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About the ECV ’Glaciers and Icecaps’

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Glaciers and icecaps have been identified as key indicators of climate change. This is due to their sensitive reaction to small changes in climate. These changes have two components:

(1) Due to the constant temperature of glacier ice (close to 0 ̊C in most cases), any excess energy is used for melting the ice. This results in a strong correlation of the annual mass budget to the meteorological forcing (e.g. temperature, precipitation, global radiation).
(2) The dynamic and hence more long-term response of a glacier to climatic changes is reflected in pronounced length changes. Such changes are well visible by a large public and makes glaciers to unique demonstration objects of climate change impacts.
To assess glacier changes quantitatively or to upscale the field-based measurements from selected glaciers to the entire sample (e.g. of a mountain range), a glacier inventory is required. Without such a sound baseline inventory (digital vector outlines) glacier specific changes (either in length, area or volume) cannot be determined. Moreover, in the tiered strategy of the Global Terrestrial Network for Glaciers (GTN-G), creation of repeat glacier inventories from satellite data form Tier 5 observations. The application of satellite data for glacier mapping is thus also recommended in the framework of GCOS.
An important point in regard to GCOS is the terminology used. According to GCOS, there are the two Icesheets (in Greenland and Antarctica) and all the other ice masses are named glaciers and icecaps. This is also how the ECVs are defined This is historically different in some countries, where also the ice sheets are named glaciers and the distinction to glaciers and icecaps in the sense of GCOS is made by naming them ‘mountain glaciers and icecaps’ or ‘small glaciers’. The latter is indeed confusing as these ‘small glaciers’ span 6 orders of magnitude in size and a size related terminology can no longer be used. The term ‘mountain glaciers’ is somewhat better in this regard, but mountain glacier is also the name of a specific glacier type in the primary classification for glaciers (like valley glaciers or cirques). In the framework of the Glaciers_cci project, we will thus stick to the GCOS terminology.