Prepared
statement of Michael C. MacCracken, Ph.D.
Director, Office of the U. S. Global Change Research
Program
Before the U. S. House of Representatives Committee on Science Hearing
on U. S. Global Change Research Programs: Data Collection and Scientific
Priorities, March 6, 1996
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Mr. Chairman, Members of the Committee, my name is Michael C. MacCracken and I have served as Director of the interagency Office of the U. S. Global Change Research Program since 1993. I am on assignment from the National Science Foundation (NSF), where I report to Dr. Robert Corell, Assistant Director for Geosciences, who is chairman of the interagency Subcommittee on Global Change Research that oversees the U. S. Global Change Research Program (USGCRP). I have in turn been on an assignment to the NSF since 1993 from the Lawrence Livermore National Laboratory (LLNL), where I was most recently the division leader for atmospheric and geophysical sciences and then of global climate research, working for more than 25 years on the development, testing and application of global climate system models. Prior to that, I was involved in modeling the climatic effects of greenhouse gases, of nuclear war, and of supersonic aircraft, in modeling the air quality of the San Francisco Bay Area (which led to a plan that has helped the Bay Area become one of the few regions in the country to meet the national oxidant air quality standard), and in leading interagency Department of Energy efforts on sulfate air pollution and massively parallel computing. A biographical statement is attached.
Introduction It is my pleasure to appear before the Committee to describe the interagency U. S. Global Change Research Program and its scientific priorities.
Program Organization The USGCRP was established
as a Presidential Initiative in the FY 1990 Budget, and was codified
in the Global Change Research Act by Congress in 1990. The USGCRP
is currently administered by the Subcommittee on Global Change
Research (SGCR), which currently reports to the Committee on Environment
and Natural Resources (CENR) of the National Science and Technology
Council (NSTC). Within this scientific framework, the USGCRP oversees
the scientific research concerning global change. I want to point
out that the policy aspects of global change research are completely
separate from the research effort and report through separate
channels--the USGCRP focuses on providing support for the fundamental
inquiry and developing the underpinning scientific information
concerning global environmental change and its consequences and
implications.
With so many agencies involved, it has been important to have an underlying scientific approach to investigating global change. The administration of President Bush presented the first scientific plan for the USGCRP in October 1990 and it has served as an important guide to research efforts over the past several years. We are currently in the process of preparing a new plan that is responsive to the advancing of scientific understanding and to the very helpful comments of the National Academy of Sciences in their review last summer. Under the original plan, the goal of the program has been to "establish the scientific basis for national and international policy-making relating to natural and human-induced changes in the global Earth system." The means for accomplishing this was to achieve a greater understanding of the Earth system "through the mutually reinforcing global change research activities of all nations and many organizations and programs ..." The programs that have developed since this goal was established reflect its striving for a better predictive understanding of the world around us through a large measure of interagency, bilateral, and multilateral cooperation. With the new plan, we have moved to make our goal statement more clear and better defined. Pending review this spring by the National Academy of Sciences and the broader scientific and stakeholder community, the proposed update to the USGCRP goal is:
To meet the original goal for the USGCRP, the SGCR identified seven broad disciplinary areas of scientific uncertainty relating to global environmental change and within each area identified the highest priority areas for research. A schematic diagram is included as Figure 1 showing these priorities. The seven areas, all of which have important elements, are:
Within this broad framework priorities were established leading to greater resources in the most important areas. Research, however, was sustained across each of these broad areas so as to encourage scientific exploration and investigation and so as not to submerge or prematurely dismiss uncertainties. For most of these areas, the program provided for both coordinated programs that involved scientists working together (which can really help to improve overall understanding of a process) and support for individual investigators (who are effective at identifying new areas and uncovering weaknesses)--both types of activity are essential to a vigorous scientific program. Like all major research activities, the USGCRP requires a range of approaches for accomplishing its goal. The original USGCRP plan can be grouped the activities into the following categories:
Research in each of these areas is vital to providing the necessary information base for decision makers : Observations and Data Management: In the area of observations and data management, the largest activity is the NASA Earth Observing System (EOS) program, which will be covered by others in testimony today. From a research perspective, it is vital to have a wide range of observations to have any hope of understanding what is happening. While some suggest that we should just start measuring a specific parameter when we know it is needed to address a particular scientific question, this is not the way in which to gain timely information about long-term changes. For this challenge, we will surely need to have a wide range of information over extended periods--waiting would only delay having any data and preclude the possibility of fortuitous discovery that is likely from having a diverse and broad observational capability. In addition, developing and deploying new instruments takes time (so waiting until all questions are completely formulated to get started also causes delays). It is generally agreed that what we need now is many more observations than we have--leading to proposals for Global Observing Systems for the atmosphere, the oceans, and the land surface. NASA's EOS will be a very important contribution to global observing, both because of what it will observe and because it is spurring other nations to make many commitments so that the world community will have an invaluable scientific data base (see Figure 2). While EOS is the most expensive of the observation programs, there are others. We rely especially on the observations taken by NOAA and many other agencies for other related purposes (e.g. weather forecasting). Similarly, while the NASA EOS program has the need for the largest new data base management system (EOSDIS) and is using it now to make available results from existing and past satellites, other agencies have joined together with NASA under the USGCRP auspices to create a common access system known as the Global Change Data and Information System (GCDIS). This system and the "full and open" data policy of the United States have provided information for projects and investigators in a way that has stimulated