Strategic Plan for the
Climate Change
Science Program
Review draft, November 2002

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Chapter 8:
Land Use / Land Cover Change

Land use and land cover change is perhaps the most prominent form of global environmental change since it occurs at spatial and temporal scales immediately relevant to our daily existence. The changes in land use and land cover, especially when coupled with climate change and variability, are likely to affect natural resources and ecosystems in complex ways. The National Research Council recently identified Land Use Dynamics as one of the grand challenges for environmental research (NRC, 2001d).

Determining the effects of land use and land cover change depends on an understanding of past land use practices, current land use and cover patterns, and projections of future land use and cover, as affected by human institutions, population size and distribution, economic development, technology, and other characteristics. The combination of climate and land use change may have profound effects on the habitability of the planet in more significant ways than either acting alone. While land use change is often a driver of environmental and climatic changes, a changing climate can in turn affect land use and land cover. Climate variability alters land use practices differently in different parts of the world, highlighting differences in societal vulnerability and resilience. The feedback between land use and climate change is poorly understood and will require the development of new models linking the geophysics of climate with the socioeconomic drivers of land use. Providing a scientific understanding of the process of land use change, the impacts of different land use decisions, and how they will be complicated by a changing climate and increasing climate variability is a priority area for research.

This research element provides the scientific underpinning for land use decisionmaking and projections of future land use, and has substantial benefits beyond climate change assessment and mitigation by supporting a wide array of issues important to public users of this information. To meet multiple objectives, the land use and land cover change research element will address two overarching questions:

To address these overarching questions and to make the science useful for decisionmaking will require a focused research agenda that includes ongoing mapping, measurement, and monitoring of land use and land cover change from local to global scales; identification of the driving forces or agents of change; the capabilities to model and project future changes in land use and land cover; and assessment of the implications of land use change. In addition, research collaboration with other program elements will be necessary to gain detailed understanding of the direct impacts of land use and land cover change on climate, as well as the combined effects of land use and climate change on ecosystems and water and carbon cycles. Answers to the overarching questions will require research focused on the five specific questions posed below.

The ability to forecast land use and land cover change and, ultimately, to predict the consequences of change, will depend on our ability to document and understand the past drivers of land use and land cover change. Historical land use and cover change has occurred primarily in response to population growth, technological advances, economic opportunity, and public policy. Patterns of human settlement are shaped by both the interaction of environmental (e.g., climate, geology, topography, and vegetation) and social (e.g., cultural customs and ethnicity) forces around the world. An improved understanding of historical land use and land cover patterns provides a means to evaluate variations in past causal factors and responses as well as a method for evaluating the trends of human activities present in the current baseline. The systematic evaluation of these historical and contemporary factors will improve the ability to develop projections of future land use and management decisions. This type of analysis will require the integration of various disciplines from the physical and social sciences.

Improvements are needed in process models of land use and land cover change dynamics in space and time, combining field-level case studies for analysis of processes, statistical studies for large regions, and empirical analyses using remote sensing change detection. This process-level understanding of land use and cover dynamics will aid the analysis of land use and land cover change across scales. Work will also be required to understand how, for example, one agent or cause of land use change influences another. This comprehensive understanding of land use and cover change processes also needs to consider interactions between socioeconomic factors and biophysical factors, including synergies between land use dynamics and climate change and variability.

Products and Payoffs

A significant component of this research element involves improvements in data collection systems and data products. Research on current land use and land cover will provide new information to enable the production of regular updates on the distribution of land cover at scales relevant for global-scale analyses and resource management decisions. The information will also provide the data needed to parameterize climate and other environmental factors in models. Remote sensing provides quick and comparatively inexpensive information about land cover changes over large areas. Ground-based networks in the United States also offer a wealth of historical data (often with data records extending back 50-100 years), and can provide detailed information on site conditions, including species composition, soil type, habitat quality, tillage and crop rotation history, wildlife population statistics, and land use classification. Integrating ground-based and remote sensing data collection systems provides an opportunity to vastly improve the speed and overall quality of land use and land cover data for use in applied research.

Evolving public and private land management questions call for new types of data and information and improved scientific bases for decisionmaking. They also require long-term continuity in data collection, and the acquisition of data at the global scale. With the current suite of satellite sensing systems and archived data sets available to the research community, studies at the large spatial scales needed to depict land cover and management changes can begin. While considerable progress has been made in mapping land cover characteristics, the ability to accurately map the wide range of landscape attributes, including land use and biomass, will require a considerable research effort. In addition, improvements in remotely-sensed data quality and in algorithms for detection of local changes and their characteristics are needed. Data integration will be a particularly important research strategy so that in situ, remotely sensed, and other forms of data can be merged and used to derive the needed land use and land cover information. As scientific demands and needs for land use and land cover information change, parallel innovation in the resulting data products will be essential.

In order to understand the historical and contemporary linkages between land use and land cover change and its resulting effects on biogeochemical cycles, climate, ecosystem health, and other systems, it will be necessary to make significant advances in documenting the rates and causes of land use and land cover change. Our current understanding of historic land use and land cover change is weak due to the anecdotal nature of past research in this area. Future understanding of land use and land cover changes will be greatly improved due to new systematic methods and study designs for land use change research. In order to understand the forces of change that operate at different scales, it will be necessary to conduct studies that explicitly reveal the regional variations in change characteristics. With this, the historical and contemporary data needed to develop models that project land use and land cover for specific intervals into the future will be produced.

