The importance of Earth observations

		Why observe the Earth? The expected global changes to the Earth system and the associated impacts on human civilisation will make information on our environment increasingly vital for the effective and sustainable future management of the Earth. This is true 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 which 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 against increased extreme weather events and natural disasters.

This information will be required on all scales – from local to global. We can anticipate that it might be used by intergovernmental bodies for decision-making and global governance to ensure sustainability, and also more locally as countries, regions, and industries compete for larger shares of smaller reserves of natural resources in order to support their growing populations and economic ambitions. Such information takes many forms, spanning data on population, demographics, economics, and environmental indicators. Observations of planet Earth itself, of man’s environment, might be regarded as the most important of all, as the context for all decisions.

Earth observing systems help to provide data in support of a wide range of information needs, on Earth parameters which are central to:

• 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 emerge in future; Earth observations will form 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.

The status of Earth observing programmes

Earth observing systems encompass a broad range of different 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 recognised 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 program, agency, or country. The main Earth observing networks are therefore typically international collaborative programmes by nature.

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 mankind.

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: of 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 287 sea level stations around the world for monitoring long term trends and accelerations in global sea level.

There are numerous other contributors to GOOS, including: voluntary observing ships providing measurements of upper ocean and meteorological parameters; the Global Temperature and Salinity Profile Programme; and the Global Coral Reef Monitoring Network.

GTOS: GTOS aims to provide the scientific and policy making community with access to the data necessary to manage the change in the capacity of terrestrial ecosystems to support sustainable development. 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 (GOFC) which aims to provide regional and global datasets containing information on location of different types of forests; major changes in forests resulting from logging, agricultural conversion, fire, and other environmental stresses.

GTOS, in collaboration with a number of partners, has also developed the Terrestrial Carbon Observations (TCO) initiative which responds to the need by the policy and scientific communities for improved knowledge of the role of the terrestrial carbon sources and sinks. It aims to provide information on the spatial and temporal distribution of carbon sources and sinks in the terrestrial biosphere using data obtained through systematic ground and satellite-based observations.

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 the 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.

IGOS-P: The Integrated Global Observing Strategy Partnership

Earth observations from satellite have revolutionized human perspectives and understanding of the planet and are highly complementary to those collected on or near the Earth’s surface by in-situ systems - such as ocean buoys or weather stations. In-situ measurements may be necessary for some high accuracy local observations, for the calibration of observations made by satellite and for models of the Earth system. Satellites are often necessary for the provision of synoptic, wide-area information required to put in-situ measurements in the global context required for the observation of many environmental and climatic phenomena.

In order to facilitate the necessary harmonisation and achieve maximum cost-effectiveness for the total set of space-based and in-situ observations the IGOS Partnership was established in June 1998 by a formal exchange of letters among the 13 founding Partners for the definition, development and implementation of an Integrated Global Observing Strategy (IGOS). IGOS brings together the major Earth and space-based systems for global environmental observations of the atmosphere, oceans and land in a strategic planning process.

The IGOS Partners recognise that many of their respective observing systems are in need of improvements. Some lack the necessary long-term continuity, and all require strengthened links between the space-based and Earth-based components, as well as between the observing programmes and the processes of scientific and environmental policymaking which define the information priorities.

Further information on IGOS-P is presented in part annex B.

Satellite Earth observations

Since the first TV images of the Earth from space were transmitted by the TIROS-1 satellite back in 1960, mankind has recognised the benefits of this unique and global perspective of our home planet. There are currently over 60 Earth observation satellite missions operating, and around 90 more missions, carrying over 300 instruments, planned for operation during the next 15 years or so by the world’s civil space agencies. An increasing number of commercial Earth observation satellites, which are funded, launched, and operated by industry, are also emerging to address important spatial information markets.

Space-based, remote sensing observations of the atmosphere-ocean-land system have evolved substantially since the first operational weather satellite systems were launched. Over the last decade Earth observation satellites have proven their capabilities to accurately monitor nearly all aspects of the total Earth system on a global basis; a capability unmatched by ground-based systems that are limited to land areas and cover only about 30% of the planetary surface. Currently, satellite systems monitor the evolution and impact of the El Niño, weather phenomena, natural hazards, and extreme events such as floods and droughts, vegetation cycles, the ozone hole, solar fluctuations, changes in snow cover, sea ice and ice sheets, ocean surface temperatures and biological activity, coastal zones and algae blooms, deforestation, forest fires, urban development, volcanic activity, tectonic plate motions, and others. These various observations are used extensively in real-time decision-making and the strategic planning and management of industrial, economic, and natural resources.

The proliferation of Earth observation satellites reflects their unique abilities and benefits, such as:

• inherent wide area observation capability: offering synoptic views of large-scale phenomena, and placing in-situ measurements in the global context required for the observation of many environmental and climatic phenomena;
• non-intrusive observations: allowing collection of data to take place without compromising national sovereignty in the way that ground-based measurements or airborne remote sensing might; this is an advantage in the context of use within international environmental treaties;
• uniformity: in that the same sensor may be used at many different places in the world (some of which are inaccessible, making in-situ measurements infeasible);
• rapid measurement capability: allowing sensors to be targeted at any point on Earth, including remote and hostile areas;
• continuity: with single sensors or series of sensors providing long time series of data which is suitable for climate studies.

Present-day applications of satellite data are widespread and cover research, operational and commercial activities. On a global scale, space-based systems make a considerable contribution to the collection of data required for climate change research, in providing high-quality, consistent, global datasets over long time periods for use in understanding the climate system, detection of potential anthropogenic change, validating climate models, and predicting future change.

Satellites are capable of obtaining global spatial coverage, particularly over the vast expanses of the oceans, sparsely populated land areas (eg deserts, mountains, forests, and polar regions), and the mid and upper troposphere and stratosphere. Satellites provide unique measurements of solar output, the Earth’s radiation budget, vegetation cover, ocean biomass productivity, atmospheric ozone, stratospheric water vapor and aerosols, greenhouse gas distributions, sea level and ocean interior, ocean surface conditions and winds, weather, and tropical precipitation, among others.

		Earth observation satellite applications are not limited to meteorology, climate and environmental studies; Earth observation satellites deliver information to a broad range of sectors, providing significant economic, societal, and humanitarian benefits as a result, including: agriculture and forestry services utilise satellite data to provide, amongst other products, mapping information, crop health statistics, yield predictions, harvest optimisation, and estimated rainfall amount; resource mapping utilising very high resolution satellite data, when combined with conventional survey techniques, provides information needed to locate both renewable and non-renewable resources, such as mineral deposits, and a cost-effective means of mapping large, sometimes inaccessible regions; hazard monitoring and disaster assessment schemes are in place which incorporate satellite data to provide wide area coverage of, amongst other things, volcano plumes and areas stricken by drought or earthquake; commercial fishing industries routinely utilise satellite-derived fishing assessments to optimise their operations; ocean wave and current information is used by offshore exploration companies and shipping to improve operational safety and route-planning; mapping and urban planning agencies exploit satellite imagery for generation of maps and digital elevation models.

CEOS is recognised as the most important framework for coordination across all spaceborne Earth observation missions. CEOS also plays an important role within the IGOS Partnership to ensure that future space-based observing systems and Earth-based observing systems will be suitably harmonised to address the most critical requirements.

The case studies presented in Part II highlight the importance of Earth observations, in particular satellite observations, in providing essential information to address some of the key issues facing mankind at the start of the 21st century.