A
Adaptation
Steps people take to adjust to the impacts of climate change—either by planning ahead or responding to changes already underway. It includes actions that reduce harm or take advantage of new conditions caused by climate shifts.
Aerosol
Tiny particles, either solid or liquid, that float in the air. These can come from natural events like volcanic eruptions or human activities like burning fossil fuels. Some aerosols warm the planet by absorbing heat, while others cool it by reflecting sunlight. They also play a role in cloud formation.
Allergen
A substance like pollen, dust, or mold that can cause allergic reactions in sensitive individuals.
Asthma
A chronic lung condition that makes breathing difficult. Triggers vary by person and can include pollutants, allergens, weather, or physical activity.
Atmosphere
The blanket of gases—mainly nitrogen and oxygen—surrounding Earth. It protects life, helps regulate temperature, and allows weather to occur.
Atom
The smallest unit of a chemical element. Everything around us is made of atoms, which combine to form molecules like water (Hâ‚‚O) or carbon dioxide (COâ‚‚).
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Barometer
A tool used to measure atmospheric pressure. Shifts in pressure help predict weather patterns—lower pressure often signals stormy conditions.
Biodiesel
A renewable fuel made from plant oils, animal fats, or recycled cooking grease. It can be used in diesel engines, sometimes on its own or blended with petroleum-based diesel.
Biofuel
Energy sources made from plants or organic waste. Common types include ethanol, biodiesel, and biogas.
Biogas
A fuel created from the breakdown of organic waste like manure or landfill materials. It mainly contains methane and can be used to generate electricity or heat.
Biomass
Any organic material from living or recently living organisms—like wood, crops, or animal waste—that can be burned or converted into energy.
C
Carbon
A key element found in all living things. It combines with other elements to form compounds like carbon dioxide, which plays a major role in the Earth’s climate system.
Carbon Cycle
The process by which carbon moves between living things, the atmosphere, oceans, rocks, and soil. This cycle is driven by natural events and human activities.
Carbon Dioxide (COâ‚‚)
An invisible, odorless gas released when living things decay or when fossil fuels are burned. Plants absorb it during photosynthesis. Human-caused emissions of COâ‚‚ are the leading driver of modern climate change.
Carbon Dioxide Equivalent (COâ‚‚e)
A way to compare the warming effects of different greenhouse gases. It expresses their impact in terms of how much COâ‚‚ would cause the same amount of warming.
Carbon Footprint
The total greenhouse gas emissions caused directly or indirectly by a person, group, product, or activity. It includes emissions from energy use, transportation, food production, and more.
Carbonic Acid
A weak acid formed when COâ‚‚ dissolves in water. As more COâ‚‚ enters oceans from the atmosphere, it turns into carbonic acid, making oceans more acidic and affecting marine life like corals and shellfish.
Carbon Sink
A natural system, like a forest or ocean, that absorbs more carbon than it releases—helping to cool the planet.
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Climate
The long-term pattern of weather in a region, usually averaged over 30 years or more. It includes temperature, rainfall, wind, and other factors.
Climate Change
Major changes in the Earth's climate systems over time, often driven by rising levels of greenhouse gases from human activities. It includes not just global warming but also changes in rainfall, sea levels, and ecosystems.
Climate Model
A computer-based simulation that shows how Earth's climate system behaves. Scientists use these models to explore possible future outcomes based on different levels of greenhouse gas emissions.
Coal
A black or dark brown rock used as a fuel. It forms from decayed plant matter and is one of the most common fossil fuels, especially in electricity generation.
Concentration
The amount of a substance in a given volume of air, water, or soil. For example, COâ‚‚ levels in the atmosphere are measured in parts per million (ppm).
Coral Bleaching
A stress response in corals where they lose the colorful algae that live in their tissues. This often happens when water becomes too warm and can lead to coral death if conditions don't improve.
D
Data
Information gathered through observation, measurement, or research. Scientists use data to study climate patterns, weather changes, and environmental systems. A single piece of information is called a datum.
Decomposition
The natural process where dead plants, animals, or organic waste break down into simpler substances. This is usually done by bacteria, fungi, and other microorganisms, and it returns nutrients to ecosystems.
Drought
A long period with much less rainfall than usual, leading to water shortages for people, crops, and natural ecosystems. Droughts can harm agriculture and increase the risk of wildfires.
