Glossary
Adapted ELI Glossary Page (ELI Report
)
Accretion: the addition of land via natural forces and processes
Adaptation to climate variability: Climate variability (and change) bring unusual weather that can pose threats as well as opportunities to people and ecosystems. The quality of life in the future will reflect the resiliency of people and ecosystems to change, and their ability to take advantage of arising opportunities. It will also depend on their ability to adapt to change; it will depend on their ability to plan for the future and manage despite uncertainties.
Aerosols: small droplets or particles, larger than a molecule in size, that remain suspended in the atmosphere (see definition). They have a variety of sources – some natural, like dust storms and volcanic activity, and some caused by human activities, like fossil fuel and biomass burning. Note that there is no connection between these particulate aerosols and pressurized products also called aerosols.
Albedo: solar radiation reflectivity, with an albedo of one being the highest (reflecting all incoming light) and zero being the lowest (absorbing all light). Albedo varies depending on such factors as cloudiness, snow, and land cover. Because of its whiteness, snow typically has an albedo close to one; dull black substances like charcoal have an albedo close to zero.
Anoxia: lacking dissolved oxygen
Anthropogenic: resulting from human activities; human-induced.
Aquaculture: commercial production of fish (differing from harvesting of fish produced without human assistance).
Aquifer: water saturated soil.
Aquatic: Living or growing in fresh water (in contrast to marine organisms found in salt water)
Atmosphere: the mixture of gases that surrounds the Earth. By volume it consists of about 79.1 percent nitrogen, 20.9 percent oxygen, 0.036 percent carbon dioxide, and trace amounts of other gases. In addition, the atmosphere contains water in the form of vapor, clouds and aerosols. Scientists divide the atmosphere into separate layers, according to mixing, chemical characteristics and thermal properties. The most important layers for climate are the troposphere, and stratosphere (see definitions of each).
Atmosphere-Ocean General Circulation Models (AOGCMs): global climate models with coupled atmosphere and ocean components. They are highly complex, and require a lot of computing power to run.
Average: see mean
Beach Erosion: wearing away of beaches by wind and waves.
Benthic: bottom dwelling aquatic and marine organisms.
Biodiversity: The range of organisms present in an ecosystem. Biodiversity can be measured by the numbers and types of different species, or the genetic variations within and between species.
Biosphere: portion of the Earth that supports living organisms—on land (the terrestrial biosphere) and in the oceans (marine biosphere), and in the atmosphere. It includes all ecosystems and living organisms, and also dead organic matter. Marine and terrestrial biospheres contribute to the atmosphere’s composition.
Boreal: northern (e.g., the CARA region has many northern forests)
Carbon cycle: the flow of carbon (in its various forms, such as carbon dioxide) through the atmosphere, ocean, terrestrial biosphere, and lithosphere.
Carbon Dioxide (CO2): the principal anthropogenic greenhouse gas that affects the Earth’s radiative balance. It occurs naturally and from such human activities as fossil fuel burning, forest clearing, and other land use changes.
Carbon sinks: reservoirs that take in and store more carbon than they release, thereby partially offsetting greenhouse gas emissions. Forests and oceans are two examples.
Chlorofluorocarbons (CFCs): compounds containing chlorine, flourine, and carbon. They are very stable in the troposphere, but in the stratosphere are broken down by strong ultraviolet light, releasing chlorine atoms that then deplete stratospheric ozone. They act also as greenhouse gases, absorbing outgoing infrared radiation in the atmosphere. Common uses are as propellants, refrigerants, blowing agents (for producing foam), and solvents.
Climate:average weather pattern for a particular region and time period. It varies from place to place, depending on such factors as latitude, distance from the sea, vegetation, and the presence/absence of mountains. And it varies over time: by season, year, decade, or much longer periods. Climate is the average weather pattern, measured over time for a defined spatial region. The same variables are used to describe climate and weather; the time span is what sets them apart.