both progress and the close examination of the understanding being pursued by my fellow witnesses. In FY-95, the USGCRP devoted about 60% of its budget to observations and data management because, once time passes and an observation is missed, the potential to observe is basically lost forever. For example, had we not been observing when the Mt. Pinatubo eruption went off, we would have missed a really unique event to use in testing our understanding and our models--waiting simply misses opportunities! Process Studies: Knowing what is happening is the first step to being able to project future conditions; understanding why is the second step. The way in which we do this is to determine how each process influencing the Earth system works; how clouds transmit and absorb radiation, what controls the amount of water vapor in the atmosphere, how the ocean takes up carbon dioxide and heat, what might cause the glaciers to melt or accumulate ice, in what ways ecosystems will respond to climate and atmospheric changes, and so on. Here, the U. S. has joined with other nations in the World Climate Research Programme (WCRP), the International Geosphere-Biosphere Programme (IGBP), and the International Human Dimensions Programme (IHDP) to consider and carefully plan coordinated and efficient research programs. Together with some additional national research programs (e.g., concerning our forests and ecosystems), these international programmes provide an organizing framework for cooperative multilateral efforts in each of the seven disciplinary areas listed above. In all of these studies, scientific questions are carefully posed, and a research plan is developed and reviewed for consideration of funding by nations and agencies. Because it is so important for scientists to understand with high confidence why and how something is happening in order to develop and improve models for making projections of what may happen in the future, about 30% of the USGCRP budget was devoted to process studies in FY-95. [This issue of the level of confidence scientists are seeking is discussed further below under assessments.] Integrative Conceptual and Predictive Modeling: For simple systems or single processes, conceptual (or mental) models can be particularly useful. For systems as complex as the full Earth system, arguably the most complex of all research endeavors, a systematic means must be found for incorporating our understanding into a quantitative framework. The approach that is used is to construct mathematical models that to the greatest extent possible rely on fundamental and immutable laws of nature. Reliance must be placed on various approximations because understanding will never be fully complete and computer size and resources are limited. Uncertainties will always exist-and there will always be questions for not everything can be explained; but uncertainties are also the reason for an aggressive associated program of observations, analysis, and process studies. The mathematical climate models (variously called climate models, general circulation models, or Earth system models depending somewhat on their implementation) strive to include all that is understood about the climate system. Because there is no means to prove them right--only to see where their projections of past climates are consistent with past variations and where they are not--the models are constantly being put through an increasingly grueling series of tests to see how well or poorly they match observations. Models reproduce many aspects of the observed climate. That there are shortcomings, however, is to be expected--all modelers acknowledge them (just as all good observationalists acknowledge the shortcomings in their observations). The challenge is identify why they are not precisely reproducing nature and how to make them better. But at any given time, models are at the cutting edge of what we understand. They treat dozens of processes spread out over the globe and up through the atmosphere and down through the oceans, all the time requiring that everything be done consistently--no leaving out a process here and including it there, no assuming that changing one thing will not change something else, and so on. While experiences from past climatic conditions can be a rich source of tests of models (hence we study paleoclimates), only models can provide quantitative projections of future conditions. [As an indication of the need to rely on computers to do the calculations, Lewis Richardson in 1917 did by hand all the calculations that a computer now does in order to predict the weather. Using a relatively simplified set of equations, he spent roughly a year of his life calculating the changes in one hour's weather over Europe --all of the citizens of the U. S. doing hand calculations could not come close to keeping up with present models that rely on advanced supercomputers.] While it might be tempting to wait until each process is understood before model calculations are attempted, making and analyzing such calculations is as much part of the research and learning process as are observational and process studies. All of these efforts must proceed in parallel. In support of modeling activities, the USGCRP devoted about 5% of its overall budget in FY-95. Environmental and Human Consequences: In that humans seem to readily survive changes in the seasons from winter to summer and back and moving from Buffalo to Phoenix, it is sometimes hard to understand the importance of what may seem like small changes in temperature. However, the types of changes that are being projected generally create conditions that cause natural conditions to reach new average levels that are generally beyond what has been experienced for thousands to tens of millions of years--times well before the establishment of human communities. Thus, increasing summertime temperatures in the Midwest by several degrees could well require adjustments in cropping, planting, and irrigation (some of which might provide opportunities for increased productivity once adjustments are made); rising temperatures in mountain regions in winter could accelerate snowmelt and runoff, requiring changes in water resource systems; shifts in the freezing line could extend the potential reach of warm weather disease vectors if we are not persistent in support of public and community health practices; rising sea levels could threaten coastal regions, especially when strong storms create very high tidal surges; and shifting patterns of temperature and precipitation could lead to die-offs and other changes in forests and grass lands as natural species shift and reestablish themselves elsewhere. In addition to what are often considered adverse effects, there are potentially beneficial consequences, including less harsh winters, increased precipitation in some regions, increased water use efficiency by plants, and enhanced growth under some conditions as a result of the increased carbon dioxide concentration. Some of these changes are subtle, many depend on the rate of change and the local environmental conditions, most are poorly understood, and the potential for surprises is high. As estimates of potential changes in the global environment have improved, it is becoming increasingly helpful to look closely at the potential consequences of changes for the environment and for human activities and natural resources. The USGCRP devoted about 3% of its FY-95 budget to these activities. Health and Resource Implications: Having projections of how climate will change and