1757

Glossary

Editorial Board Co-Chairs:

John Agard (Trinidad and Tobago), E. Lisa F. Schipper (Sweden)

Editorial Board:

Joern Birkmann (Germany), Maximiliano Campos (Costa Rica), Carolina Dubeux (Brazil),

Yukihiro Nojiri (Japan), Lennart Olsson (Sweden), Balgis Osman-Elasha (Sudan), Mark Pelling

(UK), Michael J. Prather (USA), Marta G. Rivera-Ferre (Spain), Oliver C. Ruppel (Namibia),

Asbury Sallenger (USA), Kirk R. Smith (USA), Asuncion L. St. Clair (Norway)

TSU Facilitation:

Katharine J. Mach (USA), Michael D. Mastrandrea (USA), T. Eren Bilir (USA)

ANNEX

1758

Annex II Glossary

brupt climate change

A large-scale change in the climate system that takes place over a few

decades or less, persists (or is anticipated to persist) for at least a few

decades, and causes substantial disruptions in human and natural systems.

Access to food

One of the three components underpinning food security, the other two

being availability and utilization. Access to food is dependent on (1) the

affordability of food (i.e., people have income or other resources to

exchange for food); (2) satisfactory allocation within the household or

society; and (3) preference (i.e., it is what people want to eat, influenced

by socio-cultural norms). See also Food security.

Acclimatization

A change in functional or morphological traits occurring once or repeatedly

(e.g., seasonally) during the lifetime of an individual organism in its

natural environment. Through acclimatization the individual maintains

performance across a range of environmental conditions. For a clear

differentiation between findings in laboratory and field studies, the term

acclimation is used in ecophysiology for the respective phenomena

when observed in well-defined experimental settings. The term

(adaptive) plasticity characterizes the generally limited scope of changes

in phenotype that an individual can reach through the process of

acclimatization.

Adaptability

See Adaptive capacity.

Adaptation

The process of adjustment to actual or expected climate and its effects.

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.

Incremental adaptation Adaptation actions where the central

aim is to maintain the essence and integrity of a system or process

at a given scale.

Transformational adaptation Adaptation that changes the

fundamental attributes of a system in response to climate and its

effects.

See also Autonomous adaptation, Evolutionary adaptation, and

Transformation.

Adaptation assessment

The practice of identifying options to adapt to climate change and

evaluating them in terms of criteria such as availability, benefits, costs,

effectiveness, efficiency, and feasibility.

Adaptation constraint

Factors that make it harder to plan and implement adaptation actions

or that restrict options.

daptation deficit

The gap between the current state of a system and a state that

minimizes adverse impacts from existing climate conditions and

variability.

Adaptation limit

The point at which an actor’s objectives (or system needs) cannot be

secured from intolerable risks through adaptive actions.

Hard adaptation limit No adaptive actions are possible to avoid

intolerable risks.

Soft adaptation limit Options are currently not available to avoid

intolerable risks through adaptive action.

Adaptation needs

The circumstances requiring action to ensure safety of populations and

security of assets in response to climate impacts.

Adaptation opportunity

Factors that make it easier to plan and implement adaptation actions,

that expand adaptation options, or that provide ancillary co-benefits.

Adaptation options

The array of strategies and measures that are available and appropriate

for addressing adaptation needs. They include a wide range of actions

that can be categorized as structural, institutional, or social.

Adaptive capacity

The ability of systems, institutions, humans, and other organisms to

adjust to potential damage, to take advantage of opportunities, or to

respond to consequences.

Adaptive management

A process of iteratively planning, implementing, and modifying strategies

for managing resources in the face of uncertainty and change. Adaptive

management involves adjusting approaches in response to observations

of their effect and changes in the system brought on by resulting

feedback effects and other variables.

Aggregate impacts

Total impacts integrated across sectors and/or regions. The aggregation

of impacts requires knowledge of (or assumptions about) the relative

importance of different impacts. Measures of aggregate impacts include,

for example, the total number of people affected, or the total economic

costs, and are usually bound by time, place, and/or sector.

Ancillary benefits

See Co-benefits.

Anomaly

The deviation of a variable from its value averaged over a reference

period.

Reflecting progress in science, this glossary entry differs in breadth and focus from the entry used in the Fourth Assessment Report and other IPCC reports.

This definition builds from the definition used in Park et al. (2012).

This glossary entry builds from definitions used in previous IPCC reports and the Millennium Ecosystem Assessment (MEA, 2005).

1759

Glossary Annex II

nthropogenic

Resulting from or produced by human activities.

Anthropogenic emissions

Emissions of greenhouse gases, greenhouse gas precursors, and

aerosols caused by human activities. These activities include the burning

of fossil fuels, deforestation, land use changes, livestock production,

fertilization, waste management, and industrial processes.

Arid zone

Areas where vegetation growth is severely constrained due to limited

water availability. For the most part, the native vegetation of arid zones

is sparse. There is high rainfall variability, with annual averages below

300 mm. Crop farming in arid zones requires irrigation.

Atlantic Multi-decadal Oscillation/Variability (AMO/AMV)

A multi-decadal (65- to 75-year) fluctuation in the North Atlantic, in

which sea surface temperatures showed warm phases during roughly

1860 to 1880 and 1930 to 1960 and cool phases during 1905 to 1925

and 1970 to 1990 with a range of approximately 0.4°C. See AMO Index

in WGI AR5 Box 2.5.

Atmosphere-Ocean General Circulation Model (AOGCM)

See Climate model.

Attribution

See Detection and attribution.

Autonomous adaptation

Adaptation in response to experienced climate and its effects, without

planning explicitly or consciously focused on addressing climate change.

Also referred to as spontaneous adaptation.

Baseline/reference

The baseline (or reference) is the state against which change is measured.

A baseline period is the period relative to which anomalies are computed.

The baseline concentration of a trace gas is that measured at a location

not influenced by local anthropogenic emissions.

Biodiversity

The variability among living organisms from terrestrial, marine, and

other ecosystems. Biodiversity includes variability at the genetic, species,

and ecosystem levels.

Bioenergy

Energy derived from any form of biomass such as recently living organisms

or their metabolic by-products.

Biofuel

A fuel, generally in liquid form, developed from organic matter or

combustible oils produced by living or recently living plants. Examples

of biofuel include alcohol (bioethanol), black liquor from the paper-

manufacturing process, and soybean oil.

irst-generation manufactured biofuel

irst-generation

manufactured biofuel is derived from grains, oilseeds, animal fats,

and waste vegetable oils with mature conversion technologies.

Second-generation biofuel Second-generation biofuel uses non-

traditional biochemical and thermochemical conversion processes

and feedstock mostly derived from the lignocellulosic fractions of,

for example, agricultural and forestry residues, municipal solid

waste, etc.

Third-generation biofuel Third-generation biofuel would be

derived from feedstocks such as algae and energy crops by

advanced processes still under development.

These second- and third-generation biofuels produced through new

processes are also referred to as next-generation or advanced biofuels,

or advanced biofuel technologies.

Biomass

The total mass of living organisms in a given area or volume; dead

plant material can be included as dead biomass. Biomass burning is the

burning of living and dead vegetation.

Biome

A biome is a major and distinct regional element of the biosphere,

typically consisting of several ecosystems (e.g., forests, rivers, ponds,

swamps within a region). Biomes are characterized by typical communities

of plants and animals.

Biosphere

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.

Boundary organization

A bridging institution, social arrangement, or network that acts as an

intermediary between science and policy.

Business As Usual (BAU)

Business as usual projections are based on the assumption that operating

practices and policies remain as they are at present. Although baseline

scenarios could incorporate some specific features of BAU scenarios

(e.g., a ban on a specific technology), BAU scenarios imply that no

practices or policies other than the current ones are in place. See also

Baseline/reference, Climate scenario, Emission scenario, Representative

Concentration Pathways, Scenario, Socioeconomic scenario, and SRES

scenarios.

Capacity building

The practice of enhancing the strengths and attributes of, and resources

available to, an individual, community, society, or organization to respond

to change.

This glossary entry builds from definitions used in the Global Biodiversity Assessment (Heywood, 1995) and the Millennium Ecosystem Assessment (MEA, 2005).

1760

Annex II Glossary

arbon cycle

The term used to describe the flow of carbon (in various forms, e.g., as

carbon dioxide) through the atmosphere, ocean, terrestrial and marine

biosphere, and lithosphere. In this report, the reference unit for the

global carbon cycle is GtC or equivalently PgC (10

g).

Carbon dioxide (CO

)

A naturally occurring gas, also a by-product of burning fossil fuels from

fossil carbon deposits, such as oil, gas, and coal, of burning biomass, of

land use changes, and of industrial processes (e.g., cement production).

It is the principal anthropogenic greenhouse gas that affects the Earth’s

radiative balance. It is the reference gas against which other greenhouse

gases are measured and therefore has a Global Warming Potential of 1.