Climate change: as defined by the IPCC, is any change in climate over time, whether resulting from natural causes or from human activity. These changes typically persist for decades or longer, and may affect either the average state of the climate or its variability. This definition differs from that of the UN Framework Convention on Climate Change (UNFCCC), which draws a distinction between climate change attributable to human activities, and climate variability attributable to natural causes. (The CARA website uses the IPCC definition).
Climate models: mathematical representations of the Earth’s climate system and components and their processes and interactions. They are used as a research tool to study and simulate natural climate variability, and project the climate response to human activities (i.e. human induced forcing). They are also used operationally for monthly, seasonal and multi-year climate predictions. Climate models of varying complexity depict climate system components singly and in combination (coupled models).
Climate system: for purposes of the Third Assessment Report, the IPCC defines it as an interactive system consisting of five major components: the atmosphere, the hydrosphere, the cryosphere, the land surface, and the biosphere. The climate system continues to evolve over time, influenced by: its own internal dynamics, external forcings such as volcanic eruptions, solar variations, and human-induced forcings such as fossil fuel burning and land use change.
Climate variables: measures of climate such as average, maximum and minimum temperature; precipitation, humidity, cloud type and amount, solar radiation.
Climate variability: climate changes (to mean states for example) that occur on time and spatial scales beyond those of individual weather events. Some of this variability is “forced” from outside the climate system itself—by things like anthropogenic greenhouse gases or solar variability. Other variability, such as oscillations in atmospheric-oceanic circulation, is internal to the climate system.
Coastal Erosion: wearing away of coastline by wind and waves.
Combined Sewer Overflow (CSO): systems that allow untreated municipal sewage to mix and be discharged with storm water, preventing storm water from overwhelming the sewage treatment plant.
Cryosphere: including the ice sheets of Greenland and Antarctica, continental glaciers and snow fields, sea ice and permafrost, derives its importance to the climate system from its high reflectivity (albedo) for solar radiation, its low thermal conductivity, its large thermal inertia and, especially, its crucial role in driving deep ocean water circulation. Because the ice sheets store a large amount of water, variations in their volume are a potential source of sea-level variations.(IPCC)
Diurnal temperature range: difference between the maximum and minimum temperatures during a day.
Dobson Unit (DU): a measure of the total amount of ozone in a column of the atmosphere (total column ozone) from ground level to the top of the atmosphere, based on analysis of absorbed ultraviolet light. The number of Dobson units corresponds directly with the “thickness” of the ozone layer. While measurements vary widely according to time and place, a typical reading for a healthy polar ozone layer might be in the 300-450 Dobson unit range.
Eco-region: Omernick and Bailey (1997) define eco-regions as regions that “delimit large areas within which local ecosystems reoccur more or less throughout the region in a predictable pattern.” Eco-regions exist across multiple scales, and they serve as a spatial framework for ecological assessment.
Ecosystem: a unit of ecological analysis in which the physical and biological entities are considered in relation to each other, including energy flows and chemical feedbacks within a defined geographical area.
El Niño-Southern Oscillation(ENSO): pattern of climate/weather variation, known popularly as El Niño, that results from coupled atmosphere-ocean interactions, and recurs at two- to seven-year intervals. The ENSO pattern is characterized partly by alternating warmer(El Niño) and cooler surface waters (La Niña) of the sea surface in the eastern and central tropical Pacific Ocean, which in turn are caused by changes in subsurface termperatures. It affects precipitation and temperatures over a large portion of the globe, with drastic consequences to human activities like farming and fishing, which depend on weather and ocean currents.
Energy balance (the Earth's annual and the global mean): of the incoming solar radiation, 49% (168 Wm-2) is absorbed by the surface. That heat is returned to the atmosphere as sensible heat, as evapotranspiration (latent heat) and as thermal infrared radiation. Most of this radiation is absorbed by the atmosphere, which in turn emits radiation both up and down. The radiation lost to space comes from cloud tops and atmospheric regions much colder than the surface. This causes a greenhouse effect.55
Ensemble: A set of model simulations, used to show sensitivity to changes in assumptions. Often the simulations are averaged to represent that model, rather than showing all runs for each model.