estimates of how these changes will affect particular natural resources, developing an understanding of the importance of the changes for society--for you and me--requires that an integrated consideration of all of the effects, of their economic and social importance, how adjustments and adaptation might take place, and of what options exist and technologies might emerge, all in the face of population growth and the evolution of societies. Providing precise predictions is, of course, impossible--human and natural events are simply too uncertain. However, by looking at past experiences and trends and by making some assumptions about what might happen, we can explore how environmental changes may impede or amplify particular trends or situations, what costs might arise and what approaches might reduce costs or even provide multiple benefits. Research in this area thus needs to focus on methods for weighing impacts of different types, how human health might be affected and represented, how market forces can accelerate or impede movements toward new and more efficient technologies, and much more. The USGCRP devoted about 2% of its overall budget in FY-95 to developing better techniques for evaluating the economic and societal significance of global environmental change and examining the health consequences of global environmental change. Scientific Assessments: In pursuing this wide range of research efforts involving multiple environmental stresses, multiple investigators are supported and a wide solicitation of viewpoints is sought to ensure that the full range of hypotheses is being tested. Science progresses by focusing attention on areas where there are disagreements and then developing research programs that can bring understanding. Criticism and thoughtful disagreement are normal parts of the scientific process, and when it has not been so, progress has been slow indeed. Thus, questioning, criticism, and uncertainties must always be at the forefront of scientific discussions. The USGCRP promotes open-minded, constructive criticism and questioning, carried out in a way that accommodates the participation of all who are interested. While science may thus seem disputatious and contentious to those seeking guidance for deliberative decision-making, this, along with periodic synthesis, is an important part of ensuring the scientific validity of results and makes science exciting and an effective means for developing information about complex issues. There is, however, at any given time a scientific responsibility to always provide for decision makers and the public the best possible representation of scientific thinking on critical issues facing humanity. To accomplish this, discussions among scientists and decision makers have identified broadly based scientific assessments as being the best mode of communication between the two sides. Such assessments are designed to describe what is known, what is uncertain, what is not known about how the environment is likely to change (due to both natural and human influences), how such changes will affect resource systems of importance to society (e.g., food production, water resources, public health, forests and ecosystems, coastal communities, etc.), and what the economic and social impacts of the changes and of various alternative approaches may be. The process of developing such assessments must be open, must be encompassing, must be independent, and must be carefully scrutinized. To meet this very important challenge, the U. S. participates actively in international assessments on ozone depletion, climate change, and biodiversity and undertakes national assessments on issues such as the effects of aircraft on atmospheric chemistry. We strongly commend to your attention the several assessments that have been prepared in recent years--they represent the carefully considered views of a wide array of scientists, having had input from many, many scientists and having been reviewed by other scientists, scientific program leaders in various nations, and by non-governmental organizations of many types and perspectives.
Most Scientific and Practical Importance
Since the start of the USGCRP, the focus of the research efforts has encompassed a range of environmental issues. These have included depletion of stratospheric ozone, the potential for the global climate to change, natural variations of the climate over seasons and years, and the general state of the world's ecosystems in the face of deforestation and desertification. While commending the USGCRP for the quality of the disciplinary research in the areas outlined earlier (and strongly supportive of its continuation), the review of the USGCRP by the National Academy of Sciences (NAS) in the summer of 1995 (as well as an emerging sense from within the agencies participating on the Subcommittee for Global Change Research--SGCR) recommended that, in order to be most effective, the USGCRP "should focus on priority issues in four mature areas of Earth system science that are of great scientific and practical importance." The SGCR is moving aggressively to implement the NAS recommendation. The four environmental issue areas (which are slightly renamed from the those suggested by the NAS) and their highest research priorities are: 1. Seasonal to Interannual Climate Variability The climate of the Earth continually experiences natural variations on seasonal to interannual time scales, as evidenced by the El Nino cycle. These naturally occurring fluctuations can lead to extreme climate events such as droughts, heat waves, and floods. Extended periods of drought and heat can increase the susceptibility of urban settlements and forest lands to fire, can disrupt food production and water supplies, and in developing regions, can occasionally lead to massive human migrations. Prolonged and excessive periods of precipitation can cause flooding, delay planting, contaminate water resources, and temporarily disrupt patterns of production and trade. An improved ability to document and then forecast trends and patterns of change in ocean temperature, snow cover, sea ice, and other factors that contribute to changes in the global climate over seasonal to interannual scales could lead to a reduction of adverse impacts from potentially destructive climate events. Early warnings enable communities to develop strategies to better prepare for these events by, for example, implementing revised planting schedules, switching crops, and modifying water management, all of which have been demonstrated to lead to reduced costs and impacts. Observations and analyses indicate that in some regions of the globe, seasonal to interannual variations of atmospheric conditions can be predicted up to two years in advance. These predictions are based on observed variations in parameters such as sea surface temperature, soil moisture, and snow and sea-ice cover. Significant changes in seasonal to interannual climate may be a key to the detection of longer-term climate changes. Science Goals for Research on Seasonal to Interannual Climate Variability
