Cover Image

PAPERBACK
$34.75



View/Hide Left Panel

APPENDIX

C

RESEARCH IMPERATIVES AND SCIENTIFIC QUESTIONS

A research framework across the wide scope of global environmental change is outlined in the full report, “Global Environmental Change: Research Pathways for the Next Decade,” in terms of the primary topical areas (biology and biogeochemistry of ecosystems, climate system on seasonal to interannual time scales, climate system on decadal to century timescales, chemistry of the atmosphere, paleoclimate, and human dimensions of global change). Research Imperatives are central scientific issues posed to each of the six primary topical areas by the challenge of global environmental change. Each Research Imperative is elaborated by a set of Scientific Questions. These are summarized from the full report and provided below.

Biology and Biogeochemistry of Ecosystems

Land-Surface and Climate Imperative

Understand the relationships between land-surface processes, including land-cover change, climate, and weather prediction.

Land-Surface and Climate Questions

  • How do land-surface biophysical processes interact with regional climate and modify patterns of interannual climate variability?

  • How does including knowledge of the land-surface state affect weather prediction and seasonal to interannual climate prediction?

  • How may changing patterns of land use affect the climate of the future?

  • How might large-scale atmosphere-ecosystem exchange of water and energy change in a high carbon dioxide world?

Biogeochemistry Imperative

Understand the changing global biogeochemical cycles of carbon and nitrogen.

Biogeochemistry Questions

  • How is terrestrial carbon storage regulated by land use, changes to marine ecosystems, internal ecosystem processes, and climate, and how may this storage change in response to future environmental changes?



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 51
OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade APPENDIX C RESEARCH IMPERATIVES AND SCIENTIFIC QUESTIONS A research framework across the wide scope of global environmental change is outlined in the full report, “Global Environmental Change: Research Pathways for the Next Decade,” in terms of the primary topical areas (biology and biogeochemistry of ecosystems, climate system on seasonal to interannual time scales, climate system on decadal to century timescales, chemistry of the atmosphere, paleoclimate, and human dimensions of global change). Research Imperatives are central scientific issues posed to each of the six primary topical areas by the challenge of global environmental change. Each Research Imperative is elaborated by a set of Scientific Questions. These are summarized from the full report and provided below. Biology and Biogeochemistry of Ecosystems Land-Surface and Climate Imperative Understand the relationships between land-surface processes, including land-cover change, climate, and weather prediction. Land-Surface and Climate Questions How do land-surface biophysical processes interact with regional climate and modify patterns of interannual climate variability? How does including knowledge of the land-surface state affect weather prediction and seasonal to interannual climate prediction? How may changing patterns of land use affect the climate of the future? How might large-scale atmosphere-ecosystem exchange of water and energy change in a high carbon dioxide world? Biogeochemistry Imperative Understand the changing global biogeochemical cycles of carbon and nitrogen. Biogeochemistry Questions How is terrestrial carbon storage regulated by land use, changes to marine ecosystems, internal ecosystem processes, and climate, and how may this storage change in response to future environmental changes?

OCR for page 51
OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade What are the consequences of the anthropogenically accelerated nitrogen cycle? Can we quantify the interactive roles of increasing carbon dioxide, the changing nitrogen cycle, and land use in terms of present and future terrestrial carbon storage? How will the role of marine ecosystems change with future changes to ocean circulation, temperature, and nutrient/toxic inputs? What are the current budgets for the sources and sinks of biogenic greenhouse gases, especially methane and nitrous oxide? How is current environmental change, including land-use change, fertilization, and atmospheric nitrogen deposition, affecting the sources and sinks for these gases? How might the sources and sinks change in the future with changing land management, climate, and chemical inputs? As global use of anthropogenic nitrogen increases, is there potential for nitrous oxide emission or methane consumption to change rapidly? What changes are occurring to the atmosphere-ecosystem exchange of reactive trace gas species (nitric oxide, ammonia, nonmethane hydrocarbons, dimethyl sulfide)? What biological and pyrogenic processes control these exchanges, and how might they change in the future? What is the role of changing biogenic trace gas emissions in the changing photochemistry of the troposphere and stratosphere? Aerosols have become a major issue in climate: what role do sulfur and organic compounds from biogenic sources, dust from agriculture and other soil disturbances, and biomass burning play in global aerosol forcing? Multiple Stresses Imperative Understand the responses of ecosystems to multiple stresses. Multiple Stresses Questions How do multiple global changes interact to produce ecosystem responses? What are the interactions of changing land use, climate, nutrient and toxic inputs, and hydrology on ecosystems and their ability to produce goods and services? What are the required data sets, theory, and models needed to understand the regional coupling of physical and chemical climate, land use, and ecosystems? Can we develop the science needed to manage regional systems subject to multiple stresses to provide ecosystem goods and services while maintaining ecological integrity?

