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OVERVIEW

Global Environmental Change: Research Pathways for the Next Decade



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OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade OVERVIEW Global Environmental Change: Research Pathways for the Next Decade

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OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade SUMMARY During its first 10 years of operation, the United States Global Change Research Program (USGCRP) has advanced our understanding of the Earth's ever-changing physical, chemical, and biological systems, and the growing human influences on these systems. On the basis of this knowledge, we can now focus attention on the critical unanswered scientific questions that must be resolved to fully understand and usefully predict global change. Such capability is increasingly important for developing our economy, protecting our environment, safeguarding our health, and negotiating international agreements to ensure the sustainable development of our nation and the global community of nations. There are now compelling reasons for scientific knowledge to guide and respond to policy options, both current and future. Clearly, we must delineate research pathways that will enlarge our understand ing of changes in the global environment, including climate change. At the same time, we need to reduce uncertainties in the projections that shape our decisions for the future. For all these reasons, it is essential that the USGCRP continue to receive strong financial support and continue to provide continuing strong scientific leadership. To be effective, the USGCRP must be based on a sound scientific strategy, focused on key unanswered scientific questions, using a correspondingly balanced strategy for supporting observational, data management, and analysis activities. On the basis of the continuing reviews of the Committee on Global Change Research (CGCR) and those of its collaborating bodies, the Committee reaffirms the achievements and significance of the USGCRP while finding that the Program must now be revitalized, focusing its use of funds more effectively on the principal unanswered scientific questions about global environmental change. This goal demands that funding and efforts be directed toward a coherent and coordinated suite of research activities and supporting observational, data management, and modeling capabilities, all aimed at imperative re search objectives and clearly defined scientific questions. A sharply focused scientific strategy and a coherent programmatic structure are both critically needed. This report seeks to provide a framework for such a strategy and structure. The elaboration and implementation of this scientific strategy and programmatic structure will be the principal challenge for global change research over the course of the next decade.

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OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade BACKGROUND Long before the industrial revolution, human activity began to alter the Earth's environment. However, only in this century has the scale of such alterations become global in scope; moreover, the rate of these recent changes is enormously high compared with the historical record. Today, on the threshold of a new millennium, it is clear that humans are inducing environmental changes in the planet as a whole. In fact, the human fingerprint is abundantly seen on the global atmosphere, the world oceans, and the land of all continents. This insight has brought about profound changes in the goals, priorities, and processes of both science and government. Programmatic Development The recognition that humans are causing global changes in the biology, physics, and chemistry of the environment—changes with immense significance for human society and economy—prompted the US government, and other national governments, to act. In 1990, Congress established the USGCRP to carry out an organized, coherent attack on the scientific issues posed by global environmental change. The USGCRP had its principal roots in the 1980s, as both scientists and the public became increasingly aware of the links among human activities, current and future states of the global environment, and human welfare. The most immediate concerns were human-induced climate change, stratospheric ozone depletion due to industrial emissions, and emerging evidence that the Earth's biogeochemical system was being perturbed by a broad range of human actions. Some of the many antecedents of the USGCRP were seen still earlier. In the 1970s, a convergence of long-standing scientific concerns (see below) and a series of climatic events led to the first World Climate Conference and to the establishment of the US National Climate Program and the World Climate Program.1 “If we believed that the Earth was a constant system in which the atmosphere, biosphere, oceans, and lithosphere were unconnected parts, then the traditional scientific fields that study these areas could all proceed at their own pace treating each other's findings as fixed boundary conditions. However, not only is the Earth changing even as we seek to understand it—in ways that involve the interplay of land and sea, of oceans, air, and biosphere—we cannot even presume that global change will be uniform in space and steady in time . . . Needed to resolve this complex of change and interplay are coordinated efforts between adjacent scientific disciplines and programs of synoptic observations focused on common, interrelated problems that affect the Earth as a whole.” NRC, 1983a

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OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade In parallel, beginning in the mid-1970s, the US Department of Energy (DOE) organized a major research program to assess the consequences of fossil-based energy production. Workshops chaired by the late Roger Revelle outlined a broad multidisciplinary research agenda closely congruent with today's USGCRP, including a strong emphasis on the carbon cycle, the role of ecosystems, and human dimensions research.2 The goal of the International Geosphere Biosphere Program (IGBP) is “ . . . to describe and understand the interactive physical, chemical and biological processes that regulate the total Earth system, the unique environment that it provides for life, the changes that are occurring in this system, and the manner in which they are influenced by human actions.” International Council of Scientific Unions, 1996 The immediate precursor of the USGCRP, however, was a workshop sponsored by the National Aeronautics and Space Administration (NASA) in 1982 on global habitability, which was led by Richard Goody.3 This workshop emphasized the fact that, in many critical respects, the ocean, atmosphere, and biosphere function together on long timescales as a single integrated system, a system requiring interdisciplinary research and observing programs of global scope and decadal duration. The stage had been set for encouraging similar fully integrated, long-term research by the Global Atmospheric Research Program, a program that itself arose from a seminal study by the National Research Council (NRC)4 and laid the groundwork for the World Climate Research Program. The shaping of such comprehensive endeavors, which arose by recognizing the importance of chemical and biological as well as physical factors in the global system, also led to the establishment of the International Geosphere-Biosphere Program of the International Council of Scientific Unions. The priorities and nature of this program, from a US perspective, were laid out in a sequence of NRC reports.5 Most recently, human components in global environmental change have been given wider recognition in the creation of the International Human Dimensions Program on Global Environmental Change. Still other precursors to the USGCRP include two reports in the 1980s by the NASA-sponsored Earth System Sciences Committee (ESSC),6 which sought to define a new and revolutionary scientific discipline of Earth System Science. In keeping with the Goody Report7 and the 1986 NRC report, Global Change in the Geosphere-Biosphere,8 this new discipline would be dedicated to study of the Earth as an integrated system of interacting components. Its goal would be to obtain “a scientific understanding of the entire Earth System on a global scale.”9 The emergence of a science of the Earth system, moreover, offered a promise of knowledge that would be valuable to decision makers addressing global habitability. Prominent in the ESSC documents was a recommendation for an Earth Observing System (EOS) to provide long-term global observations, with an empha-