Human society is highly dependent on the Earth's climate. Climate patterns and human adaptations determine the availability of food, fresh water, and other resources for sustaining life. The social and economic characteristics of society have also been shaped largely by adapting to the seasonal and year-to-year (interannual) patterns of temperature and rainfall. While anomalous variations in these shorter time scale patterns can have serious effects on society, the vulnerability of society to longer-term climate change, occurring over periods of decades to centuries, will depend on its ability to understand and respond to this change. Thus, it is imperative that society develop the strongest possible scientific understanding of the causes and dynamics of climate change and greenhouse warming, the potential ecological and socioeconomic impacts of change, and the implications of alternative courses of action to mitigate and adapt to change. Scientists have determined that climate can be influenced by both natural forces and human activities. For example, habitable temperatures are maintained on Earth by a natural phenomenon known as the "greenhouse effect." Solar radiation is absorbed by the Earth's atmosphere and land and water bodies. The resultant heat is re-emitted as long-wave radiation, some of which escapes to space and some of which is absorbed and trapped by atmospheric gases such as water vapor, carbon dioxide, methane, nitrous oxide, chlorofluorocarbons and ozone. While some of these gases are present naturally, increased concentrations of greenhouse gases as a result of human activity can enhance this natural greenhouse effect, creating additional warming of the surface and the atmosphere. Human activities such as fossil fuel combustion and land-use change have resulted in a 30% increase in atmospheric carbon dioxide and have contributed to more than a doubling of the methane concentration since preindustrial times. Human-induced and natural changes in global land cover (such as deforestation and desertification) and emissions of aerosols (from fossil fuel burning and volcanic eruptions) also influence climate. Although much has been learned, there are still significant improvements to be made in estimating how human activities will combine with natural influences to affect the future global climate. IPCC assessments conducted with the participation of thousands of scientists from more than 150 countries and with significant USGCRP participation, suggest that emissions of greenhouse gases and sulfate aerosols could, by end of the next century, lead to an increase in global mean temperatures of 0.8 to 3.5°C (about 1.5 to 6°F), a rise in sea level of 15 to 95 cm (about 6 to 38 inches), and a global change in precipitation patterns. Among other uncertainties, the magnitude and location of projected shifts in global precipitation patterns remain particularly difficult to predict. Observational data show an increase in global average temperature of about 0.5°C (about 1°F) over the last 100 years. The likelihood that this warming is due primarily to natural variability is low. This observed warming trend is continuing despite the influence of the Mt. Pinatubo volcanic eruption, which caused volcanic emissions to reduce incoming solar radiation for nearly two years. The most recent climate model simulations have been able to explain the magnitude and temporal pattern of this observed trend reasonably well. To build greater confidence in predictions of future climate, further improvements are needed in modeling the influence of atmospheric aerosol concentrations, the cycling of atmospheric water in all its phases, cloud-radiation interactions, ocean-atmosphere coupling, and in predicting the expected range of natural climate variability. Projected climate change over the next few decades, including changes in temperature, precipitation, and sea level, can add to other stresses on natural systems caused by other factors such as population growth, land-use changes, and pollution, posing risks to managed and unmanaged resource systems. Although temperature changes of the magnitude expected from the enhanced greenhouse effect have occurred in the distant past, the evidence suggests that the changes generally took place over centuries or millennia instead of decades. Because rates of natural migration and adaptation of species and communities appear to be much slower than may be forced by the predicted rate of climate change, populations of many species and inhabited ranges could decrease as the climate to which they are adapted effectively shifts northward or to higher elevations. Overall, various strategies for coping with climate change can be identified for "intensively managed" systems (such as agriculture, water resources, and developed coastlines). For these systems, technological and management options exist to some extent today, although they may be costly to implement. By comparison, fewer options have been identified for natural systems such as wetlands and wilderness areas. Changes in climate may also have significant impacts on human health. These impacts may include increases in mortality and morbidity as a result of a higher frequency of heat waves and synergistic effects from higher temperatures and air pollutant mixtures (higher temperatures may cause changes in urban air chemistry). There is also evidence that a changing climate will cause a migration into higher latitudes and altitudes of some diseases, such as malaria and dengue, the incidence of which is highly correlated with rainfall and elevated nighttime temperatures. Science Goals for Research on Climate Change Decades to Centuries
Life at the surface of the Earth is protected from harmful ultra-violet (UV) radiation of the Sun by the stratospheric ozone layer. Over the last several decades, synthetic chemical compounds, such as chlorofluorocarbons (CFCs) and halons, were developed to provide a new generation of refrigerants, insulating foams, fire retardants, and other products. Unfortunately, after extensive use of these compounds, it was discovered that they remain inert in the atmosphere until they reach the stratosphere, where they break down into an active form that destroys ozone. One chlorine atom originating from a CFC molecule can destroy thousands of protective ozone molecules. Satellite and ground-based observations confirm that losses of ozone are occurring seasonally, particularly in the springtime polar vortex of the Antarctic stratosphere, leading to what is known as the ozone "hole." Also of concern is the more moderate ozone depletion observed in mid-latitudes, where a large portion of the Earth's population resides. In the absence of changes in clouds or pollution, decreases in atmospheric ozone will increase ground-level UV radiation. Analyses of data related to human health, Antarctic marine phytoplankton production, and careful field and laboratory experiments on the impacts of elevated UV exposure, indicate that increased UV radiation at the surface could have substantial negative impacts on human health, fish populations, and many terrestrial and marine ecosystems. In humans and other animals, impacts include immune system suppression, increased incidence of serious sunburn, cataracts and epidermal lesions, reduced vitamin D synthesis, and cancer. In plants, exposure to enhanced UV radiation can inhibit the essential process of photosynthesis. Increased UV radiation can also influence agricultural productivity and cause deterioration of synthetic materials such as plastics. Due to global recognition of the implications of ozone depletion, emissions of many CFCs and halons are to be phased out over the next few years. Global observations of CFC concentrations in the atmosphere indicate that actions taken in response to the Montreal Protocol and its amendments are having the desired effect. Atmospheric measurements of trichloroethane, a short-lived ozone-depleting substance, indicate that its concentrations are actually declining.