OCR for page 51
OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade How do changes to climate and land use affect the transfer of water and materials between terrestrial and freshwater ecosystems? How does global environmental change affect the functioning of freshwater ecosystems? How do changes to terrestrial and hydrological systems alter coastal marine systems? How are coastal marine ecosystems changed by the interaction of climate, large-scale ocean circulation and biogeochemistry, and inputs from the land? Biodiversity Imperative Understand the relationship between changing biological diversity and ecosystem function. Biodiversity Questions How much functional redundancy exists in ecosystems? How does the functional diversity of organisms in ecosystems affect carbon uptake and sequestration, nutrient cycling, biophysical interactions with climate, and trace gas emissions? What information on plant, microbial, and animal function is needed to model the role of organisms in large-scale changes in community composition and ecosystem function? How will climate changes interact with other anthropogenic impacts to alter biodiversity? Are there critical (keystone) species governing large-scale ecosystem function, and can we identify what species could become keystone under changing environmental conditions? Can we identify either systems vulnerable to change as a consequence of biological invasion or species likely to be successful invaders? How might changes in pests and pathogens alter disturbance frequency, including land-use change? Seasonal to Interannual Climate Change El Niño–Southern Oscillation (ENSO) Imperative Maintain and improve the capability to make ENSO predictions. ENSO Questions What is the inherent limit of ENSO predictability? How can this limit be determined? What limits the skill of ENSO predictions now?

OCR for page 51
OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade What mix of observations is needed to initialize forecasts to optimize the skill of ENSO predictions? How can this mix be determined? Which are the proper measures of the skill of ENSO prediction? How does decadal variability in the Pacific affect the prediction of ENSO? Through what mechanisms do seasonal to interannual tropical Pacific variations influence the midlatitudes? What is the relationship between the annual cycle and ENSO predictability? Do models have to get the annual cycle right to predict ENSO correctly? Is there a predictability barrier? What is the effect of regions outside the tropical Pacific on the prediction of ENSO variations? Global Monsoon Imperative Define global seasonal to interannual variability, especially the global monsoon systems, and understand the extent to which it is predictable. Global Monsoon Questions What are the structure and dynamics of the annual cycle of the coupled ocean-atmosphere-land system, and what are the reasons for its large spatial variability over the globe? What is the nature of global, interannual climate variability, and what is its relationship to the annual cycle? What processes give rise to such variability? Can our increased understanding of this variability be exploited for prediction? What are the roles of slowly varying conditions at the Earth's surface [sea ice, sea surface temperature (SST), snow cover, and soil moisture] in determining the nature of interannual variation in the global atmosphere? What determines the low-level convergence of moisture in the tropics over water, land, and coasts? More generally, what determines the location and longevity of the heat sources and sinks of the atmosphere? What is the role of ENSO in creating variability in the monsoon climates of the world, and vice versa? Is there variability of the monsoon that is independent of ENSO, and is it predictable? What is the nature of tropical-extratropical interactions? Specifically, how might tropical SSTs perturb the extratropical atmosphere, thereby generating extratropical SST anomalies? For what regions of the globe can accurate predictions of tropical SSTs be translated into skillful regional climate forecasts for one to two seasons in advance? What is the role of intraseasonal variability on seasonal to interannual variability? How predictable are the amplitude, distribution, and frequency of blocking and active and break periods of the monsoon?