Estuarine: referring to an estuary
Estuary: the interface where a river meets the sea, where aquatic and marine life meet terrestrial life in marshes and wetlands, and were fresh water still can be influenced by tides. Estuaries can be defined by a salinity gradient that ranges from ocean salinity of 35.0 ppt (parts per thousand) to fresh water with salinity of less than 0.5 ppt.
Eustatic sea level change:average sea level change caused by changes in water density or in the total mass of water.
Eutrophication: a natural aging process for ponds and lakes; this is accelerated by nutrients and warmth, leading to excessive algae growth.
Evapotranspiration: loss of water from the soil by evaporation and by transpiration from trees and other plants.
Extreme weather events: Weather phenomena that occur infrequently, such as droughts, heat waves, heavy rainfall, floods, hurricanes, and tornadoes.
General Circulation Model (GCM): model of the global atmospheric circulation used to project climate conditions. Also called Global Climate Model.
Geomorphology: natural land forms (that is, physical properties) of a place. Also called physiography.
Glacial cycles: one of the most pronounced climate cycles, consisting of alternating ice ages and thaws—called glacial and interglacial periods. The last glacial cycle in human experience peaked about 20,000 years ago, with ice melting during the period 14,000-11,500 years ago. During the most recent million years or so (the epoch geologists call the Pleistocene), glacial cycles have come at fairly regular intervals of about 100,000 years.
Global climate model (GCM): Another term for General Circulation Model (also referred to as GCM); most climate models are for the entire globe; regional climate models typically are considered to be less accurate for long-term projections.
Global surface temperature:average of near surface air temperature over land, and sea surface temperature. It is derived from sea-surface measurements, and land surface readings taken 1.5 meters, or 59 inches, above the ground.
Global Warming Potential (GWP): the amount of global warming caused by substance, expressed as the ratio of the warming caused by one substance relative to that caused by a similar mass of carbon dioxide over a given period of time.
Greenhouse effect: the effect produced as certain atmospheric gases allow incoming solar radiation to pass through to the Earth’s surface, but prevent the outgoing (infrared) radiation, which is re-radiated from Earth, from escaping into outer space. A certain amount of this occurs naturally, keeping the Earth’s average temperature about 59 degrees Fahrenheit warmer than it otherwise would be.
Greenhouse gases: trace gases in the atmosphere which absorb and then emit infrared radiation in all directions including downward to the Earth’s surface thus warming the lower atmosphere (see definition). The primary greenhouse gases in the Earth’s atmosphere are carbon dioxide, nitrous oxide, methane, ozone, and water vapor.
Hydrosphere: as a climate component, comprises all liquid surface and subterranean water; both fresh water, including rivers, lakes and aquifers, and saline water of the oceans and seas. Fresh water runoff from the land returning to the oceans in rivers influences the ocean’s composition and circulation. The oceans cover approximately 70% of the Earth’s surface. They store and transport a large amount of energy and dissolve and store great quantities of carbon dioxide. Their circulation is driven by the wind and by density contrasts caused by salinity and thermal gradients (the so-called thermohaline circulation); ocean circulation is much slower than the atmospheric circulation. Mainly due to their large thermal inertia, oceans damp vast and strong temperature changes; they function as a regulator of the Earth’s climate and as a source of natural climate variability, particularly on long time scales. (IPCC)
Halocarbons: compounds that combine carbon with either fluorine, chlorine, or bromine. These compounds can act as powerful greenhouse gases. Halocarbons containing chlorine and bromine also cause ozone depletion in the stratosphere. Included in the family of halocarbons are chlorofluorocarbons (CFCs) and the hydrochlorofluorocarbons (HCFCs).
Humidity: moisture in the air.
