TOPC in situ

The Global Terrestrial Networks (GTNs) were conceived in the early 2000’s to monitor specific components of the land, particularly the hydrosphere (e.g. lakes, rivers, and other hydrological aspects) and the cryosphere (glaciers and permafrost), and link them to the climate system to understand how they are impacted by climate change and how they can in turn affect climate.

Name of Network

Areas of particular focus

GTN-related ECVs

Data information

Global Terrestrial Network for Glaciers (GTN-G)

Climate Change- 

Human Settlements– 

Land Resources- Sustainable Development- Global Sea Level Rise- Water Resources- 

Natural Hazards

Glaciers (Glacier Area, Glacier Elevation Change, Glacier Mass Change), Snow Cover, Ice Sheets and Ice Shelves, (Sea Level)

On global scale; regularly updated information on glacier distribution and changes; fluctuations database at WGMS with >3,500 glaciers since 19th century; inventory database at NSIDC with> 100,000 glaciers from mid 20th and early 21st centuries

Global Terrestrial Network for Hydrology (GTN-H)

Agriculture-

Biodiversity-

Climate Change-

Desertification-

Forests-Health-

Human Settlements-

Land Resources-

Sustainable Development-

Water and Sanitation

Precipitation, Water Vapour, River Discharge, Ground Water, Anthropogenic Water Use, Lakes, Soil Moisture

On global and regional scale (national monitoring programmes, science programmes); data from 1900 onwards (single variables, discontinuous)

Global Terrestrial Network for Lake (GTN-L)

Biodiversity-

Climate Change-

Human Settlements-

Land Resources-

Sustainable Development

Lakes ( Lake Water Level, Lake Water Extent, Lake Surface Water Temperature, Lake Ice Cover, Lake Ice Thickness, Lake Water-Leaving Reflectance)

Mainly on regional basis (>600 water level reference stations); monthly and annual data input

Global Terrestrial Network for Permafrost (GTN-P)

Biodiversity-

Climate Change-

Human Settlements-

Land Resources-

Sustainable Development

Permafrost (Permafrost Temperature, Active Layer Thickness, Rock Glacier Velocity)

Mainly on regional and national basis (80-site network under IPA’s Circumpolar Active Layer Monitoring (CALM); inventory and metadata for >200 boreholes of varying depths)

Global Terrestrial Network for Rivers (GTN-R)

Agriculture-

Climate Change-

Desertification-

Health-

Human Settlements-

Land Resources-

Sustainable Development-

Water and Sanitation

River Discharge, River Water Level

Mainly on regional basis (> 300 river discharge reference stations); daily or monthly data input; highly dependent on data provided by National Meteorological and Hydrological Services (NMHS) 

There are few other terrestrial networks, not called GTNs, but with global coverage and climate relevance, as well as connected with TOPC, like:

  • GGMN, the Global Groundwater Monitoring Network at the International Groundwater Resources Assessment Centre (IGRAC)
  • ISMN, International Soil Moisture Network