Liebig 2/6/07 11:09 AM Page 8

The Changing Earth Changing Earth Volker Liebig, Einar-Arne Herland & Stephen Briggs Directorate of Earth Observation Programmes

Hartmut Grassl Chairman of the Earth Science Advisory Committee

lobal change is the most fundamental challenge facing humanity today. As we Gbegin to understand more about the Earth as a system, it is clear that human activity is having a profound and negative impact on our environment. For example, our understanding of carbon dioxide as a greenhouse gas and the strong link between atmospheric carbon dioxide concentrations and temperature both point to human activity leading to a warmer world, unlike anything seen over the last million years. A better knowledge of the Earth System and of the effect of increasing human activity is crucially important for managing our environ- ment and our ability to derive sustainable benefit.

Introduction Since observing the Earth from space New Scientific became possible more than 40 years ago, satellite missions have become central to monitoring and learning about how the Challenges for ESA’s Earth works. When ESA established its Living Planet Programme in the mid- 1990s, a new approach to satellite Living Planet observations for Earth science began, with focused missions defined, developed and operated in close Programme cooperation with the scientific commun-

esa bulletin 129 - february 2007 9 Liebig 2/6/07 11:09 AM Page 8

The Changing Earth Changing Earth Volker Liebig, Einar-Arne Herland & Stephen Briggs Directorate of Earth Observation Programmes

Hartmut Grassl Chairman of the Earth Science Advisory Committee

lobal change is the most fundamental challenge facing humanity today. As we Gbegin to understand more about the Earth as a system, it is clear that human activity is having a profound and negative impact on our environment. For example, our understanding of carbon dioxide as a greenhouse gas and the strong link between atmospheric carbon dioxide concentrations and temperature both point to human activity leading to a warmer world, unlike anything seen over the last million years. A better knowledge of the Earth System and of the effect of increasing human activity is crucially important for managing our environ- ment and our ability to derive sustainable benefit.

Introduction Since observing the Earth from space New Scientific became possible more than 40 years ago, satellite missions have become central to monitoring and learning about how the Challenges for ESA’s Earth works. When ESA established its Living Planet Programme in the mid- 1990s, a new approach to satellite Living Planet observations for Earth science began, with focused missions defined, developed and operated in close Programme cooperation with the scientific commun-

esa bulletin 129 - february 2007 9 Liebig 2/6/07 11:09 AM Page 10

Earth Observation Changing Earth

emphasised the need for an updated science strategy. The recent Stern report ( http://www.hm-treasury.gov.uk/ independent_reviews/stern_review_economics _climate_change/stern_review_report.cfm) assesses the impact of climate change on the global economy and concludes that while ‘business as usual’ might have very high costs, preventive measures implemented from today would have a relatively minor impact on the economy. Another recent study, on the socio- economic benefits of GMES, performed by Pricewaterhouse Coopers, concluded that the benefits of GMES are potentially very large, but they require political will in order to be efficiently implemented. The updating of the strategy was The strategy report is available as ESA publication SP-1304 In 2005 a committee of six external scientists and six Earth recently undertaken under the guidance Science Advisory Committee members undertook a thorough of the Agency’s Earth Science Advisory ity. A comprehensive strategy was review of the scientific value of ESA’s Earth Observation Envelope Committee and in wide consultation Selected aspects of global change (atmospheric composition, land cover, temperature, biodiversity, nitrogen fixation and human population) based on information compiled by the International Geosphere- Programme. The review report was overall extremely positive in Biosphere Programme formulated for implementing the evaluating the science output of the Programme and contained with the scientific community. Programme, which has resulted in the 11 recommendations to the Agency. These are all being Looking to the future, the new selection of six Earth Explorer missions implemented strategy aims to assess the most user communities, in close cooperation The Challenges of a Changing World of habitat, forest degradation and loss covering a broad range of science issues. important Earth science questions to be with our international partners. Records show that the Earth has always of wetlands all remove ecological niches Six candidates for the seventh mission synergy has long been demonstrated by addressed in the years to come. It Underpinning the new strategy is a set undergone major changes. Change is a occupied by species. Over-exploitation have been identified. At the same time, the development and scientific exploit- outlines the observational challenges of ambitious objectives, which includes: natural property of the Earth System, of the natural world, as by over-fishing significant advances have been made in ation of meteorological satellites, which that these raise, and the contribution but there is mounting evidence that and over-grazing, will lead to loss of Earth science using data products and continue to be an important part of the that the Agency can make through the – launching a steady flow of missions those imposed on the system during the renewable resources and biodiversity. services from the Agency’s ERS and Living Planet Programme. programme. These challenges will guide addressing key issues in Earth science; last 150 years cannot be compared with Still more stress, and even a health Envisat satellites. Recent developments and advances ESA’s efforts in providing essential – providing an infrastructure to allow any previous changes. In the last hazard, is placed on populations by At the Ministerial Council meeting in already made in the Earth sciences have Earth observation information to the satellite data to be quickly and century, mankind has driven the water and air pollution, either through Berlin in December 2005, ESA Member efficiently exploited in areas of greenhouse-gas concentrations far catastrophic events such as oil-spills and States reconfirmed their commitment to research and applications; beyond the maxima reached during the explosions at chemical plants, or more the concept of the Living Planet – providing a unique contribution to last million years. It has become insidious effects from the long-term use Programme by funding the third phase global Earth observation capabilities, responsible for 70% of the nitrogen and of insecticides, run-off of nitrogen- covering the period 2008–2012. In complementing satellites operated by 95% of the phosphorus cycle on Earth, based fertilisers and air pollution in addition, they approved the initiation of other agencies and in situ observing and has reduced tropical forest areas by metropolitan areas. In addition to these the space component of the Global systems; 50%. To determine whether these threats to the natural world, managed Monitoring for Environment and – providing an efficient and cost- human-induced recent changes could systems are also subject to processes Security (GMES), in close cooperation effective process for rapidly transla- ultimately destabilise the Earth System, such as loss of fertility, desertification, with the European Commission. ting science priorities into space both natural system variability and the water stress and erosion. Although this programme is designed to missions, adequately resourced with consequences of human activities have Two issues are at stake here. The first provide data that underpin operational associated ground support; to be fully understood and quantified. is sustainability. Human life draws services, it will also contribute signifi- – developing innovative approaches to This is the scientific basis required for heavily on resources provided by the cantly to Earth science, in particular instrumentation. the sustainable future management of living world: clean air, fresh water, food, through the collection of long time series the Earth System as a whole. clothing and building materials. In the of observations. In turn, the Earth The overall vision for ESA’s Earth While the large-scale processes of interest of future generations, we have to Explorers will provide new understanding observation activities is to play a central global change are increasingly stressing find ways to guarantee that the that paves the way for new operational role in developing the global capability the biosphere, other less wholesale functioning of the life-support system services. In this sense, the Living Planet to understand our planet, predict changes may have equally serious and the ability of the ecosystems to Programme comprises complementary The ESA SP-1304 report emphasises the changes and mitigate the negative effects consequences for the viability of deliver goods and services are elements of research and operations. This different components of global change on its population. ecosystems. The loss and fragmentation maintained.

