Adaptation: strategies, policies and measures designed to reduce the current and future impacts of global environmental changes.

Adaptive Environmental Management: managing resources under uncertainty to reduce it. AEM's management experiments involve both people and institutions affected by the management strategy in designing the experiments and in interpreting the results.

Aerosols: A collection of airborne solid or liquid particles residing in the atmosphere for at least several hours. Aerosols may be of either natural or anthropogenic origin. Aerosols influence climate in two ways: directly through scattering and absorbing radiation, and indirectly through acting as condensation nuclei for cloud formation or modifying the optical properties and lifetime of clouds.

Agenda 21: a program of the United Nations (UN) related to sustainable development. It is a comprehensive blueprint of action to be taken globally, nationally and locally by organisations of the UN, governments, and major groups in every area in which humans impact on the environment. The number 21 refers to the 21st century.

Agrobiodiversity or Agricultural Biodiversity: all crops and animal breeds, their wild relatives, and the species that interact with and support these species, e.g. pollinators, symbionts, pests, parasites, predators, decomposers, and competitors, together with the whole range of environments in which agriculture is practiced, not restricted to crop lands or fields.

Albedo: The fraction of solar radiation reflected by a surface or object, often expressed as a percentage. Snow covered surfaces have a high albedo; the albedo of soils ranges from high to low; vegetation covered surfaces and oceans have a low albedo. The Earth?Äôs albedo varies mainly through varying cloudiness, snow, ice, leaf area and land cover changes.

Anthropocene: a term used by some scientists to describe the most recent period in the Earth's history, starting in the 18th century, when human activities first began to have a significant global impact on the Earth's climate and ecosystems. The term was coined in 2000 by the Nobel Prize winning scientist Paul Crutzen, who regards the influence of mankind on the Earth in recent centuries as so significant as to constitute a new geological era.

Anthropogenic: effects or processes that are derived from human activities, as opposed to effects or processes that occur in the natural environment without human influences

Atmosphere: the gaseous envelope surrounding the Earth. The dry atmosphere consists almost entirely of nitrogen (78.1%) and oxygen (20.9%), together with a number of trace gases, such as argon (0.93%), helium, and radiatively active greenhouse gases such as carbon dioxide (0.035%), and ozone. In addition the atmosphere contains water vapour, whose amount is highly variable but typically 1% volume mixing ratio. The atmosphere also contains clouds and aerosols.

Biodiversity: the Convention on Biological Diversity defines biological diversity as ?Äòthe variability among living organisms from all sources including... terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part: this includes diversity within species, between species and of ecosystems?Äô. Biodiversity is an attribute of life, distinguished from biological resources which ?Äòinclude genetic resources, organisms or parts thereof, populations, or any other biotic component of ecosystems with actual or potential use or value for humanity?Äô.

Biogeochemical cycling: natural processes that recycle nutrients in various chemical forms from the environment to organisms and then back to the environment.

Biogeophysical processes: a term used to encompass all of the naturally occurring materials, processes and relationships operating in an area; the natural ecosystem. The word biogeophysical was constructed so that all the natural objects and processes operating in an area can be classified as either biological (plant and animal species, ecological interactions), geological (rock types, soil types, sedimentation, erosion) or physical (heat, light, electrical, gravitational, etc.)

Biosphere: the living and dead organisms found near the Earth?Äôs surface in parts of the lithosphere, atmosphere and hydrosphere. The part of the Earth system comprising all ecosystems and living organisms, in the atmosphere, on land (terrestrial biosphere) or in the oceans (marine biosphere), including derived dead organic matter, such as litter, soil organic matter and oceanic detritus.

Carbon cycle: the term used to describe the flow of carbon (in various forms, e.g. as carbon dioxide) through the atmosphere, ocean, terrestrial biosphere and lithosphere.

Carbon dioxide (CO2): a naturally occurring gas, and also a by-product of burning fossil fuels and biomass, as well as land-use changes and other industrial processes. It is the principal anthropogenic greenhouse gas that affects the Earth?Äôs radiative balance. It is the reference gas against which other greenhouse gases are measured and therefore has a great global warming potential.