E
Ecosystem
A community of living organisms—like plants, animals, and microbes—and the environment they live in. Ecosystems include forests, wetlands, oceans, and cities, and rely on a balance between living and nonliving parts.
Element
A pure substance made of only one type of atom. Common elements include oxygen, carbon, and hydrogen. They cannot be broken down into simpler substances through chemical means.
Emissions
Gases or particles released into the air, especially from burning fuel, farming, or industry. Carbon dioxide (COâ‚‚) and methane (CHâ‚„) are examples of emissions that contribute to climate change.
Energy
The ability to do work, move things, or create change. It can take many forms—like heat, light, electricity, and motion. Most of the energy used by humans today comes from burning fossil fuels.
Energy Audit
An assessment of how much energy a building uses and where energy might be wasted. The goal is to find ways to use less energy—such as adding insulation or switching to efficient lighting.
Energy Vampire
A device that uses electricity even when it’s not in active use—for example, a charger left plugged in. These small power drains can add up over time.
Erosion
The gradual wearing away of soil, rock, or land, usually caused by wind, water, or ice. Deforestation, farming, and construction can make erosion happen faster.
Ethanol
A renewable fuel made by fermenting plant materials like corn or sugarcane. It’s often blended with gasoline to reduce pollution and reliance on oil.
F
Fluorinated Gases
Man-made greenhouse gases used in air conditioners, refrigerators, and industrial processes. These gases don’t occur naturally and can stay in the atmosphere for centuries, trapping large amounts of heat.
Fossil Fuel
Energy-rich substances like coal, oil, and natural gas formed over millions of years from ancient plant and animal remains. Burning fossil fuels releases carbon dioxide and other pollutants.
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Geothermal Energy
Heat stored beneath the Earth's surface that can be used to warm buildings or generate electricity. This renewable energy comes from hot rocks, steam, or underground reservoirs.
Global Climate
The combined average of all the Earth’s regional climates. It helps scientists understand large-scale patterns in temperature, rainfall, and weather systems over time.
Global Warming
The long-term increase in Earth’s average surface temperature. Today’s global warming is mostly caused by burning fossil fuels, which release heat-trapping greenhouse gases into the atmosphere.
Global Warming Potential (GWP)
A measure that shows how much heat a greenhouse gas traps in the atmosphere compared to carbon dioxide (COâ‚‚), which has a GWP of 1. For example, methane has a GWP of about 25, meaning it’s 25 times more powerful than COâ‚‚ over 100 years.
Greenhouse Gas
Gases that trap heat in Earth’s atmosphere, keeping the planet warm enough for life. Some occur naturally—like water vapor and carbon dioxide—while others, like fluorinated gases, are human-made.
Groundwater
Water stored beneath the surface in soil or rock layers. It supplies wells, springs, and is an important source of drinking water and irrigation in many regions.
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​​​H
Habitat
The natural environment where a plant or animal lives and grows. It includes everything the organism needs—like food, water, shelter, and space.
Heat Stroke
A serious condition caused by overheating. It happens when the body can no longer cool itself down, often during extreme heat or heat waves. It requires immediate medical attention.
Heat Wave
A stretch of days with unusually high temperatures for a region. Heat waves can stress ecosystems, worsen air pollution, and pose health risks—especially for vulnerable populations.
Hydroelectric Dam
A facility that turns the energy from flowing water into electricity. Water spins a turbine, which powers a generator. It’s a renewable energy source, but dams can also affect river ecosystems.
Hypothermia
A dangerous drop in body temperature due to exposure to cold conditions. It can happen in icy weather or cold water and becomes life-threatening without treatment.​​
​​​I
Incandescent Light Bulb
A traditional type of bulb that creates light by heating a metal wire until it glows. These bulbs use more energy than newer types like LEDs or compact fluorescents (CFLs).
Infectious Disease
An illness caused by microorganisms like bacteria, viruses, or parasites. Some diseases can spread more easily due to changes in climate, like warmer temperatures or heavier rainfall.
Infrared Radiation
A type of energy that we feel as heat. Earth gives off infrared radiation after absorbing sunlight, and greenhouse gases trap some of this heat in the atmosphere.
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Infrastructure
The basic systems that support modern life—like roads, bridges, water pipes, electric grids, and buildings. Climate change can damage infrastructure through storms, floods, or rising heat.
