Absolute error

The absolute error of an observation x is the absolute deviation of x from its ―true value.

Absolute frequency

The absolute frequency of a variate, as distinct from the relative frequency, namely the ratio of the frequency to the total frequency of all variate values.


The number of individuals or related measure of quantity (such as biomass) in a population, community or spatial unit.

Acceptance rule

Logical or arithmetic condition applied to a data item or data group that must be met if the data are to be considered correct.


Accountability is the responsibility for the deterioration of the natural environment, implying the allocation of environmental costs to the economic activities that cause such deterioration.

Accounting standards

Accounting standards are methodologies and disclosure requirements for the preparation and presentation of financial statements.

Accrual rate

The rate at which pension benefits builds up as member service is completed in a defined benefit plan.

Acid deposition

Any form of deposition on water, land and other surfaces that increases their acidity by contamination with acid pollutants, such as sulphur oxides, sulphates, nitrogen oxides and nitrates, or ammonium compounds.


Change in environment’s natural chemical balance caused by an increase in the concentration of acidic elements.


A measure of how acid a solution may be. A solution with a pH of less than 7.0 is considered acidic.


The IPCC defines adaptation as “the process of adjustment to actual or expected climate and its effects”. It further states that “in human systems, adaptation seeks to moderate or avoid harm or exploit beneficial opportunities. In some natural systems, human intervention may facilitate adjustment to expected climate and its effects” (IPCC, AR V, WG 2, 2014). Adaptation is one of the two major policy responses to the issue of global environmental climate change, the other being mitigation (IPCC, AR V, WG 2,2014). 
Read More

Adaptive capacity

The potential or ability of a system, region or community to adapt to the effects or impacts of a particular set of changes.

Administrative data

Administrative data is the set of units and data derived from an administrative source.


A collection of airborne solid or liquid particles, with a typical size between 0.01 and 10 μm, that reside in the atmosphere for at least several hours.


Establishment of forest plantations on land that is not classified as forest.

Air pollution index

An air pollution index (API) is a quantitative measure that describes ambient air quality. The index is obtained by combining figures for various air pollutants into a single measurement.

Air quality standards

Air quality standards refer to levels of air pollutants prescribed by regulations that may not be exceeded during a specified time in a defined area.

Algal beds

Reef top surface feature dominated by algae cover, usually brown algae (such as Sargassum or Turbinaria).

Alien species (also non-native, non-indigenous, foreign, exotic)

Species introduced outside its normal distribution.


Measures the wind speed and transmits wind speed data to the controller


The farming of aquatic organisms in inland and coastal areas, involving intervention in the rearing process to enhance production and the individual or corporate ownership of the stock being cultivated.

Aquatic ecosystem

Basic ecological unit composed of living and non-living elements interacting in an aqueous milieu.


An underground geological formation or group of formations, containing usable amounts of groundwater that can supply wells and springs.

Arable land

Land under temporary crops (double-cropped areas are counted only once), temporary meadows for mowing or pasture, land under market and kitchen gardens, and land temporarily fallow (less than five years).

Archetype of vulnerability

A specific, representative pattern of the interactions between environmental change and human well-being.

Area sampling

A method of sampling when no complete frame of reference is available. The total area under investigation is divided into small sub-areas which are sampled at random or by some restricted random process.

Aridity index

The long-term mean of the ratio of mean annual precipitation to mean annual potential evapotranspiration in a given area.

Carbon budget

This term refers to three concepts in the literature: (1) an assessment of carbon cycle sources and sinks on a global level, through the synthesis of evidence for fossil-fuel and cement emissions, landuse change emissions, ocean and land CO2 sinks, and the resulting atmospheric CO2 growth rate. This Approval Session Glossary IPCC SR1.5 Do Not Cite, Quote or Distribute 1-8 Total pages: 55 is referred to as the global carbon budget; (2) the estimated cumulative amount of global carbon dioxide emissions that that is estimated to limit global surface temperature to a given level above a reference period, taking into account global surface temperature contributions of other GHGs and climate forcers; (3) the distribution of the carbon budget defined under (2) to the regional, national, or sub-national level based on considerations of equity, costs or efficiency.(IPCC, Sr 1.5,2018)
Read More

