2.1   Why observe the Earth?

An improved understanding of the Earth System – of its weather, climate, oceans, land, geology, natural resources, ecosystems, and natural and human-induced hazards – is essential if we are to better predict and mitigate against the expected global changes and the impacts on human civilisation.

Data collected and information created from Earth observations constitute critical inputs to the exploration of sustainable management of the Earth – providing evidence for informed decision-making, supporting the science that underpins strategies for global environmental governance, and for monitoring our progress on all geographical scales.

The significance of Earth observations in our future decision-making processes is apparent in both:

• the long term: where high-quality information must be gathered continuously over many years in support of vital climate studies to:
  - observe and characterise the current climate;
  - detect climate change, determine the rate of change and assist in attributing the causes of change;
  - identify the climate changes resulting from human activities;
  - validate climate models and assist in prediction of the future climate;
  - understand and quantify impacts of climate change on human activities and natural systems.
  
• the short term: where better information on every-day activities that support human existence will be a vital component of the global strategy for adaptation to a world with a rapidly increasing population, depleting natural resources, and experiencing the possible consequences of human-induced climate change; regions, countries, and industries can all be expected to be striving for improved efficiency and international competitiveness in agricultural production, freshwater management, land use management, atmospheric emissions control, natural resources exploration and management – including forests and fossil fuels, as well as in the prediction and mitigation of more frequent extreme weather events and natural disasters.

• improved understanding: with a multitude of global scale observations contributing to research into Earth System processes;
  
• evidence: Earth observations support the formulation of authoritative scientific advice – which is vital for governments when deciding to fund mitigation measures in response to global change, to react to impending crises in resource shortages, or to participate in agreements or conventions which require costly changes in national consumption patterns;
  
• monitoring and compliance: we might expect to see increasing emphasis on international policy measures and treaties such as the Kyoto Protocol emerging in the future; Earth observations will play an essential role in monitoring such agreements, ensuring that countries meet their legal obligations in relation to challenges like reductions in fossil fuel emissions, or pollution dumping.
  
  The economic implications of such agreements can be enormous for countries and highly visible and public measures to deter ‘cheating’ will be an important part of their success;
  
• management and mitigation: in support of increased efficiency in providing basic resources for future generations and in predicting and countering the worst effects of severe weather and natural disasters.

• comprehensive, by including observations and products gathered from all components required to serve the needs of participating members;
  
• coordinated, in terms of leveraging resources of individual contributing members to accomplish this system, whose total capacity is greater than the sum of its parts;
  
• sustained, by the collective and individual will and capacity of participating members.

• reducing loss of life and property from natural and human-induced disasters;
  
• understanding environmental factors affecting human health and well being;
  
• improving management of energy resources;
  
• understanding, assessing, predicting, mitigating, and adapting to climate variability and change;
  
• improving water resource management through better understanding of the water cycle;
  
• improving weather information, forecasting, and warning;
  
• improving the management and protection of terrestrial, coastal, and marine ecosystems;
  
• supporting sustainable agriculture and combating desertification;
  
• understanding, monitoring, and conserving biodiversity.

• agreements on system interoperability and data sharing: thereby increasing the number and type of observations available for analysis, as well as their spatial and temporal coverage, while only marginally increasing the cost of data provision. GEOSS provides a mechanism through which partial or full data sharing can be negotiated and a technical process by which it can be achieved;
  
• collective optimisation of the observation strategy: using cooperation to avoid redundancies in sampling, and gaining synergies and cost savings by using observational infrastructure for multiple purposes;
  
• cooperative gap filling: for example, in overcoming national difficulties in justifying certain observations for local benefit, and ensuring monitoring of regions outside the territory of individual nations (such as the open oceans and Antarctica);
  
• commitments to observational adequacy and continuity: a fundamental commitment to continuation of observations at an acceptable level of accuracy and coverage is essential for realisation of all the benefits envisaged for GEOSS.

The First Earth Observation Summit

2.3   Existing observing systems

As a ‘system of systems’ GEOSS will encompass a broad range of existing and planned networks of satellite-borne and Earth-based sensors, including ocean buoys, weather stations and atmospheric radiosondes – providing important parameters relating to land, ocean, and atmospheric processes. It has long been recognized that the range of observations, many of which are global, needed to understand and monitor Earth System processes and to assess the impact of human activities cannot be satisfied by a single programme, agency, or country. The main Earth observing networks are therefore typically international collaborative programmes by nature, and include:

World Weather Watch

The best known of these networks may be the World Weather Watch (WWW) of the World Meteorological Organization (WMO). The WWW is a unique achievement in international cooperation, providing a truly world-wide operational system to which virtually every country in the world contributes, every day of every year, for the common benefit of humankind.

The Global Observing System (GOS) of the WWW - which includes around 10,000 stations on land providing observations near the Earth’s surface, at least every three hours, of meteorological parameters such as atmospheric pressure, wind speed and direction, air temperature and relative humidity – ensures that every country has all the information available to generate weather analyses, forecasts and warnings on a day-to-day basis. The most obvious benefits of the GOS are the safeguarding of life and property through the forecasting, detection and warning of severe weather phenomena such as local storms, tornadoes, and tropical cyclones. GOS provides observational data for agricultural management, aviation safety, meteorology and climatology, including the study of global change. These observations also provide an international database of upper air observations for research purposes.