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OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade sis on the long-term continuity of observations, both satellite and in situ. The importance of long-term records reflected the audience for these reports and portended a multiagency endeavor: the recommendations were made to several concerned agencies—to the National Oceanic and Atmospheric Association (NOAA) and the National Science Foundation (NSF)—in addition to the sponsoring agency, NASA. Late 1986 brought the beginnings of a coordinated government response. NASA, NOAA, and NSF had been developing parallel global change programs, but in 1987, a joint letter from these three agencies to the director of the Office of Management and Budget (OMB) proposed the idea of a budget presentation coordinated across the agencies. From this point on, OMB was instrumental in developing the USGCRP. Later that year, a consortium of eight agencies formed the federal interagency Committee on Earth Sciences (later the Committee on Earth and Environmental Sciences, now the Committee on Environment and Natural Resources). The first funding for the USGCRP per se came in fiscal year 1989, and the first related descriptive document that accompanied the President 's Budget was produced for the fiscal year 1990 submission. Joint submission of agency budgets was a novel concept, at least in the Earth sciences. The process produced new initiatives that were coordinated, if not necessarily integrated. Thus, the USGCRP was initiated and first presented in the federal budget by President Reagan, was codified into law in 1990 (see Appendix A), and was implemented by President Bush; today it is being carried forward under President Clinton. Scientific Roots of Global Climate Research The intellectual crucible in which the USGCRP was formed, however, was itself forged far earlier. The possibility of global changes in the biological, physical, and chemical environment had been recognized in the 19th century and became a widely accepted idea by the beginning of the 20th century. In 1957, Revelle and Suess10 pointed out that most of the carbon dioxide emitted from fossil fuel combustion would remain in the atmosphere for many years and drew on emerging climate modeling capabilities to suggest possibly alarming impacts on climate. In the early 1960s, two major international conferences, known by the acronyms SMIC and SCEP,11 put the issue on the international agenda. At the same time, convincing observational evidence emerged that human activities were in fact changing the chemical composition of the global atmosphere. Measurements taken first by Charles David Keeling in 1957 revealed that carbon dioxide was indeed increasing in the atmosphere at the planetary scale. In 1964, the President's Science Advisory Council brought the issue to the attention of the US Government. Subsequently, beginning in the late 1960s, early computer model simulations started to explore the possible changes in temperature and precipitation that could occur due to increasing human-induced emissions of greenhouse gases into the atmosphere.

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OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade During the 1970s and early 1980s, an important set of environmental topics was closely considered by the National Academy of Sciences (NAS). Foremost among these issues were potential changes in climate and losses in stratospheric ozone. The NAS convened several panels and committees under leading scientists such as the late Roger Revelle 12 and Jule Charney.13 The resulting reports projected that energy production from fossil fuels would continue to increase atmospheric concentrations of carbon dioxide and estimated that a doubling of the atmosphere's carbon dioxide concentration could potentially raise global average temperature by 1.5 to 4.5° C (about 2.7 to 8° F) and produce a complex pattern of worldwide climate changes. Charney and his colleagues concluded that if carbon dioxide continued to increase, there was “no reason to doubt that climate changes will result and no reason to believe that these changes will be negligible.”14 The Revelle group saw a clear need for two kinds of action in response: “organization of a comprehensive worldwide research program and new institutional arrangements.” In the same period, ecologists also recognized that massive changes in ecosystems due to land-use changes and other stresses could affect the carbon cycle. In this juncture of scientific findings, then, are the beginnings of the partnerships among the life and Earth sciences that have become the hallmark of global change science. Still other studies addressed a widening range of potential global change impacts and their policy implications.15 In 1979 and 1989, major World Climate Conferences16 were convened by the World Meteorological Organization and other international bodies. International meetings17 converged on the conclusion that the implications of changing climate should be assessed for development policy. In 1988, the Intergovernmental Panel on Climate Change, composed of hundreds of scientists from more than 50 countries, assumed responsibility for conducting periodic international assessments on climate change and its consequences. The latest of these18 affirms the validity of scientific concerns and concludes that human influences on climate are becoming discernible. Thus, throughout the last two decades, the NAS/NRC and their international counterparts have continued to examine the science of climate change and variability and the associated policy implications for the United States and other nations. Additionally, the NAS/NRC has simultaneously considered climate change and variability within the broader context of global change. The Committee on Global Change Research (CGCR), author of this report, and CGCR's predecessor, the Board on Global Change, have been charged with providing continuing guidance to national and international global change efforts. In 1995, CGCR undertook an initial assessment of the scientific programs of the USGCRP, reviewed the specific role of NASA's Mission to Planet Earth/Earth Observing System (MTPE/EOS), and issued a report with recommendations (the “La Jolla” report)19 and a follow-up report on the government response.20 The present study significantly expands that effort.