10 esa bulletin 129 - february 2007 www.esa.int www.esa.int esa bulletin 129 - february 2007 11 Liebig 2/6/07 11:09 AM Page 10

Earth Observation Changing Earth

emphasised the need for an updated science strategy. The recent Stern report ( http://www.hm-treasury.gov.uk/ independent_reviews/stern_review_economics _climate_change/stern_review_report.cfm) assesses the impact of climate change on the global economy and concludes that while ‘business as usual’ might have very high costs, preventive measures implemented from today would have a relatively minor impact on the economy. Another recent study, on the socio- economic benefits of GMES, performed by Pricewaterhouse Coopers, concluded that the benefits of GMES are potentially very large, but they require political will in order to be efficiently implemented. The updating of the strategy was The strategy report is available as ESA publication SP-1304 In 2005 a committee of six external scientists and six Earth recently undertaken under the guidance Science Advisory Committee members undertook a thorough of the Agency’s Earth Science Advisory ity. A comprehensive strategy was review of the scientific value of ESA’s Earth Observation Envelope Committee and in wide consultation Selected aspects of global change (atmospheric composition, land cover, temperature, biodiversity, nitrogen fixation and human population) based on information compiled by the International Geosphere- Programme. The review report was overall extremely positive in Biosphere Programme formulated for implementing the evaluating the science output of the Programme and contained with the scientific community. Programme, which has resulted in the 11 recommendations to the Agency. These are all being Looking to the future, the new selection of six Earth Explorer missions implemented strategy aims to assess the most user communities, in close cooperation The Challenges of a Changing World of habitat, forest degradation and loss covering a broad range of science issues. important Earth science questions to be with our international partners. Records show that the Earth has always of wetlands all remove ecological niches Six candidates for the seventh mission synergy has long been demonstrated by addressed in the years to come. It Underpinning the new strategy is a set undergone major changes. Change is a occupied by species. Over-exploitation have been identified. At the same time, the development and scientific exploit- outlines the observational challenges of ambitious objectives, which includes: natural property of the Earth System, of the natural world, as by over-fishing significant advances have been made in ation of meteorological satellites, which that these raise, and the contribution but there is mounting evidence that and over-grazing, will lead to loss of Earth science using data products and continue to be an important part of the that the Agency can make through the – launching a steady flow of missions those imposed on the system during the renewable resources and biodiversity. services from the Agency’s ERS and Living Planet Programme. programme. These challenges will guide addressing key issues in Earth science; last 150 years cannot be compared with Still more stress, and even a health Envisat satellites. Recent developments and advances ESA’s efforts in providing essential – providing an infrastructure to allow any previous changes. In the last hazard, is placed on populations by At the Ministerial Council meeting in already made in the Earth sciences have Earth observation information to the satellite data to be quickly and century, mankind has driven the water and air pollution, either through Berlin in December 2005, ESA Member efficiently exploited in areas of greenhouse-gas concentrations far catastrophic events such as oil-spills and States reconfirmed their commitment to research and applications; beyond the maxima reached during the explosions at chemical plants, or more the concept of the Living Planet – providing a unique contribution to last million years. It has become insidious effects from the long-term use Programme by funding the third phase global Earth observation capabilities, responsible for 70% of the nitrogen and of insecticides, run-off of nitrogen- covering the period 2008–2012. In complementing satellites operated by 95% of the phosphorus cycle on Earth, based fertilisers and air pollution in addition, they approved the initiation of other agencies and in situ observing and has reduced tropical forest areas by metropolitan areas. In addition to these the space component of the Global systems; 50%. To determine whether these threats to the natural world, managed Monitoring for Environment and – providing an efficient and cost- human-induced recent changes could systems are also subject to processes Security (GMES), in close cooperation effective process for rapidly transla- ultimately destabilise the Earth System, such as loss of fertility, desertification, with the European Commission. ting science priorities into space both natural system variability and the water stress and erosion. Although this programme is designed to missions, adequately resourced with consequences of human activities have Two issues are at stake here. The first provide data that underpin operational associated ground support; to be fully understood and quantified. is sustainability. Human life draws services, it will also contribute signifi- – developing innovative approaches to This is the scientific basis required for heavily on resources provided by the cantly to Earth science, in particular instrumentation. the sustainable future management of living world: clean air, fresh water, food, through the collection of long time series the Earth System as a whole. clothing and building materials. In the of observations. In turn, the Earth The overall vision for ESA’s Earth While the large-scale processes of interest of future generations, we have to Explorers will provide new understanding observation activities is to play a central global change are increasingly stressing find ways to guarantee that the that paves the way for new operational role in developing the global capability the biosphere, other less wholesale functioning of the life-support system services. In this sense, the Living Planet to understand our planet, predict changes may have equally serious and the ability of the ecosystems to Programme comprises complementary The ESA SP-1304 report emphasises the changes and mitigate the negative effects consequences for the viability of deliver goods and services are elements of research and operations. This different components of global change on its population. ecosystems. The loss and fragmentation maintained.

