Glossary

Term	Explanation	Source: Formal	Source: Informal
CMIP5	Climate modelling groups coordinate their model updates and simulations around the schedule of the Intergovernmental Panel on Climate Change (IPCC) assessment reports. A Coupled Model Intercomparison Project (CMIP) is a coordinated set of simulations run by many different models. The 2013 IPCC fifth assessment report (AR5) featured climate model simulations from CMIP5.	Source	Source
Dew point temperature	The temperature to which air must be cooled to become saturated with water vapour.	Source
ERA5	ERA5 combines vast amounts of historical weather observations into global estimates using advanced modelling and data assimilation systems.	Source
Essential Climate Variable	An Essential Climate Variable (ECV) is a physical, chemical or biological variable or a group of linked variables that critically contributes to the characterization of Earth’ s climate.	Source
GCM	Global Climate Model. Climate models use equations to represent the processes and interactions that drive the Earth’s climate. These cover the atmosphere, oceans, land and ice-covered regions of the planet.	Source	Source
Likely	66% probability of occurrence, as defined by the IPCC uncertainty scale, corresponding to the 17th-83th percentile range.	Source
Moving average	A moving average is applied to time series data to smooth out short-term fluctuations and highlight longer-term trends. The points inside a time window are averaged and the window “moves' along the time axis. For example, in a 30-year annual average, the 1996 value is the average from the 1981 to 2010 values.	Source
Multi-model ensemble	When different Global Climate Models (GCMs) are set up to run simulations which all follow the same instructions for starting conditions, historical data and projected data, that suite of simulations is known as a multi-model ensemble.	Source	Source
NUTS	The EUROSTAT NUTS classification (Nomenclature of Territorial Units for Statistics) is a hierarchical system for dividing up the economic territory of the EU and the UK. NUTS-0: Countries, NUTS-1: major socio-economic regions with a populations between 3 million and 7 million, NUTS-2: basic regions for the application of regional policies with populations between 800 000 and 3 million, and NUTS-3: small regions for specific diagnoses with populations between 150 000 and 800 000.	Source
Percentile	In statistics, a percentile (or centile) is a value below which a given percentage of the values in the data distribution lie.	Source
Radiative forcing	Radiative forcing (or climate forcing) is the change in energy flux in the atmosphere caused by natural or man caused factors as measured by watts/metre.	Source
RCP4.5	RCP4.5 is a stabilisation scenario in which total radiative forcing stabilises at 4.5 W/m2 shortly after the year 2100.	Source	Source
RCP8.5	RCP8.5 is characterised by increasing greenhouse gas emissions over time, it is representative of scenarios that lead to high greenhouse gas concentration levels and has a radiative forcing of 8.5 W/m2 in the year 2100.	Source	Source
Relative humidity	The amount of water vapour in air as a percentage of the amount of water vapour needed for saturation at the same temperature.	Source
Scenario	CMIP5 scenarios are called representative concentration pathways (RCPs). They are representative in that they are one of several different scenarios that have similar radiative forcing and emissions characteristics.	Source	Source
Standard Deviation (SD)	The standard deviation (SD) is a measure of the amount of variation in a set of values. A low standard deviation indicates that the values tend to be close to the mean, while a high standard deviation indicates that the values are spread out over a wider range.	Source
SSP	Shared Socioeconomic Pathways (SSPs) are scenarios of projected socioeconomic global changes up to 2100. They are used to derive greenhouse gas emissions scenarios with different climate policies in the IPCC Sixth Assessment Report on climate change.	Source	Source
SSP5-8.5	A very high SSP (see separate entry) GHG emissions scenario: CO2 equivalent emissions triple by 2075.	Source
SSP5-4.5	An intermediate SSP (see separate entry) GHG emissions scenario: CO2 equivalent emissions around current levels until 2050, then falling but not reaching net zero by 2100.	Source

Glossary

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