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OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade Scientific Roots of Stratospheric Ozone Research A related history of research concerns another pressing environmental issue—the depletion of the stratospheric ozone layer that shields us from damaging ultraviolet radiation. In the early 1970s, proposals to build a fleet of supersonic transports raised questions about possible damage to the ozone layer from engine emissions in the stratosphere. A major US research and assessment program was launched, and the NRC was commissioned to conduct a series of studies.21 But soon, Rowland and Molina made the startling discovery that chlorofluorocarbons (CFCs), not airplanes, were the frightening threat to our ozone shield. Eventually, an international assessment was conducted under the auspices of the World Meteorological Organization and other international bodies.22 The discovery of Rowland and Molinaa reminds us that studies and reports often do not adequately address the complexities of the real world. Indeed, they can even significantly miss the mark. Studies of ozone depletion had focused on slow incremental changes and had sought incremental improvements through corresponding models and parametric analyses. Meanwhile, observations extending back to the 1950s had been tracking the amount of ozone over the Antarctic each year through its seasonal cycle. In the late 1970s, an anomalous deficit was observed in the total amount of ozone over the Southern Hemisphere in late winter observations. Then, in 1985, the British Antarctic Survey reported dramatic—and rapidly worsening —ozone losses in springtime ozone concentrations over Halley Bay. Theories about the cause of this unprecedented and unexpected loss blossomed. Explanations ranged from the hypothesis of the simple redistribution of stratospheric ozone by atmospheric motion to proposed chemical reactions initiated by the magnetic field-focusing of solar electrons and protons. More complete information was clearly needed. In 1986, NASA began planning an airborne expedition using the ER-2 aircraft to penetrate the region of the stratosphere where ozone was disappearing. The mission, executed in August and September 1987 from Punta Arenas, Chile, demonstrated that ozone was being destroyed by chlorine and bromine radicals. The role of CFCs—molecules that transport chlorine to the stratosphere—in the destruction of Antarctic ozone was unequivocally confirmed. Shortly thereafter, laboratory and theoretical work pinned down other essential mechanisms of the process—mechanisms involving cloud particles, which had been overlooked in earlier studies. With such overwhelming evidence in hand, the nations of the world moved a The Swedish Academy of Sciences awarded the 1995 Nobel Prize in Chemistry to F. Sherwood Rowland, Mario Molina, and Paul Crutzen for their work in atmospheric chemistry. Rowland and Molina published an article in Nature in 1974 that showed that chlorofluorocarbon releases into the atmosphere cause stratospheric ozone depletion. Paul Crutzen had previously shown the importance of nitrogen oxide catalytic chain reactions in controlling the amounts of stratospheric ozone.

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OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade with remarkable alacrity to mitigate the threat. International meetings developed strategies to control emissions of ozone-destroying substances, while the chemical industry worked to devise substitutes for CFCs. Within a few short years, a comprehensive framework for controlling worldwide emissions had been put in place in the form of the justly admired “Montreal Protocol.”23 A number of lessons relevant to the broader field of global change research may be drawn from the case of research on Antarctic ozone depletion. The severity of the ozone phenomenon demonstrates that environmental changes are not always incremental or slight. Moreover, the severity of ozone loss came as a total surprise, even though the topic had been carefully considered by the scientific community. Finally, however, the problem was assessed in remarkably short order and effective remedial measures were rapidly instituted—because a solid base of related scientific understanding had been developed through decades of focused observation and research. An additional critical point to make in this context is that many issues in global environmental change, such as climate change, are far more complex than even the difficult ozone story. The chemical, physical, and biological aspects of the greenhouse problem are extraordinarily daunting to study, and yet an additional, more difficult challenge probably lies in understanding the human dimensions of global change phenomena. THE ROAD AHEAD What surprises are in store in the future? By definition, surprises cannot be fully anticipated; at best, they can be acknowledged as possibilities. As such, they pose a special challenge to science. Science must formulate specific questions to set about obtaining the critical observations and performing the analyses needed to answer them. It is hard to ask questions that will anticipate all possible surprises before a surprise occurs. Preparing science for surprise is, in part, the challenge that the CGCR faced in developing this report. Scientists believe strongly that unfocused research on the complex and varied Earth system is unlikely to be productive. On the other hand, scientists who view the world through pinholes are likely to bump into trees and fall off cliffs. How can needed focus be given to the USGCRP while still casting the research net sufficiently wide to catch the unexpected? In this report, the CGCR has sought to define a framework for this endeavor, identifying a set of coherent domains of research that are likely to provide efficient and productive progress for science and to encompass the range of scientific and social issues implicit in global environmental change. This framework builds on the initial set of guiding principles defined by the Committee in its “La Jolla” report and on the issues of great scientific and practical importance in mature areas of Earth system science that are identified in this report.