Carbon dioxide (CO

) fertilization

The enhancement of the growth of plants as a result of increased

atmospheric carbon dioxide (CO

) concentration.

Carbon sequestration

See Uptake.

Clean Development Mechanism (CDM)

A mechanism defined under Article 12 of the Kyoto Protocol through

which investors (governments or companies) from developed (Annex

B) countries may finance greenhouse gas emission reduction or removal

projects in developing (Non-Annex B) countries, and receive Certified

Emission Reduction Units for doing so, which can be credited towards

the commitments of the respective developed countries. The CDM is

intended to facilitate the two objectives of promoting sustainable

development in developing countries and of helping industrialized

countries to reach their emissions commitments in a cost-effective way.

Climate

Climate in a narrow sense is usually defined as the average weather, 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 for averaging

these variables is 30 years, as defined by the World Meteorological

Organization. The 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.

Climate-altering pollutants (CAPs)

Gases and particles released from human activities that affect the

climate either directly, through mechanisms such as radiative forcing

from changes in greenhouse gas concentrations, or indirectly, by, for

example, affecting cloud formation or the lifetime of greenhouse gases

in the atmosphere. CAPs include both those pollutants that have a

warming effect on the atmosphere, such as CO

, and those with cooling

effects, such as sulfates.

Climate change

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

he 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. See also Climate change

commitment and Detection and Attribution.

Climate change commitment

Due to the thermal inertia of the ocean and slow processes in the

cryosphere and land surfaces, the climate would continue to change

even if the atmospheric composition were held fixed at today’s values.

Past change in atmospheric composition leads to a committed climate

change, which continues for as long as a radiative imbalance persists

and until all components of the climate system have adjusted to a new

state. The further change in temperature after the composition of the

atmosphere is held constant is referred to as the constant composition

temperature commitment or simply committed warming or warming

commitment. Climate change commitment includes other future

changes, for example, in the hydrological cycle, in extreme weather

events, in extreme climate events, and in sea level change. The constant

emission commitment is the committed climate change that would

result from keeping anthropogenic emissions constant and the zero

emission commitment is the climate change commitment when emissions

are set to zero. See also Climate change.

Climate extreme (Extreme weather or climate event)

See Extreme weather event.

Climate feedback

An interaction in which a perturbation in one climate quantity causes

a change in a second, and the change in the second quantity ultimately

leads to an additional change in the first. A negative feedback is one in

which the initial perturbation is weakened by the changes it causes; a

positive feedback is one in which the initial perturbation is enhanced.

In this Assessment Report, a somewhat narrower definition is often

used in which the climate quantity that is perturbed is the global mean

surface temperature, which in turn causes changes in the global

radiation budget. In either case, the initial perturbation can either be

externally forced or arise as part of internal variability.

Climate governance

Purposeful mechanisms and measures aimed at steering social systems

towards preventing, mitigating, or adapting to the risks posed by climate

change (Jagers and Stripple, 2003).

Climate model (spectrum or hierarchy)

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

1761

Glossary Annex II

spects as the number of spatial dimensions, the extent to which

physical, chemical, or biological processes are explicitly represented, or

the level at which empirical parameterizations are involved. Coupled

Atmosphere-Ocean General Circulation Models (AOGCMs) provide a

representation of the climate system that is near or at the most

comprehensive end of the spectrum currently available. 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. See also Earth System

Model.

Climate prediction

A climate prediction or climate forecast is the result of an attempt to

produce (starting from a particular state of the climate system) an

estimate of the actual evolution of the climate in the future, for example,

at seasonal, interannual, or decadal time scales. Because the future

evolution of the climate system may be highly sensitive to initial

conditions, such predictions are usually probabilistic in nature. See also

Climate projection, Climate scenario, and Predictability.

Climate projection

A climate projection is the simulated response of the climate system to

a scenario of future emission or concentration of greenhouse gases and

aerosols, generally derived using climate models. Climate projections

are distinguished from climate predictions by their dependence on the

emission/concentration/radiative-forcing scenario used, which is in turn

based on assumptions concerning, for example, future socioeconomic

and technological developments that may or may not be realized. See

also Climate scenario.

Climate-resilient pathways

Iterative processes for managing change within complex systems in

order to reduce disruptions and enhance opportunities associated with

climate change.

Climate scenario

A plausible and often simplified representation of the future climate,

based on an internally consistent set of climatological relationships that

has been constructed for explicit use in investigating the potential

consequences of anthropogenic climate change, often serving as input

to impact models. Climate projections often serve as the raw material

for constructing climate scenarios, but climate scenarios usually require

additional information such as the observed current climate. See also

Emission scenario and Scenario.

Climate sensitivity

In IPCC reports, equilibrium climate sensitivity (units: °C) refers to the

equilibrium (steady state) change in the annual global mean surface

temperature following a doubling of the atmospheric equivalent carbon

dioxide concentration. Owing to computational constraints, the

equilibrium climate sensitivity in a climate model is sometimes estimated

by running an atmospheric general circulation model coupled to a

mixed-layer ocean model, because equilibrium climate sensitivity is

largely determined by atmospheric processes. Efficient models can be run

to equilibrium with a dynamic ocean. The climate sensitivity parameter

(units: °C (W m

–2

)

–1

) refers to the equilibrium change in the annual

lobal mean surface temperature following a unit change in radiative

forcing.

The effective climate sensitivity (units: °C) is an estimate of the global

mean surface temperature response to doubled carbon dioxide

concentration that is evaluated from model output or observations for

evolving non-equilibrium conditions. It is a measure of the strengths of

the climate feedbacks at a particular time and may vary with forcing

history and climate state, and therefore may differ from equilibrium

climate sensitivity.

The transient climate response (units: °C) is the change in the global

mean surface temperature, averaged over a 20-year period, centered

at the time of atmospheric carbon dioxide doubling, in a climate model

simulation in which CO

increases at 1% yr

–1

. It is a measure of the

strength and rapidity of the surface temperature response to greenhouse

gas forcing.

Climate system

The 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 among 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.

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 spatial and temporal 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). See

also Climate change.

Climatevelocity

The speed at which isolines of a specifiedclimatevariable travel across

landscapes or seascapes due to changing climate. For example, climate

velocityfor temperature is the speed at which isotherms move due to

changingclimate(km yr

–1

) and is calculated as the temporal change

in temperature (°C yr

–1

) divided by the current spatial gradient in

temperature (°C km

–1

). It can be calculated using additionalclimate

variables such as precipitation or can be based on theclimaticniche of

organisms.

Climatic driver (Climate driver)

A changing aspect of the climate system that influences a component

of a human or natural system.

CMIP3 and CMIP5

Phases three and five of the Coupled Model Intercomparison Project

(CMIP3 and CMIP5), coordinating and archiving climate model

simulations based on shared model inputs by modeling groups from

around the world. The CMIP3 multi-model data set includes projections

using SRES scenarios. The CMIP5 data set includes projections using the

Representative Concentration Pathways.

1762

Annex II Glossary

oastal squeeze

A narrowing of coastal ecosystems and amenities (e.g., beaches, salt

marshes, mangroves, and mud and sand flats) confined between

landward-retreating shorelines (from sea level rise and/or erosion) and

naturally or artificially fixed shorelines including engineering defenses

(e.g., seawalls), potentially making the ecosystems or amenities vanish.

Co-benefits

The positive effects that a policy or measure aimed at one objective

might have on other objectives, irrespective of the net effect on overall

social welfare. Co-benefits are often subject to uncertainty and depend

on local circumstances and implementation practices, among other

factors. Co-benefits are also referred to as ancillary benefits.

Community-based adaptation

Local, community-driven adaptation. Community-based adaptation

focuses attention on empowering and promoting the adaptive capacity

of communities. It is an approach that takes context, culture, knowledge,

agency, and preferences of communities as strengths.

Confidence

The validity of a finding based on the type, amount, quality, and

consistency of evidence (e.g., mechanistic understanding, theory, data,

models, expert judgment) and on the degree of agreement. Confidence

is expressed qualitatively (Mastrandrea et al., 2010). See Box 1-1. See

also Uncertainty.

Contextual vulnerability (Starting-point vulnerability)

A present inability to cope with external pressures or changes, such as

changing climate conditions. Contextual vulnerability is a characteristic

of social and ecological systems generated by multiple factors and

processes (O’Brien et al., 2007).

Convection

Vertical motion driven by buoyancy forces arising from static instability,

usually caused by near-surface cooling or increases in salinity in the

case of the ocean and near-surface warming or cloud-top radiative

cooling in the case of the atmosphere. In the atmosphere, convection

gives rise to cumulus clouds and precipitation and is effective at both

scavenging and vertically transporting chemical species. In the ocean,

convection can carry surface waters to deep within the ocean.

Coping

The use of available skills, resources, and opportunities to address,

manage, and overcome adverse conditions, with the aim of achieving

basic functioning of people, institutions, organizations, and systems in

the short to medium term.

