Climate Change: 2013 IPCC Update


Glossary over Climate Change: 2013 IPCC Update


The process of taking in. For a person or an animal, absorption is the process of a substance getting into the body through the eyes, skin, stomach, intestines, or lungs. (Source: ATSDR Glossary of Terms  )



An aerosol is a collection of microscopic particles, solid or liquid, suspended in a gas.

In the context of air pollution, an aerosol refers to fine particulate matter, that is larger than a molecule, but small enough to remain suspended in the atmosphere for at least several hours.

The term aerosol is also commonly used for a pressurized container (aerosol can) which is designed to release a fine spray of a material such as paint. It has also come to be associated, erroneously, with the gas (propellant) used to expel materials from an aerosol can. (Source: GreenFacts )



The establishment of a forest through tree planting or seeding on land that has lacked forest cover for a very long time or has never been forested. (Source: GreenFacts)


Originating from the activity of humans. (Source: GreenFacts )


The mass of air surrounding the Earth.

The atmosphere consists of nitrogen (78%), oxygen (21%), and traces of other gases such as argon, helium, carbon dioxide, and ozone.

The atmosphere plays an important role in the protection of life on Earth; it absorbs ultraviolet solar radiation and reduces temperature extremes between day and night. (Source: GreenFacts)



The smallest particle of an element that still conserves the chemical properties of that element. Atoms are composed of electrons, protons, and neutrons. (Source: GreenFacts)


Deviation of results or inferences from the truth, or processes leading to such systematic deviation. Any trend in the collection, analysis, interpretation, publication, or review of data that can lead to conclusions that are systematically different from the truth. (Source: CDC Glossary of Epidemiologic Terms  )


Biofuels are non-fossil fuels. They are energy carriers that store the energy derived from organic materials (biomass), including plant materials and animal waste.

They may be solid, such as fuelwood, charcoal and wood pellets; liquid, such as ethanol, biodiesel and pyrolysis oils; or gaseous, such as biogas. (Source: GreenFacts)


Biologic uptake

The transfer of substances from the environment to plants, animals, and humans. (Source: ATSDR Glossary of Terms )


Boreal forest

A forest that grows in regions of the northern hemisphere with cold temperatures. Made up mostly of cold tolerant coniferous species such as spruce and fir. (Source: LEAF Glossary   )


Carbon dioxide (CO2)

A colorless, odorless, non-combustible gas, present in low concentrations in the air we breathe (about three hundredths of one percent by volume).

Carbon dioxide is produced when any substance containing carbon is burned. It is also a product of breathing and fermentation. Plants absorb carbon dioxide through photosynthesis. (Source: The Pacific Forest Trust Glossary )


Carbon monoxide (CO)

An odorless, colorless, and highly poisonous gas.


Carbon sequestration

The removal and storage of carbon from the atmosphere in carbon sinks (such as oceans, forests or soils) through physical or biological processes, such as photosynthesis.

Humans have tried to increase carbon sequestration by growing new forests. (Source: GreenFacts)



The basic subunit of any living organism; the simplest unit that can exist as an independent living system. There are many different types of cells in complex organisms such as humans, each with specific characteristics. (Source: GreenFacts)



Chlorine (Cl2) is produced in large amounts and widely used both industrially and domestically as a disinfectant and bleach. In particular, it is widely used in the disinfection of swimming pools and is the most commonly used disinfectant and oxidant for drinking-water treatment. In water, chlorine reacts to form hypochlorous acid and hypochlorites. (Source: WHO  Guidelines for drinking water quality )

Climate change

The long-term fluctuations in temperature, precipitation, wind, and all other aspects of the Earth's climate.

It is also defined by the United Nations Convention on Climate Change as “change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods” (Source: CoRIS glossary  )


The conversion of forested land to non-forested land as a direct result of human activities. (Source: Forest Carbon Accounting Definitions  )



Any natural or human-induced factor that directly or indirectly causes a change. (Source: MA  Glossary )



The complex system of plant, animal, fungal, and microorganism communities and their associated non-living environment interacting as an ecological unit.

