Strategic Plan for the
Climate Change
Science Program
Final Report, July 2003

   This chapter also available as PDF file.

Authors of this Chapter

Final Report also is available as single PDF file (8.8 Mb)

See also:
 

Vision for the Program and Highlights of the Scientific Strategic Plan

Acronyms, Abbreviations,
and Units

Ecosystems shape our societies and nations by providing essential renewable resources and other benefits. They sustain human life by providing the goods and services it depends on, including food, fiber, shelter, energy, biodiversity, clean air and water, recycling of elements, and cultural, spiritual, and aesthetic returns. Ecosystems also affect the climate system by exchanging large amounts of energy, momentum, and greenhouse gases with the atmosphere. The goal of the Ecosystems element of the U.S. Climate Change Science Program (CCSP) is to understand and be able to project the potential effects of global change on ecosystems, the goods and services ecosystems provide, and ecosystem links to the climate system (see Box 8-1 and Figure 8-1).

Figure 8-1: Key linkages and feedbacks between ecological systems, human systems (societies), and the climate system and atmospheric composition. Spatial scales are implicit and span from local to global. Humans manage some ecosystems intensively and others lightly. All ecosystems are affected to some degree, positively or negatively, by major global changes.

Global change is altering the structure and functioning of ecosystems, which in turn affects availability of ecological resources and benefits, changes the magnitude of some feedbacks between ecosystems and the climate system, and could affect economic systems that depend on ecosystems. Research during the last decade focused on the vulnerability of ecosystems to global change and contributed to assessments of the potential effects of global change on ecological systems at multiple scales.

We now know that effects of environmental changes and variability may be manifested in complex, indirect, and conflicting ways. For example, warming may enhance tree growth by extending growing season length (in temperate and cool regions), but pathogens better able to survive the winter because of higher temperature may decrease forest productivity and increase vulnerability of forests to disturbances such as fire. Subtle changes in winds over the ocean can affect currents which in turn may alter the ranges and population sizes of fish species and increase or decrease fish catches. Whether environmental changes are anthropogenic or natural in origin, human societies face substantial challenges in ensuring that ecosystems sustain the goods and services on which we depend for our quality of life and survival itself.

Figure 8-2: Landscapes and ecosystems are managed (some intensively, some lightly) by humans to produce grain, timber, and cattle, among many other goods and services desired by societies. For example, according to the Food and Agriculture Organization of the United Nations, 96% of the protein and 99% of the energy (usable calories) in the U.S. food supply come from terrestrial ecosystems (the remainder is derived from the ocean). Globally, about 94% of protein and 99% of energy in the human food supply come from terrestrial ecosystems. Photo sources: Tim McCabe (top and middle) and Jeff Vanuga (bottom), USDA-Natural Resources Conservation Service.

During the next 10 years, research on ecosystems will focus on two overarching questions:

Research should be focused on building the scientific foundation needed for an enhanced capability to forecast effects of multiple environmental changes (such as concurrent changes in climate, atmospheric composition, land use, pollution, invasive species, and resource management practices) on ecosystems, and for developing products for decision support in managing ecosystems. Near-term priorities will be placed on economically important ecosystems (e.g., Figure 8-2) and special studies relevant to regions where abrupt environmental changes or threshold responses by ecosystems may occur. Investigations will emphasize changes in ecosystem structure and functioning and changes in the frequency and intensity of disturbance processes anticipated to have significant consequences for society during the next 50 years, including altered productivity, changes in biodiversity and species invasions (including pests and pathogens), and changes in carbon, nitrogen, and water cycles.

Ensuring the desired provision of ecosystem goods and services will require understanding of interactions among basic ecosystem processes and developing approaches to reduce the vulnerabilities to, or take advantage of opportunities that arise because of, global and climatic changes. Scientific research can contribute to this societal goal by addressing three questions that focus on linkages and feedbacks between ecosystems and drivers of global change, important consequences of global change for ecological systems, and societal options for sustaining and enhancing ecosystem goods and services as environmental conditions change. This research will produce critical knowledge and provide a forecasting capability that will continuously improve decisionmaking for resource management and policy development.

Biological, chemical, and physical processes occurring in ecosystems affect and are affected by weather and climate in many ways. For example, ecosystems (and the organisms they contain) exchange large amounts of greenhouse gases with the atmosphere, including water vapor, carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). Moreover, the reflection (or absorption) of solar radiation by ecosystems is important to the temperature of Earth's surface. Linkages among the physical, chemical, and biological components of ecosystems are important on short (minutes to days) and long (years to millennia) time scales, as well as local to global spatial scales.