Invasive Species
Plants or animals introduced to areas where they don’t naturally belong. Without natural predators, they can spread quickly and harm local ecosystems, agriculture, or human health.​
​​​K
Kilowatt-Hour (kWh)
A unit for measuring electricity use. It shows how much energy something uses if it runs for an hour. For example, running a microwave for one hour uses about 1 kilowatt-hour of electricity
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Latitude
A way to measure how far north or south a place is from the equator. It’s measured in degrees, with the equator at 0°, the North Pole at 90° north, and the South Pole at 90° south.
Light-Emitting Diode (LED)
An energy-efficient light source that uses a semiconductor to emit light. LEDs last longer and use much less electricity than incandescent bulbs.​​​​
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Magma
Molten rock beneath the Earth's surface. When it erupts through a volcano, it’s called lava. Magma plays a key role in geothermal energy and Earth’s geology.
Methane (CHâ‚„)
A powerful greenhouse gas that traps more heat than carbon dioxide in the short term. It’s produced naturally by wetlands and animal digestion and by human activities like landfills, rice farming, and fossil fuel extraction. It’s also the main ingredient in natural gas.​​
​​​N
Natural Gas
A fossil fuel made mostly of methane. It’s found deep underground and used for heating, cooking, and generating electricity. Although it burns more cleanly than coal or oil, it still contributes to climate change.
Nitrous Oxide (Nâ‚‚O)
A greenhouse gas that also contributes to the breakdown of the ozone layer. It’s released from agricultural fertilizers, livestock waste, and the burning of fossil fuels.
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Nonrenewable Resource
A resource that forms so slowly in nature that it can't be replaced quickly enough to meet demand. Fossil fuels like coal, oil, and natural gas are nonrenewable—they take millions of years to form.
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Nuclear Fission
A process where the nucleus of an atom splits, releasing a large amount of energy. Nuclear power plants use this reaction to generate electricity without releasing greenhouse gases—but they produce radioactive waste that must be carefully managed.
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Nuclear Fusion
A process where two light atoms—like hydrogen—combine to form a heavier atom, releasing an enormous amount of energy. It’s the reaction that powers the sun and stars. Scientists are working to develop fusion as a future energy source because it could create clean electricity without greenhouse gases or long-lived radioactive waste—but it’s not ready for everyday use yet.​​​​
O
Oil (Petroleum)
A thick, dark fossil fuel found underground. Crude oil can be refined into fuels like gasoline and diesel or used to make products like plastics and asphalt. Burning oil releases greenhouse gases and air pollutants.
Ozone (O₃)
A gas made of three oxygen atoms. High in the atmosphere, ozone forms a layer that protects life on Earth from harmful ultraviolet (UV) radiation. Near the surface, however, ozone is a harmful air pollutant and a greenhouse gas.​
P
Parts Per Million (ppm)
A unit that measures how much of one substance is mixed into another. COâ‚‚ levels in the air are often measured in ppm.
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Passive Solar Heating
Using windows, materials, and building design to naturally heat a space using sunlight—without extra machines.
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Permafrost
Ground that stays frozen all year. As it thaws due to warming, it can release stored methane and carbon dioxide.
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Photosynthesis
The process plants use to turn sunlight, carbon dioxide, and water into food—releasing oxygen in the process.
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Photovoltaic Cell
A device that converts sunlight directly into electricity. Solar panels are made from many of these cells.
Plate Tectonics
The theory that Earth’s surface is made of moving plates. Their movement causes earthquakes, volcanoes, and shapes continents.
Positive Feedback Loop
A cycle where one change causes even more of the same change. For example, warming melts ice, which reveals darker surfaces that absorb more heat, causing more warming.
Precipitation
Any water that falls from the sky—like rain, snow, sleet, or hail.
Product Life Cycle
All the stages of a product—from raw materials to production, use, and disposal. Helps us understand environmental impact.​​
R
Radiation
Energy that travels through space as waves or particles. The sun’s light is a type of radiation, and so are harmful rays like UV and X-rays.
Rain Gauge
A tool that measures how much rain has fallen in a specific place and time.
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Recycle
The process of turning used materials into new products. Recycling helps reduce waste and saves energy.
Refrigerant
A chemical used in cooling systems like refrigerators or air conditioners. Some types are strong greenhouse gases if they leak.