With the significant advances over the past decade in understanding stratospheric chemistry, the next ten years will see a particularly strong focus on understanding the even more complex chemistry of the lower atmosphere. The lowest portion of the Earth's atmosphere, the troposphere, is intimately involved in the chemistry of global change. Natural tropospheric processes cleanse the atmosphere of most pollutants, thereby interrupting the throughput of many ozone depleting substances to the stratosphere, and limiting the persistence in the atmosphere of the most common greenhouse gases. Accordingly, gaining a predictive understanding of tropospheric chemistry is central to quantifying how the troposphere works both to protect the stratospheric ozone layer and to determining the climatic impacts of aerosols and greenhouse gases which arise from surface pollution. Research will focus on field campaigns designed to elucidate the chemical and mixing processes that control trace substances in the lower atmosphere, on space-based observations to achieve global coverage, and on modeling studies to test and refine theories underlying prognostic capabilities. Science Goals for Research on Changes in Ozone, UV Radiation, and Atmospheric Chemistry
Human-induced changes in land cover have occurred throughout human history. Large tracts of land have been cleared for agriculture, forestry, the collection of fuelwood, and for urban and industrial growth. Ecosystems have been transformed both in response to land-cover change and as the result of the inadvertent and intentional introduction of plants and animals from outside their normal habitats, thereby introducing new pests, diseases, and competitive species. The damming, diversion, and rechanneling of rivers, the development of intensive agricultural irrigation systems, and the dramatic increases in the consumption of water for urban and industrial purposes have altered the natural water cycles of many regions, the impacts of which were often felt in remote locales because of the far-reaching character of hydrologic systems. Worldwide land-cover and ecosystem changes have become especially pronounced in recent decades. As the rate of change in many places have accelerated, so also have the magnitude of those changes and their impacts. More than ever, a comprehensive view of land-cover and ecosystem change is needed. Fortunately, new techniques for acquiring and managing information about these elements have been developed. The science and new technologies for measuring and understanding the dynamics and consequences of land-use and land-cover change have improved dramatically in the last decade. Studies in both tropical and temperature regions using Landsat data have demonstrated that rates of deforestation can be documented, and regrowth and reclearing of secondary growth also can be measured. Satellite data can be combined with ground-based and airborne measurements to determine the influence of land-cover change on biological diversity, hydrologic processes, and the potential for future resource production and utilization of an area. Research results and methods for measuring large-area land-cover and land-use change are now being used by commercial interests to develop sustainable plans for the production of livestock and forest products and to manage public lands for multiple uses. The increasing volume of data on land cover and related variables greatly facilitates analyses of the dynamics of land-cover change. USGCRP-sponsored research has examined the patterns and rates of land-cover change in a wide range of different areas, exploring different ways for classifying land cover and related land-use practices. These efforts have led to delineation of a set of land-cover regions for the globe. Regional case studies have begun in many of these regions using a common protocol developed by scientists involved in the Land-Use and Land-Cover Change (LUCC) project, a core project of both the International Geosphere-Biosphere Programme (IGBP) and the international Human Dimensions of Global Environmental change Programme (HDP). Through the use of comparable approaches in the conduct of these regional case studies, analyses of the dynamics of land-cover change in each of the regions form the basis for more general advances in understanding the complex interactions among human and natural processes. In the next decade, major new advances in the capabilities for remote sensing of land-cover and land-use dynamics are expected, resulting in an even greater increase in data available for documenting the dynamics of land-cover change. In addition to gaining a better understanding of changes associated with the land, change affecting or affected by the oceans (which cover 70% of the Earth's surface) are also critical to understanding the dynamics of the total Earth system. Warmed by the Sun and driven by winds, this vast mass of flowing water regulates the planet's seasonal and interannual climate fluctuations. The oceans are home to diverse communities of plants and animals, which take in and release dissolved carbon, nitrogen, oxygen, and other elements. Marine organisms participate in the global cycles of such elements, affecting their concentrations in the oceans, atmosphere, and land. Studies of ocean biology and circulation are crucial to understanding these biochemical cycles and their role in the maintenance of life. The oceans now are under increasing pressure from human activities. Industrial waste, synthetic fertilizers, and other pollutants are carried by rivers into the ocean, where they can injure life and cause radical changes in the composition of marine ecosystems. The species composition of algal blooms is shifting, and "red tides" of toxic algae are more common along the coasts of the world. Coral reefs, which support a wide variety of organisms in the tropical seas, have been particularly hard hit. Fish and shellfish have suffered as well, with heavy impacts on marine industries. Through significant new remote sensing capabilities and the use of other satellites, aircraft, and ground-based instruments on ships, buoys, and moorings, USGCRP-sponsored research is studying the responses of marine life to various kinds of natural and human-induced global environmental change. Humans are placing increasing demands on terrestrial and marine ecosystems. The challenge is to understand the potential consequences of natural and human-induced transformations and the effects of industrial activity on the structure and function of terrestrial and marine and coastal ecosystems. Such understanding is essential to maintaining the goods and services essential for human life provided by ecological systems and for developing mitigation options. It is also essential that the potential benefits derived from human-induced land transformations and industrial processes be balanced against the potential costs associated with the reduction or loss of ecological goods and services which result from such activities. Science Goals for Research on Changes in Land Cover and Terrestrial and Marine Ecosystems