22 Global Atmosphere Watch (GAW) stations world-wide supplement these observations with information on ozone, other greenhouse gases, solar radiation, UV, and other atmospheric and meteorological parameters.

The Global Observing Systems

Within the last decade, the Global Observing System of the World Weather Watch has been complemented by the Global Ocean Observing System (GOOS) and the Global Terrestrial Observing System (GTOS) to produce a set of Global Observing Systems integrating in-situ and remotely sensed data from a range of international, regional and national observing systems and networks, with each focusing on a major component of the Earth System. The Global Climate Observing System (GCOS) has also been planned and initiated to integrate the observing needs for climate purposes.

GOOS: GOOS is a permanent global system for observations, modelling and analysis of marine and ocean variables to support operational ocean services worldwide. GOOS will provide accurate descriptions of the present state of the oceans, including living resources; continuous forecasts of the future conditions of the sea; and the basis for forecasts of climate change. GOOS is capitalising on existing ocean observing systems, such as:

• The TAO/TRITON array: comprises 70 moored buoys in the Tropical Pacific Ocean, which since its completion in 1994 has enabled real-time collection of high quality oceanographic and surface meteorological data for monitoring, forecasting, and understanding of climate swings associated with El Niño and La Niña. Data and graphic displays from the TAO/TRITON array are updated every day, and the data are freely available to the research community, operational forecasting community, and the general public.
  
• The Global Sea Level Observing System (GLOSS): an international programme coordinated by the Intergovernmental Oceanographic Commission (IOC) for the establishment of high quality global and regional sea level networks for application to climate, oceanographic and coastal sea level research. The main component of GLOSS is the 'Global Core Network' (GCN) of 290 sea level stations around the world for monitoring long term trends and accelerations in global sea level.

GTOS: GTOS is a programme for observations, modelling, and analysis of terrestrial ecosystems to support sustainable development. GTOS facilitates access to information on terrestrial ecosystems so that researchers and policy makers can detect and manage global and regional environmental change.

To achieve this GTOS is working towards the establishment of a “system of networks", formed by linking existing terrestrial monitoring sites and networks as well as planned satellite remote sensing systems. Thematic networks have been established for ecology, glaciers, and permafrost, and a hydrology network is in progress.

Since the sustainable development of forest resources is regarded as one of the most pressing environmental issues of our time, GTOS has established a panel on Global Observations of Forest Cover and Land Cover Dynamics (GOFC-GOLD) which aims to improve the quality and availability of observations of forests at regional and global scales and to produce useful, timely and validated information products from these data for a wide variety of users.

The Global Terrestrial Network (GT-Net) links the world's terrestrial research networks together. It serves as a framework for network managers to explore areas of common interest, harmonize research efforts and share data, information and experience.

GCOS: GCOS was established in 1992 to ensure that the observations and information needed to address climate-related issues are obtained and made available to all potential users. It is co-sponsored by WMO, the IOC, the United Nations Environment Programme (UNEP) and the International Council for Science (ICSU). GCOS is intended to be a long-term, user-driven operational system capable of providing the comprehensive observations required for monitoring the climate system, for detecting and attributing climate change, for assessing the impacts of climate variability and change, and for supporting research toward improved understanding, modelling and prediction of the climate system. It addresses the total climate system including physical, chemical and biological properties, and atmospheric, oceanic, hydrologic, cryospheric and terrestrial processes.

GCOS does not itself directly make observations nor generate data products. It stimulates, encourages, coordinates and otherwise facilitates the taking of needed observations by national or international organisations in support of their own requirements as well as of common goals. It provides an operational framework for integrating, and enhancing as needed, observational systems of participating countries and organisations into a comprehensive system focussed on the requirements for climate issues.

GCOS builds upon, and works in partnership with, other existing and developing observing systems such as the Global Ocean Observing System, the Global Terrestrial Observing System, and the Global Observing System and Global Atmospheric Watch of the WMO.

The Integrated Global Observing Strategy Partnership

The Integrated Global Observing Strategy Partnership (IGOS-P) was established in June 1998 by a formal exchange of letters among the 13 founding Partners for the definition, development and implementation of the Integrated Global Observing Strategy (IGOS). The principal objectives of the IGOS are to address how well user requirements are being met by the existing mix of observations, including those of the global observing systems, and how they could be met in the future through better integration and optimisation of remote sensing (especially space-based) and in-situ systems.
The IGOS serves as guidance to those responsible for defining and implementing individual observing systems. Implementation of the Strategy, like the establishment and maintenance of the components of an integrated global observing system, lies with those governments and organisations that have made relevant commitments, for example, within the governing councils of the observing systems' sponsors.

To aid the development of the Strategy, the Partners have adopted an incremental "Themes" approach based on perceived priorities. The Ocean Theme was the first IGOS Theme report to be approved and published – in January 2001. Since then a number of other Themes have been developed, or are in progress:

- Global Carbon Cycle;
- Geo-hazards;
- Global Water Cycle;
- Atmospheric Chemistry;
- Coastal Zones/Coral Reefs;
- Land;
- Cryosphere.

The IGOS Themes represent a strong foundation in international cooperation for the future efforts of GEOSS. Further information on IGOS-P and the IGOS Themes is presented in annex B.

A multitude of in-situ and space-based sensors contribute to Earth observations

IGOS Theme Reports

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