Ecosystems have no fixed boundaries; instead their parameters are set to the scientific, management, or policy question being examined. Depending upon the purpose of analysis, a single lake, a watershed, or an entire region could be considered an ecosystem. (Source: US EPA Glossary of Climate Change Terms   )

Environmental cycles

A natural process in which elements are continuously cycled in various forms between different compartments of the environment (e.g., air, water, soil, organisms).

Examples include the carbon, nitrogen and phosphorus cycles (nutrient cycles) and the water cycle. (Source: GreenFacts)



The process by which a system responds to a disturbance that makes it deviate from its initial state. (Source: GreenFacts)



The Food and Agriculture Organization (FAO) defines “forest” as a portion of land bigger than half a hectare (5 000m2) with trees higher than 5 meters and a tree canopy cover of more than 10 %, or with trees that will be able to meet these criteria.

It does not include land that is predominantly under agricultural or urban land use.


Fossil fuel(s)

A general term for buried combustible geologic deposits of organic materials, formed from decayed plants and animals that have been converted to crude oil, coal, natural gas, or heavy oils by exposure to heat and pressure in the Earth's crust over hundreds of millions of years. (Source: US EPA Glossary of Climate Change terms  )


Water that is not salty, for instance water found in lakes, streams, and rivers, but not the ocean. Also used to refer to things living in or related to freshwater (e.g., "freshwater fish"). (Source: GreenFacts)



A moving body of ice that forms on land from the accumulation and compaction of snow, and that flows downslope or outward due to gravity and the pressure of its own weight. (Source: Alcwin Dictionary of Geology  )


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’s surface, the atmosphere and clouds.

This property causes the greenhouse effect.

Water vapour (H2O), carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4), and ozone (O3) are the primary greenhouse gases in the Earth’s 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. Beside CO2, N2O and CH4, the Kyoto Protocol deals with the greenhouse gases sulphur hexafluoride (SF6), hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs). (Source: IPCC Glossary  )


Water beneath the Earth's surface in the spaces between soil particles and between rock surfaces. (Source: ATSDR Glossary of Terms  )


An ice-like compound formed by the reaction of water and carbon dioxide (CO2), methane (CH4) or similar gases. (Source: IPCC   Glossary )

Ice cap, ice sheet, polar ice cap

An ice cap is a dome-shaped mass of glacier ice that spreads out in all directions; usually larger than an icefield but less than 50 000 km2.

An ice sheet is a dome-shaped mass of glacier ice that covers surrounding terrain and is greater than 50 000 km2, such as the Greenland and Antarctic ice sheets.

A polar ice cap, also called polar ice sheet, is a high-latitude region of land or water covered in ice-


Ice core

Cylinders of ice obtained by drilling into a glacier.

Since the different layers of ice are formed over time through build-up of snow, ice cores provide information on climate from different periods (up to almost one million years) that can be used for research. (Source: GreenFacts)


Intergovernmental Panel on Climate Change

The Intergovernmental Panel on Climate Change (IPCC) has been established by WMO and UNEP to assess scientific, technical and socio- economic information relevant for the understanding of climate change, its potential impacts and options for adaptation and mitigation.

IPCC publications are prepared by three Working Groups (WG I, II and III) composed of hundreds of scientists from many countries. The IPCC's Fourth Assessment Report (4AR), published in 2007, is available at .

The "Summaries for Policymakers" by the three Working Groups, which were used as the source for the GreenFacts Digest on Climate Change (2007), can be found below:

The IPCC's previous report on climate change, the 2001 Third Assessment Report (TAR), was also summarised by GreenFacts (click here for the Digest).

In 2007, the IPCC shared the Nobel Peace Prize with Al Gore "for their efforts to build up and disseminate greater knowledge about man-made climate change, and to lay the foundations for the measures that are needed to counteract such change". (Source: IPCC website  )

Land cover

The physical coverage of land, usually expressed in terms of vegetation cover or lack of it. Related to, but not synonymous with, land use. (Source: MA  Glossary )

Land use

The human use of a piece of land for a certain purpose (such as irrigated agriculture or recreation). Influenced by, but not synonymous with, land cover. (Source: MA  Glossary )


A site where household and industrial waste can be disposed of. It is generally spread in thin layers which are then covered with soil. (Source: GreenFacts)


Mean / Median

In statistics, mean and median both provide an idea of where the “middle” of a sample is.

