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Glossary of Climate Change Terms

Agriculture. The science, art, or practice of cultivating the soil, producing crops, and raising livestock and in varying degrees the preparation and marketing of the resulting products.

Allergens. Airborne particles, such as dust mites, mold, cockroaches, pet dander, and secondhand smoke, that can trigger allergies.

Asthma. A very serious disease of the lungs that makes it hard to breathe. Exposure to environmental allergens can bring on an asthma attack.

Atmosphere. The mixture of gases surrounding the Earth. The Earth's atmosphere consists of about 78.1% nitrogen (by volume), 20.9% oxygen, 0.93% argon, 0.038% carbon dioxide and trace amounts of other gases. The atmosphere can be divided into a number of layers with different properties.

The layer nearest the Earth is the troposphere, which reaches up to an altitude of about 8 km (about 5 miles) in the polar regions and up to 17 km (nearly 11 miles) above the equator. The weather we experience takes place within the troposphere. The stratosphere lies atop the troposphere and reaches an altitude of about 50 km (31 miles). The ozone layer that protects us from the sun’s ultraviolet radiation is within the stratosphere. The mesosphere extends from the top of the stratosphere up to 80-90 km. Finally, the thermosphere, or ionosphere, gradually diminishes and forms a fuzzy border with outer space. There is very little mixing of gases between layers.

Barometric Pressure. The pressure of the atmosphere (usually expressed in terms of the height of a column of mercury).

Barricade. An obstruction or rampart constructed to block the advance of the ocean.

Biosphere. The regions of the Earth's air, water, and land, where life exists. The biosphere is a closed and self-regulating system sustained by grand-scale cycles of energy and materials.

Carbon Dioxide. A heavy colorless gas (CO2) that does not support combustion, dissolves in water to form carbonic acid, is formed especially in animal respiration and in the decay or combustion of animal and vegetable matter, is absorbed from the air by plants in photosynthesis, and is used in the carbonation of beverages. CO2 is most important in a climate context because it acts as a greenhouse gas.

Carbon Footprint. A measure of the greenhouse gases that are produced by activities of a person, a family, a school or a business that involve burning fossil fuels.

Carbon Sink. An area that stores and traps carbon dioxide. Trees are excellent carbon sinks because they absorb the carbon dioxide from the air and replenish the air with oxygen.

Climate. The average weather (usually taken over a 30-year time period) for a particular region and time period. Climate is not the same as weather, but rather, it is the average pattern of weather for a particular region. Weather describes the short-term state of the atmosphere. Climatic elements include precipitation, temperature, humidity, sunshine, wind velocity, phenomena such as fog, frost, and hail storms, and other measures of the weather.

Climate System. The components of the Earth system which affect climate, including: the atmosphere, oceans, glaciers, the solid Earth and the biosphere.

Climatologist. A person who studies climate.

Coal. A fossil fuel composed of a mixture of carbon, hydrogen and oxygen that is used to produce heat and burned by some power plants to produce electricity.

Concentration. The amount of a substance in a given volume. In this case, a measurement of the fraction of the atmosphere composed of a certain gas.

Deforestation. The change of forested lands to non-forest uses. This is often cited as one of the major causes of the enhanced greenhouse effect for two reasons: 1) trees that are burned release carbon dioxide; and, 2) trees that are cut no longer remove carbon dioxide from the atmosphere.

ºF means and should be read as Degrees Fahrenheit. A unit for measuring temperature. Fahrenheit degrees represent a thermometric scale on which, under standard atmospheric pressure, the boiling point of water is 212 degrees, the freezing point of water is 32 degrees, and zero degrees approximates the temperature produced by mixing equal quantities by weight of snow and common salt.

Dengue Fever. A mosquito-borne, climate sensitive disease, most common in tropical countries, that causes high fevers, headache, and joint and muscle pain.

Drought. A period of abnormally dry weather long enough to cause serious shortages of water for agriculture and other needs in the affected area.

Ecological Disturbance. Ecological means related to ecology, which is the sum of the relationships between organisms and their environment. An ecological disturbance is an event that interrupts these relationships between organisms and the environment.

Ecosystem. A natural community of organisms and the physical environment in which they interact.

Environment. All of the physical, chemical, and biotic factors (climate, soil, living things, etc.) that act upon an organism or an ecological community and ultimately determine its form and survival. The circumstances, objects, and conditions that surround each of us.

Extreme weather events. Severe weather, such as floods, hurricanes and tornadoes, that damages communities and may affect our health. Hurricane Katrina is an example of an extreme weather event.

Fossil Fuel. A general term for a fuel that is formed in the Earth from plant or animal remains, including coal, oil, natural gas, oil shales, and tar sands.

Greenhouse Effect. A general warming effect felt on Earth’s surface, produced by greenhouse gases. These gases allow incoming solar radiation to pass through the Earth's atmosphere, but trap heat by preventing some of the infrared radiation from the Earth’s surface from escaping to outer space. This process occurs naturally and has kept the Earth's temperature about 60 degrees Fahrenheit warmer than it would otherwise be. Current life on Earth could not be sustained without the natural greenhouse effect. However, the greenhouse effect is becoming stronger as a result of human activities, which is causing the warming we have observed over the past century.

Greenhouse Gas. Any gas that absorbs infra-red radiation in the atmosphere. Greenhouse gases include water vapor, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), halogenated fluorocarbons (HCFCs) , ozone (O3), perfluorinated carbons (PFCs), and hydrofluorocarbons (HFCs).

Glacier. A very large body of ice moving slowly down a slope or valley or spreading outward on a land surface.

Habitat. The place or environment where a plant or animal naturally lives and grows.

