Glossary

Adaptation to climate change

Undertaking actions to minimise threats or to maximise opportunities resulting from climate change and its effects.

Adaptive responses

See Adaptation to climate change.

Aerosols

A collection of airborne solid or liquid particles, with a typical size between 0.01 and 10 microns, which reside in the atmosphere for at least several hours. Aerosols may be of either natural or anthropogenic origin.

Agenda 21

An outcome of the 1992 United Nations Conference on Environment and Development (the Earth Summit) held in Rio de Janeiro. Agenda 21 provides the philosophy and process for community-led sustainable development.

Anomaly

A difference from the long-term average climate. For example the El Niño summer rainfall anomaly is the difference between the rainfall averaged over summers when El Niño conditions are present and the rainfall averaged over all summers.

Antarctic Circumpolar Current

The westward flowing ocean current circling Antarctica, also known as the West Wind Drift. It is the largest ocean current on Earth (about three times the flow of the Gulf Stream). A branch comes up around the Campbell Plateau to the south of New Zealand.

Anthropogenic

Produced by human beings or resulting from human activities.

Anthropogenic emissions

Emissions of greenhouse gases, greenhouse gas precursors and aerosols associated with human activities. These include burning of fossil fuels for energy, deforestation, and land-use changes that result in a net increase in emissions.

AOGCM

Acronym for atmosphere-ocean general circulation model.

ARI

Acronym for Average Recurrence Interval. Same as return period.

Atmosphere-ocean general circulation model (AOGCM)

A comprehensive climate model containing equations representing the behaviour of the atmosphere, ocean and sea ice and their interactions.

Black carbon aerosol

An aerosol that consists of soot, charcoal, or other light-absorbing organic material.

Carbon dioxide (CO₂)

A naturally occurring gas and the principal anthropogenic greenhouse gas.

CFC

Acronym for Chlorofluorocarbon.

Chlorofluorocarbons

Man-made gases containing chlorine or fluorine that are used for refrigeration, air conditioning, packaging, insulation, solvents, or aerosol propellants. Since they are not destroyed in the lower atmosphere, CFCs drift into the upper atmosphere where, given suitable conditions, they break down ozone. CFCs are also Greenhouse gases, but are covered under the 1987 Montreal Protocol and explicitly excluded from the Kyoto Protocol and the United Nations Framework Convention on Climate Change.

City and district councils

The management bodies of territorial authorities, of either predominantly urban or predominantly rural character.

Climate

The "average weather", over a period of time ranging from months to thousands or millions of years. The classical period for calculating a "climate normal" is 30 years.

Climate change

A statistically significant variation in either the mean state of the climate or in its variability, persisting for an extended period (typically decades or longer).

Climate model

A numerical representation (typically a set of equations programmed into a computer) of the climate system. The most complex and complete climate models are known as General Circulation Models (below).

Climate prediction

An attempt to provide a most likely description or estimate of the actual future evolution of the climate.

Climate projection

A potential future evolution of the climate in response to an emission or concentration scenario of greenhouse gases and aerosols. Often based on a simulation by a climate model.

Climate system

The interacting system comprising the atmosphere, hydrosphere (liquid water in lakes, rivers, seas, oceans), cryosphere (snow, ice, permafrost), land surface and biosphere (ecosystems and living organisms) which determines the earth's climate.

Climate variability

Variations of the climate (e.g. of the mean state, standard deviations and extremes) on all temporal and spatial scales beyond those of individual weather events.

CLIMPACTS

An integrated assessment model for conducting analyses of the sensitivity of New Zealand's managed environments to climate variability and change. Both spatial and temporal variations can be examined. For further information, see website: http://www.waikato.ac.nz/igci/climpacts_webpage/.

Consent notice

A condition on a subdivision consent, under section 221 of the Resource Management Act, which must be complied with on a continuing basis by the subdividing owner and any subsequent owner. A consent notice is issued by a territorial authority and is deemed to be an instrument creating an interest in the land and a covenant on the land.

Diurnal temperature range

The difference between the maximum and minimum temperature during a day.

Downscaling

Deriving estimates of local climate elements (e.g. temperature, wind, rainfall), from the coarse resolution output of global climate models. Statistical downscaling uses present relationships between large scale climate variables and local variables. Nested regional climate modelling uses the coarse resolution output from a global climate model to drive a high resolution regional climate model.

El Niño

A significant increase in sea surface temperature over the eastern and central equatorial Pacific that occurs at irregular intervals, generally ranging between two and seven years. Associated changes occur in atmospheric pressure patterns and wind systems across the Pacific. These can lead to changes in seasonal rainfall and temperature in parts of Australia and New Zealand.

El Niño Southern Oscillation (ENSO)

Term coined in the early 1980s in recognition of the intimate linkage between El Niño events and the Southern Oscillation, which, prior to the late 1960s, had been viewed as two unrelated phenomena. The interactive global ocean-atmosphere cycle comprising El Niño and La Niña is often called the ENSO cycle.