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OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade THE PATHWAYS FRAMEWORK This report outlines a research framework across the wide scope of global environmental change in terms of the following primary topical areas: Changes in the Biology and Biogeochemistry of Ecosystems Changes in the Climate System on Seasonal to Interannual Timescales Changes in the Climate System on Decadal to Century Timescales Changes in the Chemistry of the Atmosphere Paleoclimate Human Dimensions of Global Environmental Change Pathways (see Appendix B) begins with biology and biogeochemistry because of our intimate dependence on biological systems, because of the sensitivity of these systems to changes in the physical and chemical environment, and because of the pivotal role of biology in the changing biogeochemical cycles of the planet. These biogeochemical cycles are, in a sense, the metabolic chart for the planet; they provide particularly useful benchmarks of global change. We look next into the climate system, focusing initially on climate variability on seasonal to interannual timescales and then on climate change on decadal to century timescales. We find we also must consider climate variability and change on the intermediate timescale of a human generation. Changes in the chemistry of the atmosphere drive many global changes; the atmosphere quickly transports chemical inputs from whatever source, and the chemical loadings are of sufficient scale that they can no longer be ignored. Testing ideas about global change on longer timescales is not like research to improve weather forecasts, in which feedback and correction are almost immediate. The paleoclimate record offers a unique opportunity to assess ideas about the dynamics and causes of global environmental change and variability. This record also tells us that large departures from simple expectations have occurred in the past, forcing the recognition that any program addressing global change must be sufficiently broad in scope to ensure that surprises are caught early. This consideration is particularly important for devising observational strategies. The human dimensions of global environmental change—that is, humans and their institutions as both agents and recipients of change—are integrated where possible into the other topical chapters of this report and are also the subject of a separate treatment. Many concerns about the changing environment are tied directly to concerns about human and ecosystem health and welfare. The discussion of each of the six primary topical areas is structured in terms of Research Imperatives—central issues posed to the corresponding scientific community by the challenge of global environmental change (see Appendix C). Four to six Research Imperatives are identified for each topical area. Sometimes these imperatives closely interconnect. The Research Imperatives provide the guideposts for the research “pathway.”

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OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade Each Research Imperative is addressed by a set of Scientific Questions. The limbs of the research strategy begin to branch and spread. If surprises are in the wind, we hope that this broadly spreading canopy of topics, Research Imperatives, and Scientific Questions will catch the signal. The Scientific Questions are posed at a level of detail from which an observational program, space-based and in situ, can be defined, refined, and realized. The observational strategy also consciously recognizes that surprises might well be in store. For this and other scientific reasons, an essential requirement of the observational strategy is to establish long-term, scientifically valid, consistent records for global change studies. It is fortunate that the paleoclimate community has provided extremely detailed histories of climate and environmental change that can underpin the instrumental records, establishing some basis for the assessment of future monitoring. Long-term monitoring is a central, scientific challenge for global change research. It is also a difficult challenge to meet in a social environment that so often values or wants something new. Observations are essential to test hypotheses from which models can be developed. Models are essential if prediction and synthesis are sought. Observations are useless, however, if the data are inaccessible to users (e.g., because of the problem of data recorded in “write-only ” memory). Data systems have been a constant challenge to all scientific investigations; they are particularly problematic when large amounts of data are involved, as in global change studies. Fortunately, through a unique confluence of satellite and computer technology, science stands on the threshold of a greatly enhanced ability to exploit such masses of data and, hence, is well positioned to monitor and predict changes in the global climate and environment. Satellites orbiting the Earth can monitor changes in sea height, wind velocity, atmospheric water vapor, snow cover, and a wide variety of other parameters. Satellite data can be merged with ground-based measurements networks in a matter of minutes through a series of telecommunication satellites, microwave links, and fiber. Data derived from these sources serve as inputs to large computer-based models, which in turn provide predictions about future environmental trends and variability. The existing and future Internet and associated services give the USGCRP an opportunity to manage this stream of data successfully and at reasonable cost. A data strategy is needed that emphasizes flexible and innovative systems— systems that are less costly than the current EOS core system, that appropriately reflect focused responsibility for data character, that provide open access to the scientific community and the public, and that rapidly track technological developments. REVIEW OF THE USGCRP As mandated in the legislation establishing the USGCRP (see Appendix A), the NRC has provided continuing oversight and review of the Program (see Bibliography.

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OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade lined, where possible, with respect to accuracy, spatial and temporal resolution, required simultaneous measurements, and other defining characteristics so that each measurement ensemble is formulated to answer a specific primary Scientific Question. The importance of accuracy, continuity, calibration, documentation, and technological innovation in observations for long-term trend analysis of global change cannot be overemphasized. A central tenet of the Committee's analysis is the necessity for the continuity of key global change observations.iFor example, with regard to the fundamental forcing parameters of global change, such as solar radiation and atmospheric carbon dioxide concentration, and response parameters, such as surface temperature and global cloudiness, discontinuities in the climate record resulting from instrument changes or drift have led to questions about the very nature of global change. Instrument or technology changes per se are not the problem; the problem is inadequate cross-calibration between instruments, and this inadequacy usually results from the absence of commitment to observational continuity. The Research Imperatives identified in this report express guiding considerations for the USGCRP to fulfill its responsibility for observing, documenting, and understanding global environmental change. The critical nature of high-quality observations to the scientific and public policy issues posed by global environmental change places demands and constraints on whatever path a USGCRP observational strategy attempts to chart; however, a specific, well-considered, and realistic strategy, including costs and schedule, for obtaining the observations of past, present, and future expressions of global environmental change is essential. The strategy will need an effective institutional mechanism for implementation. As an example, no agency currently has the responsibility for carrying out or coordinating a comprehensive program of climate observations. There are many different scientific demands for observations for exploratory surveys, hypothesis testing in coordinated process studies, repetitive analysis-forecast cycle research, documentation of long-term changes, calibration and validation of measurements, and applications or modifications of measurements that may be used primarily for purposes other than global change research. These different demands or applications must be taken into consideration in developing a coherent observational strategy. Operational demands are uniquely linked to long-term measurements and therefore are vital for obtaining them. In particular, the satellite and in situ measurements taken as part of the weather-observing system are critical to the future of the climate record. Development of the next generation of weather satellites (e.g., the National Polar-Orbiting Operational Environmental Satellite System, NPOESS) should be undertaken with the climate record and other research on relevant global change Scientific Questions clearly in mind. i We note again that the importance is in the continuity of the measurement and not in the continuity of the technology or the exact instrument.

