Environmental and Societal Impacts Group

Fundamental Research

Development of Interactive Vegetation Package for Regional Climate

Elena Tsvetsinskaya, with Mearns and Filippo Giorgi (CGD/Trieste Institute of Physics, Italy), has coupled the CERES-maize model into RegCM2. The growth functions of CERES-maize were incorporated into the biosphere-atmosphere transfer scheme (BATS), which is the surface scheme for the regional climate model, RegCM2. Off-line tests of coupled CERES-BATS indicated that strong responses (of plant height, growth of leaf area index, and surface radiative fluxes) to different temperature and precipitation conditions were found. Coupling of the interactive surface scheme with RegCM2 has been completed. RegCM2, with the coupled surface package, has been run for the domain of the Great Plains of the US to determine the effect of the growing vegetation on surface fluxes and local climate.

The model was run using European Centre for Medium Range Forecasting (ECMWF) boundary conditions for 1991, a normal year, and 1988, a dry year. Results indicate that for 1988 large differences occur between the non-interactive run and the interactive run. With the interactive growth and development module, the simulated climate is warmer and drier than in the default run, and closer to the observed climate [1988 contour plot]. Differences in 1991 were less striking [1991 contour plot]. These results indicate that including growth and development of vegetation in a climate model can have important effects on the simulated climate. Two articles on this research have been submitted to the Journal of Climate. This work formed part of the ESIG contribution to CMAP.

[Top of Page]

Effect of Changed Climate Variability on Simulated Crops and Ecosystems

While most studies of the impacts of climate change on resource systems and ecosystems have examined the effect of mean change in climate, it is widely believed that changes in variability of climate, in addition to the mean, can have substantial effects. This issue is becoming more important as we learn more about how climate variability may change in the future. During FY99, Mearns and colleagues examined the possible additional effects of changes in variability on these systems.

A variant of the daily weather generator of Richardson (1981) was modified for these studies. By manipulating the parameters of the generator, changes in the variance (daily and interannual) of time series of temperature and/or precipitation may be produced. In FY96, 97, and 98, Mearns, with colleagues at the Goddard Institute for Space Studies (GISS) and L. McDaniel, published several papers on the effect of variance changes of temperature and precipitation on simulated crop yields. Much of this work used locations in the Great Plains and considerd primarily continuous and fallowed wheat cropping. These studies established the importance of considering changes in both the mean and variability of climate on simulated crops. Additional studies were performed in FY99:

  1. Mearns, with Cynthia Rosenzweig and Richard Goldberg (NASA Goddard, New York) continued research on the effect of changes in variability of climate on simulated crop yields at other locations in the Great Plains and mid-West. They have applied time series of temperature and precipitation with changed variances to CERES-corn and CROPGRO-soybean models. Results so far indicate that increased variance of temperature and precipitation cause substantial decreases in yield, while decreases in variability cause only slight increases in yield [simulated corn yield]. They are have begun applying changes in variance from the two major AOGCMs used in the US Assessment, the HADCM2 and the CCC, found in the region of the mid-West and Great Plains to these models for the end of the 21st Century.

  2. With Marta Vinocur (National University of Redo, Cordoba, Argentina) Mearns has investigated simulated peanut crop responses to climate variability in Cordoba, Argentina. Using PeanutGRO, they explored the effects of different combinations of mean and variance changes of temperature. They found that the crop model was sensitive to both mean and variance changes, but that increases in temperature variance substantially exacerbated decreases in yield and greatly increased the likelihood of of crop failures.

  3. A project studying the impact of variability changes on forest/ecosystems in the Northwestern US, funded by NSF and in collaboration with scientists at U Washington and Oregon State U, has neared completion. Changes in variance of precipitation were applied to the MAPPS biome model for locations in Oregon. Preliminary results indicate that variance increases lead to decreased leaf area index, while decreases in variability result in slight increases. The effect is much more striking when the version of the model using daily climate input is used in contrast to the version using monthly climate input.