Carbon cycle

The term used to describe the flow of carbon (in various forms, e.g., as carbon dioxide (CO2), carbon in biomass, and carbon dissolved in the ocean as carbonate and bicarbonate) through the atmosphere, hydrosphere, terrestrial and marine biosphere and lithosphere. In this report, the reference unit for the global carbon cycle is GtCO2 or GtC (Gigatonne of carbon = 1 GtC = 1015 grams of carbon. This corresponds to 3.667 GtCO2). (IPCC, SR1.5,2018)
Read More

Carbon dioxide capture and storage (CCS)

A process in which a relatively pure stream of carbon dioxide (CO2) from industrial and energyrelated sources is separated (captured), conditioned, compressed and transported to a storage location for long-term isolation from the atmosphere. Sometimes referred to as Carbon Capture and Storage. See also Carbon dioxide capture and utilisation (CCU), Bioenergy with carbon dioxide capture and storage (BECCS), and Sequestration. ). (IPCC, SR1.5, 2018)
Read More

Carbon price

The IPCC defines  Cabon price asThe price for avoided or released carbon dioxide (CO2) or CO2-equivalent emissions. This may refer to the rate of a carbon tax, or the price of emission permits. In many models that are used to assess the economic costs of mitigation, carbon prices are used as a proxy to represent the level of effort in mitigation policies. (IPCC,SR1.5,2018)
Read More

Carbon sequestration

is the process involved in carbon capture and the long-term storage of atmospheric carbon dioxide or other forms of carbon to mitigate or defer global warming. This is one of the major strategies proposed in order to reduce atmospheric and marine accumulation of greenhouse gases, which are emitted as a result of  burning of fossil fuels. Carbon dioxide is generally naturally captured from the atmosphere through biological, chemical, and physical processes, however given the large quantities of CO2 released into the atmosphere due to fossil fuel burning, this process needs to be significantly enhanced in order to compensate for the additional emissions. In recent years, several artificial processes have been designed to produce similar effects. These include, but are not limited to large-scale, artificial capture and sequestration of industrially produced CO  using reservoirs, subsurface saline aquifers, aging oil fields, ocean water, or other carbon sinks.(Wikipedia)
Read More

Carbon sinks

Carbon sinks are natural or artificial reservoirs, which accumulate and store some carbon-containing chemical compound for an indefinite period of time. Carbon sinks perform this function of removal of atmospheric carbon dioxide (CO2) through a process referred to as carbon sequestration. Since the ratification of the Kyoto Protocol, public awareness around the importance of CO2 sinks has significantly increased. This has resulted in the promotion of their use as a form of carbon offset, necessary for mitigation of atmospheric carbon dioxide. Through the course of the past decade, several different strategies have been designed and promoted in order to enhance the process of carbon sequestration, and in the increase of numbers of carbon sinks across the world.(Wikipedia)
Read More


Chlorofluorocarbons or CHCs are often used in refrigeration, solvents, air conditioning, insulation, aerosol propellants and in packaging. Their utility emerges from the fact that they do not get destroyed in the lower atmosphere. Instead, CFCs drift into the upper atmosphere where, under suitable conditions, they break down ozone, thus resulting in depletion of the ozone layer which protects the earth from UV radiations of the sun. These greenhouse gases are covered under the 1987 Montreal Protocol. These gases have already been to a large extent, are also currently being replaced by other compounds. Some alternatives which have emerged in the past few decades have been hydrochlorofluorocarbons and hydrofluorocarbons. Both of these are greenhouse gases covered under the Kyoto Protocol (IPCC, ar5_wgII_spma)

Read More

Climate change

The IPCC defines Climate change as “change in the state of the climate that can be identified (e.g., by using statistical tests) by changes in the mean and/or the variability of its properties, and that persists for an extended period, typically decades or longer. Climate change may be due to natural internal processes or external forcings such as modulations of the solar cycles, volcanic eruptions, and persistent anthropogenic changes in the composition of the atmosphere or in land use. Note that the Framework Convention on Climate Change (UNFCCC), in its Article 1, defines climate change as: “a 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.” The UNFCCC thus makes a distinction between climate change attributable to human activities altering the atmospheric composition, and climate variability attributable to natural causes”.( IPCC,ARV,WG2,2014)
Read More

