Global Change

The goal of global change research is to observe and document global environmental changes and identify their causes, predict the responses of the earth system, determine the ecological and socioeconomic consequences of these changes, and identify strategies for adaptation and mitigation that will most benefit society and the environment.

Research is being conducted to understand major global environmental issues such as: (1) climate change resulting from human-induced enhancement of the greenhouse effect; (2) depletion of the stratospheric ozone layer; (3) disruptive seasonal and interannual variations in temperature and precipitation, such as the El Nino-southern oscillation; and (4) large-scale changes in land use and land cover.


Relevant Policies, Issues, and Legislation


Current State of Understanding

The earth's climatic, ecological, and biogeochemical record provides the context for understanding anthropogenic effects on the earth system. Over its few billion year history, the earth's geography, climate, and ecosystems have all gone through dramatic changes and fluctuations on time scales that vary from less than a decade to millions of years. Superimposed on these longer-term changes are natural fluctuations that lead to individual seasons, years, and decades with climate conditions that may differ sharply from multidecadal or centennial averages. Although global average conditions change relatively slowly, significant intra-annual and interannual to decadal variations can occur at regional (subcontinental) scales, driven to varying extent by changes in sea surface temperature and ocean circulation patterns, volcanic eruptions, soil moisture anomalies, sea ice extensions and retreats, and variations in the amount of solar radiation reaching the earth.

Since the beginning of the industrial era, atmospheric abundances of greenhouse gases have increased as a result of human activity (e.g., carbon dioxide has increased 30%), causing an increase in the radiative forcing of the earth's atmosphere. A significant fraction of this increase may have been offset by cooling associated with simultaneous increases in atmospheric sulfate and carbonaceous aerosols or by the effects of stratospheric ozone depletion. The quantitative regional and global impact of these changes on the earth's climate are strongly regionally dependent, and large uncertainties remain. Global mean surface temperatures have increased by about 0.5 C over the past century, although precipitation averaged over the world's land masses shows little or no change. However, in the contiguous United States, mean precipitation has increased by about 5%, confined to autumn. The frequency of extreme rainfall events has increased throughout much of the country. The limited set of measurements around the world, however, does not yet allow the cause (i.e., human activities or natural variability) of the small, but potentially important, changes in climate to be established.

The most important and well-defined human effects on stratospheric ozone concentrations to date have occurred through chemical changes in the stratosphere caused by increases in emissions of chlorofluorocarbons (CFCs) and other halons. The resulting stratospheric ozone depletion increases the clear-sky flux of ultraviolet (UV) radiation reaching the surface, which has been shown in field and laboratory studies to have significant harmful effects on human health and ecosystems.

Changes in land use and land cover and the resulting losses of productivity of terrestrial ecosystems are occurring on a global scale. Land-use change may lead to the depletion of localized resources of common value to social systems and have consequences that extend to the entire international community. Transformation of land from native forest cover to agriculture, grasslands, and urban development can alter the albedo and natural water cycle and result in the degradation of formerly productive land and the loss of biodiversity.

Research Program

Current global change research is focused on understanding how the earth system functions, how human activities can perturb the global environment, and the consequences of such perturbations on human health, societal support systems, natural ecosystems, and the capacity of the earth system to both sustain the natural environment and meet societal needs. Recent emphasis includes both ecological and socioeconomic impacts. Important ongoing activities that continue to be priorities include:

Climate change and greenhouse effect research to (1) observe and document the extent to which human activities influence long-term climate change; (2) improve the input to and the capability of climate system models to represent relevant processes and better predict global and regional changes in climate; (3) predict the consequences of climate change on natural and socioeconomic systems; and (4) support integrated assessments of climate change, including research on the feasibility, effectiveness, and costs (market and nonmarket) of implementing response options.