[Top of Page]

Other Changed Climate and Crop/Ecosystem Projects

  1. Mearns, Justin Wettstein (USGCRP, Washington, DC), and McDaniel, in collaboration with Allan Auclair (Rand Corporation, Washington, DC) continued the study of the effects of climate variability on forest dieback in the Northeast US (NOAA). They are devising a model that can be used to identify the effects of changes in the frequency of NAO (North Atlantic Oscillation) events on forest dieback. Preliminary results indicate a strong association between wintertime indicators of forest dieback (e.g., high maximum and minimum winter temperatures)and extreme values of the NAO.

  2. Mearns continued the study of the effect of climate change on wheat yields in Italy with Carlo Pona (Agency for New Technologies, Energies, and Environment, Italy [ENEA]). In this case, the effect of both a high spatial resolution climate change scenario (required for a land mass as small as Italy) and changed variance of climate in the future are being investigated. Climate change scenarios for Italy have been generated from output of the RegCM2 European runs. Numerous sensitivity analyses with CERES-wheat have been performed for locations in Italy; crop model runs with mean climate change scenarios throughout Italy have been made; and the effects of changes in daily and interannual climate variability are being examined at selected stations.

[Top of Page]

US Science Policy and the Atmospheric Sciences

We have become familiar with policy related to various aspects of the atmospheric sciences, such as climate policy, ozone policy, acid rain policy, and related areas such as space policy, ocean policy, and marine affairs. But there does not seem to be much attention paid at all to the issue of "weather policy." Pielke, during FY99, continued research on weather policy, defined as policies for weather research and decision making, as well as government policies about weather research, forecast operations, and responses focused primarily on the National Weather Service. As impacts of weather events in the United States continue to grow, there will be increasing demand by the public for effective responses. Such demands will pressure the research and operations communities to demonstrate their contributions to the nation's weather problems. Pielke's FY99 research in this area have resulted in a Web page on "Weather Policy," including an expanded bibliography on the use and value of weather and climate forecasts, available on the WeatherZine.

[Top of Page]

El Niño Impacts and Pacific Rim Response Strategies

Glantz continued the process of seeking funding from various foundations for a collaborative NCAR/UNU/UNEP five-year (1998-2002) project that would bring together a collaboration of individuals in science, local and national governments, nongovernmental organizations, agriculture, industry, labor, and finance from countries on all sides of the Pacific Rim. The purpose is to create and maintain new working partnerships that build focused approaches to local and regional environmental sustainability and security issues affected by the ENSO phenomenon in its totality: the warm (El Niño), the cold (La Niña), and the normal phases. Pacific Rim countries, in particular, remain vulnerable to interannual climate variability and related weather extremes of the various ENSO phases. Although the more direct impacts (e.g., droughts, floods, fires) have received more attention, the less visible impacts on local and global commodities and trade, international aid, employment, and the human psyche have been less well-studied. This project proposal was developed to conduct research, study impacts, and ultimately to develop, share, and implement response strategies among leaders and citizens alike through capacity-building and "enabling" activities. The UNEP/NCAR project was sparked by this activity.

[Top of Page]

Development of Transient Runs of the RegCM2 over Continental US

With support from CMAP (Climate Modeling, Analysis, and Prediction), Mearns, with Eric Small (New Mexico Institute of Mining and Technology) and Filippo Giorgi (CGD/Trieste Institute of Physics), have developed a project to produce multi-year runs of the RegCM2 over the continental United States at a grid point spacing of 50 km. Initial and lateral boundary conditions are being provided by Climate Systems Model (CSM) runs, including greenhouse gases and sulfate aerosols. Approximately 20 years of current climate are being produced, and 20 years along two different points in the run that extends to 2100. The first five years of the control time period (1981-1985) have been produced, as well as five years of the perturbed climate run (2081-85). Analysis of the control run indicates that the cold bias of the CSM over North America is also present in the regional model, although slighly accentuated.