The mean (or average) is the sum of all scores divided by the number of scores. For instance the sum of individual ages of persons in a group divided by the number of persons in the group, gives the average age.

The median is the number in a range of scores that falls exactly in the middle so that 50% of the cases are above or below. (Source: GreenFacts)



Methane is a colorless, flammable, nontoxic gas with the chemical formula CH4.

This gas is formed naturally by the decomposition of organic matter. Wetlands, livestock and energy are the main sources of methane emissions to the atmosphere, where it acts as a greenhouse gas.

Methane is also a major component of natural gas. It is mainly extracted from geological deposits for fuel and industrial uses (Source: GreenFacts )


Mathematical representation or simulation of an actual situation. (Source: GreenFacts)

Natural organic matter

Organic matter originating from plants and animals present in natural (untreated or raw) waters, for example, in lakes, rivers and reservoirs. (Source: GreenFacts)


Nitrogen oxides (NOx)

NOx is the generic term for a group of highly reactive gases, all of which contain nitrogen and oxygen in varying amounts [such as nitric oxide (NO) and nitrogen dioxide (NO2)].

Many of the nitrogen oxides are colorless and odorless. However, one common pollutant, nitrogen dioxide (NO2) along with particles in the air can often be seen as a reddish-brown layer over many urban areas.

Nitrogen oxides form when fuel is burned [...]. The primary sources of NOx are motor vehicles, electric utilities, and other industrial, commercial, and residential sources that burn fuels.

In the atmosphere, nitrogen oxides can contribute to formation of photochemical ozone (smog) and have health consequences. They also lead to acid rain and contribute to global warming. (Source: US EPA NOx: What is it? Where does it come from?   )


Nitrous oxide

Nitrous oxide is a colourless non-flammable gas with the chemical formula N2O.

This gas is naturally emitted by bacteria. The livestock sector and industry are the main anthropogenic sources of nitrous oxide emissions.

When released into the atmosphere it acts as a powerful greenhouse gas. (Source: GreenFacts)


A non-linear change is a change that is not based on a simple proportional relationship between cause and effect. Therefore, such changes are often abrupt, unexpected, and difficult to predict. (Source: GreenFacts)



In the context of air pollution, nucleation is the first step of the process by which gases are converted to small liquid droplets (ultrafine particles).

This occurs either when certain gases condensate or when different gases react with each other.

The ultrafine particles formed are called "nuclei" and can grow in size when more gases condensate on them or when several droplets merge. (Source: GreenFacts)


The approximately 20 chemical elements known to be essential for the growth of living organisms, including nitrogen, sulfur, phosphorus, and carbon. (Source: Millennium Ecosystem Assessment Glossary   )



Ozone is a form of oxygen having the molecular form of O3. It is a bluish, unstable gas with a pungent odour, found in two parts of the atmosphere: the stratosphere and the troposphere.

The 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. It shields the Earth from ultraviolet radiation's harmful health effects on humans and the environment. This layer is being depleted by human emissions of chlorine- and bromine-containing compounds.

Ground-level ozone: At ground level (in the troposphere), ozone is considered an air pollutant that can seriously affect the human respiratory system. It is a chemical oxidant and a major component of photochemical smog. (Source: GreenFacts)


Particulate matter

Sum of all microscopic solid and liquid particles, of human and natural origin, that remain suspended in a medium such as air for some time. These particles vary greatly in size, composition, and origin, and may be harmful.

Particulate matter may be in the form of fly ash, soot, dust, fog, fumes etc. (Source: GreenFacts)



Exposure pathway is the physical route by which a chemical substance transfers from a source to exposed organisms.