OCR for page 51
OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade Land-Surface Exchanges Imperative Understand the roles of land-surface energy and water exchanges and their correct representation in models for seasonal to interannual prediction. Land-Surface Exchanges Questions What is the appropriate level of detail in characterizing land surface for seasonal to interannual prediction with regard to (1) the nature of vegetation and soil parameters and their specification, (2) the spatial resolution in observing vegetation and soil, and (3) description of seasonal changes in vegetation cover and its vigor? What representation of runoff is best to calculate evapotranspiration in seasonal to interannual climate prediction models? What is the appropriate form for the land component of a four-dimensional data assimilation system for seasonal to interannual prediction? What are the appropriate measurement and tradeoffs? How can they be obtained and how can models be formulated to accept them? How can we use observations of the seasonal to interannual variations in biogeochemical cycles and ecosystem properties to infer the underlying dynamics determining these variations? What is the role of high-latitude feedbacks between snow cover extent, stream flow, and seasonal to interannual variability, and to what extent are these processes adequately modeled? Downscaling Imperative Improve the ability to interpret the effects of large-scale climate variability on a local scale (downscale). Downscaling Questions In what ways can local climate variance be explained in terms of large-scale climate variability? What local climate variables need to be upscaled to ensure adequate coupling of local climate to large-scale climate? Terrestrial Hydrology Imperative Understand the seasonal to interannual factors that influence land-surface manifestations of the hydrological cycle, such as floods, droughts, and other extreme weather.

OCR for page 51
OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade Terrestrial Hydrology Questions What are the implications of seasonal to interannual climate forecasts for flood prediction? What are the implications of seasonal to interannual climate forecasts for drought prediction and forecasting? What are the implications of seasonal to interannual climate forecasts under “normal” climate conditions? Decadal to Century (Dec-Cen) Climate Change Climate Patterns Imperative To understand patterns in the climate system, the following interdependent imperatives exist. Natural Climate: Improve knowledge of decadal to century-scale natural climate patterns; their distributions in time and space; and their optimal characterization, mechanistic controls, feedbacks, and sensitivities, including their interactions with, and responses to, anthropogenic climate change. Paleorecord: Extend the climate record back through data archeology and paleoclimate records for time series long enough to provide researchers a better database to analyze decadal to century-scale patterns. Specifically, achieve a better understanding of the nature and range of natural variability over these timescales. Long-Term Observational System: Ensure the existence of a long-term observing system for a more definitive observational foundation to evaluate decadal to century-scale variability and change. Ensure that the system includes observations of key state variables as well as external forcings. Climate Patterns Questions What is the longevity of climate patterns and their spatial/temporal variance? What is the best way of characterizing the known patterns, and are there additional patterns of interest? Which patterns represent true dynamic modes, and which are simply statistically consistent structures or geographically forced distributions? What mechanisms generate, maintain, and modify the patterns, what is the role of these mechanisms in the spatial propagation of regionally initiated variability and change, and what are their critical dependencies? What is the relationship between the observed climate patterns and global warming?

