms over millions of years, including coal, petroleum, and natural gas. Their combustion releases stored carbon as CO2 and is the primary driver of anthropogenic climate change.

Atmospheric gases that absorb and re-emit infrared radiation, trapping heat in the atmosphere. Major greenhouse gases include carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and fluorinated gases. Their increasing concentrations drive global warming.

Water found beneath Earth's surface in the pore spaces of soil, sediment, and rock formations. It supplies wells and springs and constitutes about 30% of global freshwater, making it a vital resource for drinking water and agriculture.

The process by which large, continuous habitats are divided into smaller, isolated patches by roads, agriculture, urban development, or other human activities. Fragmentation reduces biodiversity by limiting species movement, gene flow, and access to resources.

Non-native organisms that, when introduced to a new environment, spread rapidly and cause significant ecological or economic harm. They often outcompete native species due to the absence of natural predators, diseases, or competitors in the new habitat.

A species that has a disproportionately large effect on its ecosystem relative to its abundance. Its removal would cause significant changes to ecosystem structure and function, potentially leading to cascading species losses.

Natural resources that exist in finite quantities and cannot be replenished on a human timescale once depleted. Examples include fossil fuels (coal, oil, natural gas), mineral ores, and nuclear fuels like uranium.

The thinning of the stratospheric ozone layer caused primarily by human-produced chlorofluorocarbons (CFCs) and other ozone-depleting substances. The resulting increase in ultraviolet radiation reaching Earth's surface threatens human health, ecosystems, and agriculture.

A logarithmic scale (0-14) measuring the acidity or alkalinity of a solution, where 7 is neutral, values below 7 are acidic, and values above 7 are basic. pH is a critical environmental parameter affecting water quality, soil chemistry, and organism survival.

A device that converts sunlight directly into electricity using the photovoltaic effect in semiconductor materials. Photovoltaic technology is a key component of solar energy systems and a rapidly growing source of renewable electricity worldwide.

The introduction of harmful substances or energy (chemicals, noise, heat, light) into the environment at rates that exceed the capacity of natural systems to absorb, dilute, or decompose them, causing adverse effects on ecosystems and human health.

Energy derived from sources that are naturally replenished on a human timescale, including solar, wind, hydroelectric, geothermal, and biomass energy. Transitioning to renewable energy is central to reducing greenhouse gas emissions and achieving sustainability goals.

An area of land where all precipitation drains into a common body of water such as a river, lake, or ocean. Watersheds are fundamental units for water resource management because activities anywhere within the watershed affect downstream water quality and quantity.

An ecosystem where water covers the soil or is present at or near the surface for significant portions of the year. Wetlands include marshes, swamps, and bogs, and provide critical ecosystem services including water filtration, flood control, carbon storage, and wildlife habitat.