A new suite of models that combine physical, socioeconomic, and climate data to model projected changes at scales relevant to resource management are needed. This calls for a better understanding of the drivers of land use change and credible predictions of land cover and land use at decadal time scales. Integration among the Carbon Cycle (Chapter 9), Ecosystems (Chapter 10), and Human Contributions and Responses (Chapter 11) research elements will be needed to develop and test models needed to generate scenarios of land use and land cover change and projections of change that take into account the various influences of ecosystem functioning, carbon, water, and energy cycling as well as human managed systems. Model validation will be a particularly challenging element of this research area. Simulation of past conditions will be a necessary strategy for testing the performance of models, placing more significance on the need to understand land use and land cover change in both an historical and contemporary context.

There is clear evidence that changing land use and land cover has significant impacts on local environmental conditions and economic and social welfare. Some of the impacts are local while others have global ramifications. For example, estimates of trace gas emissions and removals by sinks depend strongly on land cover and land use practices, while the deposition of atmospheric constituents affects the potential rate and magnitude of terrestrial sinks. The water cycle depends heavily on vegetation, surface characteristics, and water resources development by humans (e.g., dam construction, irrigation, channeling, and drainage of wetlands), which in turn affect forecasts of water availability and quality. The other Climate Change Science Program (CCSP) research elements provide complementary information about the environmental and biophysical forces that influence potential land uses (e.g., atmospheric chemistry and processes, climate variability and change, water resources, nutrient flows, and ecological processes) and the anthropogenic pressures that will give rise to various land uses and processes (e.g., the Human Contributions and Responses element, Chapter 11). The land use/land cover change element will develop projections of changes in land cover and use that are critical to developing accurate forecasts in the other areas of the program. The following research questions address the effects of changes in land use and land cover on other research elements (i.e., Ecosystems, Water Cycle, and Carbon Cycle). Research will require multidisciplinary cooperation to develop land use and land cover projections that address the necessary spatial and temporal scales, and include the necessary physical, biological, and social factors of interest, to ensure that projections of land use and land cover can be incorporated into models of impacts.

In order to understand the impacts of land use and land cover change, there must be ongoing close cooperation with other CCSP research elements that will improve understanding of the interrelationships and dynamic feedbacks between land use/land cover change and carbon, ecosystems, atmospheric chemistry, water resources, and climate variability. The challenge will be to use contemporary impacts of land use and land cover change to calibrate impacts on ecosystem goods and services; biogeochemical, water, and energy cycles; and climate processes. These investigations must be undertaken on multiple scales so that the full dimensions of the perturbations of environmental processes can be determined.

Land use and land cover change is linked in complex and interactive ways to other global environmental changes, human actions (both as causes of change and responses to impacts), and environmental feedbacks at multiple spatial and temporal scales. The outflow of soil nutrients, for example, has immediate impacts on land productivity, vegetation, and soil erosion rates; medium-term impacts on landscape fragmentation, land productivity, and downstream aquatic ecosystems; and possible long-term impacts on climate. Land use and land cover change, climate change, and other environmental changes all interact to affect natural resources. The research associated with this question will require collaboration with the Climate Variability and Change (Chapter 6), Ecosystems (Chapter 10), Water Cycle (Chapter 7), and Carbon Cycle (Chapter 9) research elements.

Development of coupled climate-land use/cover models, that incorporate socioeconomic factors, should be accelerated. Simulation of climate-land use/cover feedbacks will require advancement of current understanding of multiple stress processes at local to global scales. Validation of the interacting climate-land use effects for specific regions of the globe will be particularly challenging. International cooperation will be needed to optimize the currently existing and emerging observational networks.

The implementation of the Land Use and Land Cover Change research element will require an interdisciplinary approach involving scientists from physical, natural, and social science communities. Crucial to these activities will be the transfer of accrued knowledge to policy and decisionmaking communities. Success will depend on close linkages with other CCSP research elements. In particular, collaboration with the Water Cycle (Chapter 7), Carbon Cycle (Chapter 9), Ecosystems (Chapter 10), and Climate Variability (Chapter 6) research elements will be needed to understand the larger effects of land use and land cover changes over time.

Regional observational and monitoring networks and associated case studies are key to understanding phenomena at fine scales, and provide a test bed for models and a mechanism for comparative analysis. In the next 10 years the establishment of international land use and land cover science programs will augment ongoing efforts such as the International Geosphere-Biosphere Programme to help bridge the gap between climate change researchers, land managers, and decisionmakers. For example, Global Observation of Forest and Land Cover Dynamics (GOFC-GOLD) is a new program for coordinating global land observations, implemented through regional networks of data providers and users to address a combination of global change and natural resource management questions, and engaging local scientists with local and regional expertise and knowledge.

Another example is the United Nations (UN) Land Cover Network - an emerging cooperative activity of the UN Food and Agriculture Organization (FAO) and the UN Environment Programme (UNEP) to develop monitoring and measurement of land cover change in support of their global environmental outlooks and assessments (e.g., the Millennium Ecosystem Assessment). In addition to these activities, development agencies are attempting to address questions concerning the societal impacts of global change through new programs such as the US Agency for International Development's (USAID) Geographic Information and Sustainable Development program. Such programs can help in strengthening the scientific underpinning for the decisionmaking process.

There are a number of programs that have identified land use and land cover change as part of their individual agency research agendas (e.g., the National Aeronautics and Space Administration, the US Geological Survey, the National Science Foundation, the US Environmental Protection Agency, and the US Department of Agriculture) and have played an active role in developing this research element. It will be important as the program proceeds to engage multiple agencies and organizations working in this and related fields (e.g., the National Institutes of Health, the Department of Transportation, the Bureau of Land Management, and USAID). In the next decade of global change research it will be particularly important to include stakeholders (e.g., the Council of Governors, non-governmental organizations, and state and local land managers) in guiding this research element.

NRC, 2001d. National Research Council, Committee on Grand Challenges in Environmental Sciences, Grand Challenges in Environmental Sciences  (Washington, DC: National Academy Press).