Global change has the potential to alter ecosystem structure (e.g., amount of leaf area, plant height, or species composition) and ecosystem functioning (e.g., rates of evapotranspiration, carbon assimilation, and biogeochemical cycling), and those potential changes in ecosystems might enhance or reduce global change through numerous feedback mechanisms (see Box 8-2). In addition to its direct linkages with ecological systems, global change could alter human actions that affect the structure, functioning, and spatial distribution of ecosystems, which in turn could alter important feedbacks from ecological systems to climate.

Research needs include improved experimental facilities and capabilities for making measurements in those facilities, ecosystem models, and ecosystem observing capabilities (and their related measurements) at multiple scales (to scale up from point observations with remotely sensed data). Initial efforts will be directed at enhancing existing capabilities and improving use of existing data streams. Studies should include identification of early indicators of changes in ecosystems that may be important to feedbacks to climate and atmospheric composition. Specific research needs include:

Many research programs that support long-term observations (e.g., forest productivity, ultraviolet-B (UV-B) radiation received by ecosystems, greenhouse gas concentrations and fluxes, atmospheric nitrogen deposition, nutrient loading, fisheries, and the spread of invasive species) have unambiguously established that large-scale ecological changes are occurring, and there is considerable evidence that some of those changes are the result of ecological responses to climatic variability and change. For example, recent warming has been indicated as potentially linked to longer growing seasons (i.e., period of leaf display) in temperate and boreal terrestrial ecosystems, grass species decline, changes in aquatic biodiversity, and coral bleaching (IPCC, 2001b; and see Figures 8-3 and 8-4). Natural modes of climatic variability (e.g., El Nino-Southern Oscillation, North Atlantic Oscillation, and Pacific Decadal Oscillation) are known to impact plankton and fisheries, such as sardine, anchovies, and salmon. Soil-borne plant pathogens and parasitic nematodes have been found to move northward (in the Northern Hemisphere) with increased surface temperature. Because survival and spread of pathogens and their vectors (carriers) depend on climate and weather, climatic change and increased natural climatic variability would be expected to affect disease-causing organisms that could alter the ecological status of fauna and flora. These and other observations and expectations have come from both experiments and in situ monitoring.

Figure 8-4: Top: Annual global sea-surface temperature (SST) anomalies relative to the 1880-2002 mean based on in situ and satellite measurements. The warmest annual global SST occurred in 1998. Bottom: Incidences of coral bleaching were influenced by unprecedented SST anomalies in 1998 due to a severe El Nino event as shown by this satellite retrospective annual composite monthly mean coral bleaching "HotSpot" chart for 1998. A coral bleaching HotSpot is defined as an SST anomaly above a coral-bleaching threshold SST climatology. HotSpot charts illustrate the magnitude and spatial distribution of thermal stresses that may contribute to coral bleaching. This chart was derived from the NOAA/NASA 9-km satellite AVHRR (Advanced Very High Resolution Radiometer) Oceans Pathfinder SST data set, the most refined available. Source: NOAA National Climatic Data Center.

Most ecosystems are now subject to multiple environmental changes. The dynamics and interactions of those changes and the consequences for ecological systems are poorly understood (NRC, 1999a). Recent reviews (e.g., IPCC, 2001b) summarized the range of observed and potential consequences of combinations of changes in climate, atmospheric composition, and local drivers (e.g., invasive species, pollution, and physical habitat modification) on ecological systems. For example, in aquatic systems, alterations in wind speeds and precipitation patterns, in combination with increased air temperature, would affect water column stratification and circulation, resulting in changes in the rates of nutrient supply and productivity at all trophic levels. For terrestrial ecosystems, a large knowledge base of effects of a change in a single environmental parameter exists, but effects of multiple changes on most ecosystem processes are uncertain (e.g., Table 8-1). Nonetheless, we know, for example, that interactions among changes in temperature, precipitation, and fire regimes can influence vulnerability to invasive species in terrestrial ecosystems. We also know that elevated atmospheric CO₂ concentration can sometimes eliminate the negative effects of elevated tropospheric ozone (O₃) concentration and warming on crop yields, and vice versa.

Identifying and quantifying the rates and consequences of global change for ecological systems is essential for appropriately evaluating options for responding to such changes. Determining the most important and societally relevant effects of global change on ecosystems will require collaboration among physical, biological, and social scientists and an improved understanding of complex interactions between natural and human disturbances and climatic variability. Near-term research priorities should include both ecosystems of special importance to society (e.g., major crops, commercial forests, and parks and preserves) and regions where abrupt changes or threshold responses may occur, such as high-altitude and high-latitude ecosystems and transitional zones between ecosystems (e.g., forest-grassland, agriculture-native prairie, ocean boundary currents, coastal zones, and/or rural-urban interfaces). Field studies should, where appropriate, share experimental facilities and research sites (e.g., Figure 8-5) with the Carbon Cycle and Water Cycle research elements. High-resolution ocean shoreline topographic data will be needed to adequately project effects of sea level rise on coastal ecosystems.