[Top of Page]

US Weather Research Program and World Weather Research Program

USWRPOver the past five years, ESIG has been working closely with the US Weather Research Program (USWRP) to establish connections between the needs of society and the Program's research agenda. Several workshops and research reports have resulted from this multidisciplinary collaboration. The results of one workshop were published in the Bulletin of the American Meteorological Society (BAMS). A second workshop was organized by Pielke and Jeff Kimpel (NOAA/National Severe Storms Laboratory). In FY98 Pielke was appointed to chair an advisory group to the USWRP, called the Use and Impacts Assessment Committee. The Committee has the following responsibilities:

  1. It will bring to the attention of the USWRP considerations of the societal aspects of weather, specifically: (a) state-of-the-art knowledge of the impacts of weather phenomena on society in terms of extreme events as well as routinely disruptive impacts on decision-making; and (b) current societal needs with respect to existing and improved weather forecasts, which include past use of weather information, prospects for future use, and consideration of the scientific and nonscientific obstacles in the way of improving decision making with improved weather information.

  2. It will serve for the USWRP (and, to the extent that it is practical, the weather community as a whole) as an initial evaluative tool for the performance of the Program with respect to its societal and policy objectives, specifically: (a) It will review, comment, and contribute to USWRP plans and assessments from the standpoint of the state of social science and practical knowledge of the use and value of weather information. (b) It will conduct preliminary evaluations of the scientific advances made by the Program from the standpoint of their actual and potential contributions to societal needs, including assessment of the external factors that enhance or limit the realization of their potential usefulness and value.

[Top of Page]

Precipitation and Damaging Floods

Despite extensive efforts over many years to reduce vulnerability to flooding in the US, flood losses (adjusted for inflation) have increased markedly in recent years. Pielke and Downton continued their work on a project begun in FY98 to investigate whether the increasing damage can be attributed to changes in climate; additional funding is being sought from NOAA/OGP. National precipitation averages show a slightly increasing trend since the 1930s, but a preliminary study suggests that precipitation explains less than 20% of the variability in nationwide flood losses. More extensive study of flood damages at state and regional levels is needed to assess the role of weather, climate, and human factors in the trend toward increasing flood losses. Unfortunately, the historical damage data needed for such a study are not presently available in usable form. Furthermore, it has not been determined which hydrologic data (e.g., precipitation, snowmelt, river flows) are most relevant for predicting damaging floods. Intervening socioeconomic changes must also be considered. The following steps are planned: (1) creation of an historical flood loss dataset; (2) identification of precipitation measures that are related to damaging floods; (3) identification of social and economic factors that are major contributing factors to the level of losses resulting from floods; and (4) use of the identified data to estimate the relative contributions of socioeconomic and weather-related factors to flood damages. Pielke and Downton submitted a paper, "Precipitation and Damaging Floods: Trends in the US 1932-1997," to the Journal of Climate in March 1999.

[Top of Page]

Prediction in the Earth Sciences

Pielke, Dan Sarewitz (Geological Society of America [retired], Radford Byerly [retired Chief of Staff, US House of Representatives Committee on Science, Space and Technology], and Dale Jamieson (Carleton College, Carleton, MN), continued work on an NSF-sponsored project on the use and misuse of predictive earth science by policy makers. Major financial and intellectual resources in the earth sciences are now focused on trying to predict the behavior of natural and human-induced environmental phenomena. Such efforts reflect a demand by policy-makers for predictive information that can help guide political decision-making on controversial environmental issues that include negotiation of international environmental treaties, disposal of radioactive waste, and control of development in areas prone to natural disasters. However, neither policy-makers nor scientists possess the information necessary for understanding if, how, and when research focusing on prediction can be productively applied to the policy-making process. Whereas timely, policy-relevant predictions may help policy-makers respond to some environmental problems, the misapplication of prediction research to policy problems can undermine policy goals, waste scarce financial and intellectual resources, and undermine the credibility of the scientific enterprise.