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OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade Documentation of decadal and longer term change raises other basic issues of program management and decision structure. Because adequate characterization of higher frequency variability is fundamental to this documentation, both to avoid aliasing and to help in attributing causes, there is major overlap between long-term observations and measurements that are necessary on the daily and interannual timescales. However, as the timescale of the phenomenon studied becomes longer, two other considerations become increasingly important for adequate management of the research enterprise. First, the need for comparability of measurements made at different times and places requires that high priority be given to thorough instrument calibration and measurement system validation, including the inevitable changes in technologies and observing networks. Because action is required now, but all the specific Scientific Questions may not come into focus for many years, it is necessary to invoke the concept of stewardship to justify this effort. Stewardship involves doing what is reasonable and prudent to safeguard the interests of future generations, who are not able to argue their case for the data and information. Second, to put even reliably observed interdecadal changes in context, it is necessary to invoke records of much longer duration than available based on modern instrumentation. Thus, the strategy must include the systematic search for, and recovery and exploitation of, naturally existing proxies for such instrumentation, proxies that reveal the past history over hundreds and thousands of years with adequate fidelity and temporal resolution. This activity would appear to have little relationship to what is conventionally known as an observing system. Moreover, both calibration of such proxy records in terms of modern instrumental measurements and execution of process studies aimed at their interpretation are less glamorous tasks than launching satellites to observe fine details over the next decade or so. Nevertheless, these less glamorous activities may yield much more useable information for the foreseeable future about the natural processes leading to environmental fluctuations on such timescales and hence about the modifications induced by human activities. A coherent observational strategy is needed that builds on the identified Research Imperatives and Scientific Questions and on available national and international space and in-situ networks. The USGCRP must find a mechanism to resolve the agency boundary issues that will surely arise in developing and especially in implementing a coherent observational strategy. The United States and its international partners must find a way to deal effectively with the international dimensions of an overall observational system. In sum, what is needed is not a vast new program but rather attention to coordinating, simplifying, and focusing current and planned observing systems. This work requires the sustained attention of the scientific community and the farsightedness of government to ensure the survival of key observational records. A particular challenge will be the in-situ systems.

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OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade Finding 3.1: Although extensive planning has been done for space-based systems to observe global climate, the oceans, and the land, a comprehensive space-based system does not yet exist in practice. It is a promise that remains unfulfilled. Moreover, it is not clear that current planning activities will lead to such a system. Central issues about which nation (or nations) will provide which observations and for how long and at what spatial and temporal scales (and with what assurance) remain unresolved. The situation for in-situ observations across the full global environmental change agenda is in far worse shape. Finding 3.2: The connectivity of NOAA's NPOESS program with NASA's Earth Observing System in Mission to Planet Earth is an important and not yet adequately resolved issue. The adequacy of the NPOESS measurements to meet the demands of global change research remains in question. In addition, it is essential to maintain those stations of the existing in-situ weather observation network of the United States and around the world that carry the climate record from past decades. The current and future state of this system is unclear. Although we recognize the danger in recommending another study or planning exercise, a path to a more realizable, logical, focused, and robust observing system must be found. The USGCRP must adopt multiple observational approaches, recognizing that no single approach can guarantee continuity and accuracy of measurements and that independent checks are necessary to obtain verifiable results. Recommendation 3: The strategy for obtaining long-term observations designed to define the magnitude and character of Earth system change must be reassessed. Priority must be given to identifying and obtaining accurate data on key variables carefully selected in view of the most critical Scientific Questions and practically feasible measurement capabilities. The strategy must take the following into account: The fact that observing systems have been designed for purposes other than long-term accuracy and that this has undercut the long-term calibration needed for scientific understanding of global change The overall balance and innovative treatment of observations: the balance between space-based observations and in-situ observations, between operational and research observational systems, and between observations and analysis The gaps between research and operational observational systems that could threaten needed long-term records The end-to-end responsibility and the principal investigator mode for research observational systems. Given the constraints on the budget system and the needs of the research community for observations from space, the strategy appears to involve three components:

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OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade Within NASA, build focused, less costly missions on the solid and broad foundation set by EOS. Within NOAA, build scientifically sound observational missions for monitoring global change on the foundation set by EOS; these missions must meet NOAA's operational requirements. Within the USGCRP, increase the funding for in-situ observational programs and the necessary research and analysis links necessary for the related essential science. The first component should be possible within the scope of current budget projections. The second component may require additional funds for NOAA; it may require modification of NOAA's mission (e.g., a strong commitment by NOAA to address global environmental change as part of its mission), and it definitely requires significantly improved coordination between NOAA and NASA. The third component requires both new funds, which have begun to appear in the proposed fiscal year 1999 budget, and sharper focus in using existing funds. With regard to the second component above, it is crucial to recognize that, even if NOAA were to assume prime responsibility for the USGCRP space-based, monitoring program, NASA would continue to have significant data-processing responsibilities including reanalyses. Finally, the issue of the DOD role and influence on the observational, space-based monitoring program must be addressed by USGCRP. Technical Innovation Innovation is essential for scientific progress in this global change research. Many needs illuminate the importance of innovation, foresight, and testability in this field: Obtaining simultaneous, high-resolution observations with high sensitivity of the sea surface and the marine boundary layer Determining fluxes of carbon species into and out of broad categories of ecosystems Establishing patterns of land use and the state of vegetation Observing the vertical profiles of temperature, salinity, velocity, and tracer concentrations in the oceans Establishing the distribution of water in the atmosphere and the fluxes of water between the Earth's surface and the Earth's atmosphere Obtaining isotopic composition of water in the middle/upper troposphere Determining systematically the concentrations and concentration derivatives of catalytically active free radicals at altitudes from the sea surface to the middle stratosphere Obtaining observations along Lagrangian trajectories to dissect aerosol formation processes.