OCR for page 51
OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade Climate System Components Imperative Address the issues of those individual climate components whose resolution will most efficiently and significantly advance our understanding of dec-cen climate variability. Climate System Components Questions Atmosphere How much of the dec-cen variability is unforced (reflecting nonlinear internal interactions)? How does large-scale circulation change on dec-cen timescales, and how does it interact on these scales with regional and higher frequency changes? What are the magnitudes, spatial and temporal patterns, and mechanisms of midlatitude atmospheric responses to both midlatitude and tropical SSTs? What are the mechanisms of interaction between the atmosphere and land-surface processes on dec-cen timescales? Through what mechanisms does the planetary boundary layer mediate between dec-cen variability of the surface boundary layer and the free atmosphere? What are the mechanisms of region-to-region and basin-to-basin interactions on the dec-cen timescale? How do dec-cen changes in atmospheric trace gases and aerosols affect radiative balance and atmospheric circulation and vice versa? Oceans What are the dec-cen patterns of ocean variability, and what dynamical mechanisms govern them at dec-cen timescales? What are the processes of formation and sequestering of water masses and of their subsequent modification and eventual return to the surface; what are their dec-cen variabilities? What are the dec-cen fluctuations of circulation structure and intensity, and water mass pathways, how are they affected by surface forcing, and what are the mechanisms of the fluctuations? What feedback and coupling mechanisms maintain SST, heat, freshwater, sea ice, and chemical anomalies on dec-cen timescales? What are the mechanisms of region-to-region and basin-to basin interaction on dec-cen timescales? How is carbon partitioned in the ocean, and what are the roles of physical processes in the carbon flux?

OCR for page 51
OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade Cryosphere How do sea ice and snow fields change on dec-cen timescales, and what is the relationship of these changes to atmospheric, ocean, and land-surface patterns on dec-cen timescales? What mechanisms underlie dec-cen patterns of interaction between the sea ice and snow fields and the atmosphere, ocean, and land systems? Through what mechanisms are changes in the cryosphere of the polar regions linked or teleconnected to midlatitude and tropical regions? What is the history and current global budget of land-locked ice and snow, and what are the primary mechanisms controlling this budget? Land and Vegetation What are the effects of human activity and climate change on ecosystem structure and function? What are the relative contributions of the different processes by which vegetation and soils store or lose carbon? What are the expected future emissions of methane, nitrous oxide, and volatile organic carbon compounds by soils and vegetation? How do dec-cen changes in land use and land cover affect land-surface energy balance on dec-cen time scales? How does vegetation influence the transfer of freshwater through the land surface on dec-cen timescales? How do changes in vegetation cover influence the loading and composition of atmospheric aerosols on dec-cen timescales? Hydrologic Cycle What are the patterns and mechanisms of prolonged drought on dec-cen timescales found in paleoclimatic records? How do the distributions of water vapor, precipitation, and clouds interact with surface boundary conditions and changes on dec-cen timescales? By what combination of remote and in-situ observations can we measure the large-scale distribution of precipitation on dec-cen timescales? What are the spatial and temporal changes in land storage of water and the pathways and fluxes of land water to the oceans? What are the patterns and mechanisms of the dec-cen droughts measured over the last several hundred years? Atmospheric Composition and Radiation Budget What are the changes in the spatial distribution of carbon storage and flux on dec-cen timescales? How do mixed-layer water replacement rates interact with biological processes to produce changes in ocean carbon storage?

OCR for page 51
OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade What are the uptake, pathways, and fate of anthropogenic carbon in the ocean on dec-cen timescales? What are the contributions of various sources and sinks to the recent increase in methane? How does photochemical breakdown of methane contribute to other chemical and radiative processes in the atmosphere on dec-cen timescales? Why is nitrous oxide increasing on dec-cen timescales? Why has tropospheric ozone increased since the last century, and are further increases likely? How does the coupling between chemistry, dynamics, and radiation in the lower stratosphere and upper troposphere operate on dec-cen timescales? How do the spatial distribution, chemical composition, and physical properties of aerosols vary on dec-cen timescales, and how do they interact with climate variability? How do proxies for solar activity (e.g., sunspots, cosmogenic nuclides) relate to total solar irradiance on dec-cen timescales? To what extent are dec-cen climate changes, as observed in instrumental and paleoclimate records, related to changes in the sun's output, and what mechanisms are involved in the response of climate to changes in solar radiation? What feedbacks govern climate and ecosystem responses to spectral changes in solar irradiance on dec-cen timescales? Chemistry of the Atmosphere Stratospheric Ozone and Ultraviolet Radiation Imperative Define and predict secular trends in the intensity of ultraviolet exposure the Earth receives by documenting the concentrations and distributions of stratospheric ozone and the key chemical species that control its catalytic destruction and by elucidating the coupling between chemistry, dynamics, and radiation in the stratosphere and upper troposphere. Stratospheric Ozone and Ultraviolet Radiation Questions Will the evolution of the Antarctic stratospheric ozone “hole” proceed as expected, with a period of continued increasing intensity, followed by recovery to normal conditions? Will the Arctic emulate the Antarctic? How will the midlatitude ozone depletion evolve? What mechanisms are controlling this erosion? How sensitive is this ozone erosion to temperature, water vapor partial pressure, sulfate/nitrate concentration, and aerosol loading; can we develop models to correctly simulate this evolution?

