Geoinformation, monitoring and assessment Environment

Posted September 1996

Briefing on the Global Terrestrial Observing System (GTOS)

THE FOLLOWING PROPOSAL for a Global Terrestrial Observing System (GTOS) has been prepared by the ad hoc Scientific and Technical Planning Group appointed in late 1993 by five co-sponsors - the Food and Agriculture Organization of the United Nations (FAO), the International Council of Scientific Unions (ICSU), the United Nations Educational, Scientific and Cultural Organization (UNESCO), the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO). Its work has been helped by numerous international colleagues, notably those who attended workshops or provided individual inputs, and/or took part in the external review of the penultimate draft. It has been prepared in accordance with the terms of reference given by the co-sponsors. It draws primarily on the findings of three GTOS Working Groups (on the observing system, data management and support to developing countries), on the joint GCOS/GTOS Terrestrial Observation Panel, and on the report of the Fontainebleau workshop (Heal et al 1993) which was the first major step in the GTOS preparatory process.

The Planning Group has made five main assumptions in preparing this proposal:

  1. That the objective is to provide a strategic plan. Thus it is framed around examples, without attempting to provide the detail which will have to be introduced in operational plans to be developed later.
  2. That balanced consideration must be given to national and regional development needs and to the needs of the international scientific community.
  3. That GTOS would be implemented progressively over a number of years, with relatively low expenditure in the early stages and the use of pilot activities.
  4. That GTOS would be built largely from existing research and observational activities.
  5. That it should be designed to complement the other global observing systems, GCOS and GOOS, with the maximum use of common procedures. Examples are for data management and space observations, and in joint modules for the land-climate and land-coastal zone interfaces.

Why do we need GTOS?

Terrestrial ecosystems are the foundation of social and economic well-being because they are the main source of food and other basic needs. They also play a vital role in the regulation of atmospheric, biogeochemical and hydrological processes. Yet we do not know how, where and over what time frame humankind is endangering terrestrial and freshwater ecosystems including coastal zones. We do not even fully understand the role of these ecosystems in global processes. In particular, we cannot answer five inter-related questions central to sustainable development:

  1. Food and renewable resources: can the land feed another 5-6 billion people?
  2. Fresh water: where, when and by how much will demand exceed supply so as to cause supra-national problems?
  3. Toxins: do they or will they cause major trans-boundary threats to human and environmental health and the capacity of ecosystems to detoxify them, and if so where and when?
  4. Biological diversity: where and what type of biological resources are threatened with loss, and where will these losses irreversibly damage ecosystem function or socio-economic progress?
  5. Terrestrial ecosystems: where, when and how much will they change in response to global atmospheric, climate and land-use changes, and how will this impair their capacity to sustain life?

Such questions have led nations to sign the climate change, biodiversity and desertification conventions, to adopt Agenda 21 and other actions relating to deforestation and environmental protection in general. Many of these conventions and actions require better terrestrial observation data, but the international community has yet to establish the means of obtaining them.

We lack spatially and temporally comprehensive data on the physical environment, on terrestrial ecosystem processes, and on the socio-economic driving forces that are changing them. There is no global mechanism for the collection of compatible data, and so there is a critical gap in the current observing systems for climate (GCOS) and the oceans (GOOS). Consequently, we cannot determine whether major policy changes are needed now and at high economic and social costs, or if both the impacts and the correction processes are longer term.

Without GTOS, we will continue to see major investment in non-compatible systems, a consequent data or data integration gap, and a lack of support for international conventions. With GTOS we will be better placed to identify pressure points and determine how best to use Earth's resources to achieve sustainable development.

What will GTOS do?

v Given the above questions, the central mission of GTOS should be to provide the data needed to detect, quantify, locate and give early warning of changes (especially reductions) in the national or global capacity of terrestrial ecosystems to support sustainable development and improvements in human welfare. It should also help advance our understanding of such changes.

These objectives should be accomplished through an integrated and equitable partnership of data providers and users that meets both the short-term needs of national governments and the longer-term needs of the global change research community. GTOS's focus should be on five key development issues of global concern:

  1. Land use change, land degradation and the sustainability of managed ecosystems
  2. Water resources management
  3. Pollution and toxicity
  4. Loss of biodiversity
  5. Climate change.

GTOS should be directed at specific needs and at overcoming the deficiencies in the existing global and regional observational systems. It should not be directed at data collection for its own sake, and research should not be a major function, though it should help to identify research needed to improve observational and information systems. But GTOS should support research programmes and collaborate with IGBP, DIVERSITAS and others in the assembly of appropriate data sets.