Climate justice

The IPCC defines Climate Justice that links development and human rights to achieve a human-centred approach to addressing climate change, safeguarding the rights of the most vulnerable people and sharing the burdens and benefits of climate change and its impacts equitably and fairly. This definitions builds upon the one used by the Mary Robinson Foundation - Climate Justice. (IPCC, SR 1.5,2018)
Read More

Climate model

The IPCC defines Climate model as 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 some of its known properties. The climate system can be represented by models of varying complexity; that is, for any one component or combination of components a spectrum or hierarchy of models can be identified, differing in such aspects as the number of spatial dimensions, the extent to which physical, chemical or biological processes are explicitly represented, or the level at which empirical parametrizations are involved. There is an evolution towards more complex models with interactive chemistry and biology. Climate models are applied as a research tool to study and simulate the climate and for operational purposes, including monthly, seasonal and interannual climate predictions.(IPCC,SR1.5,2018)
Read More

Climate resilience

Climate resilience refers to the capacity of socio-ecological systems to: (a) absorb external stress and to continue the maintenance of ecosystem functions despite those stresses. Such stresses are often imposed upon ecosystems as a result of changing climatic conditions; and (b) adapt, reorganize, and evolve into other desirable configurations which can enhance the overall sustainability of the entire ecosystem , thus resulting in better preparedness of the system for future impacts of climatic changes.(Wikipedia)
Read More

Climate system

The IPCC defines climate system is the highly complex system consisting of five major components: the atmosphere, the hydrosphere, the cryosphere, the lithosphere and the biosphere and the interactions between them. The climate system evolves in time under the influence of its own internal dynamics and because of external forcings such as volcanic eruptions, solar variations and anthropogenic forcings such as the changing composition of the atmosphere and land-use change. (IPCC, SR 1.5,2018)

Read More


The IPCC defines Deforestation as Conversion of forest to non-forest. For a discussion of the term forest and related terms such as afforestation, reforestation, and deforestation see the IPCC Report on Land Use, Land-Use Change and Forestry (IPCC, 2000). See also the Report on Definitions and Methodological Options to Inventory Emissions from Direct Human-induced Degradation of Forests and Devegetation of Other Vegetation Types (IPCC,ar4 2003).
Red More


The IPCC defines Desertification as Land degradation in arid, semi-arid, and dry sub-humid areas resulting from various factors, including climatic variations and human activities. Further, the United Nations Convention to Combat Desertification (UNCCD) defines land degradation as a reduction or loss in arid, semi-arid, and dry sub-humid areas of the biological or economic productivity and complexity of rainfed cropland, irrigated cropland, or range, pasture, forest and woodlands resulting from land uses or from a process or combination of processes, including those arising from human activities and habitation patterns, such as: (i) soil erosion caused by wind and/or water; (ii) deterioration of the physical, chemical, and biological or economic properties of soil; and (iii) long-term loss of natural vegetation(IPCC ar4, wg2)
Read More

Early warning systems (EWS)

The IPCC defines EWS as  The set of technical, financial and institutional capacities needed to generate and disseminate timely and meaningful warning information to enable individuals, communities and organizations threatened by a hazard to prepare to act promptly and appropriately to reduce the possibility of harm or loss. Dependent upon context, EWS may draw upon scientific and/or Indigenous knowledge. EWS are also considered for ecological applications e.g., conservation, where the organisation itself is not threatened by hazard but the ecosystem under conservation is (an example is coral bleaching alerts), in agriculture (for example, warnings of ground frost, hailstorms) and in fisheries (storm and tsunami warnings). This glossary entry builds from the definitions used in UNISDR (2009) andIPCC(2012a).(IPCC,Sr1.5,2018)
Read More


The IPCC defines Ecosystem as An ecosystem is a functional unit consisting of living organisms, their non-living environment and the interactions within and between them. The components included in a given ecosystem and its spatial boundaries depend on the purpose for which the ecosystem is defined: in some cases they are relatively sharp, while in others they are diffuse. Ecosystem boundaries can change over time. Ecosystems are nested within other ecosystems and their scale can range from very small to the entire biosphere. In the current era, most ecosystems either contain people as key organisms, or are influenced by the effects of human activities in their environment .(IPCC, SR 1.5,2018)

