Preliminary Glossary
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A
Adaptive Capacity
Adaptive capacity is the ability or potential of a system to respond successfully to Climate variability and change, and includes adjustments in both behavior and in resources and technologies.
Anomaly
The deviation of a measurable unit (e.g., temperature or precipitation) over a period in a given region from the long-term average, often the thirty-year mean, for that region.
B
Baseline Period
The baseline (or reference) is the state against which change is measured. It might be a ‘current baseline,’ in which case it represents observable, present-day conditions. It might also be a ‘future baseline,’ which is a projected future set of conditions excluding the driving factor of interest. Alternative interpretations of the reference conditions can give rise to multiple baselines.
C
Carbon uptake
The addition of carbon to a reservoir. The uptake of carbon containing substances, in particular carbon dioxide, is often called (carbon) sequestration.
Climate change signal
Observed and simulated climate change are the sum of the forced (signal) and the natural variability (noise).
Here: the difference of 2°C-Period to 1971-2000 period.
Climate Feedback processes
An interaction mechanism between processes in the climate system is called a climate feedback when the result of an initial process triggers changes in a second process that in turn influences the initial one. A positive feedback intensifies the original process, and a negative feedback reduces it.
Climate model
Mathematical representation of the climate system based on physical, biological and chemical principles of its components, their interactions and feedback processes, and accounting for all or some of its known properties. The equations derived from these laws are so complex that they must be solved numerically. As a consequence, climate models provide a solution which is discrete in space and time, meaning that the results obtained represent averages over regions, whose size depends on model resolution, and for specific times. The climate system can be represented by models of varying complexity, that is, for any one component or combination of components.
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.
Climate prediction
A climate prediction or climate forecast is the result of an attempt to produce an estimate of the actual evolution of the climate in the future, e.g., at seasonal, interannual or long-term time scales. See also climate projection.
Climate projection
The calculated response of the climate system to emissions or concentration scenarios of greenhouse gases and aerosols, or radiative forcing scenarios, often based on simulations by climate models. Climate projections are distinguished from climate predictions, in that the former critically depend on the emissions/ concentration/radiative forcing scenario used, and therefore on highly uncertain assumptions of future socio-economic and technological development.
Climate system
The climate system is defined by the dynamics and interactions of five major components: atmosphere, hydrosphere, cryosphere, land surface, and biosphere. Climate system dynamics are driven by both internal and external forcing, such as volcanic eruptions, solar variations, or human-induced modifications to the planetary radiative balance (see Surface energy balance), for instance via anthropogenic emissions of greenhouse gases and/or land-use changes.
Climate variability
Climate variability refers to variations in the mean state and other statistics (such as standard deviations, statistics of extremes, etc.) of the climate on all temporal and spatial scales beyond that of individual weather events. Variability may be due to natural internal processes within the climate system (internal variability), or to variations in natural or anthropogenic external forcing (external variability).
Climate variable
A variable is a characteristic, number, or quantity that increases or decreases over time, or takes different values in different situations.
The climate variables are most often surface variables such as temperature, precipitation, and wind but also air pressure, humidity and air density.
Cold spell
Episode of several consecutive low-temperature days/nights.
Crop (calorie) yield
Harvested production per unit of harvested area for crop products. In most of the cases yield data are not recorded but obtained by dividing the production data by the data on area harvested. Data on yields of permanent crops are not as reliable as those for temporary crops either because most of the area information may correspond to planted area, as for grapes, or because of the scarcity and unreliability of the area figures reported by the countries, as for example for cocoa and coffee.
Cryosphere
The component of the climate system consisting of all snow and ice (including permafrost) on and beneath the surface of the Earth and ocean.
D
Data sets
A data set (or dataset) is a collection of data.
Most commonly a data set corresponds to the contents of a single database table, or a single statistical data matrix, where every column of the table represents a particular variable, and each row corresponds to a given member of the data set in question. The data set lists values for each of the variables, for each member of the data set.
E
Ensemble
A collection of numerical model results that show slightly different possible outcomes.
A climate ensemble involves slightly different models of the climate system. The aim of running an ensemble is usually in order to be able to deal with uncertainties in the system. Initial condition ensembles involve the same model in terms of the same atmospheric physics parameters and forcings, but run from variety of different starting states. Because the climate system is chaotic, tiny changes in variables such as temperatures, winds, and humidity in one place can lead to very different paths for the system as a whole.
EURO-CORDEX
The World Climate Research Program (WCRP) established in 2009 the Task Force for Regional Climate Downscaling (TFRCD), which created the CORDEX initiative to generate regional climate change projections for all terrestrial regions of the globe within the timeline of the Fifth Assessment Report (AR5) and beyond. The major aims of the CORDEX initiative are to provide a coordinated model evaluation framework, a climate projection framework, and an interface to the applicants of the climate simulations in climate change impact, adaptation, and mitigation studies (Giorgi et al., 2009).