Potential pathways include air, surface water, groundwater, soil, plants, animals and humans. May not necessarily always refer to contaminants. (Source: GreenFacts)


A layer of soil or bedrock at a variable depth beneath the surface of the earth in which the temperature has been below freezing continuously from a few to several thousands of years.



pH is a measure of the concentration of protons (H+) in a solution and, therefore, its acidity or alkalinity. The concept was introduced by S.P.L. Sørensen in 1909. The p stands for the German "Potenz", meaning power or concentration, and the H for the hydrogen ion (H+). In layman's terms , the "pH" value is an approximate number between 0 and 14 that indicates whether a solution is acidic (pH < 7), basic (pH > 7) or neither (pH = 7) [neutral]. (Source: GreenFacts )


Photochemical reaction

Refers to any chemical reaction which occurs as a result of light energy from the sun.

For example, ozone is formed through a photochemical reaction involving nitrogen dioxide and reactive organic compounds. (Source: DNREC online   A history of air pollution events )



Study of the biological, chemical and physical activities and processes that underlie the functioning of living organisms (cells, tissues, organs, and organ systems) and their parts. (Source: GreenFacts)


A precursor is a chemical which precedes and is the source of another. (Source: GreenFacts)


Primary & secondary particles

Primary particles are directly released into the atmosphere by wind, combustion processes, or human activities.

Secondary particles are those that form in the atmosphere from other gaseous pollutants, particularly sulfur dioxide, nitrogen oxides, ammonia, and volatile organic compounds. (Source: GreenFacts)


Energy moving in the form of particles or waves. Familiar radiations are heat, light, radio waves, and microwaves. Ionizing radiation is a very high-energy form of electromagnetic radiation. (Source: US Center for Disease Control and Prevention Glossary of Radiological Terms   )


Radiative Forcing

In the context of the IPCC assessments, radiative forcing refers to an external perturbation in the radiative energy budget of the Earth’s climate system, which may lead to changes in climate parameters.

A positive forcing (more incoming energy) tends to warm the system, while a negative forcing (more outgoing energy) tends to cool it. This is due to changes in drivers of climate change such as the concentration of carbon dioxide or the output of the Sun.

In the IPCC reports, changes in radiative forcing are relative to the year 1750. (Source: GreenFacts)


A measure of the salt concentration of water. (Source: CoRIS Glossary  )


A plausible and often simplified description of how the future may develop, based on a coherent and internally consistent set of assumptions about key driving forces (e.g., rate of technology change, prices) and relationships.

Scenarios are neither predictions nor projections and sometimes may be based on a “narrative storyline.”

Scenarios may include projections but are often based on additional information from other sources. (Source: Millennium Ecosystem Assessment  Glossary )


Scientific Consensus

The Scientific Consensus represents the position generally agreed upon at a given time by most scientists specialized in a given field. (Source: GreenFacts)


Sea ice

Sea ice is frozen ocean water.

It occurs in both the Arctic and Antarctic and can cover large extents of water.

It grows during the winter months and melts during the summer months, but some sea ice remains all year in certain regions.

About 15 percent of the world's oceans are covered by sea ice during part of the year.

The freezing temperature of salt water is lower than fresh water; ocean temperatures must reach -1.8° C Celsius (28.8°F) to freeze. (Source: GreenFacts based on NSIDC All about sea ice )



A substance is soluble if it dissolves in certain fluids. The fluid [gas or liquid] (present in excess) is called the solvent and the substance dissolved in it is called the solute which together form a solution. The process of dissolving is called solvation. A solution that can not hold any more solute is said to be saturated. (Source: GreenFacts )

Storm surge

Storm surge is a rise in coastal water level caused by a regional low pressure area and water pushed toward coastal shores by prolonged wind forces.

A storm surge can significantly raise the mean water level if combined with astronomical high tides. This rise in water level can cause severe flooding on coastal areas, particularly along shallow slopes along the shoreline. (Source: British Columbia Flood Hazard Definitions   )



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. (Source: Climate Change Glossary)



Sulphate is a salt of sulphuric acid. It refers both to the SO42- anion and to any compound that contains this ion.



Compound combining sulphur with a valency of -2 (S-2) with a more electropositive element.