Climate change: climate change refers to a statistically significant variation in either the mean state of the climate or its variability, persisting for an extended period (typically decades or longer). Climate change may be due to natural internal processes or external forcings, or to peristent anthropogenic changes in the composition of the atmosphere or in land use.

(Climate) Impacts: consequences of climate change on natural and human systems. Depending on the consideration of adaptation, one can distinguish between potential impacts and residual impacts. Potential impacts: All impacts that may occur given a projected change in climate, without considering adaptation. Residual impacts: The impacts of climate change that would occur after adaptation.

Climate model: A numerical representation of the climate system based on the physical, chemical and biological properties of its components, their interactions and feedback processes, and accounting for all or some of its known properties. There is an evolution towards more complex models with active chemistry and biology. Climate models are applied, as a research tool, to study and simulate the climate, but also for operational purposes, including monthly, seasonal and interannual climate predictions.

Climate prediction: a climate prediction or climate forecast is the result of an attempt to produce a most likely description or estimate of the actual evolution of the climate in the future (e.g., at seasonal, interannual, or long-term time-scales).

Climate variability: climate variability refers to variations in the mean state and other statistics (such as standard deviations, the occurrence of extremes, etc.) of the climate on all temporal and spatial scales beyond that of individual weather events. Variability may be due to natural internal processes within the climate system (internal variability), or to variations in natural or anthropogenic external forcing (external variability).

Climate: climate in a narrow sense is usually defined as the ?Äúaverage weather?Äù or more rigorously as the statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands or millions of years. The classical period is 30 years, as defined by the World Meteorological Organization (WMO). These relevant quantities are most often surface variables such as temperature, precipitation, and wind. Climate in a wider sense is the state, including a statistical description, of the climate system.

Coupled human-environmental systems (e.g. Land systems): changes in the interaction between people and their environments, and the ways these have affected, and may yet affect, the sustainability of the Earth System.

Cryosphere: the component of the climate system consisting of all snow, ice and permafrost on and beneath the surface of the earth and ocean.

Drought: the phenomenon that exists when precipitation has been significantly below normal recorded levels, causing serious hydrological imbalances that adversely affect land resource production systems.

Earth System: the Earth System is the unified set of physical, chemical, biological and social components, processes and interactions that together determine the state and dynamics of Planet Earth, including its biota and its human occupants.

Earth System Science: is the study of the Earth System, with an emphasis on observing, understanding and predicting global environmental changes involving interactions between land, atmosphere, water, ice, biosphere, societies, technologies and economies.

Ecological Economics: cross-cutting discipline aiming to understand the interrelations between people and their environment, for indicators of sustainability, and for ways of bringing individual human behavior into conformity with collective human goals. This disciple uses ecletic methodologies.

Ecosystem functioning: collective term for biogeochemical and biotic processes operating in an ecosystem.

Ecosystem processes: the biogeochemical processes that transfer energy and matter within and between ecosystems (e.g. primary production is the process that fixes solar energy into ecosystems via photosynthesis).

Ecosystem services: benefits derived by humans as a result of ecosystem processes and functioning. Ecological goods are typified by the production of food and fiber. Ecosystem services include carbon storage and the reduction of greenhouse gases, the maintenance of water quality and soil fertility, resistance to climate and other environmental changes, or the maintenance of ecological conditions favorable for human health. Ecosystem services can be classified in four categories (Millennium Ecosystem Assessment, 2005):

1. provisioning services: food, fiber, fuel, genetic resources, biochemicals, fresh water
2. cultural services: spiritual and religious values, knowledge system, education and inspiration, recreation and aesthetic values, sense of place.
3. supporting services: primary production, provision of habitat, nutrient cycling, soil formation and retention, production of atmospheric oxygen, water cycling
4. regulating services: species invasion resistance, herbivory, pollination, seed dispersal, climate regulation, pest regulation, disease regulation, natural hazard protection, erosion regulation, water purification.

Ecosystem: dynamic complex formed by the community of plants, animals and micro-organisms and by their non-living environment and their interactions, which together form a functional unit.

