Previous Page Table of Contents Next Page


Identifying the gaps required to monitor
terrestrial processes that affect or are being
affected by climate change


Jointly established by the Global Climate Observing System (GCOS) and the Global Terrestrial Observing System (GTOS), the Terrestrial Observation Panel for Climate (TOPC) is involved in long-term projects monitoring terrestrial processes that affect or are being affected by climate change. During this biennium, the main focus of TOPC was on the second Report on the Adequacy of Global Climate Observing Systems, being prepared for the Conference of the Parties to the United Nations Framework Convention on Climate Change (UNFCCC). The process included assessing current observing capacities relative to the needs of the Convention; identifying gaps in the scientific requirements; and providing preliminary views on progress since the first Adequacy Report.


TOPC has identified over 80 terrestrial variables needing to be included in characterizing the climate system and for modelling and analysis of terrestrial ecosystems in support of sustainable development. Descriptions of these can be found on the GCOS and GTOS Web sites.

Global measurement of all variables is currently impossible because of technical, economic and logistical (e.g. physical access) constraints, but progress is being made. In the last few years, substantial progress has been made by the Global Terrestrial Networks for Glaciers (GTN-G) and Permafrost (GTN-P), and a new Global Terrestrial Network for Hydrology (GTN-H) will improve access to hydrological measurements and provide coordination of near-real-time data collection. The Terrestrial Ecosystem Monitoring Sites (TEMS) database is helping coordinate ecosystem observations, and the availability of CO2 and water flux measurements is improving as the FLUXNET programme expands. In addition to these in situ developments, a number of space agencies are now providing relevant observations on an increasingly routine basis.

Of the 80 or more variables currently considered necessary for TOPC, the second Adequacy Report highlighted river discharge, water use, groundwater, lake levels, snow cover, glaciers and ice caps, permafrost and seasonally frozen ground, albedo, land cover, fraction of absorbed photosynthetically active radiation (FAPAR), leaf-area index (LAI), biomass and fire disturbance, for early implementation, because of their significance for UNFCCC. For these parameters, the technology to make adequate measurements is effectively proven, and an infrastructure already exists for making operational measurements. The other 70-plus variables, including soil physical properties and soil moisture, are no less important, and TOPC - working within the GCOS and GTOS frameworks - will strive to improve the adequacy of these observations. In this respect, reference sites measuring such variables (e.g. FLUXNET) need to be sustained and strengthened, with a view to incorporating some of these additional variables into GCOS and GTOS.


In spite of the modest advances achieved, it is all too clear that the terrestrial component of the global observing systems remains the least well developed. Yet terrestrial data for climate science, impact and mitigation studies and for sustainable development is significantly increasing. The limited involvement of non-Annex 1 countries in the collection, analysis and dissemination of terrestrial observations is a particular cause for concern, as is the lack of an appropriate intergovernmental organization with a mandate to prepare regulatory and guidance material relating to terrestrial observations. The scientists who have made their expertise available to TOPC will continue to identify ways to redress these shortcomings, and sincere thanks are given for all their efforts.

Box 1. The essential atmospheric variables required over land, ice and sea

1. Atmospheric variables
Air temperature
Air pressure
Wind speed and direction

Upper atmosphere
Upper air temperature
Wind speed and direction
Earth radiation budget
Solar Irradiance

Atmospheric composition
Carbon dioxide
Other long-lived greenhouse gases

2. Ocean variables
Sea-surface temperature
Sea-surface salinity
Wave characteristics
Sea ice
Ocean colour (for biological activity)
Air/sea exchange (fluxes) of water, momentum, heat and gases especially carbon dioxide

Ocean tracers

3. Terrestrial
Glaciers and ice caps
Permafrost layer
River discharge
Water use
Lake levels
Fraction of absorbed photosynthetically active radiation
Leaf Area Index
Surface Temperature
Fire disturbance
Land cover

Previous Page Top of Page Next Page