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Earth Observation Changing Earth

The second is biodiversity. On our evaluating the models also requires data. own planet, we are pursuing a course Hence our total knowledge about the that is reducing the richness of life, and system is contained in our models, our diminishing the world that we will hand measurements and how we put them on to future generations. The fact that together. Improved understanding of life on Earth has existed continuously how to represent the dynamics of the for several billion years is due to its Earth processes, together with the diversity. It is very likely that in the explosion in computing power, has course of the present reduction of allowed the construction of ever more biodiversity, the Earth System’s powerful computer codes capable of extraordinary stability in the face of solving the coupled equations that make external forcing is also being reduced. up an Earth System model with a spatial Global variations in the Earth System resolution as high as about 10 km. An display very large regional differences. equally influential development has been The human inputs to the system also the explosion in the size of databases, show widely different patterns of change both from models and satellite data, and across the globe, be it deforestation, Information that can be acquired from space relevant to Solid Earth and Earth System Science the interconnectivity of computer manipulation of hydrological resources, Envisat SCIAMACHY measurements of column-averaged methane volume mixing ratio (VMR), in parts per billion, averaged over the systems and databases. Pinning these occurrence of fires, fossil-fuel burning constitutes the scientific discipline the spatial patterns and overall mean of period August – November 2003 on a 1 x 1º horizontal grid. At least five (and up to 150) measurements are taken for each grid cell. together has led to enormous advances in or land-use management. What seems known as ‘Earth System Science’. global vegetation productivity. Only a few observations are available over the ocean, since low ocean reflectivity substantially reduces the retrieval quality. the methods of model-data fusion and Occasionally, Sun-glint or clouds at low altitudes do allow measurements over the ocean. (University of Heidelberg/ESA) clear is that these highly variable local Major progress in many Earth science Spectacular new evidence from Antarctic data assimilation. These have been driven and regional types of environmental disciplines has revealed that traditionally ice cores has shown that, over long time primarily by the needs of Numerical management sum together to produce separated disciplines, such as oceano- scales driven by orbital fluctuations, the spheric concentrations of these trace Our perception of the Earth as a Weather Prediction, but the methods are global changes with major influences on graphy and atmospheric dynamics, are in Earth’s mean atmospheric temperature is gases lie naturally within well-defined system finds its scientific expression in a cascading down to encompass all aspects the Earth System. We are only just fact intimately connected on a range of intimately connected to the atmospheric bounds. modelling spectrum running from the of the Earth System. beginning to understand the related time and spatial scales. For example, the composition, notably the greenhouse A primary lesson learned is that conceptual to the highly computational.

feedbacks and consequences for the irregular El Niño Southern Oscillation gases carbon dioxide (CO2), methane understanding the strongly nonlinear These models encapsulate our under- The Wider Context

Earth as a living planet, with humanity (ENSO) shows strong coupling of (CH4) and nitrous oxide (N2O). It is very behaviour of the Earth System requires standing of the Earth’s processes, their From the outset, ESA’s Living Planet as one of its life-forms. Measurements atmospheric and oceanic processes, striking that over at least six periods of atmospheric, ocean, land, cryospheric dynamic behaviour, their relations and Programme had the ambition to of the Earth’s properties provided by which are in turn strongly connected to about 100 000 years duration the atmo- and Earth-interior processes all to be their feedbacks. Quantitative models, by facilitate international cooperation and satellites are critical in providing access considered, in addition to the external their very nature, consist of equations use existing facilities and competences to many of the key elements of the The mean tropospheric nitrogen dioxide content for 2003 as measured by Envisat’s SCIAMACHY instrument. Hot spots are the solar driver. The Earth needs to be whose solution requires input data, and within the ESA Member States and Earth System. industrialised areas of Europe, China, the USA and South Africa. Many mega-cities elsewhere can also be identified as localised spots thought of as a system that naturally with enhanced concentrations. (KNMI/BIRA-IASB/ESA) regulates itself through a complex web Strike probability of Typhoon Matsa, starting from the European Centre for Medium-range Weather Forecasts ECMWF) analysis of The Rationale of Earth System Science of interactions and feedbacks between 4 August 2005 00:00 UT. The ECMWF operates an ‘Ensemble Plotting System’ in which, in addition to the operational high-resolution The latter half of the 20th century saw processes. forecast, alternative forecasts are made at a lower resolution. (ECMWF) the full emergence of the concept that At the same time as we began to the behaviour of planet Earth can only understand better the Earth as a system, be understood in terms of the coupling it became clear that recent human between the dynamic processes in the activities are having a profound impact atmosphere, solid Earth, hydrosphere, on this system, pushing it into states cryosphere, biosphere and anthropo- with unknown consequences for the sphere. All of these components are planet and mankind. An unequivocal

interlinked by a network of forcing and indicator of this is the atmospheric CO2 feedback mechanisms that affect the concentration, which, since the other components. Global-scale effects Industrial Revolution and the mass use can arise from regional processes, and of fossil fuels, has risen far beyond its global-scale behaviour can have widely natural limits. Our understanding of

different regional manifestations. In CO2 as a greenhouse gas, and the strong addition, processes acting at one time link between its concentration and scale can have consequences across a temperature, both point to human wide range of longer time scales. This activity leading to a warming world, paradigm, in which the Earth is seen as unlike anything seen over at least the last a coupled set of dynamical systems, million years.

