# What are climate indices and indicators?

**URL:** <https://forum.ecmwf.int/t/what-are-climate-indices-and-indicators/1503>\
**Category:** C3S - Datasets and Usage\
**Tags:** c3s, ecde, sis\
**Created:** [6 February 2023 09:27 UTC](https://forum.ecmwf.int/t/what-are-climate-indices-and-indicators/1503 "2023-02-06T09:27:47Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Vivien\_MAVEL](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/v/ecccb3/32.png) [@Vivien\_MAVEL](https://forum.ecmwf.int/u/Vivien_MAVEL)\
**Post date:** [6 February 2023 09:27 UTC](https://forum.ecmwf.int/t/what-are-climate-indices-and-indicators/1503/1 "2023-02-06T09:27:47Z")

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The terminology concerning climate indices and indicators differs, with no consistent definitions in the literature. Climate indices generally refer to the diagnostic quantity of one or several meteorological and/or hydrological variables including possible thresholds, for different temporal and spatial aggregations (cf.&nbsp;[Kjellström et al., 2016](https://doi.org/10.1016/j.cliser.2016.06.004)), whereas indicators refer to the function of a variable to represent a phenomenon (cf.&nbsp;[Hinkel, 2011](https://doi.org/10.1016/j.gloenvcha.2010.08.002)), such as climate change hazards, impacts or vulnerabilities. Climate indices can be used as indicators to understand phenomena and to support adaptation planning and decision making ([Dubois et al., 2016](https://doi.org/10.1186/s40322-016-0034-y),&nbsp;[WMO, 2014](https://gfcs.wmo.int/sites/default/files/Components/Capacity%20Development/GFCS-ANNEXES-CD-FINAL-14143_en.pdf)), and in such cases their definitions are the same. However, a climate index is not intuitively or necessarily an indicator.