OCR for page 51
OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade What is the role of the largely unexplored tropical region of the stratosphere in global ozone change? What are the interactions between stratospheric ozone depletion and climate change? What are the consequences of current and future perturbations, such as aircraft emissions and volcanic eruptions, on stratospheric ozone concentrations? Atmospheric Greenhouse Gases Imperative Determine the fluxes of greenhouse gases into and out of the Earth 's systems and the mechanisms responsible for the exchange and distribution between and within those systems. Atmospheric Greenhouse Gases Questions What are the regional sources and sinks of carbon dioxide other than fossil fuel burning? How large are the individual methane sources? What are the missing sources of nitrous oxide? What causes year-to-year changes in the trends of the greenhouse gases? How are the carbon dioxide increases correlated with oxygen decreases as a function of altitude, latitude, longitude, and season? Are the Montreal Protocols and successor agreements effective in mitigating the climatic warming from chlorofluorocarbons and hydrochlorofluorocarbons? Which new halogenated compounds may affect climate in the future? What are the trends in ozone in the troposphere and stratosphere, and what are the causes of these trends? In the upper troposphere, how are the formation of subvisible and visible cirrus—significant modulators of the escape of infrared radiation from the Earth system—affected by the presence of water vapor, sulfate, and nitrates? What are the trends in water vapor in the upper troposphere and lower stratosphere, and what are the causes of these trends? Photochemical Oxidants Imperative Develop the observational and computational tools and strategies that policy makers need to effectively manage ozone pollution, and elucidate the processes that control and the relationships that exist among ozone precursor species, tropospheric ozone, and the oxidizing capacity of the atmosphere. Develop a better understanding of what determines the ability of the atmosphere to cleanse itself of pollutants, both now and in the coming decades.

OCR for page 51
OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade Photochemical Oxidants Questions To what extent does our current understanding satisfactorily explain simultaneous measurements of hydroxide concentrations and the principal hydroxide chemical production and loss processes? Can the oxidation of compounds or appearance of their oxidation products be successfully used to infer representative concentrations of hydroxide, whether seasonally and regionally or annually and globally? To what extent do other oxidants (nitric oxide, hydrogen peroxide, halogen atoms, etc.) play significant roles? To what extent do changes in stratospheric ozone, climate, and/or cloud cover affect the oxidizing capacity of the lower atmosphere? What determines the distribution of ozone in the troposphere and how is the distribution likely to change in the coming decades? More specifically— What fraction of tropospheric ozone can be attributed to transport from the stratosphere and how does this change with meteorology and season? What portion of ozone precursors are emitted from natural (biogenic) sources, and how will these emissions change with natural perturbations (e.g., meteorological variability) and human-induced perturbations (e.g., land use, climate change)? What is the contribution of urban pollution to rural and regional ozone, and conversely, what is the impact of rural and regional ozone on urban pollution? How does meteorological variability affect the trends of ozone and/or its precursors? What are the major sources of nitrogen oxides in each region of the atmosphere over various geographic regions? What are the rates of nitrogen oxide and nitrogen dioxide (NOx) emissions from these sources? Which major reservoir and oxidizing species and which gas-phase and heterogeneous chemical processes are responsible for the partitioning within the NOx family? Where and when is the production of ozone limited by the availability of volatile organic compounds (VOC) or nitric oxide? What are the trends in regional and local ozone precursors (NOx, VOC, carbon monoxide)? What design and implementation strategies will provide monitoring networks capable of determining, whether control measures for photochemical oxidants are having the intended impact? What design and implementation strategies will yield monitoring networks capable of determining, for a particular air qua 28%>> oblem, what part of the problem is essentially irreducible (i.e., natural emissions of ozone precursors and stratospheric influx of ozone) and what part of the ozone problem is potentially controllable (i.e., human-made precursor emissions)?