EURO-CORDEX is the European branch of the CORDEX initiative and will produce ensemble climate simulations based on multiple dynamical and empirical-statistical downscaling models forced by multiple global climate models from the Coupled Model Intercomparison Project Phase 5 (CMIP5).
Evapotranspiration
The combined process of evaporation from the Earth’s surface and transpiration from vegetation.
F
Fixed-effects model
In econometrics and statistics, a fixed effects model is a statistical model that represents the observed quantities in terms of explanatory variables that are treated as if the quantities were non-random. This is in contrast to random effects models and mixed models in which either all or some of the explanatory variables are treated as if they arise from random causes.
Freeze-thaw days
Freeze-thaw days are defined as days on which daytime temperatures are above freezing (> +3°C) and night-time temperatures are below freezing (< -3°C). Under these conditions, the upper soil layer thaws and freezes again every day.
G
Gradient
The rate of change with respect to distance of a variable quantity, as temperature or pressure, in the direction of maximum change.
It’s a vector (a direction to move) that points in the direction of greatest increase of a function and is zero at a local maximum or local minimum (because there is no single direction of increase).
Grid
Threedimensional set of points that cover the region of interest and approximates the atmosphere, because the atmosphere cannot be represented perfectly by the model due to the amount of computer processor time, memory, and disk storage required to run numerical models.
Gross hydropower potential
Theoretical possibility for electricity generation by hydropower.
Gross Primary Production (GPP)
Gross Primary Production denotes the total amount of carbon fixed in the process of photosynthesis by plants in an ecosystem, such as a stand of trees. GPP is measured on photosynthetic tissues, principally leaves. Global total GPP is estimated to be about 120 Gt C yr-1.
H
Heat wave
A period of abnormally hot weather. Heat waves and warm spells have various and in some cases overlapping definitions
Hydrosphere
The hydrosphere is the component of the climate system comprising all liquid surface and subterranean water, both fresh water, including rivers, lakes and aquifers, and saline water of the oceans and seas.
I
Intergovernmental Panel on Climate Change (IPCC)
The Intergovernmental Panel on Climate Change (IPCC) is the leading international body for the assessment of climate change. It was established by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO) in 1988 to provide the world with a clear scientific view on the current state of knowledge in climate change and its potential environmental and socio-economic impacts. In the same year, the UN General Assembly endorsed the action by WMO and UNEP in jointly establishing the IPCC. The IPCC is a scientific body under the auspices of the United Nations (UN). It reviews and assesses the most recent scientific, technical and socio-economic information produced worldwide relevant to the understanding of climate change. It does not conduct any research nor does it monitor climate related data or parameters.
Intermittent renewable energies
An intermittent energy source is a source of energy that is not continuously available due to some factor outside direct control.
L
M
Model spread
The difference between the extreme results from a same model.
Multi model ensemble
A set of simulations from multiple models.
N
Natural variations in the climate (unrelated to greenhouse gas induced warming)
Natural climate variability, as the name suggests, is caused by natural factors. There are lots of natural factors that cause significant changes in the climate. These causes can be within the earth or coming from outside the earth.
Externally Induced Climate Variability refers to the impact of some external factor that leads to variability, such as the impact of variations in solar radiation or Solar and lunar tides.
Internally Induced Climate Variability refers to internal interactions between components of the climate system, such as the interaction between Ocean and atmosphere or Atmosphere and biosphere.
See also Climate variability.
Net Biome Production (NBP)
Net Biome Production (NBP) denotes the net production of organic matter in a region containing a range of ecosystems (a biome) and includes, in addition to heterotrophic respiration, other processes leading to loss of living and dead organic matter (harvest, forest clearance, and fire, etc.)
Net Primary Production (NPP)
Net Primary Production (NPP) denotes the net production of organic matter by plants in an ecosystem-that is, GPP reduced by losses resulting from the respiration of the plants (autotrophic respiration). Global NPP is estimated to be about half of the GPP-that is, about 60 Gt C yr-1.
P
Percentiles
A percentile is a measure used in statistics indicating the value below which a given percentage of observations in a group of observations fall.
Projection
The potential evolution of a quality or set of quantities, often computed with the aid of a model. Projections are distinguished from predictions in order to emphasise that projections involve assumptions – concerning, for example, future socio-economic and technological developments, that may or may not be realised – and are therefore subject to substantial uncertainty. See also climate projection and climate prediction.
R
RCP
Representative Concentration Pathways (RCPs) are four greenhouse gas concentration (not emissions) trajectories adopted by the IPCC for its fifth Assessment Report (AR5) in 2014. The pathways are used for climate modelling and research. They describe four possible climate futures, all of which are considered possible depending on how much greenhouse gases are emitted in the years to come. The four RCPs, RCP2.6, RCP4.5, RCP6, and RCP8.5, are named after a possible range of radiative forcing values in the year 2100 relative to pre-industrial values (+2.6, +4.5, +6.0, and +8.5 W/m2, respectively).