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Earth Observation Changing Earth

The second is biodiversity. On our evaluating the models also requires data. own planet, we are pursuing a course Hence our total knowledge about the that is reducing the richness of life, and system is contained in our models, our diminishing the world that we will hand measurements and how we put them on to future generations. The fact that together. Improved understanding of life on Earth has existed continuously how to represent the dynamics of the for several billion years is due to its Earth processes, together with the diversity. It is very likely that in the explosion in computing power, has course of the present reduction of allowed the construction of ever more biodiversity, the Earth System’s powerful computer codes capable of extraordinary stability in the face of solving the coupled equations that make external forcing is also being reduced. up an Earth System model with a spatial Global variations in the Earth System resolution as high as about 10 km. An display very large regional differences. equally influential development has been The human inputs to the system also the explosion in the size of databases, show widely different patterns of change both from models and satellite data, and across the globe, be it deforestation, Information that can be acquired from space relevant to Solid Earth and Earth System Science the interconnectivity of computer manipulation of hydrological resources, Envisat SCIAMACHY measurements of column-averaged methane volume mixing ratio (VMR), in parts per billion, averaged over the systems and databases. Pinning these occurrence of fires, fossil-fuel burning constitutes the scientific discipline the spatial patterns and overall mean of period August – November 2003 on a 1 x 1º horizontal grid. At least five (and up to 150) measurements are taken for each grid cell. together has led to enormous advances in or land-use management. What seems known as ‘Earth System Science’. global vegetation productivity. Only a few observations are available over the ocean, since low ocean reflectivity substantially reduces the retrieval quality. the methods of model-data fusion and Occasionally, Sun-glint or clouds at low altitudes do allow measurements over the ocean. (University of Heidelberg/ESA) clear is that these highly variable local Major progress in many Earth science Spectacular new evidence from Antarctic data assimilation. These have been driven and regional types of environmental disciplines has revealed that traditionally ice cores has shown that, over long time primarily by the needs of Numerical management sum together to produce separated disciplines, such as oceano- scales driven by orbital fluctuations, the spheric concentrations of these trace Our perception of the Earth as a Weather Prediction, but the methods are global changes with major influences on graphy and atmospheric dynamics, are in Earth’s mean atmospheric temperature is gases lie naturally within well-defined system finds its scientific expression in a cascading down to encompass all aspects the Earth System. We are only just fact intimately connected on a range of intimately connected to the atmospheric bounds. modelling spectrum running from the of the Earth System. beginning to understand the related time and spatial scales. For example, the composition, notably the greenhouse A primary lesson learned is that conceptual to the highly computational.

feedbacks and consequences for the irregular El Niño Southern Oscillation gases carbon dioxide (CO2), methane understanding the strongly nonlinear These models encapsulate our under- The Wider Context

Earth as a living planet, with humanity (ENSO) shows strong coupling of (CH4) and nitrous oxide (N2O). It is very behaviour of the Earth System requires standing of the Earth’s processes, their From the outset, ESA’s Living Planet as one of its life-forms. Measurements atmospheric and oceanic processes, striking that over at least six periods of atmospheric, ocean, land, cryospheric dynamic behaviour, their relations and Programme had the ambition to of the Earth’s properties provided by which are in turn strongly connected to about 100 000 years duration the atmo- and Earth-interior processes all to be their feedbacks. Quantitative models, by facilitate international cooperation and satellites are critical in providing access considered, in addition to the external their very nature, consist of equations use existing facilities and competences to many of the key elements of the The mean tropospheric nitrogen dioxide content for 2003 as measured by Envisat’s SCIAMACHY instrument. Hot spots are the solar driver. The Earth needs to be whose solution requires input data, and within the ESA Member States and Earth System. industrialised areas of Europe, China, the USA and South Africa. Many mega-cities elsewhere can also be identified as localised spots thought of as a system that naturally with enhanced concentrations. (KNMI/BIRA-IASB/ESA) regulates itself through a complex web Strike probability of Typhoon Matsa, starting from the European Centre for Medium-range Weather Forecasts ECMWF) analysis of The Rationale of Earth System Science of interactions and feedbacks between 4 August 2005 00:00 UT. The ECMWF operates an ‘Ensemble Plotting System’ in which, in addition to the operational high-resolution The latter half of the 20th century saw processes. forecast, alternative forecasts are made at a lower resolution. (ECMWF) the full emergence of the concept that At the same time as we began to the behaviour of planet Earth can only understand better the Earth as a system, be understood in terms of the coupling it became clear that recent human between the dynamic processes in the activities are having a profound impact atmosphere, solid Earth, hydrosphere, on this system, pushing it into states cryosphere, biosphere and anthropo- with unknown consequences for the sphere. All of these components are planet and mankind. An unequivocal

interlinked by a network of forcing and indicator of this is the atmospheric CO2 feedback mechanisms that affect the concentration, which, since the other components. Global-scale effects Industrial Revolution and the mass use can arise from regional processes, and of fossil fuels, has risen far beyond its global-scale behaviour can have widely natural limits. Our understanding of

different regional manifestations. In CO2 as a greenhouse gas, and the strong addition, processes acting at one time link between its concentration and scale can have consequences across a temperature, both point to human wide range of longer time scales. This activity leading to a warming world, paradigm, in which the Earth is seen as unlike anything seen over at least the last a coupled set of dynamical systems, million years.