Coping capacity

The ability of people, institutions, organizations, and systems, using

available skills, values, beliefs, resources, and opportunities, to address,

manage, and overcome adverse conditions in the short to medium

term.

oral bleaching

Loss of coral pigmentation through the loss of intracellular symbiotic

algae (known as zooxanthellae) and/or loss of their pigments.

Cryosphere

All regions on and beneath the surface of the Earth and ocean

where water is in solid form, including sea ice, lake ice, river ice, snow

cover, glaciers and ice sheets, and frozen ground (which includes

permafrost).

Cultural impacts

Impacts on material and ecological aspects of culture and the lived

experience of culture, including dimensions such as identity, community

cohesion and belonging, sense of place, worldview, values, perceptions,

and tradition. Cultural impacts are closely related to ecological impacts,

especially for iconic and representational dimensions of species and

landscapes. Culture and cultural practices frame the importance and

value of the impacts of change, shape the feasibility and acceptability

of adaptation options, and provide the skills and practices that enable

adaptation.

Dead zones

Extremely hypoxic (i.e., low-oxygen) areas in oceans and lakes, caused

by excessive nutrient input from human activities coupled with other

factors that deplete the oxygen required to support many marine

organisms in bottom and near-bottom water. See also Eutrophication

and Hypoxic events.

Decarbonization

The process by which countries or other entities aim to achieve a low-

carbon economy, or by which individuals aim to reduce their consumption

of carbon.

Deforestation

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 Special 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, 2003).

Desertification

Land degradation in arid, semi-arid, and dry sub-humid areas resulting

from various factors, including climatic variations and human activities.

Land degradation in arid, semi-arid, and dry sub-humid areas is reduction

or loss 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 processes arising from human activities and

habitation patterns, such as (1) soil erosion caused by wind and/or

water; (2) deterioration of the physical, chemical, biological, or economic

properties of soil; and (3) long-term loss of natural vegetation (UNCCD,

1994).

This glossary entry builds from the definition used in UNISDR (2009) and IPCC (2012a).

1763

Glossary Annex II

etection and attribution

Detection of change is defined as the process of demonstrating that

climate or a system affected by climate has changed in some defined

statistical sense, without providing a reason for that change. An identified

change is detected in observations if its likelihood of occurrence by

chance due to internal variability alone is determined to be small, for

example, <10%. Attribution is defined as the process of evaluating the

relative contributions of multiple causal factors to a change or event

with an assignment of statistical confidence (Hegerl et al., 2010).

Detection of impacts of climate change

For a natural, human, or managed system, identification of a change

from a specified baseline. The baseline characterizes behavior in the

absence of climate change and may be stationary or non-stationary

(e.g., due to land use change).

Disadvantaged populations

Sectors of a society that are marginalized, often because of low

socioeconomic status, low income, lack of access to basic services such

as health or education, lack of power, race, gender, religion, or poor

access to communication technologies.

Disaster

Severe alterations in the normal functioning of a community or a society

due to hazardous physical events interacting with vulnerable social

conditions, leading to widespread adverse human, material, economic,

or environmental effects that require immediate emergency response

to satisfy critical human needs and that may require external support

for recovery.

Disaster management

Social processes for designing, implementing, and evaluating strategies,

policies, and measures thatpromote and improve disaster preparedness,

response, and recovery practices at different organizationaland societal

levels.

Disaster risk

The likelihood within a specific time period of disaster. See Disaster.

Disaster Risk Management (DRM)

Processes for designing, implementing, and evaluating strategies,

policies, and measures to improve theunderstanding of disaster risk,

foster disaster risk reduction andtransfer, and promote continuous

improvement in disaster preparedness, response, and recovery practices,

with the explicit purpose of increasing human security, well-being,

quality of life,andsustainable development.

Disaster Risk Reduction (DRR)

Denotes both a policy goal or objective, and the strategic and instrumental

measures employed for anticipating future disaster risk; reducing existing

exposure, hazard, or vulnerability; and improving resilience.

Discounting

A mathematical operation making monetary (or other) amounts received

or expended at different times (years) comparable across time. The

iscounter uses a fixed or possibly time-varying discount rate (>0) from

year to year that makes future value worth less today.

Disturbance regime

Frequency, intensity, and types of disturbances of ecological systems,

such as fires, insect or pest outbreaks, floods, and droughts.

Diurnal temperature range

The difference between the maximum and minimum temperature

during a 24-hour period.

Downscaling

Downscaling is a method that derives local- to regional-scale (10 to

100 km) information from larger-scale models or data analyses. Two

main methods exist: dynamical downscaling and empirical/statistical

downscaling. The dynamical method uses the output of regional climate

models, global models with variable spatial resolution, or high-resolution

global models. The empirical/statistical methods develop statistical

relationships that link the large-scale atmospheric variables with local/

regional climate variables. In all cases, the quality of the driving model

remains an important limitation on quality of the downscaled information.

Drought

A period of abnormally dry weather long enough to cause a serious

hydrological imbalance. Drought is a relative term; therefore any

discussion in terms of precipitation deficit must refer to the particular

precipitation-related activity that is under discussion. For example,

shortage of precipitation during the growing season impinges on crop

production or ecosystem function in general (due to soil moisture

drought, also termed agricultural drought), and during the runoff and

percolation season primarily affects water supplies (hydrological drought).

Storage changes in soil moisture and groundwater are also affected

by increases in actual evapotranspiration in addition to reductions in

precipitation. A period with an abnormal precipitation deficit is defined

as a meteorological drought. A megadrought is a very lengthy and

pervasive drought, lasting much longer than normal, usually a decade

or more. For the corresponding indices, see WGI AR5 Box 2.4.

Dynamic Global Vegetation Model (DGVM)

A model that simulates vegetation development and dynamics through

space and time, as driven by climate and other environmental changes.

Early warning system

The set of 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.

Earth System Model (ESM)

A coupled atmosphere-ocean general circulation model in which a

representation of the carbon cycle is included, allowing for interactive

calculation of atmospheric CO

or compatible emissions. Additional

components (e.g., atmospheric chemistry, ice sheets, dynamic vegetation,

nitrogen cycle, but also urban or crop models) may be included. See

also Climate model.

This glossary entry builds from the definition used in UNISDR (2009) and IPCC (2012a).

1764

Annex II Glossary

cophysiological process

Processes in which individual organisms respond continuously to

environmental variability or change, such as climate change, generally

at a microscopic or sub-organ scale. Ecophysiological mechanisms

underpin individual organisms’ tolerance to environmental stress, and

comprise a broad range of responses defining the absolute tolerances

by individuals of environmental conditions. Ecophysiological responses

may scale up to control species’ geographic ranges.

Ecosystem

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.

Ecosystem approach

A strategy for the integrated management of land, water, and living

resources that promotes conservation and sustainable use in an equitable

way. An ecosystem approach is based on the application of scientific

methodologies focused on levels of biological organization, which

encompass the essential structure, processes, functions, and interactions

of organisms and their environment. It recognizes that humans, with

their cultural diversity, are an integral component of many ecosystems.

The ecosystem approach requires adaptive management to deal with

the complex and dynamic nature of ecosystems and the absence of

complete knowledge or understanding of their functioning. Priority

targets are conservation of biodiversity and of the ecosystem structure

and functioning, in order to maintain ecosystem services.

Ecosystem-based adaptation

The use of biodiversity and ecosystem services as part of an overall

adaptation strategy to help people to adapt to the adverse effects of

climate change. Ecosystem-based adaptation uses the range of

opportunities for the sustainable management, conservation, and

restoration of ecosystems to provide services that enable people to

adapt to the impacts of climate change. It aims to maintain and increase

the resilience and reduce the vulnerability of ecosystems and people in

the face of the adverse effects of climate change. Ecosystem-based

adaptation is most appropriately integrated into broader adaptation

and development strategies(CBD, 2009).

Ecosystem services

Ecological processes or functions having monetary or non-monetary

value to individuals or society at large. These are frequently classified as

(1) supporting services such as productivity or biodiversity maintenance,

(2) provisioning services such as food, fiber, or fish, (3) regulating services

such as climate regulation or carbon sequestration, and (4) cultural

services such as tourism or spiritual and aesthetic appreciation.

l Niño-Southern Oscillation (ENSO)

The term El Niño was initially used to describe a warm-water current

that periodically flows along the coast of Ecuador and Peru, disrupting

the local fishery. It has since become identified with a basin-wide

warming of the tropical Pacific Ocean east of the dateline. This oceanic

event is associated with a fluctuation of a global-scale tropical and

subtropical surface pressure pattern called the Southern Oscillation. This

coupled atmosphere-ocean phenomenon, with preferred time scales of

2 to about 7 years, is known as the El Niño-Southern Oscillation (ENSO).

