Enhancing Productivity and
Resilience of Natural Resources

[ Climate Variability and Agriculture in the Southeastern United States ]
[ Soil Organic Matter and the Sustainability of Chinese Agriculture ]
[ Transboundary Fisheries: Pacific Salmon ]
[ US National Assessment ]
[ Water Resources in the West ]
[ Will Tropical Forests Survive the Twenty-First Century? ]
[ Yangtze Basin Floods of 1998: Forecasts and Responses ]
[ Yangtze Delta in China as Evolving Metro-Agro-Plex ]


Climate Variability and Agriculture
in the Southeastern United States

Research on three overlapping multiyear projects (NASA/USEPA/USDA) has continued by Linda Mearns, Richard Katz, Larry McDaniel, Elena Tsvetskinskaya, Gregory Carbone (U South Carolina), Bette Walter-Shea (U Nebraska), and William Easterling (Pennsylvania State U). Regional climate modeling and conditioned stochastic modeling form the basis of several different types of climate change scenarios. Remote sensing, crop and economic model, and spatial scaling analysis make up the other elements of the projects. Major accomplishments in the projects include:

  • Production runs of six different crop models with and without direct CO2 effects and with adaptation, using a baseline climate data set and the two different resolution climate scenarios on a baseline grid of 0.5 by 0.5 degrees, calculation of percentage changes in yield (from baseline), and comparison of these for the coarse and fine scenarios; Application of an additional cotton model, GOSSYM;

  • Application of complex spatial statistics to determine significance of contrast in mean and spatial patterns of yields;

  • Production of two different resolutions scenarios for the rest of the United States (with a coarser baseline grid);

  • Application of all yield results to an agricultural sector model (ASM);

  • Analysis of observed temperature and precipitation data sets in the Southeast United States for development of stochastic models conditioned on the Bermuda High Index. (For more information, see the last paragraph in this section on "Statistical Downscaling of Weather Generators.")

Highlights of Results: We found that significantly different changes in most yields resulted from the two different scenarios, when calculated on the common 50-km grid of the regional climate model for the case of climate change only, climate change plus CO2, and adaptation effects. In the climate-change-only case, for most crops, yield decreased for the two scenarios, but decreases were greater when determined from the regional climate scenario. Mearns and colleagues then aggregated the yield results to the economic units (usually states) required for use in the ASM and found that for some states the significantly different results persisted. The economic model was run for the base case and for the two climate-change-plus-direct-CO2 cases, and for the two adaptation cases. For the country as a whole, the coarse-scale scenario resulted in substantially increased total surplus for the agricultural sector, but the fine-scale scenario produced a very small increase. Regional index numbers for the total value of production, which is a measure of economic activity within the regions, show interesting contrasts across the regions, based on the scenarios. The southeast and Appalachian regions show the largest decreased in activity for both scenarios, but the decrease with the fine-scale scenario is much larger. With adaptation, the contrast between the scenario scale effect decreased, but was still discernable. Results indicate that the scale of climate change scenario substantially affects the simulation of changes in crop yields on various levels of spatial aggregation. These results further confirm the earlier results of Mearns et al. (1999, 2001), but for a larger region and a greater variety of crops. Moreover, Mearns and colleagues have demonstrated that these contrasts in changes in yield are substantial enough to affect the results of an agricultural economic model, both on national and regional levels.

Statistical Downscaling of Weather Generators: The goal of this research is to develop improved statistical methodology for generating climate change scenarios at local/regional spatial scale and on daily time scales conditional on large-scale circulation patterns. In collaboration with Marc Parlange (Johns Hopkins U) and Claudia Tebaldi (NCAR/RAP), Richard Katz neared completion of work on the development of stochastic weather generators for locations in Southeast United States conditional on indices of large-scale atmospheric/ oceanic circulation (especially the so-called Bermuda High).