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Earth Observation Changing Earth

The Major Challenges for Understanding the Earth System Canada. This cooperation takes several data assimilation. This approach was observation applications, the develop- – the Scientific Direction for ESA’s Living Planet Programme forms, from direct cooperation on the first successfully developed in ment of operational systems for implementation of specific missions, meteorology, where the European meteorology being a prime example. Key characteristics of satellite spheric circulations, and the apparent carbon cycle and its dynamics by through joint science activities in Centre for Medium-Range Weather Other areas are also progressing, and changes in these circulations. measurements quantifying their control and feedback connection with ESA’s and other Forecasts, together with partner political decisions like international They are global, enabling us to deal Challenge 5: contribute to sustainable mechanisms for determining future meaningfully with the overall properties of development through interdisciplinary trends. agencies’ missions, to interaction with European meteorological centres, has treaties on, for example, ozone and the system, while also providing research on climate circulation patterns international scientific research acquired an undisputed lead. Similar carbon, emphasise and formalise the observations of spatial heterogeneity. and extreme events. The Challenges of the Solid Earth programmes, in order to ensure that data-assimilation techniques are also need for related applications. The link They are repetitive and homogeneous, Challenge 1: identification and quantific- ESA’s activities have an optimum impact being developed in the other fields of between science and applications works so that time-varying phenomena can be The Challenges of the Cryosphere ation of physical signatures associated discriminated. In many cases, long time- Challenge 1: quantify the distribution of with volcanic and earthquake processes from a global point of view. Earth science. both ways. On the one hand, scientific series are available, so that oscillations sea-ice mass and freshwater equivalent, from terrestrial and space-based observ- Over the years, European countries An important benefit of Earth progress forms the basis for the and trends can be recognised, and assess the sensitivity of sea ice to ations. have developed a strong leadership in Science satellite missions and other development of new applications, but signatures of anthropogenic change can climate change, and understand Challenge 2: improved knowledge of Earth System Science. The development activities is the well-established potential operational systems also make be distinguished from natural fluctuations. thermodynamic and dynamic feedbacks physical properties and geodynamic Near-simultaneous observations of to the ocean and atmosphere. processes in the deep interior, and their of fully coupled Earth System models is they provide for developing new Earth important contributions to scientific many different variables can be made, Challenge 2: quantify the mass balance of relationship to Earth-surface changes. well underway at the Hadley Centre and allowing the state of the whole system to grounded ice sheets, ice caps Challenge 3: improved understanding of the University Global Atmospheric be diagnosed, and interrelations within and glaciers, partition their relative mass transport and mass distribution in the system to be identified. contributions to global eustatic sea-level the other Earth System components, Modelling Programme (UGAMP; UK), The Kiruna ground station, in Sweden, used for data Near-realtime data delivery (within a change, and understand their future which will allow the separation of the at the Max Planck Institute for reception and processing few hours) can be ensured, which sensitivity to climate change through individual contributions and a clearer Meteorology in Hamburg (D) and at the facilitates assimilation of satellite data into dynamic processes. picture of the signal due to solid-Earth Institut Pierre Simon Laplace and complex models of the behaviour of the Challenge 3: understand the role of snow processes. Earth System. and glaciers in influencing the global Challenge 4: an extended understanding Meteo-France (F), to cite but a few. water cycle and regional water of core processes based on comple- Many other European organisations are The Challenges of the Oceans resources, identify links to the mentary sources of information working in the same direction. Europe atmosphere, and assess likely future Challenge 1: quantify the interaction and the impact of core processes on also holds a strong position in other key between variability in ocean dynamics, trends. Earth System science. thermohaline circulation, sea level, and Challenge 4: quantify the influence of ice Challenge 5: the role of magnetic-field areas of Earth System Science, such as climate. shelves, high-latitude river run-off and changes in affecting the distribution of oceanography and glaciology. Further- Challenge 2: understand physical and bio- land ice melt on global thermohaline ionised particles in the atmosphere and more, several European organisations chemical air/sea interaction processes. circulation, and understand the their possible effects on climate. Challenge 3: understand internal waves sensitivity of each of these fresh-water with an interest in Earth System and the mesoscale in the ocean, its sources to future climate change. modelling have grouped together within relevance for heat and energy transport Challenge 5: quantify current changes the European Network for Earth System Melting duration for the Greenland ice-sheet surface for the and its influence on primary productivity. taking place in permafrost and frozen- Modelling (ENES). Challenge 4: quantify marine-ecosystem ground regimes, understand their years shown, estimated using ERS Scatterometer image variability, and its natural and anthropo- feedback to other components of the data. The conclusion is that melting is increasing. Earth System models are developed genic physical, biological and geo- climate system, and evaluate their (I. Ashcraft, Brigham Young University) through a complex and systematic chemical forcing. sensitivity to future climate forcing. process of comparison with observa- Challenge 5: understand land/ocean tions at the relevant scale. Systematic interactions in terms of natural and The Challenges of the Land Surface anthropogenic forcing. Challenge 1: understand the role of differences between model simulations Challenge 6: provide reliable model- and terrestrial ecosystems and their and observations, called ‘biases’, point data-based assessments and predictions interaction with other components of the to the incorrect representation of some of the past, present and future state of Earth System for the exchange of water, process that must be improved in the the oceans. carbon and energy, including the 1992 1993 1994 quantification of the ecological, models, or to systematic observational The Challenges of the Atmosphere atmospheric, chemical and anthropogenic errors that must be corrected. Once the Challenge 1: understand and quantify the processes that control these bio- biases are reduced to a minimum, the chemical luxes. natural variability and the human- remaining random differences between induced changes in the Earth’s climate Challenge 2: understand the interactions system. between biological diversity, climate the models and the observations can be Challenge 2: understand, model and variability and key ecosystem character- exploited to improve further the forecast atmospheric composition and istics and processes, such as 1995 1996 1997 model’s formulation, or to create a set air quality on adequate temporal and productivity, structure, nutrient cycling, spatial scales, using ground-based and water redistribution and vulnerability. of model variables representing the satellite data. Challenge 3: understand the pressure reality at a specific point in time. The Challenge 3: better quantification of the caused by anthropogenic dynamics on model can then be used for predictions. physical processes determining the life land surfaces (use of natural resources, This whole process is called ‘data cycle of aerosols and their interaction and land-use and land-cover change) with clouds. and their impact on the functioning of assimilation’ and lies at the heart of 1998 1999 2000 Challenge 4: observe, monitor and under- terrestrial ecosystems. Earth System Science. Europe has stand the chemistry-dynamics coupling of Challenge 4: understand the effect of developed a very strong leadership in the stratospheric and upper tropo- land-surface status on the terrestrial 0120Days pioneering the variational approach to