Concerning Climate Change over Decades to Centuries The charter for this hearing indicates a special interest in the scientific priorities concerning climate change research. As part of our periodic planning effort, the USGCRP is presently renewing its program structure in response to the helpful comments coming from the National Academy of Sciences review of last summer. As I indicated above, this is only one of our several research areas, each of which is going through a similar redefining effort and review by various National Academy committees and panels. For each we are updating our overall research plan. The updated objective of our climate change research is to more reliably predict the changes in climate and the global environment that will occur over decades to centuries as a result of the continuing and projected changes in population, energy use, and other factors. In support of this objective, we are proposing six sub-objectives:
As part of the on-going scientific process of questioning and critiquing, with everyone checking each others results, it is quite natural that, in addition to there being areas for which there is strong agreement, seeming inconsistencies will be identified and areas will be found where the explanation of scientific findings can be improved. The USGCRP is very open to this process, and, in fact, its many research programs are all focused around questions and uncertainties. We prioritize our program around addressing those questions that are most important and where progress is most needed. In the recent IPCC assessments, an interesting revelation has been the difference in confidence levels that are expected and are justified by the present state of knowledge. For IPCC WG I on the expected changes in climate (and a similar perspective applies for the ozone assessment), traditional scientific analyses are seeking high levels of certainty (e.g., 90-95%) before drawing conclusions and the results are given with uncertainty bounds. For WG II on the impacts of climate change, levels of certainty tend to be lower, but still significant, and again ranges of impacts are suggested. For WG III on economic implications of change, only rough central estimates that are acknowledged to be incomplete are available. What is most surprising about some of the statements about today's hearing and the public discussion of uncertainties is that the discussion tends to focus on the results that are most certain in the IPCC findings, findings for which mainstream scientists are arguing about whether the odds of their central predictions are 5 to 1, 10 to 1 or even 20 to 1. While by no means all aspects of the climatic effects can be estimated with such certainty, such levels are well above those for which many societal decisions are made. It is not the right to question these findings that is at issue in any of the debates and discussions that we are having. What is at issue is the best way for that process to proceed while at the same time developing a consensus view on the best scientific statements of what is known, unknown and uncertain. The community of scientists largely believes that the best way is to periodically conduct open, international, scientific assessments that provide the opportunity for all to participate and to make their cases to their fellow scientists and the broader community. We believe that the IPCC process largely meets that challenge, representing the central consensus of the world scientific community. It is for this reason that we so strongly urge the wide consideration of this report as the authoritative base for scientific findings on global climate change. There will always be critics and those not fully satisfied, and indeed there are both those who believe the conclusions should be weaker and those who believe the conclusions should be stronger. However, at this time, the IPCC results are the most thoroughly reviewed and considered views on global climate change and they deserve very high respect. The very great importance of this issue for society in terms of the threat of environmental change and the potential for changing aspects of important societal activities has generated considerable public discussion of both the findings and the uncertainties concerning climate change. Trying to iron out dueling perspectives through the media and otherwise outside the scientific process will never be satisfactory. Nonetheless, some sides seem to be resorting to this approach. Brief comments on these issues cannot, in most cases, do them justice, but can perhaps provide some understanding of the issues, what is understood, and what the often underreported consensus views may be. I include below a few of my thoughts on some of the key issues raised and invite the Committee and its members to provide follow-up questions for response in writing. 1. Data for the full year clearly indicate that the global average surface temperature for 1995 was near or actually the warmest on record (see Figure 3)--and was likely the warmest since 1400 and even much earlier. What is most interesting is that 1995 set surpassed (or matched) the record for the previous warmest year even though there was no El Nino, the solar cycle was near a minimum, and ozone depletion was near record levels whereas in 1990 (the next warmest year) these comparative cooling influences were not present. Between these record years, the global average temperatures were suppressed mostly by aerosols injected by the Mt. Pinatubo volcanic eruption. 2. Global average temperatures have risen about 0.5°C (about 1°F) during the past 140 years (the period for which we have the best observations of surface air temperatures); these results are similar to records of ground temperature. As clearly summarized in the IPCC Second Assessment, the results of model simulations that include both greenhouse gases and sulfate aerosols, to the extent that we understand their influences, show good agreement with the observed record. 