Indicator: quantitative or qualitative measure, often of change, typically intended to represent a complex system. Climate examples include temperature, precipitation, sea level; land use/land cover examples include percent of land in wetlands or developed, dominant types of vegetation, ...
Intergovernmental Panel on Climate Change (IPCC): organization established jointly by the United Nations Environmental Programme and the World Meteorological Organization in 1988 to assess information in the scientific and technical literature related to all significant components of the issue of climate change. http://www.ipcc.ch/
Kyoto Protocol to the United Nations Framework Convention on Climate Change (UNFCCC): international agreement, adopted in 1997 in Kyoto Japan, wherein signatories agreed to reduce their anthropogenic greenhouse gas emissions (CO2, CH4, N2O, HFCs, PFCs, and SF6) to at least 5 percent below 1990 levels in the commitment period 2008 to 2012. Taking effect without ratification or approval by the U.S.
Land Cover: refers to the properties of a portion of the surface of the earth. For example, we can describe an area as covered in grassland, forests, or desert.
Land Use: refers to how land is utilized by humans, as in agricultural land use, urban development, or mining.
Marine and terrestrial biospheres: have a major impact on the atmosphere’s composition. The biota influence the uptake and release of greenhouse gases. Through the photosynthetic process, both marine and terrestrial plants (especially forests) store significant amounts of carbon from carbon dioxide. The biosphere plays a central role in the carbon cycle, as well as in the atmosphere amounts of many other gases, such as methane and nitrous oxide. Other biospheric emissions are the so-called volatile organic compounds (VOC) which could have important effects on atmospheric chemistry, on aerosol formation and therefore on climate. Because the storage of carbon and the exchange of trace gases are influenced by climate, there can be feedbacks between climate change and atmospheric concentrations of trace gases. The influence of climate on the biosphere is preserved as fossils, tree rings, pollen and other records, so that much of what is known of past climates comes from such biotic indicators. (IPCC)
Mean: value obtained by dividing the sum of a set of numbers and dividing by the number of numbers in the set. Also referred to as the average.
Montreal Protocol on Substances that Deplete the Ozone Layer: international agreement, adopted in Montreal in 1987 and modified five times since then, that called for a freeze on production and use of halocarbons at 1986 levels by mid-1989, and over the next 10 years a reduction in CFC production by half. The U.S. and more than 180 other nations have ratified the agreement.
Nonpoint source pollution: pollution from dispersed sources, such as farm fields or roads (compared with a point source such as a smokestack or sewer pipe).
North Atlantic Oscillation (NAO): dominant pattern of northern wintertime atmospheric circulation variability.
Nor'easter (or northeaster): an "extratropical coastal storm," typically covering a larger area than a hurricane, but with lower wind speeds. Nor'easter damage tends to be mostly from wave action and restricted to the coastal zone, while hurricane damage often extends inland because of wind damage as well as storm surge.
Ocean-Atmosphere Oscillations: The earth has its own internal climate oscillations. Some examples are the North Atlantic Oscillation (NAO), the Pacific Decadal Oscillation (PDO), and the El Nino_Southern Oscillation (ENSO).
Ozone (O3): bluish gas that is harmful to breathe, consisting of three bound atoms of oxygen. Nearly 90 percent of Earth’s ozone is in the stratosphere, where it provides important benefits in absorbing harmful UV-B radiation, preventing most of it from reaching Earth’s surface.
Ozone hole: observed depletion of the ozone layer over the Antarctic region that occurs yearly during the Southern Hemisphere spring. It is thought to be caused by the joint effects of human-made chlorine and bromine compounds and meteorological conditions that are specific to the region.
Ozone layer: ozone in the stratosphere where it occurs in its highest concentrations—roughly from 1 to 10 parts per million. This atmospheric zone lies between 15 and 50 kilometers above the Earth’s surface, depending on latitude, season, and other factors. The term “ozone layer” is somewhat of a misnomer, since ozone does not occur in a flat layer in the atmosphere.