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Soil Organic Matter and the Sustainability of Chinese Agriculture

Robert Harriss is a member of an international team investigating the trends and status of soil organic matter in China's major crop growing regions. A modeling study was conducted that integrates geospatial data on soil resources with information on farming practices to estimate potential changes in soil carbon and nitrogen stocks and fluxes. We discovered that, on average, cropland soils were losing organic carbon at a rate of 1.8% per year, primarily due to burning crop residues rather that re-incorporating them into the soil. This study relates both soil degradation and freshwater eutrophication to the same source - long-term losses of soil organic matter. These results have been submitted for publication in Ecological Applications.

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Transboundary Fisheries: Pacific Salmon

Kathleen Miller is the co-Principal Investigator of this NOAA/OGP-funded project, working with Robert McKelvey (U Montana) and Gordon Munro (U British Columbia). Pacific salmon are anadromous fish that cross state and international boundaries in their oceanic migrations. The history of attempts by the United States and Canada to cooperatively manage their respective salmon harvests suggests that environmental variability may complicate the management of such shared resources. Miller and colleagues prepared two papers, the first of which draws lessons from the recent period of turmoil to identify strengths and weaknesses in the new abundance-based management approach, and to suggest avenues for further negotiations to secure more rational management of Pacific salmon resources. This paper, "Climate, Uncertainty and the Pacific Salmon Treaty: Insights on the Harvest Management Game," was published in FY01 in the Proceedings of the International Institute of Fishery Economics and Trade. A second, more extensive paper focuses on the 1999 Pacific Salmon Agreement. This paper, entitled: "The 1999 Pacific Salmon Agreement: A Sustainable Solution?" provides a more complete description of the application of game theoretic concepts to understanding the role of climate-related changes in abundance and migratory patterns in the history of the U.S./Canadian Pacific salmon management. This paper also provides an updated analysis of experience under the new Agreement, and draws upon experience in other fisheries to evaluate further options for maintaining cooperation in the Pacific salmon case. This paper was published in FY01 as Canadian-American Public Policy Occasional Paper No. 47, University of Maine.

The project also has encompassed considerable development of the game theoretic models by Robert McKelvey. Two NCAR technical reports were published this period: (1) McKelvey, R., 2001. The Split-Stream Harvesting Game I: Mathematical Analysis, NCAR Technical Report, NCAR/TN-449+STR - Part I; (2) McKelvey, R., and G. Cripe, 2001: The Split-Stream Harvesting Game II: Numerical and Simulation Studies, NCAR Technical Report, NCAR/TN-449+STR - Part II. These papers provided part of the theoretical foundation for the Canadian-American Public Policy Paper and are the basis for continuing collaboration between McKelvey and Miller on the general problem of international management of shared fishery resources under conditions of environmental variability.

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U.S. National Assessment

Linda Mearns and Kathleen Miller were members of various U.S. National Assessment teams. Mearns is a member of the National Agriculture Sector Team and is a major contributor to the Report (published by Cambridge University Press) on that sector, particularly the chapter on climate variability and crops. A paper has been submitted to Climatic Change on Agriculture Sector results. Mearns is also a member of the Climate Change Scenarios Writing Team for the Assessment. On a regional level, Mearns is a member of the Assessment Teams for the Southwest Region and the Rocky Mountain Basin and Range Region. Miller is on the Assessment Teams for the Great Plains Region and the Water Resources Sector. On these teams, they provided advice on development and use of climate change scenarios and contributed to Regional Assessment Reports.

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Water Resources in the West

The climate of the West continues to play a role in the developing western economy. Much of the West is arid, and climate is one factor attracting a new wave of migration into the region. However, limited water supplies create tensions between the "old West" that was built on irrigated agriculture and the "new urban West." A paper published in FY01 by Kathleen Miller, "Climate and Water Resources in the West: Past and Future," was included in a special issue of Journal of the West. This paper discusses the role of climate and streamflow characteristics in the historical development of water resources in the western United States, and the challenges presented by changing demands on water resources, coupled with the possible impacts of climate change. Miller and Steven Gloss (U Wyoming) have also prepared a paper on "Climate Variability and Water Resources in the Interior West: Social, Policy, and Institutional Issues," which will be published in FY02 by the University of Colorado Press. This paper deals with climate variability in the region over the past several decades. The authors argue that research on effective policy and institutional arrangements is necessary to take advantage of recent scientific and technical advances in predicting the nature and extent of climate variability.