3. Climate model projections for the next century show a significant warming, with a central estimate of about 2.5°C (about 4.5°F). Such a rate of warming would be about four times the rate since the last century, creating the strong potential for significant environmental impacts. The reason for the acceleration in the rate of warming is that, because carbon dioxide has an average net lifetime in the atmosphere of perhaps two hundred years, it will build up substantially as coal use increases whereas sulfate aerosols get washed efficiently from the atmosphere within a few days (acidifying precipitation). The IPCC-organized scenarios of emissions assume that, because of concerns about acid deposition and because of the adverse health effects of small particles, sulfur dioxide emissions will decline in some areas while increasing in others. Hence, the warming effect of carbon dioxide will more and more exceed the sulfate influence. 4. The IPCC central estimate of warming for the year 2100 has come down from about 3°C (about 5.4°F) in 1990 to about 2.5°C (about 4.5°F) in 1992 to about 2°C (about 3.6°F) in 1995. These changes were not generally due to reductions in model uncertainties or to model improvements, although models are improving; instead, the reductions were due primarily to changes in the presumed scope of human activities in the future and the inclusion in the predictions of their effects on temperature. The 1990 and 1992 estimates were for changes in the concentrations of greenhouse gases only, and caveats were included recognizing that aerosols would have some cooling influence, but could not then be treated; the 1995 IPCC estimate includes the effects of greenhouse gases and the effects of aerosols outside of clouds (the effects of aerosols on clouds and some other human influences likely to create either modest warming or cooling are still not included in the calculations). With respect to the range of estimates, in 1992 the IPCC projected that the warming by the year 2100 compared to the present due to greenhouse gases only could range from about 1 to about 5°C (or about 1.8°F to about 9°F), depending on model sensitivity and the scenario of emissions; in 1995, the IPCC projected that the warming due to greenhouse gases and the moderating of this warming by aerosols could range from a warming of about 0.8 to 3.5°C (or about 1.4 to 6°F)--see Figure 4. Ranges are included in the IPCC estimates because they recognize that both models and societal projections have uncertainties (and these two factors contribute about equally to the range of estimates).The slightly lower estimates of warming in 1995 (and note that the central estimate of warming in 1995 is within the earlier range of estimates) had much less to do with uncertainties in the climate models themselves or their responsiveness to human activities than to changes in the estimates of the emissions that societal activities would contribute to the changes in atmospheric concentration. To a first order approximation, the differences were caused by the inclusion in the 1995 simulations of the cooling effects of sulfate aerosols and the earlier phasing out of CFCs in order to protect the ozone layer. Climate models are becoming even more representative of the global climate system, but improvements in models were not the primary cause of reductions in the estimates of future warming. 5. Despite the projections of global warming of surface air temperatures, this does not mean that the tropospheric temperature [measured by the Microwave Sounding Unit (MSU) instrument] should be warming in exactly the same way. While much has been made of the observations that the 16 year MSU record doesn't show a warming of the atmosphere, there are several possible aspects to consider and detailed analyses are indicating the reason for the records giving different results (Dr. Christy covers this in his testimony). Furthermore, it is very problematic to draw conclusions about long-term trends from such a short record. The somewhat longer radiosonde [weather balloon] record of tropospheric temperatures, which the MSU mimics quite well over the years for which comparisons are possible, does show overall warming over the past three decades, in long-term and general agreement with the surface record. 6. Regarding the supposed difference in the MSU and model-predicted rates of warming, such comparisons that have been done have been of fundamentally different quantities. To make the comparison, the model run that is used has been adjusted in several ways that are inappropriate. Quite simply, the comparison is totally inappropriate to do and is presented in a misleading way. 7. There are significant limitations in using the climate record to make empirical estimates of how the climate may change in the future. If we could, it would certainly be desirable to be able to either do an experiment or analyze evidence of past climate changes or the present behavior of the climate to determine how sensitive the climate is to human influences. A number of approaches have been tried (e.g., paleoclimatic, year-to-year variability, etc.), but they give quite diverse results and none are particularly satisfactory. About all that can be concluded, is that the sensitivity can't be lower than about the lower limit used by IPCC or we would have no chance at all of explaining how climate changed in the geological past, and that the sensitivity can't be much higher than the upper limit used by the IPCC or we could not explain the amazing stability of climate over the last 10,000 years before human activities started to warm the climate. 8. Human-induced climate change is now "discernible." A major scientific advance in the last few years has been the ability to search for patterns of climate change, not just changes in the global average change. This has been possible because more realistic cases have been run using the climate models. The IPCC conclusion recognized the following four points: (1) the global average temperature of the latter part of this century is at least as high as for any time in the last six hundred years (the period for which we can reasonably construct temperature changes) ; (2) the temperature trend has been upward since the last century; (3) the latitude-longitude pattern of global temperature trend is unlike patterns associated with natural variability (including solar variations) and quite similar to the predicted response in models to increasing carbon dioxide and sulfate aerosol concentrations; (4) the vertical and pole-to-pole pattern of temperature change is unlike that for natural variability (including solar and volcanic variations) and in general agreement with changes from greenhouse gases, sulfate aerosols, and ozone depletion; and (5) the magnitude of the changes is about as estimated by models. While no one or two of these would be as convincing, the IPCC concluded, rather conservatively, that the "balance of evidence suggests that there is a discernible human influence on global climate."