It is often measured by the surface pressure anomaly difference between

Tahiti and Darwin or the sea surface temperatures in the central and

eastern equatorial Pacific. During an ENSO event, the prevailing trade

winds weaken, reducing upwelling and altering ocean currents such that

the sea surface temperatures warm, further weakening the trade winds.

This event has a great impact on the wind, sea surface temperature,

and precipitation patterns in the tropical Pacific. It has climatic effects

throughout the Pacific region and in many other parts of the world,

through global teleconnections. The cold phase of ENSO is called La

Niña. For the corresponding indices, see WGI AR5 Box 2.5.

Emergent risk

A risk that arises from the interaction of phenomena in a complex

system, for example, the risk caused when geographic shifts in human

populationin response to climate change lead to increased vulnerability

and exposure of populations in the receiving region.

Emission scenario

A plausible representation of the future development of emissions of

substances that are potentially radiatively active (e.g., greenhouse

gases, aerosols) based on a coherent and internally consistent set

of assumptions about driving forces (such as demographic and

socioeconomic development, technological change) and their key

relationships. Concentration scenarios, derived from emission scenarios,

are used as input to a climate model to compute climate projections. In

IPCC (1992) a set of emission scenarios was presented, which were used

as a basis for the climate projections in IPCC (1996). These emission

scenarios are referred to as the IS92 scenarios. In the IPCC Special

Report on Emissions Scenarios (Nakićenović and Swart, 2000) emission

scenarios, the so-called SRES scenarios, were published, some of which

were used, among others, as a basis for the climate projections

presented in Chapters 9 to 11 of IPCC (2001) and Chapters 10 and 11

of IPCC (2007). New emission scenarios for climate change, the four

Representative Concentration Pathways, were developed for, but

independently of, the present IPCC assessment. See also Climate

scenario and Scenario.

Ensemble

A collection of model simulations characterizing a climate prediction or

projection. Differences in initial conditions and model formulation result

in different evolutions of the modeled system and may give information

on uncertainty associated with model error and error in initial conditions

in the case of climate forecasts and on uncertainty associated with

model error and with internally generated climate variability in the case

of climate projections.

This glossary entry builds from definitions used in CBD (2000), MEA (2005), and the Fourth Assessment Report.

1765

Glossary Annex II

nvironmental migration

Human migration involves movement over a significant distance and

duration. Environmental migration refers to human migration where

environmental risks or environmental change plays a significant role in

influencing the migration decision and destination. Migration may

involve distinct categories such as direct, involuntary, and temporary

displacement due to weather-related disasters; voluntary relocation as

settlements and economies become less viable; or planned resettlement

encouraged by government actions or incentives.All migration decisions

are multi-causal, and hence it is not meaningful to describe any migrant

flow as being solely for environmental reasons.

Environmental services

See Ecosystem services.

Eutrophication

Over-enrichment of water by nutrients such as nitrogen and phosphorus.

It is one of the leading causes of water quality impairment. The two most

acute symptoms of eutrophication are hypoxia (or oxygen depletion)

and harmful algal blooms. See also Dead zones.

Evolutionary adaptation

For a population or species, change in functional characteristics as a result

of selection acting on heritable traits. The rate of evolutionary adaptation

depends on factors such as strength of selection, generation turnover time,

and degree of outcrossing (as opposed to inbreeding). See also Adaptation.

Exposure

The presence of people, livelihoods, species or ecosystems, environmental

functions, services, and resources, infrastructure, or economic, social, or

cultural assets in places and settings that could be adversely affected.

External forcing

External forcing refers to a forcing agent outside the climate system

causing a change in the climate system. Volcanic eruptions, solar variations,

and anthropogenic changes in the composition of the atmosphere and

land use change are external forcings. Orbital forcing is also an external

forcing as the insolation changes with orbital parameters eccentricity,

tilt, and precession of the equinox.

Externalities/external costs/external benefits

Externalities arise from a human activity when agents responsible for

the activity do not take full account of the activity’s impacts on others’

production and consumption possibilities, and no compensation exists

for such impacts. When the impacts are negative, they are external costs.

When the impacts are positive, they are external benefits.

Extratropical cyclone

A large-scale (of order 1000 km) storm in the middle or high latitudes

having low central pressure and fronts with strong horizontal gradients

in temperature and humidity. A major cause of extreme wind speeds

and heavy precipitation especially in wintertime.

Extreme climate event

See Extreme weather event.

xtreme sea level

See Storm surge.

Extreme weather event

An extreme weather event is an event that is rare at a particular place

and time of year. Definitions of rare vary, but an extreme weather event

would normally be as rare as or rarer than the 10th or 90th percentile

of a probability density function estimated from observations. By

definition, the characteristics of what is called extreme weather may vary

from place to place in an absolute sense. When a pattern of extreme

weather persists for some time, such as a season, it may be classed as

an extreme climate event, especially if it yields an average or total that

is itself extreme (e.g., drought or heavy rainfall over a season).

Famine

Scarcity of food over an extended period and over a large geographical

area, such as a country, or lack of access to food for socioeconomic,

political, or cultural reasons. Famines may be caused by climate-related

extreme events such as droughts or floods and by disease, war, or other

factors.

Feedback

See Climate feedback.

Fire weather

Weather conditions conducive to triggering and sustaining wild fires,

usually based on a set of indicators and combinations of indicators

including temperature, soil moisture, humidity, and wind. Fire weather

does not include the presence or absence of fuel load.

Fitness (Darwinian)

Fitness is the relative capacity of an individual or genotype to both

survive and reproduce, quantified as the average contribution of the

genotype to the gene pool of the next generations. During evolution,

natural selection favors functions providing greater fitness such that

the functions become more common over generations.

Flood

The overflowing of the normal confines of a stream or other body of

water, or the accumulation of water over areas not normally submerged.

Floods include river (fluvial) floods, flash floods, urban floods, pluvial

floods, sewer floods, coastal floods, and glacial lake outburst floods.

Food security

A state that prevails when people have secure access to sufficient

amounts of safe and nutritious food for normal growth, development,

and an active and healthy life.

See also Predictability.

North Atlantic Oscillation (NAO)

The North Atlantic Oscillation consists of opposing variations of surface

pressure near Iceland and near the Azores. It therefore corresponds to

fluctuations in the strength of the main westerly winds across the Atlantic

into Europe, and thus to fluctuations in the embedded extratropical

cyclones with their associated frontal systems. See NAO Index in WGI

AR5 Box 2.5.

Ocean acidification

Ocean acidification refers to a reduction in the pH of the ocean over an

extended period, typically decades or longer, which is caused primarily

by uptake of carbon dioxide from the atmosphere, but can also be

caused by other chemical additions or subtractions from the ocean.

Anthropogenic ocean acidification refers to the component of pH

reduction that is caused by human activity (IPCC, 2011, p. 37).

Opportunity costs

The benefits of an activity forgone through the choice of another

activity.

Outcome vulnerability (End-point vulnerability)

Vulnerability as the end point of a sequence of analyses beginning with

projections of future emission trends, moving on to the development of

climate scenarios, and concluding with biophysical impact studies and

the identification of adaptive options. Any residual consequences that

remain after adaptation has taken place define the levels of vulnerability

(Kelly and Adger, 2000; O’Brien et al., 2007).

Oxygen Minimum Zone (OMZ)

The midwater layer (200 to 1000 m) in the open ocean in which oxygen

saturation is the lowest in the ocean. The degree of oxygen depletion

depends on the largely bacterial consumption of organic matter, and the

distribution of the OMZs is influenced by large-scale ocean circulation.

In coastal oceans, OMZs extend to the shelves and may also affect

benthic ecosystems.

1770

Annex II Glossary

zone

Ozone, the triatomic form of oxygen (O

), 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 (O

). Stratospheric ozone plays a dominant role in the

stratospheric radiative balance. Its concentration is highest in the ozone

layer.

Pacific Decadal Oscillation (PDO)

The pattern and time series of the first empirical orthogonal function

of sea surface temperature over the North Pacific north of 20°N. The

PDO broadened to cover the whole Pacific Basin is known as the Inter-

decadal Pacific Oscillation (IPO). The PDO and IPO exhibit similar

temporal evolution.

Parameterization

In climate models, this term refers to the technique of representing

processes that cannot be explicitly resolved at the spatial or temporal

resolution of the model (sub-grid scale processes) by relationships

between model-resolved larger-scale variables and the area- or time-

averaged effect of such sub-grid scale processes.

Particulates

Very small solid particles emitted during the combustion of fossil and

biomass fuels. Particulates may consist of a wide variety of substances.

Of greatest concern for health are particulates of diameter less than or

equal to 10 nm, usually designated as PM

Pastoralism

A livelihood strategy based on moving livestock to seasonal pastures

primarily in order to convert grasses, forbs, tree leaves, or crop residues

into human food. The search for feed is however not the only reason

for mobility; people and livestock may move to avoid various natural

and/or social hazards, to avoid competition with others, or to seek more

favorable conditions. Pastoralism can also be thought of as a strategy

that is shaped by both social and ecological factors concerning

uncertainty and variability of precipitation, and low and unpredictable

productivity of terrestrial ecosystems.

