William E. Easterling

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 Williamset 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.

Adapting North American agriculture to climate change in review

Abstract The adaptability of North American agriculture to climate change is assessed through a review of current literature. A baseline of North American agriculture without climate change suggests that farming faces serious challenges in the future (e.g. declining domestic demand, loss of comparative advantage, rising environmental costs). Climate change adjustments at the farm-level and in government policy, including international trade policy, are inventoried from the literature. The adaptive potential of agriculture is demonstrated historically with situations that are analogous to climate change, including the translocation of crops across natural climate gradients, the rapid introduction of new crops such as soybeans in the US and canola in Canada, and resource substitutions prompted by changes in prices of production inputs. A wide selection of modeling studies is reviewed which, in net, suggests several agronomic and economic adaptation strategies that are available to agriculture. Agronomic strategies include changes in crop varieties and species, timing of operations, and land management including irrigation. Economic strategies include investment in new technologies, infrastructure and labor, and shifts in international trade. Overall, such agronomic strategies were found to offset either partially or completely the loss of productivity caused by climate change. Economic adaptations were found to render the agricultural costs of climate change small by comparison with the overall expansion of agricultural production. New avenues of adaptive research are recommended including the formalization of the incorporation of adaptation strategies into modeling, linkage of adaptation to the terrestrial carbon cycle, anticipation of future technologies, attention to scaling from in situ modeling to the landscape scale, expansion of data sets and the measurement and modeling of unpriced costs. The final assessment is that climate change should not pose an insurmountable obstacle to North American agriculture. The portfolio of assets needed to adapt is large in terms of land, water, energy, genetic diversity, physical infrastructure and human resources, research capacity and information systems, and political institutions and world trade—the research reviewed here gives ample evidence of the ability of agriculture to utilize such assets. In conclusion, the apparent efficiency with which North American agriculture may adapt to climate changes provides little inducement for diverting agricultural adaptation resources to efforts to slow or halt the climate changes.

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 CO2 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 maxL.), winter wheat (Triticum aestivumL.) 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 CO2 concentrations ([CO2]) at 365 and 560 ppm to consider the CO2-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 CO2-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 CO2 set to 560 ppm. Yields increased above baseline for 34% of the soybean and 37% of the winter wheat farms under RegCM/[CO2] D 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

Comparative responses of EPIC and CERES crop models to high and low spatial resolution climate change scenarios

We compared the responses of the CERES and EPIC crop models, for wheat and corn, to two different climate change scenarios of different spatial scales applied to the central Great Plains. The scenarios were formed from a high-resolution regional climate model (RegCM) and a coarse resolution general circulation model, which provided the initial and boundary conditions for the regional model. Important differences in yield were predicted by the two models for the two different scenarios. For corn, CERES simulated moderate yield decreases for both scenarios, while EPIC simulated a decrease for the coarse scenario but no change for the fine scale scenario. Differences in the simulation of wheat yields were also found. These differences were traced to the contrasting ways in which the models form final yield, even though their strategies for simulating potential total biomass are similar. We identify the crop model type as an important uncertainty in impacts assessment in addition to the spatial resolution of climate change scenarios.

Assessing the Consequences of Climate Change for Food and Forest Resources: A View from the IPCC