OCR for page 51
OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade Atmospheric Modeling Imperative Improve atmospheric models to better represent current atmospheric oxidants and predict the atmosphere's response to future levels of pollutants. Atmospheric Modeling Questions What laboratory research is required to understand the fundamental chemical processes (heterogeneous and homogeneous) involved in tropospheric oxidant formation? What atmospheric measurements are required, and of what precision and accuracy, to evaluate and apply diagnostic and predictive models of tropospheric oxidant chemistry? What are the quantitative certainties associated with the estimates from diagnostic and predictive models of tropospheric oxidant chemistry? How can models of tropospheric oxidant chemistry be improved to incorporate direct and indirect effects of multiple, interacting forcing agents (such as climate change, stratospheric ozone depletion, and anthropogenic perturbations)? Atmospheric Aerosols and Ultraviolet Radiation Imperative Document the chemical and physical properties of atmospheric aerosols; and elucidate the chemical and physical processes that determine the size, concentration, and chemical characteristics of atmospheric aerosols. Atmospheric Aerosols and Ultraviolet Radiation Questions What is the role of natural and anthropogenic aerosols in climate, and how might future changes in levels of aerosol precursors affect this role? How are natural and anthropogenic aerosols likely to affect stratospheric and tropospheric ozone and the cleansing capacity of the atmosphere in the future? What is the role of atmospheric chemistry in changing the composition of aerosols that affect human health, the environment, visibility, and infrastructural materials? Toxics and Nutrients Imperative Document the rates of chemical exchange between the atmosphere and ecosystems of critical economic and environmental import, and elucidate the extent to which interactions between the atmosphere and biosphere are influenced by changing concentrations and depositions of harmful and beneficial compounds.

OCR for page 51
OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade Toxics and Nutrients Questions How are interactions between the atmosphere and biosphere influenced by changing atmospheric concentrations and by the deposition of harmful and beneficial compounds? More specifically, from the viewpoint of atmospheric chemistry, what are the rates at which biologically important atmospheric trace species are transferred from the atmosphere to terrestrial and marine ecosystems through dry and wet deposition? Paleoclimate Paleoclimate Imperatives Document how the global climate and Earth's environment have changed in the past and determine the factors that caused these changes. Explore how this knowledge can be applied to understand future climate and environmental change. Document how the activities of humans have affected the global environment and climate and determine how these effects can be differentiated from natural variability. Describe what constitutes the natural environment prior to human intervention. Explore the question of what are the natural limits of the global environment and determine how changes in the boundary conditions for this natural environment are manifested. Document the important forcing factors that are controlling and will control climate change on societal timescales (season to century). Determine what were the causes of the rapid climate change events and rapid transitions in climate state. Paleoclimate Questions Stream One—The Last 2000 Years Is the warming experienced during the 20th century unusual? Are there major modes of subdecadal, decadal, and centennial scale variability? Do certain regions on Earth play leading roles in climate change by either driving or responding to climate change (e.g., North Atlantic, Southern Ocean, tropics)? Are climate change events (e.g., Little Ice Age, Medieval Warm Period) synchronous in magnitude and timing in both hemispheres or do some display regional differences? Have major atmospheric circulation systems such as ENSO, Asian-Aus-