Pacific Decadal Oscillation: cyclic variations in sea-surface temperature in the Northern Pacific—an example of natural climate variability. These occur on decadal timescales and affect the weather in places like the U.S. Pacific Northwest region.
Paleoclimate: pertaining to the earth's climate in early geological time; prior to modern observations of climate variables such as temperature and precipitation. Insights about earlier climate come from core sediments from water bodies such as the Chesapeake Bay, from tree rings, and from diaries, newspapers and periodicals.
Physiography: natural land forms (that is, physical properties) of a place. Also called geomorphology.
Precipitation: rainfall and snow.
Proxy record: historical record of climate-related variations obtained by examining tree rings, corals, ice cores, etc.
Radiative forcing: change in the balance between incoming solar radiation and outgoing infrared radiation. Causes include internal changes and external forcing, such as changes in solar output or carbon dioxide concentrations. Without any radiative forcing, solar radiation coming to the Earth would approximately equal to the infrared radiation emitted from Earth. A positive forcing warms the Earth, a negative forcing cools it.
Relative sea-level rise (RSLR): the sum of local and global components of sea-level rise.
Saltwater Intrusion: salt water is denser than fresh water, so fresh groundwater tends to form a “lens” on top of saltwater in coastal areas. Sea-level rise tends to increase the salinity of groundwater, tending to push the freshwater lens inland and toward the surface. Withdrawals of fresh groundwater can be faster than its replenishment, which would tend to pull saltwater into what had been freshwater areas. These push and pull effects can allow saltwater to intrude into freshwater aquifers and wells.
Sea-level rise: the increase in average ocean levels that occurs because warmer water has a higher volume than cooler water and because of melt water from glaciers.
Sensitivity: often used to describe the degree to which exposure to a stimulus (such as severe weather) could affect a receptor (such as a coastline, or an agricultural crop). Also used to analyze what difference it makes to change one or more values for variables in equations used to model physical or socioeconomic systems.
Solar radiation: energy from the sun—includes ultraviolet radiation, visible radiation, and infrared radiation.
Solar Cycles: The sun's energy output varies with time and may have significant impacts on climate. One example is the 11-year cycle related to sunspots.
Solar “11-year” Cycle: recurring pattern of solar output modulation, on scales of nine to 13 years.
Storm-surge flooding: There is a drop in surface pressure over ocean areas affected by a hurricane. A surge in the ocean water is caused by the drop in surface pressure, and the surge builds as the hurricane's swirling winds push the water toward the shore. Flooding is worse when the surge coincides with high tide.
Stratosphere: zone of the atmosphere above the troposphere, extending from about 10 km (ranging from 9 km in high latitudes to 16 km in the tropics on average) to about 50 km above Earth’s surface. Commercial airplanes routinely fly in the lower stratosphere.
Temperature: a measure of the warmth (or coolness) of air, water, or soil. Temperature is measured locally and can be aggregated across regions or the globe. Of course, a global average will not distinguish between usual temperatures in cold climates compared with warmer areas. Temperature varies during the day and by season in a particular location, so sometimes is averaged for the time period of interest. Scientists usually measure temperature in degrees Celsius, but temperatures also are reported in degrees Fahrenheit because many people prefer these units.
Thermohaline circulation (THC): global-scale overturning of the ocean driven by density differences arising from temperature and salinity effects. One of the best known examples of thermohaline circulation is the Gulf Stream, a river of warmer, fresher surface water that flows to the North Atlantic, where it gives up its heat and sinks, making much of Western Europe considerably warmer than it would otherwise be.
Tidal Basin: a relatively low-lying area that can be affected by tides, such as around an estuary.
Total Maximum Daily Load (TMDL): maximum daily amounts allowed in a body of water.
Trace gas: any one of the less common gases, together making up less than 1 percent of the Earth’s atmosphere. Among these are carbon dioxide, water vapor, methane, nitrous oxide, ozone, and ammonia. Though small in absolute volume, they have significant effects on the Earth’s weather and climate.