Heat Stress. A variety of problems associated with very warm temperatures and high humidity.

Heat exhaustion is a condition marked by weakness, nausea, dizziness, and profuse sweating that results from physical exertion in a hot environment.

Heat stroke is a condition marked especially by cessation of sweating, extremely high body temperature, and collapse that results from prolonged exposure to high temperature.

Industrial Revolution. A rapid major change in an economy marked by the general introduction of power-driven machinery or by an important change in the prevailing types and methods of use of such machines. In a historical context, this refers to the period lasting throughout much of the 19th century in which the United States and Europe shifted from an agricultural to a manufacturing based economy.

Industrial. Relating to industry; in this case, industrial practices referring to how products are made and used.

Infectious diseases. Kill more people worldwide than any other single cause. Infectious diseases are caused by germs. Germs are tiny living things that are found everywhere - in air, soil and water. You can get infected by touching, eating, drinking or breathing something that contains a germ. Germs can also spread through animal and insect bites, kissing and sexual contact. Vaccines, proper hand washing and medicines can help prevent infections.

Lyme disease. A tick-borne disease that can cause a rash, fever, fatigue and headaches. If it isn’t treated it can cause infection in the joints, heart or nervous system. In the Northeastern United States, Lyme disease affects about 100,000 people every year, many of them children.

Malaria. A mosquito-borne, climate sensitive disease caused by the parasite Plasmodium. It causes fever, chills and other flu-like symptoms and is responsible for over one million deaths worldwide each year, most of them children in sub-Saharan Africa.

Meteorologist. A person who studies the science of weather-related phenomena.

Methane. A colorless, odorless, flammable hydrocarbon (CH4) that is produced by the decomposition of organic matter, and other processes. Methane is a greenhouse gas; one molecule of methane is 25 times more effective at trapping heat than a molecule of carbon dioxide, when their effects are compared over 100 years.

Ozone. Ozone consists of three atoms of oxygen bonded together in contrast to normal atmospheric oxygen which consists of two atoms of oxygen. Ozone is an important greenhouse gas found in both the stratosphere (about 90% of the total atmospheric loading) and the troposphere (about 10%). Ozone has other effects beyond acting as a greenhouse gas. In the stratosphere, ozone provides a protective layer shielding the Earth from ultraviolet radiation and subsequent harmful health effects on humans and the environment. In the troposphere, ozone combines with other chemicals and gases (oxidization) to cause smog.

Particulate Matter (PM) or Particle Pollution. Small particles of matter such as dust and soot that are suspended in the air. PM is emitted from sources such as motor vehicles, some industrial processes and forest fires.

Photosynthesis. The process by which green plants use light to synthesize organic compounds from carbon dioxide and water. In the process oxygen and water are released. Increased levels of carbon dioxide can increase net photosynthesis in some plants. Plants create a very important reservoir for carbon dioxide.

Post-traumatic stress. A condition that is the result of a terrible event, such as hurricanes, tornadoes or other very bad experiences. It may cause behavioral changes and loss of interest in everyday activities. Children who experience extreme weather events may have post-traumatic stress.

Precipitation. Rain, hail, mist, sleet, snow or any other moisture that falls to the Earth.

Radiation. Energy emitted in the form of electromagnetic waves. Radiation has different characteristics depending upon the wavelength. Because the radiation from the Sun is relatively energetic, it has a short wavelength (ultra-violet, visible, and near infra-red). Radiation emitted from the Earth's surface and the atmosphere has a longer wavelength (infra-red radiation) than solar radiation because the Earth is cooler than the Sun. Greenhouse gases have little impact on short wave radiation, allowing energy from the Sun to reach Earth’s surface, but absorb long wave radiation emitted by the surface of the Earth, and thereby trap heat.

Smog. Hazy, polluted air caused by the combination of ultraviolet rays from the sun and automobile and industrial emissions in the atmosphere

Solar Energy. Energy from the sun, also known as solar radiation and short-wave radiation. Solar energy includes ultra-violet radiation, visible radiation, and infra-red radiation.

Stratosphere. The part of the atmosphere directly above the troposphere. See Atmosphere.

Thermal. Thermal properties are dependent on temperature; they are related to, or caused by heat.

Topography. The configuration of a surface including its relief and the position of its natural and man-made features. The shape of a surface.

Urban Heat Island effect. Warmer air temperatures in cities compared to the surrounding countryside. Because cities replace natural land with pavement, sidewalks, and buildings, heat is absorbed and collected causing it to be hotter than the countryside where there is more vegetation.

Urushiol. The oil in poison ivy that 80% of people are allergic to; scientists believe it will become more potent with increased concentrations of carbon dioxide and climate change.

Weather. Weather is the specific condition of the atmosphere at a particular place and time. It is measured in terms of such things as wind, temperature, humidity, atmospheric pressure, cloudiness, and precipitation. In most places, weather can change from hour-to-hour, day-to-day, and season-to-season. Climate is the average of weather over time and space. A simple way of remembering the difference is that 'climate' is what you expect (e.g., cold winters) and 'weather' is what you get (e.g., a blizzard).

Wildfires. Naturally occurring fires that result from dry, excess vegetation. Climate change is predicted to cause periods of heavy rainfall, which may cause vegetation to flourish, along with periods of drought, which would dry out the vegetation. This may increase the occurrence of wildfires.

Vector-borne diseases. Ticks or mosquitoes are examples of ‘vectors’ that can carry some diseases from an infected person to another person. Vector-borne diseases are climate sensitive because the vectors that carry them are affected by changes in the climate.

Waterborne diseases. Diseases that a person gets by drinking polluted water. These diseases are climate sensitive because weather events can cause water contamination, increasing the risk of disease.