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Earth Observation Changing Earth

The Major Challenges for Understanding the Earth System Canada. This cooperation takes several data assimilation. This approach was observation applications, the develop- – the Scientific Direction for ESA’s Living Planet Programme forms, from direct cooperation on the first successfully developed in ment of operational systems for implementation of specific missions, meteorology, where the European meteorology being a prime example. Key characteristics of satellite spheric circulations, and the apparent carbon cycle and its dynamics by through joint science activities in Centre for Medium-Range Weather Other areas are also progressing, and changes in these circulations. measurements quantifying their control and feedback connection with ESA’s and other Forecasts, together with partner political decisions like international They are global, enabling us to deal Challenge 5: contribute to sustainable mechanisms for determining future meaningfully with the overall properties of development through interdisciplinary trends. agencies’ missions, to interaction with European meteorological centres, has treaties on, for example, ozone and the system, while also providing research on climate circulation patterns international scientific research acquired an undisputed lead. Similar carbon, emphasise and formalise the observations of spatial heterogeneity. and extreme events. The Challenges of the Solid Earth programmes, in order to ensure that data-assimilation techniques are also need for related applications. The link They are repetitive and homogeneous, Challenge 1: identification and quantific- ESA’s activities have an optimum impact being developed in the other fields of between science and applications works so that time-varying phenomena can be The Challenges of the Cryosphere ation of physical signatures associated discriminated. In many cases, long time- Challenge 1: quantify the distribution of with volcanic and earthquake processes from a global point of view. Earth science. both ways. On the one hand, scientific series are available, so that oscillations sea-ice mass and freshwater equivalent, from terrestrial and space-based observ- Over the years, European countries An important benefit of Earth progress forms the basis for the and trends can be recognised, and assess the sensitivity of sea ice to ations. have developed a strong leadership in Science satellite missions and other development of new applications, but signatures of anthropogenic change can climate change, and understand Challenge 2: improved knowledge of Earth System Science. The development activities is the well-established potential operational systems also make be distinguished from natural fluctuations. thermodynamic and dynamic feedbacks physical properties and geodynamic Near-simultaneous observations of to the ocean and atmosphere. processes in the deep interior, and their of fully coupled Earth System models is they provide for developing new Earth important contributions to scientific many different variables can be made, Challenge 2: quantify the mass balance of relationship to Earth-surface changes. well underway at the Hadley Centre and allowing the state of the whole system to grounded ice sheets, ice caps Challenge 3: improved understanding of the University Global Atmospheric be diagnosed, and interrelations within and glaciers, partition their relative mass transport and mass distribution in the system to be identified. contributions to global eustatic sea-level the other Earth System components, Modelling Programme (UGAMP; UK), The Kiruna ground station, in Sweden, used for data Near-realtime data delivery (within a change, and understand their future which will allow the separation of the at the Max Planck Institute for reception and processing few hours) can be ensured, which sensitivity to climate change through individual contributions and a clearer Meteorology in Hamburg (D) and at the facilitates assimilation of satellite data into dynamic processes. picture of the signal due to solid-Earth Institut Pierre Simon Laplace and complex models of the behaviour of the Challenge 3: understand the role of snow processes. Earth System. and glaciers in influencing the global Challenge 4: an extended understanding Meteo-France (F), to cite but a few. water cycle and regional water of core processes based on comple- Many other European organisations are The Challenges of the Oceans resources, identify links to the mentary sources of information working in the same direction. Europe atmosphere, and assess likely future Challenge 1: quantify the interaction and the impact of core processes on also holds a strong position in other key between variability in ocean dynamics, trends. Earth System science. thermohaline circulation, sea level, and Challenge 4: quantify the influence of ice Challenge 5: the role of magnetic-field areas of Earth System Science, such as climate. shelves, high-latitude river run-off and changes in affecting the distribution of oceanography and glaciology. Further- Challenge 2: understand physical and bio- land ice melt on global thermohaline ionised particles in the atmosphere and more, several European organisations chemical air/sea interaction processes. circulation, and understand the their possible effects on climate. Challenge 3: understand internal waves sensitivity of each of these fresh-water with an interest in Earth System and the mesoscale in the ocean, its sources to future climate change. modelling have grouped together within relevance for heat and energy transport Challenge 5: quantify current changes the European Network for Earth System Melting duration for the Greenland ice-sheet surface for the and its influence on primary productivity. taking place in permafrost and frozen- Modelling (ENES). Challenge 4: quantify marine-ecosystem ground regimes, understand their years shown, estimated using ERS Scatterometer image variability, and its natural and anthropo- feedback to other components of the data. The conclusion is that melting is increasing. Earth System models are developed genic physical, biological and geo- climate system, and evaluate their (I. Ashcraft, Brigham Young University) through a complex and systematic chemical forcing. sensitivity to future climate forcing. process of comparison with observa- Challenge 5: understand land/ocean tions at the relevant scale. Systematic interactions in terms of natural and The Challenges of the Land Surface anthropogenic forcing. Challenge 1: understand the role of differences between model simulations Challenge 6: provide reliable model- and terrestrial ecosystems and their and observations, called ‘biases’, point data-based assessments and predictions interaction with other components of the to the incorrect representation of some of the past, present and future state of Earth System for the exchange of water, process that must be improved in the the oceans. carbon and energy, including the 1992 1993 1994 quantification of the ecological, models, or to systematic observational The Challenges of the Atmosphere atmospheric, chemical and anthropogenic errors that must be corrected. Once the Challenge 1: understand and quantify the processes that control these bio- biases are reduced to a minimum, the chemical luxes. natural variability and the human- remaining random differences between induced changes in the Earth’s climate Challenge 2: understand the interactions system. between biological diversity, climate the models and the observations can be Challenge 2: understand, model and variability and key ecosystem character- exploited to improve further the forecast atmospheric composition and istics and processes, such as 1995 1996 1997 model’s formulation, or to create a set air quality on adequate temporal and productivity, structure, nutrient cycling, spatial scales, using ground-based and water redistribution and vulnerability. of model variables representing the satellite data. Challenge 3: understand the pressure reality at a specific point in time. The Challenge 3: better quantification of the caused by anthropogenic dynamics on model can then be used for predictions. physical processes determining the life land surfaces (use of natural resources, This whole process is called ‘data cycle of aerosols and their interaction and land-use and land-cover change) with clouds. and their impact on the functioning of assimilation’ and lies at the heart of 1998 1999 2000 Challenge 4: observe, monitor and under- terrestrial ecosystems. Earth System Science. Europe has stand the chemistry-dynamics coupling of Challenge 4: understand the effect of developed a very strong leadership in the stratospheric and upper tropo- land-surface status on the terrestrial 0120Days pioneering the variational approach to