Troposphere: lowest part of the atmosphere, extending from the Earth’s surface to about 10 km in altitude in mid-latitudes (ranging from 9 km in high latitudes to 16 km in the tropics on average) where almost all “weather” phenomena occur. In the troposphere, temperatures generally decrease with altitude.
Turbidity: sediment or particles suspended in water, which reduce the clarity of the water
Ultraviolet (UV) radiation: that portion of the electromagnetic spectrum with wavelengths shorter than visible light. UV is commonly split into three bands: UV-A, UVB, and UV-C. UV-A is not absorbed by ozone, UV-B is mostly absorbed by ozone, and UV-C is completely absorbed by ozone and normal oxygen.
United Nations Environment Programme (UNEP): the UN agency with a mission “to provide leadership and encourage partnership in caring for the environment by inspiring, informing, and enabling nations and peoples to improve their quality of life without compromising that of future generations.”
United Nations Framework Convention on Climate Change (UNFCC): agreement signed at the 1992 Earth Summit in Rio de Janeiro by more than 150 countries and the European Community, with ultimate objective the “stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system.”
Urban Heat Island: dark surfaces such as pavement and rooftops reflect less light than fields and forests, so cities absorb more heat from sunlight. This makes them warm more during the day and cool less at night, compared with surrounding areas.
Vegetation and soils: at the land surface control how energy received from the Sun is returned to the atmosphere. Some is returned as long-wave (infrared) radiation, heating the atmosphere as the land surface warms. Some solar energy evaporates water, in the soil or in the leaves of plants, bringing water back into the atmosphere. Because the evaporation of soil moisture requires energy, soil moisture has a strong influence on the surface temperature. The texture of the land surface (its roughness) influences the atmosphere dynamically as winds blow over the land’s surface. Roughness is determined by both topography and vegetation. Wind also blows dust from the surface into the atmosphere, which interacts with the atmospheric radiation. (IPCC)
Vulnerability: there are several definitions. For the CARA, vulnerability is biophysical risk and a social or ecological response, so that potential harm depends on exposure, sensitivity, and the ability to adapt or cope.
Water cycle: the hydrologic cycle in which precipitation (rain and snow) falls on land or on water bodies such as oceans, lakes, and streams. Some of the water evaporates or is taken up by plants and some of it percolates into the soil and eventually reaches lakes or the ocean (where water also evaporates). Plants give up moisture through evapotranspiration. (Humans and other animals also take up water, later releasing it as perspiration or waste.) Evaporation adds humidity to the atmosphere, eventually leading to precipitation again.
Weather: the fluctuating state of the atmosphere, characterized by temperature, wind, precipitation, clouds, and other weather elements. Weather is the daily outside conditions created by atmospheric variables such as temperature, precipitation, humidity, cloudiness, wind, and air pressure. The same variables are used to describe climate and weather; the time span is what sets them apart.
Weather Balloon: a balloon equipped with instruments to measure and transmit data about weather features such as air pressure, humidity, and temperature.
Weather Satellite: a satellite equipped with instruments to measure and transmit data about weather features such as air pressure, humidity, and temperature. Weather satellite observations can cover high parts of the atmosphere that cannot be reached by weather balloons.
Weather Station: a location equipped with instruments to measure and record data about weather features such as air pressure, humidity, wind speed, temperature, and precipitation.
Wetland: any area that is more-or-less regularly wet or flooded, where the water table stands at or above the land surface for at least part of the year. Coastal wetlands include salt marshes, tidal marshes, and brackish marshes subject to saline and tidal influences.
Wind Speed: a measure of how fast air currents are moving
World Meteorological Organization(WMO): Geneva based 185 member United Nations organization that provides “authoritative scientific voice on the state and behavior of the Earth’s atmosphere and climate.” Its stated purpose is to facilitate international cooperation in the establishment of networks of stations for making meteorological, hydrological, and other observations, and to promote the rapid exchange of meteorological information, the standardization of meteorological observations, and the uniform publication of observations and statistics.