Path dependence

The generic situation where decisions, events, or outcomes at one point

in time constrain adaptation, mitigation, or other actions or options at

a later point in time.

Permafrost

Ground (soil or rock and included ice and organic material) that remains

at or below 0°C for at least 2 consecutive years.

Persistent Organic Pollutants (POPs)

Toxic organic chemical substances that persist in the environment for

long periods of time, are transported and deposited in locations distant

from their sources of release, bioaccumulate, and can have adverse

effects on human health and ecosystems.

henology

The relationship between biological phenomena that recur periodically

(e.g., development stages, migration) and climate and seasonal changes.

Photochemical smog

A mix of oxidizing air pollutants produced by the reaction of sunlight

with primary air pollutants, especially hydrocarbons.

Poverty

Poverty is a complex concept with several definitions stemming from

different schools of thought. It can refer to material circumstances (such

as need, pattern of deprivation, or limited resources), economic conditions

(such as standard of living, inequality, or economic position), and/or

social relationships (such as social class, dependency, exclusion, lack of

basic security, or lack of entitlement).

Poverty trap

Poverty trap is understood differently across disciplines. In the social

sciences, the concept, primarily employed at the individual, household,

or community level, describes a situation in which escaping poverty

becomes impossible due to unproductive or inflexible resources. A

poverty trap can also be seen as a critical minimum asset threshold,

below which families are unable to successfully educate their children,

build up their productive assets, and get out of poverty. Extreme poverty

is itself a poverty trap, since poor persons lack the means to participate

meaningfully in society. In economics, the term poverty trap is often

used at national scales, referring to a self-perpetuating condition

where an economy, caught in a vicious cycle, suffers from persistent

underdevelopment (Matsuyama, 2008). Many proposed models of

poverty traps are found in the literature.

Predictability

The extent to which future states of a system may be predicted based on

knowledge of current and past states of the system. Because knowledge

of the climate system’s past and current states is generally imperfect,

as are the models that utilize this knowledge to produce a climate

prediction, and because the climate system is inherently nonlinear and

chaotic, predictability of the climate system is inherently limited. Even

with arbitrarily accurate models and observations, there may still be

limits to the predictability of such a nonlinear system (AMS, 2000).

Preindustrial

See Industrial Revolution.

Probability Density Function (PDF)

A probability density function is a function that indicates the relative

chances of occurrence of different outcomes of a variable. The function

integrates to unity over the domain for which it is defined and has the

property that the integral over a sub-domain equals the probability that

the outcome of the variable lies within that sub-domain. For example,

the probability that a temperature anomaly defined in a particular way

is greater than zero is obtained from its PDF by integrating the PDF over

all possible temperature anomalies greater than zero. Probability density

functions that describe two or more variables simultaneously are

similarly defined.

This glossary entry builds from the definition in the Stockholm Convention on Persistent Organic Pollutants (Secretariat of the Stockholm Convention, 2001).

1771

Glossary Annex II

rojection

A projection is a potential future evolution of a quantity or set of

quantities, often computed with the aid of a model. Unlike predictions,

projections are conditional on assumptions concerning, for example,

future socioeconomic and technological developments that may or may

not be realized. See also Climate prediction and Climate projection.

Proxy

A proxy climate indicator is a record that is interpreted, using physical

and biophysical principles, to represent some combination of climate-

related variations back in time. Climate-related data derived in this way

are referred to as proxy data. Examples of proxies include pollen analysis,

tree ring records, speleothems, characteristics of corals, and various data

derived from marine sediments and ice cores. Proxy data can be calibrated

to provide quantitative climate information.

Public good

A good that is both non-excludable and non-rivalrous in that individuals

cannot be effectively excluded from use and where use by one individual

does not reduce availability to others.

Radiative forcing

Radiative forcing is the change in the net, downward minus upward,

radiative flux (expressed in W m

–

) at the tropopause or top of atmosphere

due to a change in an external driver of climate change, such as a

change in the concentration of carbon dioxide or the output of the Sun.

Sometimes internal drivers are still treated as forcings even though they

result from the alteration in climate, for example aerosol or greenhouse

gas changes in paleoclimates. The traditional radiative forcing is computed

with all tropospheric properties held fixed at their unperturbed values,

and after allowing for stratospheric temperatures, if perturbed, to

readjust to radiative-dynamical equilibrium. Radiative forcing is called

instantaneous if no change in stratospheric temperature is accounted

for. The radiative forcing once rapid adjustments are accounted for is

termed the effective radiative forcing. For the purposes of this report,

radiative forcing is further defined as the change relative to the year

1750 and, unless otherwise noted, refers to a global and annual average

value. Radiative forcing is not to be confused with cloud radiative forcing,

which describes an unrelated measure of the impact of clouds on the

radiative flux at the top of the atmosphere.

Reanalysis

Reanalyses are estimates of historical atmospheric temperature and

wind or oceanographic temperature and current, and other quantities,

created by processing past meteorological or oceanographic data using

fixed state-of-the-art weather forecasting or ocean circulation models

with data assimilation techniques. Using fixed data assimilation avoids

effects from the changing analysis system that occur in operational

analyses. Although continuity is improved, global reanalyses still suffer

from changing coverage and biases in the observing systems.

Reasons for concern

Elements of a classification framework, first developed in the IPCC Third

Assessment Report, which aims to facilitate judgments about what level

of climate change may be “dangerous” (in the language of Article 2 of

the UNFCCC) by aggregating impacts, risks, and vulnerabilities.

eference scenario

See Baseline/reference.

Reflexivity

A system attribute where cause and effect form a feedback loop, in

which the effect changes the system itself. Self-adapting systems such

as societies are inherently reflexive, as are planned changes in complex

systems. Reflexive decision making in a social system has the potential

to change the underpinning values that led to those decisions. Reflexivity

is also an important aspect of adaptive management.

Reforestation

Planting of forests on lands that have previously contained forests but

that have been converted to some other use. For a discussion of the

term forest and related terms such as afforestation, reforestation, and

deforestation, see the IPCC Special 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, 2003).

Relative sea level

Sea level measured by a tide gauge with respect to the land upon which

it is situated. See also Mean sea level and Sea level change.

Representative Concentration Pathways (RCPs)

Scenarios that include time series of emissions and concentrations of

the full suite of greenhouse gases and aerosols and chemically active

gases, as well as land use/land cover (Moss et al., 2008). The word

representative signifies that each RCP provides only one of many

possible scenarios that would lead to the specific radiative forcing

characteristics. The term pathway emphasizes that not only the long-

term concentration levels are of interest, but also the trajectory taken

over time to reach that outcome (Moss et al., 2010).

RCPs usually refer to the portion of the concentration pathway extending

up to 2100, for which Integrated Assessment Models produced

corresponding emission scenarios. Extended Concentration Pathways

(ECPs) describe extensions of the RCPs from 2100 to 2500 that were

calculated using simple rules generated by stakeholder consultations,

and do not represent fully consistent scenarios.

Four RCPs produced from Integrated Assessment Models were selected

from the published literature and are used in the present IPCC Assessment

as a basis for the climate predictions and projections in WGI AR5 Chapters

11 to 14:

RCP2.6 One pathway where radiative forcing peaks at approximately

3 W m

–2

before 2100 and then declines (the corresponding ECP

assuming constant emissions after 2100).

RCP4.5 and RCP6.0 Two intermediate stabilization pathways in

which radiative forcing is stabilized at approximately 4.5 W m

–2

and

6.0 W m

–2

after 2100 (the corresponding ECPs assuming constant

concentrations after 2150).

1772

Annex II Glossary

CP8.5

ne high pathway for which radiative forcing reaches

greater than 8.5 W m

–

by 2100 and continues to rise for some

amount of time (the corresponding ECP assuming constant emissions

after 2100 and constant concentrations after 2250).

For further description of future scenarios, see WGI AR5 Box 1.1.

Resilience

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.

Return period

An estimate of the average time interval between occurrences of an

event (e.g., flood or extreme rainfall) of (or below/above) a defined size

or intensity. See also Return value.

Return value

The highest (or, alternatively, lowest) value of a given variable, on

average occurring once in a given period of time (e.g., in 10 years). See

also Return period.

Risk

The potential for consequences where something of value is at stake and

where the outcome is uncertain, recognizing the diversity of values.

Risk is often represented as probability of occurrence of hazardous

events or trends multiplied by the impacts if these events or trends

occur. Risk results from the interaction of vulnerability, exposure, and

hazard. In this report, the term risk is used primarily to refer to the risks

of climate-change impacts.

Risk assessment

The qualitative and/or quantitative scientific estimation of risks.

Risk management

Plans, actions, or policies to reduce the likelihood and/or consequences

of risks or to respond to consequences.