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OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade There is also a fundamental problem in global change observations that can be attacked only by technical innovation. The ocean-atmosphere-biosphere is seriously undersampled—mechanistically, spatially, and temporally. Finding 4: The capability, availability, cost, and character of observational platforms are critical considerations in global change research strategies. Observational platforms are the foundation of the nation's research efforts, and the design of these platforms can profit significantly from the lessons learned in carrying out global change research to date. Consideration of these lessons demonstrates that the successful execution of global change research is closely tied to technical innovation. Investment in observational platforms to date has been focused on a small number of large satellites, a limited number of marginally funded aircraft, a small number of ocean buoy systems, and a sparse network of ground-based efforts. This balance among the space-based, airborne, and ground-based observations does not reflect the spectrum of requirements that the Research Imperatives demand. Indeed, space-based observations and their associated data-management systems dominate the resources of the USGCRP, a trend that impinges on both the research and analysis support and the in-situ observational networks. Recommendation 4: The restructured national strategy for Earth observations must more aggressively employ technical innovation. Because of fixed budgets, resources should be reallocated from the large, amalgamated space-based approach to a more agile, responsive ensemble of observations. This goal will require carefully placed investments in technologies. Technological advances in small satellite systems, robotics, micro-electronics, and materials must be exploited to establish a sound balance between in-situ ground/ocean-based, airborne, and space-based observations. Innovative treatment of the nation's research aircraft capability, piloted and robotic, is strongly advised. The R&Acomponent of the national research effort must be recognized for its central contributions to science, public policy, and understanding of human-dimensions issues. Data Systems The issue of data systems and the design of those systems closely tied to the character of the observational strategy and the associated theoretical and modeling effort used to address the important questions. A key common component of major scientific advances has been the focus of responsibility: a specific principal investigator (or close collaboration of coinvestigators) must bear the end-to-end responsibility that connects the posing of a scientific question to the execution of an observational strategy with associated theoretical analysis and through to the publication of scientific conclusions in the refereed scientific literature. A plan in

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OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade which committees and/or agencies are assigned responsibility for data quality and distribution in a manner that breaks the end-to-end responsibility of the principle investigator is almost invariably critically flawed. The scientific method depends on a strategic combination of observations, selected from an array of possible observables, that can dissect a problem to the satisfaction of peer critics. This achievement demands specific choices, and it demands focused responsibility. The NRC Committee on Data Management and Computation has already shown that effective data systems require continuous and widespread involvement of the science team. Connected with the fundamental role of the investigator in assuring appropriateness and quality of observations is the rapidly advancing state of information systems, which can allow distribution of activities in time and space while preserving the essential responsibility of the scientific investigator. It is important, in considering the scientist and the information system, to consider the nature of the future of this interaction. The evolution of information systems will likely be characterized by rapid, dramatic shifts, as much as by any smooth, “predictable ” process. In an industry that shows a quadrupling of capability every 3 years, there are no stationary solutions. Stability and success can be attained only by development of a solid, well-grounded information model that describes how the pieces and subsystems, including as they develop, are related to each other. This model should be based on science that incorporates a database-driven approach; the technical implementation can then be more flexible and take advantage of technological advances in a more rational manner. To date, the concentration has been on processing and storage, but the network infrastructure as well as the software is undergoing fundamental changes. Although the scientific community has logically paid attention mainly to such government and academic backbones as vBNS and Internet-2, the more important shift is occurring in the widespread distribution of high bandwidth (1-10 Mbps) to the home. This shift has an implication for the USGCRP. First, more home users will likely be searching NASA, NOAA, and other global change archives for interesting or educational material. The networking capabilities of these more informal users will be competing with scientists for access to the archives. Second, these users will likely demand different types of products than scientists. This probable situation needs to be recognized. The NSF Knowledge and Distributed Intelligence solicitation in the fiscal year 1999 budget is an example of government-encouraged partnerships with the private sector that may accelerate this trend. Just as the Internet has changed the model of how we conduct research, so these new distribution channels will change our model again. Ultimately, the USGCRP is about information. Information must flow within the Program and also to the broad community of users. The subject of the Program's research demands that information flow effectively to the public at