Read More

Energy efficiency

The IPCC defines Energy efficiency as the ratio of output or useful energy or energy services or other useful physical outputs obtained from a system, conversion process, transmission or storage activity to the input of energy (measured as kWh kWh-1, tonnes kWh-1 or any other physical measure of useful output like tonne-km transported). Energy efficiency is often described by energy intensity. In economics, energy intensity describes the  ratio of economic output to energy input. Most commonly energy efficiency is measured as input energy over a physical or economic unit, i.e. kWh USD-1 (energy intensity), kWh tonne-1. For buildings, it is often measured as kWh m-2, and for vehicles as km liter-1or liter km-1. Very often in policy "energy efficiency" is intended as the measures to reduce energy demand through technological options such as insulating buildings, more efficient appliances, efficient lighting, efficient vehicles, etc.( IPCC,Sr1.5,2018)
Read More

Global warming

The IPCC defines Global warming as  An increase in global mean surface temperature (GMST) averaged over a 30-year period, relative to 1850-1900 unless otherwise specified. For periods shorter than 30 years, global warming refers to the estimated average temperature over the 30 years centred on that shorter period, accounting for the impact of any temperature fluctuations or trend within those 30 years.(IPCC, SR 1.5,2018)
Read More

Greenhouse gas

The IPCC defines Greenhouse gas as 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 terrestrial radiation emitted by the earth's surface, the atmosphere itself, and by clouds. This property causes the greenhouse effect. Water vapour (H2O), carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4) Final Government Draft Glossary IPCC SR1.5 Do Not Cite, Quote or Distribute 1-27 Total pages: 55 and ozone (O3) are the primary GHGs in the earth's atmosphere. Moreover, there are a number of entirely human-made GHGs 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 GHGs sulphur hexafluoride (SF6), hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs). (IPCC, SR 1.5,2018)
Read More


The IPCC defines Halocarbons as A collective term for the group of partially halogenated organic species, which includes the chlorofluorocarbons (CFCs), hydro chlorofluorocarbons (HCFCs), ydrofluorocarbons (HFCs), halons, methyl chloride and methyl bromide. Many of the halocarbons have large Global Warming Potentials. The chlorine and bromine-containing halocarbons are also involved in the depletion of the ozone layer(IPCC, SR 1.5, 2018)

Read More


The IPCC defines Impacts as “Climate change refers to a change in the state of the climate that can be identified (e.g., by using statistical tests) by changes in the mean and/or the variability of its properties, and that persists for an extended period, typically decades or longer. Climate change may be due to natural internal processes or external forcings such as modulations of the solar cycles, volcanic eruptions, and persistent anthropogenic changes in the composition of the atmosphere or in land use. Note that the Framework Convention on Climate Change (UNFCCC), in its Article 1, defines climate change as: “a 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.” The UNFCCC thus makes a distinction between climate change attributable to human activities altering the atmospheric composition, and climate variability attributable to natural cause IPCC,ARV,WG2,2014)

Read More

Kyoto Protocol

The IPCC defines The Kyoto Protocol to the United Nations Framework Convention on Climate Change (UNFCCC) is an international treaty adopted in December 1997 in Kyoto, Japan, at the Third Session of the Conference of the Parties (COP3) to the UNFCCC. It contains legally binding commitments, in addition to those included in the UNFCCC. Countries included in Annex B of the Protocol (mostly OECD countries and countries with economies in transition) agreed to reduce their anthropogenic greenhouse gas (GHG) emissions (carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulphur hexafluoride (SF6)) by at least 5%  below 1990 levels in the first commitment period (2008-2012). The Kyoto Protocol entered into force on 16 February 2005 and as of May 2018 had 192 Parties (191 States and the European Union). A second commitment period was agreed in December 2012 at COP18, known as the Doha Amendment to the Kyoto Protocol, in which a new set of Parties committed to reduce GHG emissions by at least 18% below 1990 levels in the period from 2013 to 2020. However, as of May 2018, the Doha Amendment had not received sufficient ratifications to enter into force.(IPCC, SR 1.5)

Read More


The IPCC defines Impacts as “Technological change and changes in activities that reduce resource inputs and emissions per unit of output. Although several social, economic and technological policies would produce an emission reduction, with respect to climate change, mitigation means implementing policies to reduce greenhouse gas emissions and enhance sinks. Renewable energy deployment is a mitigation option when avoided greenhouse gas emissions exceed the sum of direct and indirect emissions”(IPCC,SRREN)
Read More