Energy balance: averaged over the globe and over longer time periods, the energy budget of the climate system must be in balance. Because the climate system derives all its energy from the Sun, this balance implies that, globally, the amount of incoming solar radiation must on average be equal to the sum of the outgoing reflected solar radiation and the outgoing infrared radiation emitted by the climate system. A perturbation of this global radiation balance, be it human-induced or natural, is called radiative forcing.

Environmental Economics: this discipline addresses how environmental problems arise, how market mechanisms can be used to improve environmental quality, and the level of quality that most efficiently balances preferences for material goods and for environmental services.

Ex-situ conservation: literally means, "off-site conservation". It is the process of protecting an endangered species of plant or animal by removing it from an unsafe or threatened habitat and placing it or part of it under the care of humans. Zoos, botanical gardens and arboretums are the most conventional methods of ex-situ conservation, all of which house whole, protected specimens for breeding and reintroduction into the wild when necessary and possible. Endangered plants and animals may also be preserved in part through seedbanks or germplasm banks.

Extreme (weather) event: an extreme weather event is an event that is rare within its statistical reference distribution at a particular place. Definitions of ?Äúrare?Äù vary, but an extreme weather event would normally be as rare as or rarer than the 10th or 90th percentile. By definition, the characteristics of what is called extreme weather may vary from place to place. An extreme climate event is an average of a number of weather events over a certain period of time, an average which is itself extreme (e.g. rainfall over a season).
Freshwater habitat: all continental waters and terrestrial habitats that receive ?Äòsubsidies?Äô of water from surface and groundwater flow systems, such as groundwater-fed wetlands, river-fed floodplain forests, karst aquifer springs, and so forth.

Global Environmental Change: the set of biophysical transformation of states and flows of land, oceans and atmosphere, driven by an interwoven system of human and natural processes; these are intimately connected with processes of socio-economic and cultural globalization.

Global Warming Potential: an index, describing the radiative characteristics of well-mixed greenhouse gases, that represents the combined effect of the differing times these gases remain in the atmosphere and their relative effectiveness in absorbing outgoing infrared radiation. This index approximates the time-integrated warming effect of a unit mass of a given greenhouse gas in today?Äôs atmosphere.

Greenhouse gas: greenhouse gases are those gaseous constituents of the atmosphere, both natural and anthropogenic, that absorb and emit radiation at specific wavelengths within the spectrum of infrared radiation emitted by the Earth?Äôs surface, the atmosphere, and clouds. This property causes the greenhouse effect. Water vapor (H2O), carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4), and ozone (O3) are the primary greenhouse gases in the Earth?Äôs atmosphere. Moreover there are a number of entirely human-made greenhouse gases in the atmosphere, such as the halocarbons and other chlorine- and bromine-containing substances, dealt with under the Montreal Protocol.

Human Dimensions of Global Environmental Change: global environmental change has many anthropogenic causes. At the same time, it affects the quality of human life and sustainable development on a worldwide scale. Global environmental change is driven by and takes influence on processes of socio-economic, political and cultural globalization.

Human Security: is achieved when and where individuals and communities: have the option to end, mitigate, or adapt to risks to their human, environmental and social rights; have the capacity and freedom to exercise these options; and actively participate in attaining these options.

Hydrosphere: the part of the Earth composed of water: clouds, oceans, ice caps, lakes, etc. The component of the climate system comprising liquid surface and subterranean water, such as: oceans, seas, rivers, fresh water lakes, underground water etc.

In-situ conservation: literally means "on-site conservation". It is the process of protecting an endangered plant or animal species in its natural habitat, either by protecting or cleaning up the habitat itself, or by defending the species from predators. The benefit to in-situ conservation is that it maintains recovering populations in the surrounding where they have developed their distinctive properties. Wildlife conservation is mostly based on in situ conservation, involving the protection of wildlife habitats.

Institutions: clusters of rights, rules, and decision-making procedures that give rise to social practices, assign roles to participants in these practices and govern interactions among players of these roles.