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OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade large as well as to researchers. This is an important issue, and it should not be ignored by either the community of scientists engaged in global change research or by the agencies that support this research with public funds. Finding 5: Data systems must be agile and responsive to technology developments and to emerging techniques for data handling, analysis, and transfer. Data systems must also maintain scientific discipline and focused responsibility, so that the link between scientific question and clear scientific conclusion is not broken. An appropriate system is one that charges the government with initiallevel processing and long-term archiving and that charges the scientific community with producing the scientific products by the most effective means possible. Recommendation 5: The USGCRP must revitalize its strategy for the data systems used for global change research. Emphasis must be placed on designing and selecting flexible and innovative systems that appropriately reflect focused responsibility for data character, that provide open access to the scientific community and the public, and that rapidly evolve to exploit technological developments. In particular, the USGCRP must closely monitor the progress of the innovative “federation ” concept for data systems.j As suggested in the last finding, it is likely that the government will continue to provide the primary long-term archive for space and Earth science data, but it must also maintain the capability to enable long-term reprocessing of these time series; archiving must not continue to be a burial ground for data. With more rapid distribution channels and more powerful archive and processing systems at the fringes, perhaps one part of the government's role is to provide an on-line repository of data recipes rather than fully processed data sets. This service would enable more customized processing with the government serving as the warehouse for raw materials and generating specific products on demand. Finally, changes in technology will allow and force us to rethink our strategy often; any strategy must accommodate and encourage this eventuality. Models and Looking into the Future As mandated by its implementing legislation, the USGCRP seeks to provide useful information to the policy process. A direct implication of this responsibility is that the information must be scientifically credible, that it be of genuine interest and value, and that, to the greatest extent possible, it provide lead time for policy action. The last requirement implies provision of some prognostic infor- j The “federation” concept was recommended in a 1995 NAS Review of the USGCRP and refers to a federation of partners selected through a competitive process and open to all.

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OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade mation. This requirement does not necessarily entail a “prediction,” but it does raise the same concerns as any prediction or predictive process. These concerns revolve around general, and not necessarily scientific, issues such as usefulness, trustworthiness, and credibility of the information. In general, a model or a set of models will often be at the center of the predictive process. Finding 6: The policy issues that confront global change research, like the Scientific Questions, are serious, particularly with regard to their impact on humans. These issues will rely on models of exceedingly complex behaviors over a significant range of scales in space and time. Significant challenges face the scientific community in the form of many and various modeling issues, from initialization to validation. Important, unsolved, difficult problems remain for formulating useful prognostic models over a range of topics in human-dimensions research. Advances in developing and most importantly in testing and evaluating models are needed. The United States is no longer in the lead in this critical field. The fact that the United States is no longer in the lead in applying global models is not purely a statement of criticism. Strong scientific work, particularly in the area of modeling, has been advancing around the world. This is to be applauded. Global change research, particularly in the area of prognostic activities, requires a full suite of models to adequately bracket the complex problems that USGCRP seeks to address. Thus, advances in modeling capabilities in other parts of the world are of significant benefit to the USGCRP. Testing adequately complex models is very computing intensive, and if computing resources are not adequate and available then there is clearly the danger that the dynamical aspects of models will not be sufficiently understood and hence that the models will be misapplied. Currently, the potential exists that the advanced models built in the United States cannot (or will not) be adequately tested and properly applied to key problems, such as national and regional expressions of transient climate variability and change because of a lack of available computing resources. The United States must apply greater resources, particularly (but not exclusively) in the area of advanced computing machines. National boundaries should not influence where machines are purchased. Recommendation 6: The USGCRP must foster the development and application of models at the scales of time and space needed to understand and project the specific mechanisms controlling changes in the state of the Earth system thus providing the information required to support important policy processes. The USGCRP must give increased emphasis to models that treat multiple stresses on systems; it must therefore secure adequate computing resources so that large-scale, complex models can be rigorously tested under multiple forcings.

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OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade Models must be tested and evaluated with observations. This means that adequate observations and advanced computing resources must be available to adequately evaluate models and their potential utility for the public policy process. Consequently, there must be a greater commitment to advanced computing resources, as well as human resources, by the USGCRP to ensure that global modeling is achieved at spatial and temporal scales appropriate to the needs of the policy community and the private sector. As the USGCRP enters this second critical decade of its existence, the scientific challenges it faces are heightened by the need to understand and foreshadow the regional, as well as other, impacts of global environmental changes. The causes of global change are now also more complex, the need to understand the effects of multiple stresses are more apparent, and the likelihood of realizing significant near-term global reductions that would lead to stabilization of the forcing terms (such as greenhouse gas concentrations in the atmosphere) before a doubling of the radiative effects are more remote. In short, the need for useful prognostic information will only increase in the future. In view of these considerations, the current circumstances within the USGCRP, and the current status of modeling and available computing resources to the global change scientific community, there must be a considerably expanded commitment of resources to modeling, particularly at the temporal and spatial scales needed by the policy community. NOTES 1. WMO, 1979. 2. DOE, 1977, 1980. 3. Goody, 1982. 4. NRC, 1966; Fein et al., 1983. 5. There have been dozens of NRC reports addressing this topic; the Bibliography contains many examples. 6. ESSC, 1986, 1988. 7. Goody, 1982. 8. NRC, 1986. 9. ESSC, 1986, 1988 10. Revelle, R., and H. E. Suess, 1957. 11. MIT, 1970, 1971. 12. NRC, 1982a. 13. NRC, 1979. 14. NRC, 1979. 15. NRC, 1982b, 1991. 16. WMO, 1979, 1990. 17. WMO, 1984, 1986. 18. IPCC, 1995. 19. NRC, 1995. 20. NRC, 1996. 21. e.g., NRC, 1982c. 22. A recent update is contained in UNEP, 1994. 23. Montreal Protocol to the Vienna Convention on Substances that Deplete the Ozone Layer, 1987.