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Reforestation
The process of replanting trees in areas where forests have been cut down. It improves biodiversity and pulls COâ‚‚ out of the air.
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Regional Climate
The average long-term weather patterns in a specific area. It affects local ecosystems, farming, and water supplies.
Renewable Resource
A resource that naturally replaces itself quickly—like sunlight, wind, and rain. Unlike fossil fuels, it won’t run out.​​
S
Smog
A type of air pollution that forms when sunlight reacts with chemicals in the air—especially from cars and factories. Smog often contains ozone and other harmful substances that can make it hard to breathe.
Snowpack
The buildup of snow on the ground, especially in mountains. When it melts in spring, it becomes an important source of fresh water for rivers, farms, and cities.
Solar Energy
Power from the sun. It can be captured using solar panels or mirrors and turned into electricity or heat. Solar energy is renewable, clean, and available almost everywhere.
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Solar Panel
A device made up of many photovoltaic cells that collect sunlight and turn it into electricity. Solar panels can power homes, schools, and even entire communities.
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Solar Thermal Technology
A way to use sunlight to heat water or create steam. The heat can be used directly or turned into electricity in solar power plants.
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Subtropics
Regions just north or south of the tropics. These areas usually have hot summers, mild winters, and more rainfall than deserts. The southern U.S. is an example of a subtropical region.
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Sunspot
A dark area on the sun’s surface caused by magnetic activity. Sunspots are cooler than the rest of the sun and can affect how much solar energy reaches Earth.
T
Thermal Expansion
When a material—like water—gets warmer, it takes up more space. In the ocean, this causes sea levels to rise as water heats up and expands.
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Tidal Power
A clean energy source that uses the rise and fall of ocean tides to generate electricity. It's predictable and reliable, though it only works well in places with strong tides.
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Tides
The regular rise and fall of sea levels caused mainly by the gravitational pull of the moon (and to a lesser extent, the sun). Most coasts experience two high tides and two low tides each day.
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Tropics
The warm regions near the equator that get the most direct sunlight year-round. Tropical areas have hot climates and are home to rainforests, coral reefs, and many unique species.
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Turbine
A machine with blades that spin when moved by wind, water, or steam. This spinning motion drives a generator to produce electricity.
U
Ultraviolet (UV) Radiation
A type of energy from the sun that you can’t see but can feel. Some UV rays help our bodies make vitamin D, but too much can cause sunburn, skin damage, and eye problems. Earth’s ozone layer helps block most harmful UV radiation.
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Uranium
A heavy metal that’s naturally radioactive and used as fuel in nuclear power plants. When uranium atoms split (in nuclear fission), they release energy that can be turned into electricity.​​
V
Vapor
The gas form of a substance that is usually a liquid or solid at normal temperatures. For example, water vapor is water in its gaseous state, and it plays a key role in the water cycle and the greenhouse effect.
Volcano
An opening in the Earth's surface where magma, ash, and gases can escape. Volcanic eruptions can influence climate by sending particles into the atmosphere that reflect sunlight and temporarily cool the planet.​​
W
Waste-to-Energy
A process that burns trash or captures gases from landfills to make electricity or heat. It reduces the amount of waste in landfills and provides an energy source, but it must be carefully managed to avoid air pollution.
Waterborne Disease
Illnesses spread through contaminated water, such as cholera or E. coli. These diseases are more common in places with poor sanitation and can increase after floods or heavy rains.
Water Vapor
A greenhouse gas made of water in its gas form. It’s naturally present in the atmosphere and helps trap heat, but it also forms clouds and precipitation when it condenses.
Watt
A unit that measures the rate of energy use. For example, a 100-watt light bulb uses 100 watts of electricity each second it's on.
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Weather
The short-term conditions of the atmosphere—like temperature, wind, humidity, and precipitation. Weather can change daily, while climate describes long-term patterns.
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Wetland
A low-lying area where land stays wet for long periods—like swamps, marshes, and bogs. Wetlands help filter water, prevent floods, and support many plants and animals.
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Wind Turbine
A tall machine with rotating blades that uses wind to spin a generator and make electricity. Wind energy is renewable, clean, and growing fast around the world.​
Z
Zero-Emission
Refers to vehicles, buildings, or energy systems that don’t release greenhouse gases into the air while operating. Examples include electric cars powered by renewable energy or solar-powered homes.