Evapotranspiration

The combined process of evaporation from the earth's surface and transpiration from vegetation.

Extreme weather event

An event that is rare at a particular place. Rare would normally be defined as rare as or rarer than the 10th or 90th percentile.

ENSO

Acronym for El Niño Southern Oscillation.

General Circulation Model (GCM)

A global, three-dimensional computer model of the climate system, which can be used to simulate the general circulation and climate of the atmosphere and ocean, and particularly human-induced climate change. GCMs are highly complex and they represent the effects of such factors as reflective and absorptive properties of atmospheric water vapour, greenhouse gas concentrations, clouds, annual and daily solar heating, ocean temperatures and ice boundaries. GCMs include global representations of the atmosphere, oceans, and land surface.

GCM

Acronym for General Circulation Model or Global Climate Model.

Global Climate Model (GCM)

The same as General Circulation Model.

Global surface temperature

The global surface temperature is the area-weighted global average of:

(i) the sea-surface temperature over the oceans (i.e. the subsurface bulk temperature in the first few metres of the ocean), and

(ii) the surface-air temperature over land at 1.5 m above the ground.

Global warming

Usually used to refer to the rise of the earth's surface temperature predicted to occur as a result of increased emissions of greenhouse gases.

Greenhouse effect

An increase in the temperature of the earth's surface and the lowest 8 km or so of the atmosphere, caused by the trapping of heat by greenhouse gases. Naturally occurring greenhouse gases cause a greenhouse effect at the earth's surface of about 30oC. Further temperature increases caused by anthropogenic emissions are termed the enhanced greenhouse effect.

Greenhouse gases

Gases in the earth's atmosphere that absorb and re-emit infra-red (heat) radiation. Many greenhouse gases occur naturally in the atmosphere, but concentrations of some (such as carbon dioxide, methane, and nitrous oxide) have increased above natural levels because of anthropogenic emissions.

Homogenised climate record

A climate record that has been screened and adjusted for errors (because of changes in site, observing location environs, instrumentation and observation methods) to produce a high quality climate record for the purpose of detecting climate trends and variability.

Interdecadal Pacific Oscillation (IPO)

A long timescale oscillation in the Pacific Ocean-atmosphere system which shifts climate every one to three decades. The IPO has positive (warm) and negative (cool) phases. Positive phases tend to be associated with an increase in El Niños, and negative phases with an increase in La Niñas.

Intergovernmental Panel on Climate Change (IPCC)

The body established in 1988 by the World Meteorological Organisation (WMO) and the United Nations Environment Programme (UNEP) to objectively assess scientific, technical and socioeconomic information relevant to understanding the scientific basis of risk of human-induced climate change, its potential impacts and options for adaptation and mitigation.

IPCC

Acronym for Intergovernmental Panel on Climate Change.

IPO

Acronym for Interdecadal Pacific Oscillation.

Kaitiakitangi

Stewardship, or the awareness of and care for natural and cultural resources, according to customary principles.

Kyoto Protocol

The Kyoto Protocol to the United Nations Framework Convention on Climate Change (UNFCCC) was adopted at the Third Session of the Conference of the Parties (COP) to the UNFCCC, in 1997 in Kyoto, Japan. It contains legally binding commitments on countries included in Annex B of the Protocol (most OECD countries and some others) to reduce their anthropogenic greenhouse gas emissions to some (negotiable) value below 1990 levels in the commitment period 2008 to 2012. New Zealand ratified the Kyoto Protocol in December 2002, committing to a reduction of 0% relative to 1990. The Kyoto Protocol has not yet entered into force.

La Niña

A significant decrease in sea surface temperature in the central and eastern equatorial Pacific that occurs at irregular intervals, generally ranging between two and seven years. La Niña is the cool counterpart to the El Niño warm event, and its spatial and temporal evolution in the equatorial Pacific is, to a considerable extent, the mirror image of El Niño. Like El Niño, there are associated changes in atmospheric pressures and wind systems across the Pacific, and related changes can occur in temperature and rainfall in parts of Australia and New Zealand.

Lifelines

Key networks for communication and survival during emergency conditions, including connected links and operating facilities in electricity, telecommunications, roading, water supply and wastewater systems. They may also include key emergency services such as ambulance, fire and civil defence services, and facilitates such as hospitals and medical centres.

Limitation adaptations

Those adaptations that are aimed at lessening or minimising the consequences of the most adverse effects of climate change as they arise over time.

Low-regrets adaptations

Those adaptations that are aimed at pro-actively minimising adverse effects that may arise over time from climate change.

Meridional temperature gradient

The rate of change of air (or sea) temperature in the south to north direction. Stronger meridional temperature gradients are related to a more rapid increase in wind strength with height. Thus, the stronger westerlies are associated with the stronger north-south temperature gradients in large-scale climate.

Mitigation (of climate change)

Activities undertaken to reduce the sources or increase the sinks of greenhouse gases.