OCR for page 51
OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade tralian-African monsoon, westerlies shifted over time? Is there a recognizable pattern to these changes? Why have these changes occurred? Are there regularities, synchronisms, or teleconnections that can be used for developing predictive model capability? Have these changes been a response to changes in boundary conditions (e.g., sea-surface temperature, Tibetan snow cover, clouds)? Are there teleconnections in the atmospheric circulation systems of both hemispheres that lead to parallel records of climate change on dec-cen timescales? How has the hydrology of the planet changed over the last two millennia? How has the record of ENSO and its climate teleconnections changed over the last two millennia? How has the record of explosive volcanism changed over the last two millennia? How does this record relate to climate change? How do natural feedbacks (dusts, biogenic trace gases) operate and affect the climate system? How has solar irradiance varied over the last two millennia? What are the mechanisms by which changes in solar irradiance cause climate change? How has the environment responded to these variations? How has sea level changed over the last two millennia? How do ice sheets, mountain glaciers, and other changes in the hydrologic cycle contribute to this change? How have ecosystems (e.g., equatorial rain forests, tundra, forest, steppe, glacial) responded to environmental change over the last two millennia? How has human activity impacted the environment? How have humans responded to environmental change? Paleoclimate Questions Stream Two—The Last 250,000 Years Are there major modes of centennial-millennial scale variability? What is the phasing of climate evolution between the two hemispheres? How have changes in Milankovitch insolation cycles, thermohaline circulation, trace gases, aerosols, and solar variability affected climate evolution in the two hemispheres? Are the rapid climate change events recorded in the Greenland ice sheet found in the southern hemisphere? Are these events found also in marine and terrestrial records? Are these events synchronous in timing and magnitude? How have boundary conditions changed in specific regions (e.g., south Asian “warm pool,” Tibetan Plateau) and have these changes caused responses in major atmospheric circulation systems such as ENSO, Asian-Australian monsoon, intertropical convergence zone, and jet streams?

OCR for page 51
OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade How are hydrologic changes in the tropics related to climate change in extratropical regions? What causes these hydrologic changes? How are changes in biomass productivity linked to changes in trace gases in the atmosphere? How has monsoonal circulation varied in the past and are these changes synchronous in different regions? Human Dimensions of Global Change Human Dimensions Imperatives Understand the major human causes of changes in the global environment and how they vary over time, across space, and between economic sectors and social groups. Determine the human consequences of global environmental change on key life support systems, such as water, health, energy, natural ecosystems, and agriculture, and determine the impacts on economic and social systems. Develop a scientific foundation for evaluating the potential human responses to global change, their effectiveness and cost, and the basis for deciding among the range of options. Understand the underlying social processes or driving forces behind the human relationship to the global environment, such as human attitudes and behavior, population dynamics, and institutions and economic and technological transformations. Human Dimensions Questions What Is the Role of Consumption in Causing Global Change? What are the constituents and determinants of energy use and other environmentally significant consumption in countries and populations at different levels of economic development? How is consumption likely to change with increasing affluence in low-income countries and populations, and does this change always follow the path that high-income countries and populations have followed? What social forces drive the most environmentally significant consumption types, such as travel, the diffusion of electrical appliances, agricultural intensification, water use, and purchases of highly energy-consuming vehicles? What are the relative roles of various determinants of consumption in different countries?