To make a unique contribution to our ability to manage the planet wisely, GTOS must:

How GTOS will be organized

GTOS should operate on the basis of a partnership of partnerships formed largely from existing sites and networks (plus others like WHYCOS which are in the process of development), and on present and planned remote sensing systems. Implementation should be essentially bottom-up, with GTOS providing the framework within which the output from the space-based Earth Observing Systems and the existing databases such as GEMS/Water and the Global Runnoff Data Centre (GRDC) can be integrated with in situ observations. Actions should be both direct and catalytic. The core of the proposed system is a hierarchical sampling strategy, with four tiers of decreasing complexity and frequency of in situ observations and a fifth tier to provide global coverage largely through satellite remote sensing. At one extreme, detailed data is collected almost continuously at a few large sites and, at the other, a large number of small systematically located sites are sampled at intervals of five years.

The establishment of such a hierarchy and the data management and exchange system to support it should be undertaken by a Central Coordinating Unit (CCU) with some international secretariat functions. The CCU should be linked to regional and national bodies of variable form and structure, since they should evolve in response to user and provider initiatives rather than being part of a pre-set structure. The CCU should have two guidance mechanisms - a Steering Committee for strategic considerations and a Technical Advisory Group - plus some 40-50 corresponding members who would contribute to and/or comment in writing on proposals for the implementation of GTOS. In addition, ad-hoc or permanent supporting bodies should be established to guide the development of operational plans for particular functional or thematic components of the programme. As far as possible, these bodies should be joint activities with GCOS and GOOS.

Guiding principles

Guiding principles for GTOS's data management system should be common to or compatible with those for GOOS and GCOS. The data management system should be constructed, as far as possible, using off-the-shelf application tools and existing or planned communication systems. It should be sufficiently flexible to incorporate or link to data sets originating outside GTOS, since GTOS may not hold much of the data but provide an access mechanism for dispersed data sets. Data links between the centre, the regions and other data centres would be primarily electronic with magnetic and optical disks as a parallel alternate system, especially during the transitional period.

How much cost, how much gain?

A substantial proportion of the required infrastructure is already in place and funded, so the incremental costs of the proposals will be low compared with those for a totally new system. The operating costs of existing terrestrial observing systems are over US$300 million. GTOS, on the other hand will initially cost less than one million dollars per year possibly rising to about US$3.4 million after five years.

The cost of launching GTOS should be phased over five or ten years, and built up in a modular fashion. This would permit multiple financial mechanisms to operate, with individual donors supporting those modules that are consistent with their issues or regional priorities. In the early stages, average annual operating costs could be some US$700-850k for the CCU, guidance bodies, and initial actions to link existing monitoring sites and networks. During the first five years the operating costs of strengthening and extending these activities, and some capital costs would rise to about US$5 million. In the medium-term total costs could rise to around US$12 million if the resources can be found to extend regional activities, improve some existing sites and to fill gaps in the spatial coverage of monitoring sites.

The proposed activities would improve the returns from major investments in independent in situ observation systems by providing complimentary regional or global data, and in earth observation satellites and remote sensing devices by providing comprehensive ground truthing. The drawing together of existing but disparate databases, sites and networks into a common framework with the standardization or harmonization of measurements and terminology would increase substantially the usage and value of such data and information. The GTOS activities would support global change research programmes by contributing to the refinement, calibration and validation of the GCM, ecosystem and carbon cycle models.

The provision of globally comprehensive and timely data on anthropogenic impacts on terrestrial ecosystems will help UN agencies - and the secretariats of the Climate, Biodiversity, Desertification, Ozone and other conventions and treaties - to fulfil their mandates. It will also help them and multi-lateral donors advise their member governments on priorities for sustainable development.

National benefits include support to planning, natural resource management and environmental agencies, opportunities for staff training, promotion of contacts and interactions between scientists of participating nations, and greater access both to new technology for environmental assessment and management and to financial support catalyzed by GTOS. The strengthening of national terrestrial ecosystem monitoring should make a contribution to more general socio-economic development by helping to identify opportunities for - and undesirable consequences of - development projects at all scales. GTOS would help countries add the global dimension to national environmental strategy formulation, obtain data for national global research programmes, develop better policy planning tools and meet reporting obligations under the post Rio conventions.

Where do we go from here?

The Planning Group recommends the progressive implementation of GTOS, starting in 1996 with a five-year programme. Priority in 1996 should be given to:

Over the following four years, a start should be made on upgrading existing sites and filling the most urgent of the gaps in the geographic, biome or crop coverage of natural and managed terrestrial ecosystems, and promoting regional bodies.

Visit the GTOS Web Page at

For further information, contact:
GTOS Secretariat
Viale delle Terme di Caracalla
00100 Rome, Italy

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