In summary, the USGCRP is a broad-based research program focusing on the full range of issues that will determine the world that we pass on to our grandchildren and their grandchildren--the issues are that important. There is much that we do not yet fully understand, which is why we must have a strong and vigorous research program. There is also, and this is very important, much that we do understand and which cannot be dismissed. In the area of climate change (not even considering the environmental consequences and other aspects described in the testimony of Dr. Watson), scientific consensus agrees that:
In FY-96, the likely appropriation is about $1.7B for USGCRP activities. While detailed consideration of this request is more appropriate for other hearings, it is interesting to note that this is just less than two pennies a day for every citizen of the United States-- a bit more than a penny a day for the Earth observing system and a bit less than a penny a day for research to understand all of these issues. My strong feeling is that this is an excellent investment in our future and that every American is more than getting their two cents worth each day. Thank you, and I would be pleased to answer any questions.
Michael C. MacCracken was appointed Director of the Office of the U.S. Global Change Research Program (USGCRP) in September, 1993. In this role, he is responsible for supporting the interagency Subcommittee on Global Change Research (SGCR) of the Committee on Environment and Natural Resources (CENR) in its efforts to promote an integrated and cohesive research effort on such global change issues as climate change and greenhouse warming, ozone depletion and atmospheric chemistry, seasonal to interannual climate fluctuations, land cover change, and the ecological and societal impacts of global environmental change and to promote the development of methodologies for analyzing the consequences and evaluating the options for addressing global change. Dr. MacCracken was born in Schenectady, New York in 1942. He received his B.S. in Engineering from Princeton University in 1964 and his Ph.D. degree in Applied Science in 1968 from the University of California, Davis/Livermore. Based on a question suggested by Dr. Edward Teller, his dissertation research involved use of a climate model to study the self-consistency of various hypotheses of the causes of ice ages. Following graduation in 1968, Dr. MacCracken joined Lawrence Livermore National Laboratory (LLNL) and for twenty-five years was a leader in their atmospheric and climate modeling effort. Early in his career, he led development of the San Francisco Bay Area air quality model, which was used to develop the Bay Area's successful air quality maintenance plan for photochemical oxidants. In his climate-related research, he also modified the global climate model used in his dissertation research to study the potential climatic effects of volcanic eruptions, of an increased carbon dioxide concentration, and of other climatic perturbations. During the 1970s, he led the project at LLNL to assess the climatic effects of supersonic transport aircraft and served as leader of a multi-DOE laboratory investigation (MAP3S) of the effects of sulfur emissions on air quality in the northeastern United States. Dr. MacCracken was appointed Division Leader of what became LLNL's Global Climate Research Division in October 1987, having served as Deputy Division Leader of the Atmospheric and Geophysical Sciences Division since its founding in 1974. In addition, he has been co-project leader of LLNL's study of the atmospheric effects of a nuclear war, an advisor to the Department of Energy (DOE) on the climate element of their carbon dioxide research program, and a co-leader of the joint University of California cooperative research project on global modeling. His most recent research activities included leading a special LLNL project to develop an Earth Systems Model incorporating atmospheric, oceanic, land surface, and biological components and serving as Chief Scientist for DOE's Computer Hardware, Advanced Mathematics and Model Physics (CHAMMP) program to implement the next generation of global climate models on massively parallel computer architectures. Dr. MacCracken is the co-author of several books and of many articles and reports in the general area of climate change. From 1983 to early 1985, Dr. MacCracken was chairman of the American Meteorological Society's Committee on Climate Variations. From 1984 to 1992, he was U.S. co-chairman of the climate project under the US/USSR bilateral agreement on environmental protection, and he was co-editor of the joint US/USSR report Prospects for Future Climate, which compared the predictions of climate models with the paleoclimatic evidence for climate sensitivity. In 1986, he was co-author of the ICSU/SCOPE assessment on the physical and climatic effects of nuclear war and later of a similar report for the World Meteorological Organization. He served as co-editor and co-author of DOE state-of-the-art volumes issued in 1985 on projecting and detecting the climatic effects of the increasing carbon dioxide concentration. In 1990 he was chairman of a DOE Multi-laboratory Climate Change Committee that summarized findings on climate change issue in the book Energy and Climate Change, which was prepared in support of development of the National Energy Strategy. During the 1990s, he has been a co-author and contributor to chapters in the assessment reports of the Intergovernmental Panel on Climate Change (IPCC), and coordinated the U. S. Government reviews in 1995. Dr. MacCracken is currently chair of the International Commission on Climate of the International Association of Meteorology and Atmospheric Sciences, for which he has organized two international symposia on climate in the past three years, and chair of the Atmospheric and Hydrospheric Sciences section of the American Association for the Advancement of Science (AAAS). He is also a member of the American Meteorological Society, the American Geophysical Union, the Oceanography Society, and the American Quaternary Association. Dr. MacCracken is married and lives in Chevy Chase, Maryland. He and his wife Sandy have two sons in graduate school. From 1971 to 1978, Mike was an elected member of the Board of Directors of the Livermore Area Recreation and Park District (Livermore CA), serving as chairman in 1974 and 1978.
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