Missouri-Iowa-Nebraska-Kansas Research Articles

Potential production and environmental effects of switchgrass and traditional crops under current and greenhouse-altered climate in the central United States: a simulation study

If, as many climate change analysts speculate, industrial and other emissions of CO 2 can be offset by substitution of biofuels, large areas of land, including agricultural land, may be converted to the production of biomass feedstocks. This paper explores the feasibility for the Missouri–Iowa–Nebraska–Kansas (MINK) region of the US of converting some agricultural land to the production of switchgrass ( Panicum virgatum L.), a perennial warm season grass, as a biomass energy crop. The erosion productivity impact calculator (EPIC) crop growth model simulated production of corn ( Zea mays L.), sorghum ( Sorghum bicolor (L.) Moench), soybean ( Glycine max L.), winter wheat ( Triticum aestivum L.) and switchgrass at 302 sites within the MINK region. The analysis is done for both current climatic conditions and a regional climate model-based scenario of possible climate change. Daily climate records from 1983 to 1993 served as baseline and the NCAR-RegCM2 model (RegCM hereafter) nested within the CSIRO general circulation model (GCM) provided the climate change scenario. Crop production was simulated at two atmospheric CO 2 concentrations ([CO 2]) at 365 and 560 ppm to consider the CO 2-fertilization effect. Simulated yields of the perennial switchgrass increased at all sites with a mean yield increase of 5.0 Mg ha −1 under the RegCM climate change scenario. Switchgrass yields benefited from temperature increases of 3.0–8.0°C, which extended the growing season and reduced the incidence of cold stress. Conversely, the higher temperatures under the RegCM scenario decreased yields of corn, soybean, sorghum and winter wheat due to increased heat stress and a speeding of crop maturity. With no CO 2-fertilization effect, EPIC simulated maximum decreases from baseline of 1.5 Mg ha −1 for corn, 1.0 Mg ha −1 for sorghum, 0.8 Mg ha −1 for soybean and 0.5 Mg ha −1 for winter wheat. Simulated yields increased for all crops under the RegCM scenario with CO 2 set to 560 ppm. Yields increased above baseline for 34% of the soybean and 37% of the winter wheat farms under RegCM/[CO 2] = 560 ppm scenario. Water use increased for all crops under the higher temperatures of the CSIRO scenario. Precipitation increases resulted in greater runoff from the traditional crops but not from switchgrass due to the crop’s increased growth and longer growing season. Simulated soil erosion rates under switchgrass and wheat cultivation were less severe than under corn management. However, simulated erosion under switchgrass was considerable in eastern Iowa during the period of crop establishment because of strong winds at that time.

Development of Regional Climate Scenarios Using a Downscaling Approach

As the debate on potential climate change continues, it is becoming increasingly clear that the main concerns to the general public are the potential impacts of a change in the climate on societal and biophysical systems. In order to address these concerns researchers need realistic, plausible scenarios of climate change suitable for use in impacts analysis. It is the purpose of this paper to present a downscaling method useful for developing these types of scenarios that are grounded in both General Circulation Model simulations of climate change, and in situ station data. Free atmosphere variables for four gridpoints over the Missouri, Iowa, Nebraska, Kansas (MINK) region from both control and transient simulations from the GFDL General Circulation Model were used with thirty years of nearby station data to generate surface maximum and minimum air temperatures and precipitation. The free atmosphere variables were first subject to a principal components analysis with the principal component (PC) scores used in a multiple regression to relate the upper-air variables to surface temperature and precipitation. Coefficients from the regression on station data were then used with PC scores from the model simulations to generate maximum and minimum temperature and precipitation. The statistical distributions of the downscaled temperatures and precipitation for the control run are compared with those from the observed station data. Results for the transient run are then examined. Lastly, annual time series of temperature for the downscaling results show less warming over the period of the transient simulation than the time series produced directly from the model.