Risk perception

The subjective judgment that people make about the characteristics and

severity of arisk.

Risk transfer

The practice of formally or informally shifting the risk of financial

consequences for particular negative events from one party to

another.

Runoff

That part of precipitation that does not evaporate and is not transpired,

but flows through the ground or over the ground surface and returns

to bodies of water. See also Hydrological cycle.

alt-water intrusion/encroachment

Displacement of fresh surface water or groundwater by the advance of

salt water due to its greater density. This usually occurs in coastal and

estuarine areas due to decreasing land-based influence (e.g., from

reduced runoff or groundwater recharge, or from excessive water

withdrawals from aquifers) or increasing marine influence (e.g., relative

sea level rise).

Scenario

A plausible 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 technological change, prices) and relationships. Note

that scenarios are neither predictions nor forecasts, but are useful to

provide a view of the implications of developments and actions. See

also Climate scenario, Emission scenario, Representative Concentration

Pathways, and SRES scenarios.

Sea level change

Sea level can change, both globally and locally due to (1) changes in

the shape of the ocean basins, (2) a change in ocean volume as a result

of a change in the mass of water in the ocean, and (3) changes in ocean

volume as a result of changes in ocean water density. Global mean sea

level change resulting from change in the mass of the ocean is called

barystatic. The amount of barystatic sea level change due to the addition

or removal of a mass of water is called its sea level equivalent (SLE).

Sea level changes, both globally and locally, resulting from changes in

water density are called steric. Density changes induced by temperature

changes only are called thermosteric, while density changes induced by

salinity changes are called halosteric. Barystatic and steric sea level

changes do not include the effect of changes in the shape of ocean

basins induced by the change in the ocean mass and its distribution.

See also Relative sea level and Thermal expansion.

Sea Surface Temperature (SST)

The sea surface temperature is the subsurface bulk temperature in the

top few meters of the ocean, measured by ships, buoys, and drifters.

From ships, measurements of water samples in buckets were mostly

switched in the 1940s to samples from engine intake water. Satellite

measurements of skin temperature (uppermost layer; a fraction of a

millimeter thick) in the infrared or the top centimeter or so in the

microwave are also used, but must be adjusted to be compatible with

the bulk temperature.

Semi-arid zone

Areas where vegetation growth is constrained by limited water availability,

often with short growing seasons and high interannual variation in

primary production. Annual precipitation ranges from 300 to 800 mm,

depending on the occurrence of summer and winter rains.

Sensitivity

The degree to which a system or species is affected, either adversely or

beneficially, by climate variability or change. The effect may be direct

(e.g., a change in crop yield in response to a change in the mean, range,

This definition builds from the definition used in Arctic Council (2013).

This definition builds from the definitions used in Rosa (1998) and Rosa (2003).

1773

Glossary Annex II

r variability of temperature) or indirect (e.g., damages caused by an

increase in the frequency of coastal flooding due to sea level rise).

Significant wave height

The average trough-to-crest height of the highest one-third of the wave

heights (sea and swell) occurring in a particular time period.

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.

Social Cost of Carbon (SCC)

The net present value of climate damages (with harmful damages

expressed as a positive number) from one more tonne of carbon in the

form of CO

, conditional on a global emissions trajectory over time.

Social protection

In the context of development aid and climate policy, social protection

usually describes public and private initiatives that provide income or

consumption transfers to the poor, protect the vulnerable against livelihood

risks, and enhance the social status and rights of the marginalized, with

the overall objective of reducing the economic and social vulnerability of

poor, vulnerable, and marginalized groups (Devereux and Sabates-Wheeler,

2004). In other contexts, social protection may be used synonymously

with social policy and can be described as all public and private initiatives

that provide access to services, such as health, education, or housing,or

income and consumption transfers to people. Social protection policies

protect the poor and vulnerable against livelihood risks and enhance

the social status and rights of the marginalized, as well as prevent

vulnerable people from falling into poverty.

Socioeconomic scenario

A scenario that describes a possible future in terms of population,

gross domestic product, and other socioeconomic factors relevant to

understanding the implications of climate change.

Southern Annular Mode (SAM)

The leading mode of variability of Southern Hemisphere geopotential

height, which is associated with shifts in the latitude of the midlatitude

jet. See SAM Index in WGI AR5 Box 2.5.

Species distribution modeling

Simulation of ecological effects of climate change. Species distribution

modeling uses statistically or theoretically derived response surfaces to

relate observations of species occurrence or known tolerance limits to

environmental predictor variables, thereby predicting a species’ range

as the manifestation of habitat characteristics that limit or support its

presence at a particular location. Species distribution models are also

referred to as environmental niche models. Bioclimate envelope models

can be considered as a subset of species distribution models that predict

species occurrence or habitat suitability based on climatic variables only.

SRES scenarios

SRES scenarios are emission scenarios developed by Nakićenović and

Swart (2000) and used, among others, as a basis for some of the climate

projections shown in Chapters 9 to 11 of IPCC (2001) and Chapters 10

nd 11 of IPCC (2007). The following terms are relevant for a better

understanding of the structure and use of the set of SRES scenarios:

Scenario family Scenarios that have a similar demographic, societal,

economic, and technical change storyline. Four scenario families

comprise the SRES scenario set: A1, A2, B1, and B2.

Illustrative scenario A scenario that is illustrative for each of the

six scenario groups reflected in the Summary for Policymakers of

Nakićenović and Swart (2000). They include four revised marker

scenarios for the scenario groups A1B, A2, B1, and B2, and two

additional scenarios for the A1FI and A1T groups. All scenario

groups are equally sound.

Marker scenario A scenario that was originally posted in draft

form on the SRES web site to represent a given scenario family. The

choice of markers was based on which of the initial quantifications

best reflected the storyline, and the features of specific models.

Markers are no more likely than other scenarios, but are considered

by the SRES writing team as illustrative of a particular storyline.

They are included in revised form in Nakićenović and Swart (2000).

These scenarios received the closest scrutiny of the entire writing

team and via the SRES open process. Scenarios were also selected

to illustrate the other two scenario groups.

StorylineA narrative description of a scenario (or family of scenarios),

highlighting the main scenario characteristics, relationships between

key driving forces, and the dynamics of their evolution.

Storm surge

The temporary increase, at a particular locality, in the height of the sea

due to extreme meteorological conditions (low atmospheric pressure

and/or strong winds). The storm surge is defined as being the excess

above the level expected from the tidal variation alone at that time and

place.

Storm tracks

Originally, a term referring to the tracks of individual cyclonic weather

systems, but now often generalized to refer to the main regions where

the tracks of extratropical disturbances occur as sequences of low

(cyclonic) and high (anticyclonic) pressure systems.

Stratosphere

The highly stratified region of the atmosphere above the troposphere

extending from about 10 km (ranging from 9 km at high latitudes to

16 km in the tropics on average) to about 50 km altitude.

Stressors

Events and trends, often not climate-related, that have an important

effect on the system exposed and can increase vulnerability to climate-

related risk.

Subsistence agriculture

Farming and associated activities that together form a livelihood

strategy in which most output is consumed directly but some may be

sold at market. Subsistence agriculture can be one of several livelihood

activities.

1774

Annex II Glossary

urface temperature

See Global mean surface temperature, Land surface air temperature,

and Sea Surface Temperature.

Sustainability

A dynamic process that guarantees the persistence of natural and

human systems in an equitable manner.

Sustainable development

Development that meets the needs of the present without compromising

the ability of future generations to meet their own needs (WCED, 1987).

Thermal expansion

In connection with sea level, this refers to the increase in volume (and

decrease in density) that results from warming water. A warming of the

ocean leads to an expansion of the ocean volume and hence an increase

in sea level. See also Sea level change.

Thermocline

The layer of maximum vertical temperature gradient in the ocean, lying

between the surface ocean and the abyssal ocean. In subtropical regions,

its source waters are typically surface waters at higher latitudes that have

subducted and moved equatorward. At high latitudes, it is sometimes

absent, replaced by a halocline, which is a layer of maximum vertical

salinity gradient.

Thermohaline circulation (THC)

Large-scale circulation in the ocean that transforms low-density upper

ocean waters to higher-density intermediate and deep waters and

returns those waters back to the upper ocean. The circulation is

asymmetric, with conversion to dense waters in restricted regions at

high latitudes and the return to the surface involving slow upwelling

and diffusive processes over much larger geographic regions. The

THC is driven by high densities at or near the surface, caused by cold

temperatures and/or high salinities, but despite its suggestive though

common name, is also driven by mechanical forces such as wind and

tides. Frequently, the name THC has been used synonymously with

Meridional Overturning Circulation. See also Meridional Overturning

Circulation.

Tipping point

A level of change in system properties beyond which a system reorganizes,

often abruptly, and does not return to the initial state even if the drivers

of the change are abated.