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Will Tropical Forests Survive the Twentieth Century?

The need for accurate estimates of forest cover and of forest fragmentation is a critical issue for developing countries such as Costa Rica, which holds between 4% to 5% of all biodiversity in the world. In this study, Robert Harriss and colleagues provide comprehensive and accurate estimates of forest cover for Costa Rica using LANDSAT-5 Thematic Matter satellite scenes acquired between 1986 and 1991. This study concludes that:

  1. In 1991, 29% (~14,000 km2) of the land cover of Costa Rica was evergreen forest cover. Of that forested area, approximately 30% is protected by national conservation policies.

  2. Forest loss in a study area representing 93% of Costa Rica's territory during a five-year period (1986-1991) was 2,250 km2, and the estimated deforestation rate of ~450 km2 per year or ~4.2% per year of remaining forest cover.

  3. Tropical forests are almost completely eliminated from the moist tropical and moist premontane forest life zones.

  4. The level of forest fragmentation in remaining forested areas may be more advanced that previously understood.

These results were published in Biotropica, 33(3), 378-384. A follow-on study is planned using LANDSAT-7 scenes acquired in 2000-2001.

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Yangtze Basin Floods of 1998: Forecasts and Responses

Michael Glantz and ESIG visitor Qian Ye (Institute of Atmospheric Physics, Chinese Academy of Sciences), began a project in FY01 supported by NOAA's Office of Global Programs to research the setting for the 1998 Great Flood in the Yangtze River basin in the context of the 1997-98 ENSO event by studying various reports in China that were filed by government agencies and research institutes. Study results will include an investigation of how ENSO information was used for: (1) the forecasting of snow cover in the Tibetan-Qinghai Plateau, (2) management of the Yangtze River flow, and (3) making short-term forecasts. Analysis of the difference between using ENSO information for differing time scales is being carried out, and comparison of the value of forecasts from differing points of view (i.e., the meteorological community, users of forecast information, and the general public) is being analyzed as well.

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Yangtze Delta in China as Evolving Metro-Agro-Plex

A three-year project funded by NASA continued on this subject during FY01. Linda Mearns, Larry McDaniel, Filippo Giorgi (CGD/Trieste Institute of Physics) and Wei Gao (NREL, Fort Collins) worked in collaboration with Bill Chameides (Georgia Institute of Technology). This is an international, multidisciplinary research project focusing on the effects of regional environmental change on agriculture in China, the most populous and rapidly developing nation in the world. The project includes the assessment of major pollutants (ground-level ozone, nitrogen oxides, gaseous sulfur oxides) and their effects on present-day and future agriculture yields of crops, as well as the effects of particulate emissions and land-use changes on the regional climate in China and their concomitant impact on future agricultural yields. Mearns and colleagues primarily modeled wheat and rice crops for the region, using CERES and UCLA-YIELD crop models. The CERES wheat and rice models were validated and tested for locations within the Yangtze River Delta using data supplied by colleagues at the Jiangsu Academy of Agricultural Sciences in Nanjing, China. Sensitivity analyses of the crop model responses to decreased solar radiation have been performed. Decreases in solar radiation occur in the region due to heavy sulfate emissions. Results indicate that a ten percent increase (decrease) in solar irradiance produces about a ten percent increase (decrease) in simulated wheat yields. A similar linear response was found for rice (percentage change in crop yields). A paper on these results was published in the Proceedings of the National Academy of Sciences during FY01.

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