Paper 2. agricultural impacts of and responses to climate change in the Missouri-Iowa-Nebraska-Kansas (MINK) region

The climate of the 1930s was used as an analog of the climate that might occur in Missouri, Iowa, Nebraska and Kansas (the MINK region) as a consequence of global warming. The analog climate was imposed on the agriculture of the region under technological and economic conditions prevailing in 1984/87 and again under a scenario of conditions that might prevail in 2030. The EPIC model of Williams et al. (1984), modified to allow consideration of the yield enhancing effects of CO2 enrichment, was used to evaluate the impacts of the analog climate on the productivity and water use of some 50 representative farm enterprises. Before farm level adjustments and adaptations to the changed climate, and absent CO2 enrichment (from 350 to 450 ppm), production of corn, sorghum and soybeans was depressed by the analog climate in about the same percent under both current and 2030 conditions. Production of dryland wheat was unaffected. Irrigated wheat production actually increased. Farm level adjustments using low-cost currently available technologies, combined with CO2 enrichment, eliminated about 80% of the negative impact of the analog climate on 1984/ 87 baseline crop production. The same farm level adjustments, plus new technologies developed in response to the analog climate, when combined with CO2 enrichment, converted the negative impact on 2030 crop production to a small increase. The analog climate would have little direct effect on animal production in MINK. The effect, if any, would be by way of the impact on production of feed-grains and soybeans. Since this impact would be small after on-farm adjustments and CO2 enrichment, animal production in MINK would be little affected by the analog climate.

An introduction to the methodology, the region of study, and a historical analog of climate change

We introduce a methodology for simulating the impact of climate change induced by greenhouse warming and the direct effects of the rising atmospheric CO 2 concentration on agricultural productivity and for considering the farm-level response to these impacts. The methodology permits the climate change-agriculture question to be viewed in terms of future changes and provides for systematic consideration of the role of adaptation. The methodology has been applied to the four-state Missouri-Iowa-Nebraska-Kansas (MINK) region—a region whose economy is heavily based on natural resources likely to be affected by climate change. In this first application the weather records of the Dust Bowl Era (1931–1940) were used as the basis for a scenario of climate change. That decade was warmer and drier than the current climatic normal in the MINK region. However, the methodology is not dependent specifically on climate analogs for scenario building; general circulation model experiments or other appropriate surrogates can be used, as well. The general structure of the methodology is described in this paper; details are given in the five subsequent papers.

Validation of EPIC model simulations of crop responses to current climate and CO 2 conditions: comparisons with census, expert judgment and experimental plot data

A crop simulation model must first be capable of representing the actual performance of crops grown in any particular region before it can be applied to the prediction of climate change impacts. Erosion productivity impact calculator (EPIC) simulations of crop productivity in the Missouri-Iowa-Nebraska-Kansas (MINK) region under the 1951–1980 climate were compared with the US Department of Agriculture's ‘County Yield Estimates’ data (averaged over 1984–1987), with expert estimates of yields for each ‘representative’ farm and with the results of agronomic experiments reported in the literature. Most EPIC-simulated yields agreed to within ±20% with USDA reported yields and expert estimates, although there were some outliers. EPIC-simulated yields, evapotranspiration and water use efficiency fell well within the range of experimental results. Perfect agreement with observed crop performance was not a requisite nor should it have been expected. We judged the EPIC simulations sufficiently reliable to justify use of the model in simulating the effects of climate change on crops.

Preparing the erosion productivity impact calculator (EPIC) model to simulate crop response to climate change and the direct effects of CO 2

The adaptation of a crop simulation model to deal with the impacts of rising CO 2 and climate change is described in this paper. Algorithms that represent the direct effects of atmospheric CO 2 on crop photosynthetic efficiency and water use were developed for use with the erosion productivity impact calculator (EPIC), a mechanistic crop simulation model. Representative farms were designed to reflect the major cropping systems in the MINK (Missouri-Iowa-Nebraska-Kansas) region and data were assembled to simulate them in EPIC. Climate data were compiled to represent conditions under the control (1951–1980) and analog (1931–1940) climates. Actual daily temperature and precipitation data from a number of climatological stations across the MINK region were used in the simulations. Daily values of solar radiation, relative humidity, and wind speed were simulated stochastically from monthly First Order Weather Station records.