An example is hydrogen sulphide H2S, which is a toxic gas that smells like rotten eggs. (Source: GreenFacts )

Sulphur dioxide (SO2)

A corrosive gas produced by the burning of fuels, such as coal and oil, that contain sulphur. It is also produced from sea spray, organic decomposition and volcanic eruptions.

When combined with water in the air, it produces a weak, corrosive sulfuric acid - an ingredient of "acid rain". (Source: GreenFacts)

Surface water

Water on the surface of the Earth, such as in lakes, rivers, streams, ponds, and springs. (Source: ATSDR Glossary of Terms   )

The Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection

The Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP) is an advisory body, established in 1969, that advises the United Nations (UN) system on the scientific aspects of marine environmental protection.

At present GESAMP is jointly sponsored by nine UN organizations with responsibilities relating to the marine environment, and they utilize GESAMP as a mechanism for coordination and collaboration among them. GESAMP functions are to conduct and support marine environmental assessments, to undertake in-depth studies, analyses, and reviews of specific topics, and to identify emerging issues regarding the state of the marine environment. GESAMP itself today consists of 16 experts, drawn from a wide range of relevant disciplines, who act in an independent and individual capacity. Studies and assessments are usually carried out by dedicated working groups, most of whose members are not sitting members of GESAMP but part of the broader GESAMP network.


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Threshold (in an ecosystem)

The level of magnitude of a system process at which sudden or rapid change occurs. (Source: Glossary of terms  )



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 "weather" phenomena occur. In the troposphere temperatures generally decrease with height. (Source: GreenFacts)


United Nations

"The United Nations was established on 24 October 1945 by 51 countries committed to preserving peace through international cooperation and collective security. Today, nearly every nation in the world belongs to the UN: membership totals 191 countries*.

When States become Members of the United Nations, they agree to accept the obligations of the UN Charter, an international treaty that sets out basic principles of international relations. According to the Charter, the UN has four purposes: to maintain international peace and security; to develop friendly relations among nations; to cooperate in solving international problems and in promoting respect for human rights; and to be a centre for harmonizing the actions of nations." (Source: UN website )

United Nations Environment Programme

"The United Nations Environment Programme (UNEP), established in 1972, works to encourage sustainable development through sound environmental practices everywhere. Its activities cover (...) the promotion of environmental science and information, to an early warning and emergency response capacity to deal with environmental disasters and emergencies."

See also UNEP.Net , which "delivers authoritative environmental information from a broad range of information and data providers (...)". (Source: UNEP website )

US Environment Protection Agency

The Environment Protection Agency's of the USA was founded in 1970. It's "mission is to protect human health and to safeguard the natural environment — air, water, and land — upon which life depends."

The EPA enforces federal environmental protection laws. It registers and regulates pesticides, enforces laws covering outdoor air and drinking water quality and regulates the disposal of hazardous and solid wastes.

It has now grown into a big and powerful administration: "18,000 people in Headquarters program offices, 10 regional offices, and 17 labs across the country, EPA employs a highly educated, technically trained staff, more than half of whom are engineers, scientists, and environmental protection specialists. A large number of employees are legal, public affairs, financial, and computer specialists."

U.S. EPA's scientific publications are widely recognized as reference materials. (Source: US EPA website  )


Able to readily evaporate at normal temperatures and pressures. (Source: GreenFacts)

Vulnerability (in health science)

The likelihood of being unusually severely affected by a substance either as a result of susceptibility to the effects of these substances or as a result of a greater than average [exposure]. (Source: WHO Europe  Answers to follow-up questions from CAFE )

Water vapor

Water in its gaseous form.

In the atmosphere it acts as a natural greenhouse gas. (Source: GreenFacts)


World Wide Fund for Nature

The World Wide Fund for Nature (WWF) was founded in 1961 (formerly known as the World Wildlife Fund) and today is the world's largest conservation organization.

"WWF's mission is to stop the degradation of the planet's natural environment and to build a future in which humans live in harmony with nature, by:

  • conserving the world's biological diversity
  • .
  • resources is sustainable
  • promoting the reduction of pollution and wasteful consumption."

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