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research, particularly by providing long in order to ensure that the concepts exponential increase in the demand time-series of global data, something finally selected for implementation during the design phase, in order to meet that is notoriously difficult to justify in correspond to the highest priority user the actual demand at the start of research-oriented space activities. A needs and have the broadest possible mission operations. Modelling and long- good example in this respect are the scientific impact. term trend monitoring have led to a missions of Eumetsat and similar The goals of the science strategy will large increase in the demand for time- organisations. be achieved only if the data gathered are series and historical data, including During the last decade, the Integrated validated and exploited thoroughly by regular reprocessing. Global Observing Strategy Partnership all the research communities concerned. The evolution in the scientific require- (IGOS-P) has formulated global observ- To achieve the envisaged scale of impact ments, where the science projects ing needs for a number of themes. Other within the science community and in represent large investments both finan- more recent developments are the GMES society at large, a strong European role, cially and in terms of manpower, means intiative by the European Union, ESA innovation and commitment in the area that operations and ground segments for and other partners, and the Global Earth of data exploitation must be main- scientific missions now have to: Observation System of Systems tained. Data exploitation under the (GEOSS), to which GMES is Europe’s Living Planet Programme should, in – offer the same level of reliability and planned contribution. Although these terms of its prime objectives, maximise operability as former ‘operational’ initiatives go well beyond the scientific advances and achievements in European missions; needs, these are also included and these scientific understanding of the Earth – additionally provide a higher degree of This Envisat/MERIS image of 13 December 2003 is dominated by a dust and sand storm covering the Envisat ASAR image of the Scott Coast, Antarctica, showing the collision of the B15A Gulf of Oman. The scene includes a large part of Baluchistan, a mountainous region with some deserts iceberg with the Drygalski ice tongue in April 2005. (ESA) intiatives therefore provide a natural link System, develop new applications that flexibility in adjusting and tuning the and barren plains, and parts of southwestern Pakistan and southeastern Iran (top right & top centre). It between science and applications. can benefit society and contribute to operations schemes to new projects shows the dust particles (aerosols) of a continental air-mass interacting with a humid marine boundary Development of specific collaborations improved quality of life, and demon- and technologies, and offer a much layer (Somali jet), leading to cloud at the edge of the outbreak. (ESA) with major science initiatives through, for strate new techniques and technologies closer and intelligent dialogue with the example, the Earth Systems Science that can strengthen European industry’s user community. Partnership and with international user competitiveness. Specific attention organisations such as the United Nations should be given to stimulating and Science today relies on a multitude of Conventions, have also been a feature of facilitating the use of Earth observation Earth observation data sources, which the Programme. In all its aspects, it has data by research communities that do can no longer be characterised as also been a major contributor to the not specialise in remote sensing. science-only missions. Data from public, development of European industry in the Manifested in ESA’s day-to-day operational or commercial missions, as technology-development, manufacturing contacts with the science community, well as non-space data, are often and service sectors. the requirements associated with Earth indispensable inputs to science projects. observation mission operations, ground A technically simple and coherent (and Living Planet Contributions segments, data and information hand- financially affordable) access mechanism ESA’s primary contribution to Earth ling can be summarised as: needs to be established. Science is the provision of data products It is essential for the success of the and associated services from the – easiest possible data access, continu- science strategy that the technology Agency’s Earth observation satellites. In ously adapting to the latest technology; developments, scientific investigations Banda Aceh as seen by Spot-5 before (2003; left) and after (30 December 2004) the devastating Indonesian tsunami. The damaged infrastructure and areas still under water are clearly visible. addition to data from its own satellites, – coherent access to many (ideally all) and applications developments carried (CNES/SpotImage, 2004; processing SERTIT) ESA also facilitates the provision of sources of Earth observation data and out under the Programme are accom- data from other organisations’ satellites. even other geo-data; panied by a systematic and concerted Earth observation satellites for Earth – fast access, ideally in near-realtime; effort to communicate the achievements science are identified, selected and – long-term access over many (tens of) to a much wider audience, both within developed in close cooperation with the years; Europe and beyond. This effort should scientific community. Identification of – adaptation of mission, acquisition address the general public, political candidate missions or mission concepts planning and operations strategies to decision-makers, schools and universities, is regularly conducted via open calls for user demand. all of whom need to be made aware of, proposals to the scientific community, kept regularly informed about and kept where the newly identified challenges Today’s users can handle and process, interested in Europe’s achievements in guide future calls. New concepts usually and therefore request, substantially Earth observation. They must be Global topography and bathymetry measured by space-based require a stepwise approach, where higher volumes of Earth observation convinced of the tangible benefits of radar altimetry. (ESA, using bathymetry data courtesy of: e W. Smith, NOAA Geosciences Lab., USA, D. Sandwell, Scripps studies and campaigns are undertaken data than ever before. This trend is investing public funds in this effort. Institute of Oceanography, USA, and altimeter-corrected in order to advance the concepts. The increasing exponentially. Payload ground elevations from P. Berry, DeMontfort Univ., UK) Agency undertakes preparatory activities segments must anticipate such an