Specific research needs include:

Experiments and observations have demonstrated linkages between climate and ecological processes, indicating that future changes in climate could alter the flow of ecosystem goods and services (IPCC, 2001b). Several specific mitigation and adaptation measures have been identified and evaluated, including integrated land and water management; genetic selection of plants and livestock; multiple cropping systems; multiple use of freshwater and terrestrial ecosystems; programs for protection of key habitats, landscapes, and/or species; intervention programs (e.g., captive breeding and (re)introduction programs); more efficient use of natural resources; and institutional and infrastructure improvements (e.g., market responses, crop insurance, and water flow and supply management) (IPCC, 2001c).

It is clear that management practices can affect climate-related ecosystem goods and services. For example, management can influence the emission of greenhouse gases and aerosols from ecosystems; the rate at which ecosystems gain or lose carbon, nitrogen, phosphorus, and other elements as well as the total amount of those elements stored; the radiation balance of ecosystems (i.e., land surface albedo); and the production of goods valued by humans. While some management strategies have been studied, society's knowledge and ability to manage the broad array of ecosystem goods and services in the context of increasing and potentially conflicting demands (e.g., increasing food and fiber production while storing more carbon in soils and reducing CH₄ emissions) is very limited.

Much ecosystem management for the foreseeable future will proceed with imperfect knowledge about the effects of multiple global change processes and about fundamental aspects of ecosystem structure and functioning. Routine monitoring (e.g., Figure 8-6), scientific evaluation, and feedback from managers could enable adaptive shifts in management strategies as knowledge about an ecological system grows, and at the same time will provide important opportunities for scientists to test hypotheses about ecosystem responses to environmental change. Substantial improvements in modeling capabilities are also needed to develop and deploy effective options to maintain and enhance the supply of critical goods and services and to evaluate alternative management options under changing environmental conditions. Modeling alternative management options will require evaluation of the influence of societal demands on ecosystems.

Specific research needs include:

Figure 8-6: Brightly colored waters in the Gulf of Mexico indicate the presence of sediment, detritus, and blooms of marine plants called phytoplankton (noted by arrow). The blooms may be caused, or enhanced, by changes in land management "upstream" and/or changes in regional climate. By late November, the bloom appears to have subsided. Images are true-color Moderate Resolution Imaging Spectroradiometer (MODIS) products. This type of remote sensing technology is essential to monitoring and quantifying ecosystem and landscape states and changes. Source: NASA MODIS Ocean Team.

Interagency and international facilities and mechanisms must be in place to process, archive, and distribute the data collected and to generate relevant products. Given the nature of global change, research must span large spatial scales (from small experimental plots to global satellite image mosaics, e.g., Figure 8-7), long time scales (paleontological data from ice cores, tree rings, and fossil pollen to near-real-time forecast models), and monitor a wide range of variables important for characterizing the state of ecosystems. National and international observing systems at multiple spatial scales are needed to develop a consistent record of environmental change over time. Data from such observing systems would provide inputs to models and allow evaluation and improvement of model performance. The resulting large collections of ecological and environmental data will necessitate large databases and new approaches to data integration and analysis and will require new and enhanced national and international partnerships.

Future experimental and observing systems may rely on networks of terrestrial and aquatic ecosystem observatories within particular biomes or larger ecoregions. They should link together efficiently and build on existing networks of field stations, experimental forests and ranges, environmental and resource monitoring programs, and long-term ecological research sites sponsored by many governmental and nongovernmental organizations, some of which have lengthy records (many in non-machine-readable forms) of ecological and environmental data.

Scientists conducting research under the Ecosystems element of the CCSP will participate in the planning of international collaboration activities, including those sponsored wholly or in part by the International Geosphere -- Biosphere Programme (IGBP), such as the Global Climate and Terrestrial Ecosystems (GCTE) project, the Global Environmental Change and Food Systems (GECaFS) project, the Land -- Ocean Interactions in the Coastal Zone (LOICZ) project, the Surface Ocean -- Lower Atmosphere Study (SOLAS), the Global Ocean Ecosystem Dynamics (GLOBEC) program, the Global Ecology and Oceanography of Harmful Algal Bloom (GEOHAB) program, and the Biospheric Aspects of the Hydrological Cycle (BAHC) project. Also important are the Global Ocean Observing System (GOOS), the Global Terrestrial Observing System (GTOS), the Global Climate Observing System (GCOS), the Millennium Ecosystem Assessment, and the International Long-Term Ecological Research (ILTER) network.