Understanding Land Use Change
Our first priority is to develop a science plan for research on land use change. Changes in land use are among the important forces driving global climate change. Climate change can also be expected to have an important impact on land use change. But it is the context within which land use change is occurring that gives it special importance. The forces that determine the trajectory of land use change will affect not only the natural environment, but also the human consequences of climate change—both its socioeconomic impacts and the policy options available for mitigation and adaptation. For example, the impact of climate change will depend on changes in land use occasioned by growing demand for agricultural commodities, human habitation, and the preservation of natural habitats.
By the middle of the next century, the demand for agricultural commodities —primarily food—will rise by a multiple of 3 to 4 at the global level. Population growth alone may cause an approximate doubling of the demand for the products of agriculture. But even moderate growth in income in the developing world will add at least as much to increases in demand as population alone—thus increasing demand to at least 3 times the present level. Those increases must be achieved in an environment of increased competition for land—for human settlement, transportation, biomass production for energy, preservation of biodiversity, and expansion in the supply of environmental amenities.
An important implication is that we must anticipate substantial intensification of human activities on land currently devoted to agricultural pro-
duction. Unless this intensification is addressed by new technologies that are not now in the pipeline, we can expect additional impacts on global climate change from land use conversion and ntensification —for example, use of nitrogen fertilizer may increase by a factor of 6 to 10. This and other increased material inputs into agricultural production will have environmental implications that are not yet well understood, but that are likely to include impacts on global environmental systems. In addition, as agricultural intensity increases, the effects of any environmentally induced changes in the productivity of agricultural lands will increase proportionally; and to the extent that nonagricultural demands on the land also grow, options for responding to those effects will be limited. For these reasons, it is important to understand the linkages of agricultural and other demands on land, land use change, and changes in agricultural and industrial metabolism or ecology.
The role of market forces in land use change for the production of agricultural commodities has long been a subject of substantial research. The issue of land use and supply response was an active field of research in agricultural economics and development economics from the mid-1950s through the 1960s (Krishna, 1967). There is also a literature on the relationships of population change and land use change in the tropics (Grainger, 1992; Jolly and Torrey, 1993).
Efforts to estimate global demand for agricultural land depend on data on market forces and population. But because these data often exist only at the national level and above, it can be difficult to model processes at the subnational (regional and local) levels, where actual land use change is taking place. There, a wide variety of social, political, and cultural institutions mediate the pace and character of land cover conversion for human use, the interaction of market and nonmarket influences, and the influence of national and international policies. In order to understand the driving forces of land use change at the global level, it is essential to know the mechanisms and dynamics by which land use managers at the local level govern land. That includes analysis of land use institutions, assessment of short-term biophysical constraints and feedbacks, and cross-scale macroeconomic and macropolitical influences involving markets and states.
RELATION TO USGCRP PRIORITIES
A focused research effort on land use change will support the wider needs of the USGCRP in at least the following ways:
by improving forecasts of the future status of land cover and thus changes in the earth's albedo and other physical parameters affecting climate change;
by improving forecasts of land uses that affect the earth's biogeochemical cycles;
by improving forecasts of future land uses that will bear the impacts of climate changes, thus putting analysis of the ecological and human consequences of climate change in the context of likely future terrestrial, social, and economic conditions; and
by providing more realistic estimates of the costs and benefits of mitigation and adaptation options based on likely future conditions of land use and of demand for land and agricultural commodities.
TIMELINESS OF EFFORT
Focused research on land use change is particularly timely now for at least the following reasons:
recent developments in geographic information systems, including projects to include georeferenced social data, make possible analyses that could not have been done before;
modeling projects using geographic information systems can help select from among feasible priorities for other kinds of research those most likely to decrease key uncertainties in understanding;
the International Geosphere-Biosphere Programme (IGBP) and the Human Dimensions of Environmental Change Programme (HDP) are in the process of developing an organized international scientific research program in this area, and an effort to focus research within the United States now would both assist the international effort and leverage that effort to strengthen work being done domestically; and
a focused research priority in this area would help coalesce the growing interest in human dimensions research within agencies that have not previously been major contributors to the USGCRP (e.g., the Department of the Interior, the Department of Agriculture).
The following are among the several issues on which research might be expected to make significant progress in the short term (2-5 years) and longer term (10-20 years).