Montreal Protocol

An international agreement adopted in 1987 to control the consumption and production of chemicals such as chlorofluorocarbons that destroy stratospheric ozone.

Natural variability

Non-anthropogenic climate variability that may be irregular or quasi-cyclic. El Niño-Southern Oscillation is probably the best-known example of a natural oscillation of the climate system, but there are many others. Changes caused by volcanic eruptions and solar variations can also be considered "natural".

No regrets adaptation

Those adaptations that generate net social, economic and environmental benefits whether or not there is anthropogenic climate change climate, or at least have no net adverse effects.

Ozone

The triatomic form of oxygen (O₃). It acts as a greenhouse gas in the troposphere. In the stratosphere (about 10-50 km above the ground) it absorbs harmful UV radiation emanating from the sun.

Percentile

Used to give an observed value a ranking within the historical record. For example, only 5% of observations lie below the 5-percentile (i.e. the coldest 5% of the record) and 5% of observations lie above the 95-percentile (i.e. the warmest 5% of the record).

Precursors

Atmospheric compounds which are not themselves greenhouse gases or aerosols, but which take part in processes regulating their production or destruction.

Radiative forcing

The perturbation to the energy balance of the earth-atmosphere system following, for example, a change in the concentration of carbon dioxide or a change in the output of the sun. The climate system responds to the radiative forcing so as to re-establish the energy balance. A positive radiative forcing tends to warm the earth's surface and a negative radiative forcing tends to cool the surface.

Regional Climate Model (RCM)

A climate model which is run at high resolution over a 'region' (for example the eastern part of Australia, Tasman Sea plus New Zealand) to describe climate at the regional scale. RCMs are typically driven with data from Global Climate Models, which run at lower resolution and therefore do not accurately simulate (for example) the effects of the Southern Alps on New Zealand's climate.

Regional councils

Constituted under the Local Government Act 2002 with the functions and responsibilities that relate to defined local government regions.

Relative sea level

Sea level measured by a tide gauge with respect to the land upon which it is situated. Mean Sea Level (MSL) is normally defined as the average Relative Sea Level over a period, such as a month or a year, long enough to average out transients such as waves.

Return period

The probable time period between repetition of extreme weather events, such as heavy rainfall or flooding, in a stationary climate (that is, a climate without global warming or other trends). In the case of rainfall, a return period is always related to a specific duration (e.g. 50-year return period of 24-hour extreme rainfall).

Scenario

A plausible and often simplified description of how the future may develop, based on a coherent and internally consistent set of assumptions about key driving forces.

Screening assessment

An initial risk assessment, which involves identifying current sensitivity to climate and possible future sensitivity to climate change and the likely duration and extent of effects that may arise as a consequence of climate change.

SOI

Acronym for Southern Oscillation Index.

Southern oscillation

A multi-year low-latitude seesaw in sea level pressure, with one pole in the eastern Pacific and the other in the western Pacific/Indian Ocean region. This pressure seesaw is associated with a global pattern of atmospheric anomalies in circulation, temperature, and precipitation. Its opposite extremes are the El Niño and La Niña events.

Southern oscillation index

An index calculated from anomalies in the pressure difference between Tahiti and Darwin. Low negative values of this index correspond to El Niño conditions, and high positive SOI values coincide with La Niña episodes.

SRES scenarios

A set of greenhouse gas and aerosol emissions scenarios developed in 2000 by Working Group III of the IPCC and used, among others, as a basis for the climate projections in the IPCC's 2001 Third Assessment Report.

SST

Acronym for Sea Surface Temperature (see Global surface temperature).

Storm surge

The excess above the level expected from the tidal variation alone at that time and place. The temporary increase in the height of the sea is caused by extreme meteorological conditions such as low atmospheric pressure and/or strong winds.

Stratosphere

The region of the atmosphere extending from about 10 km to 50 km altitude.

Sustainability

"... development that meets the needs of the present without compromising the ability of future generations to meet their own needs" (Bruntland Report, Our Common Future, Report of the World Commission on Environment and Development, 1978).

Territorial authorities

Constituted under the Local Government Act 2002, comprising city and district councils and (for some functions) unitary authorities.

Troposphere

The lowest part of the atmosphere, which in mid-latitude locations like New Zealand extends from the earth's surface to about 10 km altitude.

Unitary authorities

Territorial authorities which also have regional council responsibilities.

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 "stabilisation 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 aim to return greenhouse gas emissions not controlled by the Montreal Protocol to 1990 levels. The convention entered into force in March 1994. See also Kyoto Protocol.

Weather generator

Weather generators produce multiple time series of numbers whose statistical properties resemble those of historical weather records. The most common weather generators produce output representing daily time series of maximum and minimum temperature, rainfall and solar radiation. The numbers preserve observed characteristics such as persistence of temperature (e.g. one hot day is often followed by another), as well as inter-relationships (e.g. wet days tend to have lower solar radiation and lower maximum temperature but higher minimum temperature).

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