During FY99, Pielke, Sarewitz, and Byerly edited a series of papers from the workshop convened in FY98 and negotiated with Island Press to produce an edited volume. This volume, Prediction: Decision-Making and the Future of Nature, was delivered to Island Press in September 1999 for production in FY00. This volume attempts to paint a comprehensive portrait of the troubled relationship between predictive science and environmental decision making. It also provides insights into the promise and limitations of prediction for decision makers, explores alternatives to prediction, and makes concrete recommendations to increase the likelihood of effective environmental decisions.

[Top of Page]

La Niña, El Niño, and Hurricane Damages in the
United States
(Bulletin of the American Meteorological Society)

Hurricanes result in considerable damage in the United States. Previous work by Pielke and others has shown that Atlantic hurricane landfalls in the United States have a strong relationship to the ENSO phenomena. This paper by Pielke and Christopher Landsea (Hurricane Research Division, AOML, Miami, FL) compares the historical record of La Niña and El Niño events defined by eastern Pacific Sea surface temperature with a data set of hurricane losses normalized to 1997 values. A significant relationship was found between the ENSO cycle and US hurricane losses, with La Niña years exhibiting much more damage. Used appropriately, this relationship is of potential value to decision makers who are able to manage risk based on probabilistic information.

[Top of Page]

Methods for Assessing Economic Value of Weather and Climate Forecasts

book coverKatz continued work on a review of Bayesian decision-theoretic studies of the economic value of imperfect weather and climate forecasts (i.e., a prescriptive approach). This review focuses on work of the late Allan Murphy and includes treatment of the controversy over the most appropriate approach to valuing forecasts. In part, this controversy arises over limitations of both the normative/prescriptive approach and the alternative approach based on willingness-to-pay/contingent valuation.

In a related activity, Katz updated a web site, originally developed by Shelly Knight (intern, Univ. of Colorado; now NCAR/RAP), that categorizes recent case studies (based on the prescriptive approach) of the value of weather and climate forecasts.

[Top of Page]

Extreme Value Theory and Climate Change

Katz, in collaboration with Philippe Naveau (NCAR/GSP), continued work on a review of the use of the statistical theory of extremes in research on climate, especially as applied to climate change and its impacts. Among other things, the implications of the lack of use of this theory in searching for trends in climate extremes are examined. These implications include the underestimation of the likelihood of extremes through failure to take into account the heavy-tailed nature of distributions of climate variables such as precipitation.

[Top of Page]

Climate Scenario Generation/Statistical Downscaling

Katz, in collaboration with Marc Parlange (Johns Hopkins University) and Claudia Tebaldi (NCAR/GSP), continued work on the development of stochastic weather generators for locations in Southeast U.S. conditional on indices of large-scale atmospheric circulation (such as El Niño, North Atlantic Oscillation, and especially the Bermuda High). Innovative statistical methods were developed to determine the nature of the dependence of daily weather statistics (for both precipitation and temperature) on such indices. These methods include the concept of "borrowing strength," in which the relationship between a circulation index and weather at sites within a region is constrained.

[Top of Page]

Stochastic Models for Damage from Extreme Weather

Katz, in collaboration with Pielke, developed a stochastic model for economic damage associated with rare/extreme weather events, such as hurricanes. This model is based on the concept of a "random sum," as a representation for the distribution of total damage (e.g., on an annual basis) caused by a particular weather phenomenon. In this way, total variations in damage can be decomposed into those whose source is variations in the number of events (e.g., annual number of hurricanes) as opposed to those attributable to variations in damage from event to event. With this methodology, it is straightforward to test for trends (both in climate and in damage response) as well as to condition on covariates (such as the El Niño phenomenon).