Simulations of crop response to climate change: effects with present technology and no adjustments (the ‘dumb farmer’ scenario)

The climate of the 1930s—our analog of climate change—was imposed on farms representative of agriculture in the Missouri-Iowa-Nebraska-Kansas (MINK) region through the erosion productivity impact calculator (EPIC) model. Two levels of atmospheric CO 2 were considered: 350 and 450 ppm. No attempts to adjust or adapt the farms to the climate change were made. Results from simulations under the analog climate (1931–1940) were compared with results from simulations under the control climate (1951–1980). EPIC-simulated yields of warm-season crops were reduced by the analog climate. Yield reductions ranged from 7% for irrigated corn to 25% for dryland and soybeans. Simulated yields of dryland wheat were, on the whole, unchanged by the analog climate. Crops under irrigation fared better than dryland crops, although irrigation demand increased markedly. The simulated loss of crop yields under the analog climate was due to truncated growing seasons accompanied by reduced evapotranspiration. The higher level of atmospheric CO 2 alleviated simulated yield losses for all crops, although for corn and soybeans, particularly, yield losses remained significant.

Simulations of crop responses to climate change: effects with present technology and currently available adjustments (the ‘smart farmer’ scenario)

If climate changes, farmers will have to adapt to a new set of climate constraints. In this paper we examine the efficacy of strategies for dealing with climate change that are currently available to farmers and that are inexpensive to use; we refer to this group of strategies as ‘adjustments’. Adjustment schemes of various kinds were identified for us by agricultural experts in the Missouri-Iowa-Nebraska-Kansas (MINK) states. These can involve changes in land use, changes in variety and crop selection, changes in planting and harvesting practices, and changes in fertility and pest management. Using the erosion productivity impact calculator (EPIC) model on a small set of representative farms, we tested adjustments of these kinds. The simulations show that earlier planting, longer-season cultivars and the use of furrow diking for moisture conservation would offset some of the yield losses induced by climate change in warm-season crops. Longer-season varieties of wheat (a cool-season crop) and shorter-season varieties of the perennials wheatgrass and alfalfa were also effective. The adjustments to climate change diminished yield losses in all crops but irrigated wheat. Despite the positive effects of adjustments, however, yields of all dryland warm-season crops remained lower than control levels. The adjustments also increased demand for irrigation water. Carbon dioxide enrichment had the same incremental effect on crop yields with or without adjustments (see the fourth paper in this issue), except in the case of alfalfa and sorghum, where a CO 2-adjustment interaction was found. We conclude that currently available techniques would partially offset the yield reductions caused by a 1930s-like climate, but that in most crops the yield reductions would still be substantial.

The MINK Project: A New Methodology for Identifying Regional Influences of, and Responses to, Increasing Atmospheric CO2 and Climate Change

In a study that was recently completed at Resources for the Future, the impacts of a future change in climate on the total economy of the Missouri–Iowa–Nebraska–Kansas (MINK) region were assessed, as were the possibilities of response (including adaptation) to the climatic change. Impacts on agriculture, forestry, water resources, and energy, were emphasized. The study was future-oriented, focusing on the year 2030, by which time the effects of ‘greenhouse’ warming may be felt. The records of the AD 1930s were used to provide an analog of the kinds of climate change (warmer and drier) that climate models predict will occur in the MINK region.Our results indicate that impacts of the projected climate change on agriculture, at least in the future, are expected to be profound, but that likely-to-be available technologies should facilitate substantial adaptation; that current water-resource limitations in the region would be exacerbated and lead to an eastward shift in irrigation; that impacts on forestry would be severe, and that opportunities for forestry adaptation would be very limited unless biomass production were to become economically viable; and that the net impacts on energy supply and demand would be small and adaptation to them relatively simple.Climate change in the MINK region could, of course, go somewhat beyond the conditions represented by the AD 1930s analog, in which case the findings of this study may be too optimistic. However, the future-oriented ‘MINK methodology’ is not scenario-dependent, and can be used to test other, more severe (or benign), scenarios as well. Further, the capacity for adaptation to climate change demonstrated in this study, may remain applicable even in more stringent circumstances.