Traditional knowledge

The knowledge, innovations, and practices of both indigenous and local

communities around the world that are deeply grounded in history and

experience. Traditional knowledge is dynamic and adapts to cultural and

environmental change, and also incorporates other forms of knowledge

and viewpoints. Traditional knowledge is generally transmitted orally

from generation to generation. It is often used as a synonym for

indigenous knowledge, local knowledge, or traditional ecological

knowledge.

ransformation

A change in the fundamental attributes of natural and human systems.

Tree line

The upper limit of tree growth in mountains or at high latitudes. It is

more elevated or more poleward than the forest line.

Tropical cyclone

A strong, cyclonic-scale disturbance that originates over tropical oceans.

Distinguished from weaker systems (often named tropical disturbances

or depressions) by exceeding a threshold wind speed. A tropical storm is

a tropical cyclone with 1-minute average surface winds between 18 and

32 m s

–1

. Beyond 32 m s

–1

, a tropical cyclone is called a hurricane,

typhoon, or cyclone, depending on geographic location.

Troposphere

The lowest part of the atmosphere, from the surface to about 10 km in

altitude at mid-latitudes (ranging from 9 km at high latitudes to 16 km

in the tropics on average), where clouds and weather phenomena occur.

In the troposphere, temperatures generally decrease with height. See

also Stratosphere.

Tsunami

A wave, or train of waves, produced by a disturbance such as a submarine

earthquake displacing the sea floor, a landslide, a volcanic eruption, or

an asteroid impact.

Tundra

A treeless biome characteristic of polar and alpine regions.

Uncertainty

A state of incomplete knowledge that can result from a lack of information

or from disagreement about what is known or even knowable. It may

have many types of sources, from imprecision in the data to ambiguously

defined concepts or terminology, or uncertain projections of human

behavior. Uncertainty can therefore be represented by quantitative

measures (e.g., a probability density function) or by qualitative statements

(e.g., reflecting the judgment of a team of experts) (see Moss and

Schneider, 2000; Manning et al., 2004; Mastrandrea et al., 2010). See

also Confidence and Likelihood.

United Nations Framework Convention

on Climate Change (UNFCCC)

The Convention was adopted on 9 May 1992 in New York and signed

at the 1992 Earth Summit in Rio de Janeiro by more than 150 countries

and the European Community. Its ultimate objective is the “stabilization

of greenhouse gas concentrations in the atmosphere at a level that

would prevent dangerous anthropogenic interference with the climate

system.” It contains commitments for all Parties. Under the Convention,

Parties included in Annex I (all OECD countries and countries with

economies in transition) aim to return greenhouse gas emissions not

controlled by the Montreal Protocol to 1990 levels by the year 2000.

The convention entered in force in March 1994. In 1997, the UNFCCC

adopted the Kyoto Protocol.

The glossary for the Working Group I contribution to the Fifth Assessment Report defines tipping point in the context of climate: “In climate, a hypothesized critical threshold

when global or regional climate changes from one stable state to another stable state. The tipping point event may be irreversible.”

1775

Glossary Annex II

ptake

The addition of a substance of concern to a reservoir. The uptake of

carbon containing substances, in particular carbon dioxide, is often

called (carbon) sequestration.

Upwelling region

A region of an ocean where cold, typically nutrient-rich waters well up

from the deep ocean.

Urban heat island

The relative warmth of a city compared with surrounding rural areas,

associated with changes in runoff, effects on heat retention, and

changes in surface albedo.

Volatile Organic Compounds (VOCs)

Important class of organic chemical air pollutants that are volatile

at ambient air conditions. Other terms used to represent VOCs are

hydrocarbons (HCs), reactive organic gases (ROGs), and non-methane

volatile organic compounds (NMVOCs). NMVOCs are major contributors

(together with NO

and CO) to the formation of photochemical oxidants

such as ozone.

Vulnerability

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.

Vulnerability index

A metric characterizing the vulnerability of a system. A climate

vulnerability index is typically derived by combining, with or without

weighting, several indicators assumed to represent vulnerability.

Water cycle

See Hydrological cycle.

Water-use efficiency

Carbon gain by photosynthesis per unit of water lost by evapotranspiration.

It can be expressed on a short-term basis as the ratio of photosynthetic

carbon gain per unit transpirational water loss, or on a seasonal basis

as the ratio of net primary production or agricultural yield to the amount

of water used.

References

AMS, 2000: AMS Glossary of Meteorology, Second Edition [Glickman, T.S. (ed.)].

American Meteorological Society (AMS), Boston, MA, USA, http://glossary.

ametsoc.org/?s=A&p=1.

Arctic Council, 2013: Glossary of terms. In: Arctic Resilience Interim Report 2013.

Stockholm Environment Institute (SEI) and Stockholm Resilience Centre,

Stockholm, Sweden, p. viii.

CBD, 2000: COP 5 Decision V/6: Ecosystem Approach. Fifth Ordinary Meeting of the

Conference of the Parties to the Convention on Biological Diversity, 15 - 26

May 2000, Nairobi, Kenya, Secretariat of the Convention on Biological Diversity

(CBD), Montreal, QC, Canada, www.cbd.int/decision/cop/?id=7148.

CBD, 2002: Decision VI/23: Alien Species that Threaten Ecosystems, Habitats or

Species. Sixth Ordinary Meeting of the Conference of the Parties to the

Convention on Biological Diversity, 7 - 19 April 2002, The Hague, Netherlands,

Secretariat of the Convention on Biological Diversity (CBD), Montreal, QC,

Canada, www.cbd.int/decision/cop/?id=7197.

CBD, 2009: Connecting Biodiversity and Climate Change Mitigation and Adaptation:

Report of the Second Ad Hoc Technical Expert Group on Biodiversity and

Climate Change. Technical Series No. 41, Secretariat of the Convention on

Biological Diversity (CBD), Montreal, QC, Canada, 126 pp.

Cobo, J.R.M., 1987: Study of the Problem of Discrimination Against Indigenous

Populations. Volume 5: Conclusions, Proposals and Recommendations. Sub-

commission on Prevention of Discrimination and Protection of Minorities,

United Nations, New York, NY, USA, 46 pp.

Devereux, S. and R. Sabates-Wheeler, 2004: Transformative Social Protection. IDS

Working Paper 232, Institute of Development Studies (IDS), University of

Sussex, Brighton, UK, 30 pp.

FAO, 2000: State of Food Insecurity in the World 2000. Food and Agricultural

Organization of the United Nations (FAO), Rome, Italy, 31 pp.

Hegerl, G.C., O. Hoegh-Guldberg, G. Casassa, M.P. Hoerling, R.S. Kovats, C. Parmesan,

D.W. Pierce, and P.A. Stott, 2010: Good practice guidance paper on detection

and attribution related to anthropogenic climate change. In: Meeting Report

of the Intergovernmental Panel on Climate Change Expert Meeting on

Detection and Attribution of Anthropogenic Climate Change [Stocker, T.F., C.B.

Field, D. Qin, V. Barros, G.-K. Plattner, M. Tignor, P.M. Midgley, and K.L. Ebi

(eds.)]. IPCC Working Group I Technical Support Unit, University of Bern, Bern,

Switzerland, 8 pp.

Heywood, V.H. (ed.), 1995: The Global Biodiversity Assessment. United Nations

Environment Programme (UNEP), Cambridge University Press, Cambridge, UK,

1152 pp.

IPCC, 1992: Climate Change 1992: The Supplementary Report to the IPCC Scientific

Assessment [Houghton, J.T., B.A. Callander, and S.K. Varney (eds.)]. Cambridge

University Press, Cambridge, UK and New York, NY, USA, 116 pp.

IPCC, 1996: Climate Change 1995: The Science of Climate Change. Contribution of

Working Group I to the Second Assessment Report of the Intergovernmental

Panel on Climate Change [Houghton, J.T., L.G. Meira Filho, B.A. Callander, N.

Harris, A. Kattenberg, and K. Maskell (eds.)]. Cambridge University Press,

Cambridge, UK and New York, NY, USA, 572 pp.

IPCC, 2000: Land Use, Land-Use Change, and Forestry. Special Report of the

Intergovernmental Panel on Climate Change [Watson, R.T., I.R. Noble, B. Bolin,

N.H. Ravindranath, D.J. Verardo, and D.J. Dokken (eds.)]. Cambridge University

Press, Cambridge, UK and New York, NY, USA, 377 pp.

IPCC, 2001: Climate Change 2001: The Scientific Basis. Contribution of Working Group

I to the Third Assessment Report of the Intergovernmental Panel on Climate

Change [Houghton, J.T., Y. Ding, D.J. Griggs, M. Noguer, P.J. van der Linden, X.

Dai, K. Maskell, and C.A. Johnson (eds.)]. Cambridge University Press,

Cambridge, UK and New York, NY, USA, 881 pp.