Stratospheric ozone and UV effects research to (1) support international space- and surface-based observation programs to document the response of stratospheric ozone to changes in atmospheric composition; (2) develop a network to monitor surface UV radiation; (3) observe, predict, and understand the consequences to ecosystems, agriculture, and human health of long-term changes in UV radiation; (4) evaluate new and substitute compounds for their effects on the ozone layer, the environment, and human health; and (5) evaluate the role of subsonic and supersonic aircraft for their effects on stratospheric ozone.

Seasonal to interannual climate fluctuations research to (1) expand and maintain global ocean observing systems; (2) develop modeling capabilities for forecasting seasonal to interannual climate fluctuations and the expectation of unusual and extreme events; and (3) encourage multilateral collaboration in the establishment of regional application centers for using forecasts to reduce disruptive consequences of extreme climate events.

Large-scale ecosystem productivity research to (1) map global productivity of terrestrial, freshwater, and marine ecosystems using remotely sensed data (such as that from past and continuing Landsat observations); (2) determine the results of changes in land cover, desertification, and deforestation on ecosystem vitality, carbon storage and release, and the cycling of soil nutrients; and (3) conduct studies to understand the socioeconomic causes and implications of land-use change.

Areas of Enhanced Emphasis

Selected Milestones, 1995 - 1998

Research Successes - Global Change


Natural Disaster Reduction

The goal of federal research in natural disaster reduction is to provide the scientific information necessary to make our society resilient to natural disasters by reducing the loss of life, property damage, and economic disruption caused by earthquakes, floods, hurricanes, tornados, fires, and volcanoes. This goal can only be achieved through integrated efforts in the areas of assessment, mitigation, and warning. Federal research in natural disaster reduction focuses on the development of the predictive understanding, technological capabilities, and societal frameworks necessary for a sustainable society that is resilient to natural hazards.


Relevant Policies, Issues, and Legislation


Current State of Understanding

Although the understanding of the physical characteristics of many natural hazards has increased dramatically over the past decade, much more can be achieved to allow for timely prediction of many hazards. Important progress has been made in predicting the effects of earthquakes and in delineating zones of potential damage, but many potentially active fault zones remain unidentified. Furthermore, prediction of earthquakes themselves remains elusive. Volcano monitoring has reached an advanced stage, and the importance of certain precursors for many eruptions is now recognized. The use of Doppler radar systems, together with high-speed computers that allow forecasters to diagnose and comprehend the state of the atmosphere in a more detailed way, has dramatically advanced our understanding of severe weather. However, we still cannot predict, or interpret, many events. For example, there is currently no fully accepted explanation of the entire causal series of processes responsible for the 1993 Midwest floods.

Although the physical forces responsible for natural disasters are at least partially understood, a clear understanding of the socioeconomic forces needed to reduce natural disasters, versus those that exacerbate the problem, is only now coming into focus. A knowledge of the role of massive urbanization, technological advance, globalization of society, and cultural diversity in changing societal vulnerability to natural hazards is particularly rudimentary, as is our understanding of the options and opportunities for reducing the impact of natural hazards and adapting to their occurrence. Especially worrisome is the prospect of more complex, massive disasters in the world of the future. The major policy tool of the past has been insurance, and as the scale and costs of natural disasters have grown, casualty insurers are threatened with massive future losses. What is needed is the application of new technologies that will allow structures and lifelines to withstand hazards so that societal, and personal, losses are decreased. Information on technological solutions and other forms of natural disaster reduction have been made available to the pubic sector, but much of the information remains fragmented and difficult to access.

Research Program

Important ongoing research and development in natural disaster reductions focuses on improved understanding of the nature and impact of hazards and the means to mitigate risks. Important ongoing research activities receiving strong emphasis include:

Areas of Enhanced Emphasis

The agencies conducting research in natural disaster reduction recognize the need for coordinated federal research and close collaboration among federal agencies, state and local governments, the private sector, and the general public in three important areas:

Selected Milestones, 1995 - 1998

Research Successes - Natural Disaster Reduction

Chapter 3 (continued)