Analyses of the roles of market forces, population pressures, property rights institutions, and technological change in land cover conversion from primary forests, grasslands, and other critical land cover types.
Analyses of the role of economic and institutional incentives for reconversion of degraded agricultural and forest lands, as well as the impact of existing protected areas in regional-scale land use and land cover dynamics.
Analyses of opportunities for and constraints on reducing emissions of greenhouse gases resulting from agricultural land use practices (e.g., methane from rice fields, nitrous oxide from fertilizer use).
Analyses of the sources of differences in urban density across regions and of changes in urban density within regions; implications of urban-rural linkages and intensification for land use conversion.
Continuous monitoring of land use, land cover, and land use technologies is needed to generate evidence required to improve understanding of land use change. Monitoring should cover spatial units that are sufficiently flexible to be useful for environmental (including remotely sensed) data as well as socioeconomic and demographic data. Particular attention should be given to change in technologies involved in land use since the capability to improve production while protecting environmental quality is, to a significant extent, a function of technology.
Analyses of economic, cultural, and biological implications of changes in biodiversity.
Analyses of the political and economic viability of policies and institutional design for adaptation and mitigation strategies in areas such as (a) coastal resource use and (b) transfer of water resources from low value to higher-value uses.
Models linking the mechanisms and dynamics of anthropogenic land use changes to biophysical modeling efforts. These would include models of land use “transformation in . . . tropical forests and coastal wetlands . . . to provide regional forecasts of the impact of human activities on the extent of the affected land uses over decades-to-century scales” (National Research Council, 1990a:118). In these environments, land transformation can be both a source and a consequence of global change. Model construction would be designed to analyze the sensitivity of land use and land cover changes to two broad categories of policy regimes: (a) those that rely primarily on market or market-like incentives and disincentives (i.e., those that operate through the price mechanism) and (b) those that rely primarily on regulatory (command and control) approaches.
Further identification and selection of research objectives would be made in the process of developing the science and implementation plans for this area.
RELATION TO INTERNATIONAL RESEARCH
A Land Use/Land Cover Core Planning Project is now being developed under the HDP and the IGBP with B.L. Turner and David Skole serving as cochairs. This research effort is designed to answer three questions:
How has land cover been changed by human use over the past 300 years?
What are the major human causes of land use change in different spatial (and temporal) contexts?
How will global environmental changes affect land use and land cover?
The international effort will emphasize three interrelated activities: a global-to-national modeling effort, an empirically generated local-to-national modeling effort (both of these are organized consistently with the research directions recommended above), and a data generation component intended to link socioeconomic data at the global and national levels to land cover and other biophysical classification and data efforts, such as the IGBP Data and Information System.
The substantial involvement of U.S. researchers and research institutions in the creation of the international research program and the natural complementarity of the U.S. and international research efforts on the human dimensions of global change make it important that the USGCRP science plan in the area of land use change draw on and reinforce the IGBP/HDP effort.
The research program should represent a mix of institutional support and project support for investigator-initiated research. The case for investigator-initiated research rests on the potential for advancing science and methods related to analysis of the sources and consequences of land use change. The case for institutional support rests on the need for a core budget commitment for long-term research on issues of strategic importance. (An example from a closely related field is the multiyear effort led by John Krutilla and Allen Kneese at Resources for the Future to develop methods for valuing unique environments and estimating the costs and benefits of limiting the spillover of residuals from agricultural and industrial production.) The case for institutional support is particularly strong when the research requires modeling efforts based on the analysis of large georeferenced data sets.
The science plan should be developed in the context of considering the
center(s) for human dimensions of climate change that Congress has called for establishing in 1995, because such center(s) could play an important role in land use change research. The implementation plan should clarify the roles of research in centers, contracts or cooperative agreements between centers and individual researchers, research supported directly by agencies, and the networking function of centers for linking investigator-initiated research with the center-based research.
The proposed research on land use change should be a significant part of the U.S. human dimensions research program. One should not underestimate the costs of conducting research that is intended to become policy relevant. An objective must be to identify not only the driving forces and the existing relationships among them and changes in land use, but also the mechanisms explaining those relationships and the variables that can be manipulated to achieve desired policy goals. Research focused on global change consequences and options in the land use area must include careful attention to the fact that agents anticipate such changes and respond, rationally or otherwise, to anticipated changes and to anticipated policy responses.