OCR for page 51
OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade What policies at the national level lead to greater attention in communities to issues such as urban sprawl, reducing the cost of home-to-work commuting, expansion of green spaces, and enhanced recycling of materials? Which materials transformations have the greatest environmental significance, and what determines related kinds of consumption? What interventions can effectively alter the course of the most environmentally significant kinds of consumption? What determines public support for effective consumption policies, and how do these factors vary across countries? What Are the Social Driving Forces for Land-Use and Land-Cover Change? What comparative case studies of land-use and land-cover change are useful for the modeling of land-use change at regional and global scales? Which human activities (e.g., patterns of land use and management, chemical releases) can significantly alter the potential for major environmental surprises? How Does Technological Transformation Influence Global Change? What factors determine variations among sectors and actors and change over time in the approximately 1% per year decrease in national energy intensity generally attributed to technological change? What factors determine average rates and variations around the average in the adoption of new production technologies that reduce inputs of energy and virgin materials per unit output? What factors determine the rate at which production costs of environmentally benign technology decline as output increases? What have been the effects of prescriptive standards, best-available-technology rules, public recognition and awards to encourage voluntary technology adoption, and other technology-related environmental policy instruments on actual rates of innovation? What Are the Regional Vulnerabilities to, and Consequences of, Global Change? What are the sectoral impacts of regionally relevant climate change assessments and seasonal to interannual climate predictions? Are there impact and vulnerability indicators that can be useful to detect the extent and severity of the impacts of global change on human populations? Can historical data be used to project future human vulnerabilities to climatic variation and change? How does climate change interact with other social and ecological changes to influence crop yields, water use, and other impacts?

OCR for page 51
OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade Can the mesoscale outputs of climate models be better linked to models predicting the regional impacts of climate change? What are the human consequences of rapid climate changes in the past and present? What are the global environmental change implications of rapid political and social changes in the past and present? How have environmental and social surprises interacted? How can we improve geographic links to existing social and health data? What Are the Most Effective Responses to Global Change? How can society deal with the possibility that citizens will become immobilized by warnings of possible, but highly improbable, environmental catastrophes? What are the characteristics of effective institutions for managing global environmental change? What are the correlates of effectiveness for international regimes and institutions and for management of international environmental and natural resource issues, particularly regarding the effective implementation of commitments to protect biodiversity, forests, oceans, and stratospheric ozone and to prevent climate change? What are the implications, applicability, and limits of particular policy instruments, including market-based instruments and alterations in property rights institutions at international, national, and local levels? How do declaratory targets, consensus policies, and review processes interact to influence behavior and restructure the power relationships of states and nonstate actors? Which characteristics of national institutions are most conducive to sustainable resource management by local institutions? How can knowledge about the conditions for successful local resource management be applied to problems at national and international levels? What are the links among land-use change, migration, political and economic changes, cultural factors, and household decision making? Understanding the interrelations between migration and environmental change. What Methods Can Be Used to Improve Decision Making About Global Change? Are there ways to improve the economic assessments of the costs, benefits, and distributional effects of forecasted climate changes and variations, taking adaptive capacity into account? When science can provide early warnings of possible catastrophes, how can this information be transformed effectively into public understanding and appropriate policy responses?

OCR for page 51
OVERVIEW: Global Environmental Change: Research Pathways for the Next Decade How can hazard management systems, including insurance strategies, subsidies, technological investment, and warning systems, be organized to increase resilience in the face of major surprises, and at what cost? What are the best ways of communicating uncertainty, providing early warnings of food and health problems, and introducing climate information in the policy process? How can environmental quality be incorporated into national accounting systems so it can be more easily considered in the policy-making process? How can information about the nonmarket values of environmental resources be incorporated effectively into decision making about resource use? How can we better represent, propagate, analyze, and describe uncertainties and surprises in integrated assessment (e.g., integrating quantitatively specified uncertainty with subjective probability distributions, clarifying the relationship between uncertainty and disagreement)? What are the characteristics of institutional processes that ensure that scientific analyses are organized to meet the needs of the full range of decision-making participants for information and involvement? How can the knowledge and concerns of those participating in or affected by environmental decisions be used to inform scientists about how to make environmental information more decision relevant? How do expert advice and assessment influence policy, decision making, and collective knowledge of global change issues, and how do policy makers interpret information about scientific uncertainty as they frame global change issues? How can decision-making procedures be structured to bring the quantitative and formal information embedded in assessment models together with scientific judgment and the judgments, values, preferences, and beliefs of elite and nonelite citizens in decision-making processes that meet the informational needs of the participants and are appropriate to the decision at hand? How can the integration of human dimensions research within the USGCRP and other international research programs be improved?