Net-zero emissions

The IPCC defines Net-zero emissions as  Net-zero emissions are achieved when emissions of greenhouse gases to the atmosphere are balanced by anthropogenic removals. Where multiple greenhouse gases are involved, the quantification of net-zero emissions depends on the climate metric chosen to compare emissions of different gases (such as Global warming potential, global temperature change potential, and others, as well as the chosen time horizon).(IPCC,Sr1.5,2018)
Read More

Ocean acidification

The IPCC defines Impacts as “Increased concentrations of CO2 in sea water causing a measurable increase in acidity (i.e., a reduction in ocean pH). This maylead to reduced calcification rates of calcifying organisms such as corals, molluscs, algae and crustacean”. Ocean acidification is the ongoing decrease in the pH of the Earth's oceans, caused by the uptake of carbon dioxide (CO2) from the atmosphere.[2] Seawater is slightly basic (meaning pH > 7), and ocean acidification involves a shift towards pH-neutral conditions rather than a transition to acidic conditions (pH < 7).[3] An estimated 30–40% of the carbon dioxide from human activity released into the atmosphere dissolves into oceans, rivers and lakes.[4][5] To achieve chemical equilibrium, some of it reacts with the water to form carbonic acid. Some of the resulting carbonic acid molecules dissociate into a bicarbonate ion and a hydrogen ion, thus increasing ocean acidity (H ion concentration). Between 1751 and 1996, surface ocean pH is estimated to have decreased from approximately 8.25 to 8.14,[6] representing an increase of almost 30% in H ion concentration in the world's oceans.[7][8] Earth System Models project that, within the last decade, ocean acidity exceeded historical analogues[9] and, in combination with other ocean biogeochemical changes, could undermine the functioning of marine ecosystems and disrupt the provision of many goods and services associated with the ocean beginning as early as 2100
(IPCC, ar4, wg2)

Read More


The IPCC defines Ozone, the triatomic form of oxygen (O3), is a gaseous atmospheric constituent. In the troposphere, it is created both naturally and by photochemical reactions involving gases resulting from human activities (smog). Tropospheric ozone acts as a greenhouse gas. In the stratosphere, it is created by the interaction between solar ultraviolet radiation and molecular oxygen (O2). Stratospheric ozone plays a dominant role in the stratospheric radiative balance. Its concentration is highest in the ozonelayer.(IPCC,Sr,1.5,2018)
Read More

Paris Agreement

The IPCC defines The Paris Agreement under the United Nations Framework Convention on Climate Change (UNFCCC) was adopted on December 2015 in Paris, France, at the 21st session of the Conference of the Parties (COP) to the UNFCCC. The agreement, adopted by 196 Parties to the UNFCCC, entered into force on 4 November 2016 and as of May 2018 had 195 Signatories and was ratified by 177 Parties. One of the goals of the Paris Agreement is “Holding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels”, recognising that this would significantly reduce the risks and impacts of climate change. Additionally, the Agreement aims to strengthen the ability of countries to deal with the impacts of climate change. The Paris Agreement is intended to become fully effective in 2020.(IPCC, Sr 1.5,2018)
Read More


The IPCC defines Impacts as The capacity of social, economic, and environmental systems to cope with a hazardous event or trend or disturbance, responding or reorganizing in ways that maintain their essential function, identity, and structure, while also maintaining the capacity for adaptation, learning, and transformation. (IPCC Ar5, Wg 2)

Read More

Sustainable Development Goals (SDGs)

The IPCC defines SDGs The 17 global goals for development for all countries established by the United Nations through a participatory process and elaborated in the 2030 Agenda for Sustainable Development, including ending poverty and hunger; ensuring health and wellbeing, education, gender equality, clean water and energy, and decent work; building and ensuring resilient and sustainable infrastructure, cities and consumption; reducing inequalities; protecting land and water ecosystems; promoting peace, justice and partnerships; and taking urgent action on climate change.(IPCC, Sr 1.5,2018)
Read More


The IPCC defines Vulnerability as The propensity or predisposition to be adversely affected. Vulnerability encompasses a variety of concepts and elements including sensitivity or susceptibility to harm and lack of capacity to cope and adapt. See also Contextual vulnerability and Outcome vulnerability. . (IPCC, Ar5, wg2)
Read More