Reanalysis
Reanalyses are atmospheric and oceanic analyses of temperature, wind, current, and other meteorological and oceanographic quantities, created by processing past meteorological and oceanographic data using fixed state-of-the-art weather forecasting models and data assimilation techniques. Using fixed data assimilation avoids effects from the changing analysis system that occurs in operational analyses. Although continuity is improved, global reanalyses still suffer from changing coverage and biases in the observing systems.
Reference Period
Climate “normals” are reference points used by climatologists to compare current climatological trends to that of the past or what is considered “normal”. A Normal is defined as the arithmetic average of a climate element (e.g. temperature) over a 30-year period. A 30 year period is used, as it is long enough to filter out any interannual variation or anomalies, but also short enough to be able to show longer climatic trends. The current climate normal period is calculated from 1 January 1961 to 31 December 1990.
See also: Baseline period.
River Discharge
Water flow within a river channel, for example expressed in m3/s. A synonym for streamflow.
River runoff
River runoff refers to all water that comes into a river water system from sources such as rainfall, snowmelt and groundwater and is not transpired, but flows over the ground and returns to a larger body of water, such as a sea or ocean.
S
Shared Socioeconomic Pathways Database (SSP)
The SSP database aims at the documentation of quantitative projections of the so-called Shared Socioeconomic Pathways (SSPs) and related Integrated Assessment scenarios. The SSPs are part of a new framework that the climate change research community has adopted to facilitate the integrated analysis of future climate impacts, vulnerabilities, adaptation, and mitigation. The SSPs can be used in conjunction with the RCPs to develop scenarios for use by the research community.
Snow water equivalent (SWE)
The equivalent volume/mass of water that would be produced if a particular body of snow or ice was melted.
Soil Organic Carbon (SOC)
Soils contain carbon (C) in both organic and inorganic forms. In most soils (with the exception of calcareous soils) the majority of C is held as soil organic carbon (SOC). Organic carbon (OC) enters the soil through the decomposition of plant and animal residues, root exudates, living and dead microorganisms, and soil biota. SOC is the main source of energy for soil microorganisms.
Solar Photovoltaic (PV)
A photovoltaic system, also solar PV power system, or PV system, is a power system designed to supply usable solar power by means of photovoltaics. It consists of an arrangement of several components, including solar panels to absorb and convert sunlight into electricity.
Solar radiation
Energy radiated from the sun in the form of electromagnetic waves, including visible and ultraviolet light and infrared radiation.
Streamflow
The streamflow is the water-flow within a river channel, for example, expressed in m3 s-1. A synonym for river discharge.
Streamflow drought
In general terms, drought is a prolonged absence or marked deficiency of precipitation, a deficiency of precipitation that results in water shortage for some activity or for some group; or a period of abnormally dry weather sufficiently prolonged for the lack of precipitation to cause a serious hydrological imbalance. Streamflow drought is related to below-normal streamflow.
Surface energy balance
For a stable climate, a balance is required between incoming solar radiation and the outgoing radiation emitted by the climate system. Details of this energy balance can be seen in the figure below, which shows on the left hand side what happens with the incoming solar radiation, and on the right hand side how the atmosphere emits the outgoing infrared radiation.
Swell wave
Series of wind generated mechanical waves that are not affected by the local wind at that time, that propagate along the interface between water and air and were generated by distant weather systems, where wind blow for a longer time over a fetch of water.
T
Temporal average
The temporal mean is the arithmetic mean of a series of values over a time period. Assuming equidistant measuring or sampling times, it can be computed as the sum of the values over a period divided by the number of values.
Terrestrial biosphere
The biosphere is the total sum of living organisms and one of five separate components of the climate system. The terrestrial biosphere is the sum of living organism living on the continents.
Thermal growing season length
length of time in a calendar year when temperatures are consistently warm enough for agricultural activity. Thermal growing season length is defined as the number of days between the first five days period with average temperatures above 5°C to the first five days period with temperatures below 5°C.
Tourism Climate Index (TCI)
The Tourism Climate Index (TCI) is a summary of ratings of five human comfort indices related to sightseeing tourism. This index is composed of several climatic parameters such as temperature, sunshine duration, wind and others. TCI ranges between 0 and 100, with the optimal to be 90 to 100.
Tropical night
During a tropical night, the air temperature does not fall below 20.0°C.
V
Value at risk (VAR)
Value at Risk is used as a measurement of the risk of loss on a specific economic sector.
In economics and finance, Value at Risk (VaR) is the maximum loss not exceeded with a given probability defined as the confidence level, over a given period of time. It is commonly used by security houses or investment banks to measure the market risk of their asset portfolios (market value at risk), however VaR is a very general concept that has broad applications.
W
Wind energy density
The wind power density, measured in watts per square meter, indicates how much energy is available at the site for conversion by a wind turbine.
Wind farm fleet
Synonym for the entire wind power plant farm.
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2°C / 3°C - Period
See 2°C-Period