IPCC, 2003: Definitions and Methodological Options to Inventory Emissions from

Direct Human-induced Degradation of Forests and Devegetation of Other

Vegetation Types [Penman, J., M. Gytarsky, T. Hiraishi, T. Krug, D. Kruger, R.

Pipatti, L. Buendia, K. Miwa, T. Ngara, K. Tanabe, and F. Wagner (eds.)]. The

Institute for Global Environmental Strategies (IGES), Hayama, Japan, 32 pp.

IPCC, 2007: Climate Change 2007: The Physical Science Basis. Contribution of Working

Group I to the Fourth Assessment Report of the Intergovernmental Panel on

Climate Change [Solomon, S., D. Qin, M. Manning, M. Marquis, K. Averyt,

M.M.B. Tignor, H.L. Miller Jr., and Z. Chen (eds)]. Cambridge University Press,

Cambridge, UK and New York, NY, USA, 996 pp.

IPCC, 2011: Workshop Report of the Intergovernmental Panel on Climate Change

Workshop on Impacts of Ocean Acidification on Marine Biology and Ecosystems

[Field, C.B., V. Barros, T.F. Stocker, D. Qin, K.J. Mach, G.-K. Plattner, M.D.

Mastrandrea, M. Tignor, and K.L. Ebi (eds.)]. IPCC Working Group II Technical

Support Unit, Carnegie Institution, Stanford, CA, USA, 164 pp.

IPCC, 2012a: Managing the Risks of Extreme Events and Disasters to Advance

Climate Change Adaptation. A Special Report of Working Groups I and II of

the Intergovernmental Panel on Climate Change [Field, C.B., V. Barros,

T.F. Stocker, D. Qin, D.J. Dokken, K.L. Ebi, M.D. Mastrandrea, K.J. Mach, G.-K.

Reflecting progress in science, this glossary entry differs in breadth and focus from the entry used in the Fourth Assessment Report and other IPCC reports.

1776

Annex II Glossary

Plattner, S.K. Allen, M. Tignor, and P.M. Midgley (eds.)]. Cambridge University

Press, Cambridge, UK, and New York, NY, USA, 582 pp.

IPCC, 2012b: Meeting Report of the Intergovernmental Panel on Climate Change

Expert Meeting on Geoengineering [Edenhofer, O., R. Pichs-Madruga, Y.

Sokona, C. Field, V. Barros, T.F. Stocker, Q. Dahe, J. Minx, K. Mach, G.-K. Plattner,

S. Schlömer, G. Hansen, and M. Mastrandrea (eds.)]. IPCC Working Group III

Technical Support Unit, Potsdam Institute for Climate Impact Research,

Potsdam, Germany, 99 pp.

IUCN, 2000:IUCN Guidelines for the Prevention of Biodiversity Loss Caused by Alien

Invasive Species. Prepared by the Species Survival Commission, Invasive

Species Specialist Group, International Union for Conservation of Nature

(IUCN), Approved by the 51

Meeting of the IUCN Council, Gland, Switzerland,

24 pp., https://portals.iucn.org/library/efiles/documents/Rep-2000-052.pdf.

Jagers, S.C. and J. Stripple, 2003: Climate governance beyond the state. Global

Governance, 9, 385-399.

Kelly, P.M. and W.N. Adger, 2000: Theory and practice in assessing vulnerability to

climate change and facilitating adaptation. Climatic Change, 47, 325-352.

Manning, M.R., M. Petit, D. Easterling, J. Murphy, A. Patwardhan, H.-H. Rogner, R.

Swart, and G. Yohe (eds.), 2004: IPCC Workshop on Describing Scientific

Uncertainties in Climate Change to Support Analysis of Risk of Options.

Workshop Report, Intergovernmental Panel on Climate Change (IPCC),

Geneva, Switzerland, 138 pp.

Mastrandrea, M.D., C.B. Field, T.F. Stocker, O. Edenhofer, K.L. Ebi, D.J. Frame, H. Held,

E. Kriegler, K.J. Mach, P.R. Matschoss, G.-K. Plattner, G.W. Yohe, and F.W.

Zwiers, 2010: Guidance Note for Lead Authors of the IPCC Fifth Assessment

Report on Consistent Treatment of Uncertainties. Intergovernmental Panel on

Climate Change (IPCC), Published online at: www.ipcc-wg2.gov/meetings/

CGCs/index.html#UR.

Matsuyama, K., 2008: Poverty Traps. In:The New Palgrave Dictionary of Economics,

Edition [Blume, L. and S. Durlauf (eds.)]. Palgrave Macmillan, New York,

NY, USA, www.dictionaryofeconomics.com/article?id=pde2008_P000332.

MEA, 2005: Appendix D: Glossary. In: Ecosystems and Human Well-being: Current

States and Trends. Findings of the Condition and Trends Working Group, Vol.

1 [Hassan, R., R. Scholes, and N. Ash (eds.)]. Millennium Ecosystem Assessment

(MEA), Island Press, Washington, DC, USA, pp. 893-900.

Moss, R. and S. Schneider, 2000: Uncertainties in the IPCC TAR: recommendations to

lead authors for more consistent assessment and reporting. In: IPCC

Supporting Material: Guidance Papers on Cross Cutting Issues in the Third

Assessment Report of the IPCC [Pachauri, R., T. Taniguchi, and K. Tanaka (eds.)].

Intergovernmental Panel on Climate Change (IPCC), Geneva, Switzerland, pp.

33-51.

Moss, R., M. Babiker, S. Brinkman, E. Calvo, T. Carter, J. Edmonds, I. Elgizouli, S. Emori,

L. Erda, K. Hibbard, R. Jones, M. Kainuma, J. Kelleher, J.F. Lamarque, M.

Manning, B. Matthews, J. Meehl, L. Meyer, J. Mitchell, N. Nakicenovic, B. O’Neill,

R. Pichs, K. Riahi, S. Rose, P. Runci, R. Stouffer, D. van Vuuren, J. Weyant, T.

Wilbanks, J.-P. van Ypersele, and M. Zurek, 2008: Towards New Scenarios for

Analysis of Emissions, Climate Change, Impacts and Response Strategies. IPCC

Expert Meeting Report, 19-21 September, 2007, Noordwijkerhout, Netherlands,

Intergovernmental Panel on Climate Change (IPCC), Geneva, Switzerland,

132 pp.

Moss, R., J.A. Edmonds, K.A. Hibbard, M.R. Manning, S.K. Rose, D.P. van Vuuren, T.R.

Carter, S. Emori, M. Kainuma, T. Kram, G.A. Meehl, J.F.B. Mitchell, N. Nakićenović,

K. Riahi, S.J. Smith, R.J. Stouffer, A.M. Thomson, J.P. Weyant, and T.J. Wilbanks,

2010: The next generation of scenarios for climate change research and

assessment. Nature, 463, 747-756.

Nakićenović, N. and R. Swart (eds.), 2000: Special Report on Emissions Scenarios. A

Special Report of Working Group III of the Intergovernmental Panel on Climate

Change. Cambridge University Press, Cambridge, UK and New York, NY, USA,

599 pp.

O’Brien, K., S. Eriksen, L.P. Nygaard, and A. Schjolden, 2007: Why different

interpretations of vulnerability matter in climate change discourses. Climate

Policy, 7, 7-88.

OECD, 2003: OECD Glossary of Statistical Terms. Organisation for Economic Co-

operation and Development (OECD), Paris, France, http://stats.oecd.org/

glossary/detail.asp?ID=1313.

Park, S.E., N.A. Marshall, E. Jakku, A.M. Dowd, S.M. Howden, E. Mendham, and A.

Fleming, 2012: Informing adaptation responses to climate change through

theories of transformation. Global Environmental Change, 22, 115-126.

Rosa, E.A., 1998: Metatheoretical foundations for post-normal risk. Journal of Risk

Research, 1(1), 15-44.

Rosa, E.A., 2003: The logical structure of the social amplification of risk framework

(SARF): metatheoretical foundation and policy implications. In: The Social

Amplification of Risk [Pidgeon, N., R.E. Kasperson, and P. Slovic (eds.)].

Cambridge University Press, Cambridge, UK, pp. 47-79.

Secretariat of the Stockholm Convention, 2001: The Stockholm Convention on

Persistent Organic Pollutants (as amended in 2009). Secretariat of the

Stockholm Convention,Châtelaine, Switzerland, 63 pp.

UNCCD, 1994: Article 1: Use of Terms. United Nations Convention to Combat

Desertification (UNCCD), Paris, France, www.unccd.int/en/about-the-

convention/Pages/Text-Part-I.aspx.

UNISDR, 2009: 2009 UNISDR Terminology on Disaster Risk Reduction. United Nations

International Strategy for Disaster Reduction (UNISDR), United Nations,

Geneva, Switzerland, 30 pp.

WCED, 1987: Our Common Future. World Commission on Environment and

Development (WCED), Oxford University Press, Oxford, UK, 300 pp.