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OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade 24. NRC, 1995. 25. NRC, 1996. 26. USGCRP, 1997, p. 3. 27. USGCRP, 1997, p. 78. 28. USGCRP, 1995, p. 109. 29. NRC, 1995. 30. The Committee benefited from advice from several individuals in the area of data systems and their evolution. Professor Mark Abbott was particularly constructive, and a White Paper by him was most useful. BIBLIOGRAPHY Goody, R. 1982. Global Change: Impacts on Habitability. Report by the Executive Committee of a Workshop held at Woods Hole, Massachusetts, June 16-21, 1982. JPL D-95. National Aeronautics and Space Administration, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, 15p. Earth System Sciences Committee (ESSC), 1986. Earth System Science. Overview. NASA Advisory Council, National Aeronautics and Space Administration Washington, D.C., 48p. Earth System Sciences Committee (ESSC), 1988. Earth System Science. A Closer View. NASA Advisory Council, National Aeronautics and Space Administration Washington, D.C., 208p. Fein, J. S., P. L. Stephens, and K. S. Loughran. 1983. The Global Atmospheric Research Program: 1979-1982. Reviews of Geophysical and Space Physics. 21: 1076-1096. International Council of Scientific Unions (ICSU), 1996. Understanding Our Planet. ICSU Press, Paris, France, 48p. Intergovernmental Panel on Climate Change (IPCC), 1995. Climate Change 1995: IPCC Second Assessment Report. Cambridge University Press, 448p. Massachusetts Institute of Technology (MIT), 1970. Man's Impact on the Global Environment. Report of the Study of Critical Environmental Problems (SCEP). MIT Press, 319p. Massachusetts Institute of Technology (MIT), 1971. Inadvertent Climate Modification. Report of the Study of Man's Impact on Climate (SMIC). MIT Press, 308p. National Research Council (NRC), 1966. The Feasibility of a Global Observation and Analysis Experiment. Committee on Atmospheric Sciences. National Academy Press, 172p. National Research Council (NRC), 1979. Carbon Dioxide and Climate: A Scientific Assessment. Ad Hoc Study Group on Carbon Dioxide and Climate. National Academy Press, 22p. National Research Council (NRC), 1982a. Energy and Climate. Geophysics Study Committee. National Academy Press, 158p. National Research Council (NRC), 1982b. Carbon Dioxide and Climate: A Second Assessment. CO2/Climate Review Panel. National Academy Press, 72p. National Research Council (NRC), 1982c. Causes and Effects of Stratospheric Ozone Reduction: An Update. Board on Environmental Studies and Toxicology. National Academy Press, 339p. National Research Council (NRC), 1983a. Toward an International Geosphere-Biosphere Program. National Academy Press, 81p. National Research Council (NRC), 1983b. Changing Climate. Carbon Dioxide Assessment Committee, Board on Atmospheric Sciences and Climate. National Academy Press, 486p. National Research Council (NRC), 1983c. El Niño and the Southern Oscillation: A Scientific Plan. Board on Atmospheric Sciences and Climate. National Academy Press, 72p. National Research Council (NRC), 1986. Global Change in the Geosphere-Biosphere. Initial Priorities for an IGBP. U.S. Committee for an International Geosphere-Biosphere Program. National Academy Press, 91p. National Research Council (NRC), 1991. Policy Implications of Greenhouse Warming. Committee on Science, Engineering, and Public Policy. National Academy Press, 944p.

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OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade National Research Council (NRC), 1995. A Review of the U.S. Global Change Research Program and NASA's Mission to Planet Earth/Earth Observing System (La Jolla Report). Committee on Global Change Research and Board on Sustainable Development. National Academy Press, 96p. National Research Council (NRC), 1996. A Review of the U.S. Global Change Research Program. Committee on Global Change Research. Letter report, 20p. [Post-La Jolla Report.] Revelle, R., and H. E. Suess. 1957. Carbon dioxide exchange between atmosphere and ocean and the question of an increase of atmospheric CO2 during the past decades. Tellus 9: 18. United Nations Environment Program (UNEP), 1994. Scientific Assessment of Ozone Depletion 1994. United Nations Environment Program, Geneva, 578p. U.S. Department of Energy (DOE), 1977. Workshop on the Global Effects of Carbon Dioxide from Fossil Fuel. William P. Elliot and Lester Machta, eds. Held March 7-11, Miami Beach, FL. U.S. Department of Energy (DOE), 1980. Workshop on Environmental and Societal Consequences of a Possible CO2—Induced Climate Change. Conducted by the American Association for the Advancement of Science on April 2-6, 1979, Annapolis, MD. USGCRP, 1992. Our Changing Planet: the FY 1993 U.S. Global Change Research Program. A Supplement to the President's Fiscal Year 1993 Budget. U.S. Global Change Research Program Office, 79p. USGCRP, 1995. Our Changing Planet: the FY 1996 U.S. Global Change Research Program. A Supplement to the President's Fiscal Year 1996 Budget. U.S. Global Change Research Program Office, 151p. USGCRP, 1997. Our Changing Planet: the FY 1998 U.S. Global Change Research Program. A Supplement to the President's Fiscal Year 1998 Budget. U.S. Global Change Research Program Office, 118p. World Meteorological Organization (WMO), 1979. Proceedings of the World Climate Conference. World Meteorological Organization, Geneva. World Meteorological Organization (WMO), 1984. Report of the Study Conference on Sensitivity of Ecosystems and Society to Climate Change, Villach, Austria, Sept. 1983. WCP Publication 83. World Meteorological Organization, Geneva. World Meteorological Organization (WMO), 1986. Report of the International Conference on the Assessment of the Role of Carbon Dioxide and of Other Greenhouse Gases in Climate Variations and Associated Impacts, Villach, Austria. World Meteorological Organizations, Geneva. Publication 661, 78p. World Meteorological Organization (WMO), 1990. Proceedings of the Second World Climate Conference. World Meteorological Organization, Geneva.