16 esa bulletin 129 - february 2007 www.esa.int www.esa.int esa bulletin 129 - february 2007 17 Liebig 2/6/07 11:09 AM Page 16

Changing Earth

research, particularly by providing long in order to ensure that the concepts exponential increase in the demand time-series of global data, something finally selected for implementation during the design phase, in order to meet that is notoriously difficult to justify in correspond to the highest priority user the actual demand at the start of research-oriented space activities. A needs and have the broadest possible mission operations. Modelling and long- good example in this respect are the scientific impact. term trend monitoring have led to a missions of Eumetsat and similar The goals of the science strategy will large increase in the demand for time- organisations. be achieved only if the data gathered are series and historical data, including During the last decade, the Integrated validated and exploited thoroughly by regular reprocessing. Global Observing Strategy Partnership all the research communities concerned. The evolution in the scientific require- (IGOS-P) has formulated global observ- To achieve the envisaged scale of impact ments, where the science projects ing needs for a number of themes. Other within the science community and in represent large investments both finan- more recent developments are the GMES society at large, a strong European role, cially and in terms of manpower, means intiative by the European Union, ESA innovation and commitment in the area that operations and ground segments for and other partners, and the Global Earth of data exploitation must be main- scientific missions now have to: Observation System of Systems tained. Data exploitation under the (GEOSS), to which GMES is Europe’s Living Planet Programme should, in – offer the same level of reliability and planned contribution. Although these terms of its prime objectives, maximise operability as former ‘operational’ initiatives go well beyond the scientific advances and achievements in European missions; needs, these are also included and these scientific understanding of the Earth – additionally provide a higher degree of This Envisat/MERIS image of 13 December 2003 is dominated by a dust and sand storm covering the Envisat ASAR image of the Scott Coast, Antarctica, showing the collision of the B15A Gulf of Oman. The scene includes a large part of Baluchistan, a mountainous region with some deserts iceberg with the Drygalski ice tongue in April 2005. (ESA) intiatives therefore provide a natural link System, develop new applications that flexibility in adjusting and tuning the and barren plains, and parts of southwestern Pakistan and southeastern Iran (top right & top centre). It between science and applications. can benefit society and contribute to operations schemes to new projects shows the dust particles (aerosols) of a continental air-mass interacting with a humid marine boundary Development of specific collaborations improved quality of life, and demon- and technologies, and offer a much layer (Somali jet), leading to cloud at the edge of the outbreak. (ESA) with major science initiatives through, for strate new techniques and technologies closer and intelligent dialogue with the example, the Earth Systems Science that can strengthen European industry’s user community. Partnership and with international user competitiveness. Specific attention organisations such as the United Nations should be given to stimulating and Science today relies on a multitude of Conventions, have also been a feature of facilitating the use of Earth observation Earth observation data sources, which the Programme. In all its aspects, it has data by research communities that do can no longer be characterised as also been a major contributor to the not specialise in remote sensing. science-only missions. Data from public, development of European industry in the Manifested in ESA’s day-to-day operational or commercial missions, as technology-development, manufacturing contacts with the science community, well as non-space data, are often and service sectors. the requirements associated with Earth indispensable inputs to science projects. observation mission operations, ground A technically simple and coherent (and Living Planet Contributions segments, data and information hand- financially affordable) access mechanism ESA’s primary contribution to Earth ling can be summarised as: needs to be established. Science is the provision of data products It is essential for the success of the and associated services from the – easiest possible data access, continu- science strategy that the technology Agency’s Earth observation satellites. In ously adapting to the latest technology; developments, scientific investigations Banda Aceh as seen by Spot-5 before (2003; left) and after (30 December 2004) the devastating Indonesian tsunami. The damaged infrastructure and areas still under water are clearly visible. addition to data from its own satellites, – coherent access to many (ideally all) and applications developments carried (CNES/SpotImage, 2004; processing SERTIT) ESA also facilitates the provision of sources of Earth observation data and out under the Programme are accom- data from other organisations’ satellites. even other geo-data; panied by a systematic and concerted Earth observation satellites for Earth – fast access, ideally in near-realtime; effort to communicate the achievements science are identified, selected and – long-term access over many (tens of) to a much wider audience, both within developed in close cooperation with the years; Europe and beyond. This effort should scientific community. Identification of – adaptation of mission, acquisition address the general public, political candidate missions or mission concepts planning and operations strategies to decision-makers, schools and universities, is regularly conducted via open calls for user demand. all of whom need to be made aware of, proposals to the scientific community, kept regularly informed about and kept where the newly identified challenges Today’s users can handle and process, interested in Europe’s achievements in guide future calls. New concepts usually and therefore request, substantially Earth observation. They must be Global topography and bathymetry measured by space-based require a stepwise approach, where higher volumes of Earth observation convinced of the tangible benefits of radar altimetry. (ESA, using bathymetry data courtesy of: e W. Smith, NOAA Geosciences Lab., USA, D. Sandwell, Scripps studies and campaigns are undertaken data than ever before. This trend is investing public funds in this effort. Institute of Oceanography, USA, and altimeter-corrected in order to advance the concepts. The increasing exponentially. Payload ground elevations from P. Berry, DeMontfort Univ., UK) Agency undertakes preparatory activities segments must anticipate such an

16 esa bulletin 129 - february 2007 www.esa.int www.esa.int esa bulletin 129 - february 2007 17