[Top of Page]

Regional Climate Modeling and Crops

  1. Comparison of Empirical Statistical Downscaling and Regional Climate Modeling Scenarios

    A comparison of regional climate model results with a semi-empirical statistical downscaling technique (SDS) (developed by Bogardi and colleagues at the University of Nebraska) for the Central Great Plains was completed and published. Results indicated that climate changes in the Regional Model were more pronounced than those calculated via the semi-empirical downscaling of the GCM results. Different directions of change of climate, particularly for higher-order moments, are found in the two models. Other major results include [contrast in climate change scenarios]:

    • SDS exhibits larger amplitude of change in mean temperature -- larger in winter, very small in summer.
    • In all seasons except summer both methods show decrease in daily variance of temperature; in summer - RegCM shows increase; EDS decrease. RegCM changes are usually larger.
    • Direction of change in mean precipitation often disagrees.
    • Direction of change of probability of precipitation often disagrees - SDS produces only increases in probability; RegCM produces larger changes.
    • Direction of change of mean intensity agrees in January and October, but disagrees in April and July. SDS produces larger absolute values of change, but maginitudes of relative change are similar.

    This work was published in 1999 in Journal of Geophysical Research.

  2. Regional Climate and Crops in the Great Plains

    CropsLinda Mearns, along with Larry McDaniel, Elena Tsvetsinskaya (University Nebraska-Lincoln), Theo Mavromatis (University Florida-Gainesville), William Easterling (Pennsylvania State University) and Cynthia Hays (University Nebraska-Lincoln), completed work on a four-year NIGEC (National Institute for Global Environmental Change) project, "Development of a Nested Regional Climate Change Scenario with an Application to Crop Models." The project involved regional climate modeling with RegCM2 by Filippo Giorgi (Salam International Centre for Theoretical Physics, Trieste, Italy) and Christine Shields (CGD), detailed climate model evaluation, and application to crop models. Each stage of the work focused on some kind of uncertainty analysis of: (1) spatial scale of climate change; (2) effect of scale differences on agricultural impacts; and (3) choice of impact model. Numerous publications have resulted from this work.

    1. A high-resolution climate change scenario (control and doubled carbon dioxide) was formed using the RegCM2 at 50-km grid point spacing of the western two-thirds of the United States. A coarse resolution scenario was formed from the output of the CSIRO general circulation model, which provided the boundary conditions for the regional model runs.

    2. They applied the two different scales of climate change scenarios to the EPIC corn, wheat, and soybean crop models for the GCM grid boxes in the central Great Plains. We found that the different scale scenarios produced substantial differences in the impacts of climate change on these agricultural crops [EPIC simulated yields, change in simulated crop yields]. They also analyzed the spatial patterns of the simulated yields, and found some important differences in spatial variances among the treatments. Tempero-spatial statistical models were developed with the assistance of D. Marx of the University of Nebraska and T. Haas on University Wisconsin, Milwaukee, who is a visitor with the Geophysical Statistics Project at NCAR. Two articles on this work have been submitted to Climatic Change, and are currently being revised.

    3. They went on to compare the results from EPIC corn and wheat models for parts of the Great Plains with those of the CERES corn and wheat models. We found that the CERES model produced very different changes in yield from those of the EPIC model [change in cimulated crop yields].

    This work was published in 1999 in Journal of Geophysical Research.

[Top of Page]

Table of Contents | Enhancing Resilience of Natural Resources | Protection of Life & Property
Fundamental Research | Education & Outreach | FY99 Scientific Highlights
FY99 Publications | FY99 Educational Activities | FY99 Community Service
FY99 Staff, Visitors & Collaborators | Environmental & Societal Impacts Group
ESIG 1999 Annual Scientific Report Home Page | NCAR 1999 Annual Scientific Report Home Page

FY99 Scientific Highlights Education and Outreach Fundamental Research Protection of Life and Property Enhancing Resilience of Natural Resources Table of Contents Environmental and Societal Impacts Group FY99 Staff, Visitors and Collaborators FY99 Community Service FY99 Educational Activities FY99 Publications NCAR Annual Scientific Report NCAR Annual Scientific Report NCAR Annual Scientific Report