Integrated assessment: a method of analysis that combines results and models from the physical, biological, economic and social sciences, and the interactions between these components, in a consistent framework, to evaluate the status and the consequences of environmental change and the policy responses to it.
Land change scienceSystem: an abbreviated term for the coupled socio-environmental terrestrial system that includes land use, land cover and ecosystems.

Lithosphere: the upper layer of the solid Earth, both continental and oceanic, which comprises all crustal rocks and the cold, mainly elastic, part of the uppermost mantle.

Mitigation: strategies, policies and measures designed to stop detrimental environmental changes.

Ocean acidification: the name given to the ongoing decrease in the pH of the Earth's oceans, caused by their uptake of anthropogenic carbon dioxide from the atmosphere

Ozone layer: the stratosphere contains a layer in which the concentration of ozone is greatest, the so-called ozone layer. The layer extends from about 12 to 40 km. The ozone concentration reaches a maximum between about 20 and 25 km. This layer is being depleted by human emissionsof chlorine and bromine compounds. Every year, during the Southern Hemisphere spring, a very strong depletion of the ozone layer takes place over the Antarctic region, also caused by human-made chlorine and bromine compounds in combination with the specific meteorological conditions of that region. This phenomenon is called the ozone hole.

Ozone: a form of oxygen containing three instead of two atoms joined together. Ozone in the upper atmosphere protects life from the sun?Äôs ultraviolet radiation. CFCs and other chemicals can damage this ozone layer. In the lower atmosphere, ozone is a pollutant.

Radiative forcing: the change in the net vertical irradiance (expressed in Wm-2) at the tropopause due to an internal change or a change in the external forcing of the climate system, such as, for example, a change in the concentration of carbon dioxide or the output of the Sun. Usually radiative forcing is computed after allowing for stratospheric temperatures to readjust to radiative equilibrium, but with all tropospheric properties held fixed at their unperturbed values.

Resilience: rate at which a system returns to its former state after being displaced from it by a perturbation.
Resistance: capacity of a system to remain in the same state at the face of perturbation.

Scenarios: a plausible and often simplified description of how the future may develop, based on a coherent and internally consistent set of assumptions about driving forces and key relationships. Scenarios may be derived from projections, but are often based on additional information from other sources, sometimes combined with a ?Äúnarrative storyline?Äù.

Sink: any process, activity or mechanism that removes a greenhouse gas, an aerosol or a precursor of a greenhouse gas or aerosol from the atmosphere.
Stratosphere: the highly stratified region 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.

Sustainability: the development of systems capable of ensuring that future generations will have coupled human-environment systems capable of providing goods and services without degradation of structure or function.

Sustainable development: development that "meets the needs of the present without compromising the ability of future generations to meet their own needs" (Brundtland Report, 1987). Sustainable development uses biological resources at a rhythm that does not entail their impoverishment, even their depletion but, on the contrary, that preserves their potential over the course of time. On an even bigger scale, a development is "sustainable" when decisions aim to preserve the maximum choice possible for generations to come.

Sustainable use: the use of components of biological diversity in ways and at rates that support their long-term availability. Emphasis is placed on maintaining biodiversity?Äôs potential to meet the needs and aspirations of present and future generations.

Thermohaline circulation: large-scale density-driven circulation in the ocean, caused by differences in temperature and salinity. In the North Atlantic the thermohaline circulation consists of warm surface water flowing northward and cold deep water flowing southward, resulting in a net poleward transport of heat.

Traditional knowledge, indigenous knowledge, and local knowledge: generally refer to the matured long-standing traditions and practices of certain regional, indigenous, or local communities. Traditional knowledge also encompasses the wisdom, knowledge, and teachings of these communities. In many cases, traditional knowledge has been orally passed for generations from person to person. Such knowledge typically distinguishes one community from another and becomes their "identity." It can also reflect a community's interests and some communities even depend on their traditional knowledge for survival. Subsequently, communities argue that traditional knowledge warrants respect and sensitivity.

Troposphere: the lowest part of the atmosphere from the 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 clouds and ?Äúweather?Äù phenomena occur. In the troposphere temperatures generally decrease with height.
Vulnerability: the degree to which a system, subsystem or system component is likely to experience harm due to exposure to a hazard.