Important findings on the consequences of climate change for agriculture and forestry from the recently completed Third Assessment Report (TAR) of the Intergovernmental Panel on Climate Change (IPCC) are reviewed, with emphasis on new knowledge that emerged since the Second Assessment Report (SAR). The State-Pressure-Response-Adaptation model is used to organize the review. The major findings are: Constant or declining food prices are expected for at least the next 25 yr, although food security problems will persist in many developing countries as those countries deal with population increases, political crisis, poor resource endowments, and steady environmental degradation. Most economic model projections suggest that low relative food prices will extend beyond the next 25 yr, although our confidence in these projections erodes farther out into the 21st century. Although deforestation rates may have decreased since the early 1990s, degradation with a loss of forest productivity and biomass has occurred at large spatial scales as a result of fragmentation, non-sustainable practices and infrastructure development. According to United Nations estimates, approximately 23% of all forest and agricultural lands were classified as degraded over the period since World War II. At a worldwide scale, global change pressures (climate change, land-use practices and changes in atmospheric chemistry) are increasingly affecting the supply of goods and services from forests. The most realistic experiments to date – free air experiments in an irrigated environment – indicate that C3 agricultural crops in particular respond favorably to gradually increasing atmospheric CO2 concentrations (e.g., wheat yield increases by an average of 28%), although extrapolation of experimental results to real world production where several factors (e.g., nutrients, temperature, precipitation, and others) are likely to be limiting at one time or another remains problematic. Moreover, little is known of crop response to elevated CO2 in the tropics, as most of the research has been conducted in the mid-latitudes. Research suggests that for some crops, for example rice, CO2 benefits may decline quickly as temperatures warm beyond optimum photosynthetic levels. However, crop plant growth may benefit relatively more from CO2 enrichment in drought conditions than in wet conditions. The unambiguous separation of the relative influences of elevated ambient CO2 levels, climate change responses, and direct human influences (such as present and historical land-use change) on trees at the global and regional scales is still problematic. In some regions such as the temperate and boreal forests, climate change impacts, direct human interventions (including nitrogen-bearing pollution), and the legacy of past human activities (land-use change) appear to be more significant than CO2 fertilization effects. This subject is, however an area of continuing scientific debate, although there does appear to be consensus that any CO2 fertilization effect will saturate (disappear) in the coming century. Modeling studies suggest that any warming above current temperatures will diminish crop yields in the tropics while up to 2–3 ∘C of warming in the mid-latitudes may be tolerated by crops, especially if accompanied by increasing precipitation. The preponderance of developing countries lies in or near the tropics; this finding does not bode well for food production in those countries. Where direct human pressures do not mask them, there is increasing evidence of the impacts of climate change on forests associated with changes in natural disturbance regimes, growing season length, and local climatic extremes. Recent advances in modeling of vegetation response suggest that transient effects associated with dynamically responding ecosystems to climate change will increasingly dominate over the next century and that during these changes the global forest resource is likely to be adversely affected. The ability of livestock producers to adapt their herds to the physiological stress of climate change appears encouraging due to a variety of techniques for dealing with climate stress, but this issue is not well constrained, in part because of the general lack of experimentation and simulations of livestock adaptation to climate change. Crop and livestock farmers who have sufficient access to capital and technologies should be able to adapt their farming systems to climate change. Substantial changes in their mix of crops and livestock production may be necessary, however, as considerable costs could be involved in this process because investments in learning and gaining experience with different crops or irrigation. Impacts of climate change on agriculture after adaptation are estimated to result in small percentage changes in overall global income. Nations with large resource endowments (i.e., developed countries) will fare better in adapting to climate change than those with poor resource endowments (i.e., developing countries and countries in transition, especially in the tropics and subtropics) which will fare worse. This, in turn, could worsen income disparities between developed and developing countries. Although local forest ecosystems will be highly affected, with potentially significant local economic impacts, it is believed that, at regional and global scales, the global supply of timber and non-wood goods and services will adapt through changes in the global market place. However, there will be regional shifts in market share associated with changes in forest productivity with climate change: in contrast to the findings of the SAR, recent studies suggest that the changes will favor producers in developing countries, possibly at the expense of temperate and boreal suppliers. Global agricultural vulnerability is assessed by the anticipated effects of climate change on food prices. Based on the accumulated evidence of modeling studies, a global temperature rise of greater than 2.5 ∘C is likely to reverse the trend of falling real food prices. This would greatly stress food security in many developing countries.

Adaptation to climate variability and change in the US Great Plains:: A multi-scale analysis of Ricardian climate sensitivities

Abstract The Ricardian approach to estimating climate change impacts is an important technique for incorporating how adaptations modulate the overall effect. Past Ricardian work expresses climate sensitivities in terms of local effects only, ignoring the influence on adaptation of broader-scale social, environmental and economic factors. This paper extends the Ricardian approach to account for influences at multiple spatial scales. Results from multi-level modeling support the hypothesis that a county’s Ricardian climate sensitivity is influenced not only by its climate but also by social factors associated with the climate of the agro-climatic zone in which it is located. The model estimates a non-linear, hill-shaped relationship between July maximum temperatures and agricultural land values, with initial increases beneficial in all counties but more beneficial in districts of high interannual temperature variability. Farmers and institutions in districts of high variability have therefore adapted to be more resilient to variability than farmers in areas of comparatively stable climate. However, the underlying reasons for this lessened vulnerability are unclear and may be associated with unsustainable land-use practices. Future research should investigate the precise form of these local and extra-local adaptations to determine if implementing the adaptations elsewhere would compromise agricultural system sustainability.

Greenhouse warming: Abatement and adaptation

This book focuses on two possible paths of living with a changing climate--abatement and adaptation. The adaptation path is well represented in the book, with chapters on responses to rise in sea level, future agricultural adaptations, Third World agriculture, possibilities presented by currently unmanaged forests, and water resource management. Although the adaptation discussions suggest that adaptive steps will be very difficult and very expensive unless the rate of climate change is slowed, abatement processes are much less well represented in the book. Climate scientists, here and elsewhere, do not report any estimates of how large a decrease in the emissions of infrared-trapping gases would be required in order to slow the climate heating rate by some amount. Only one chapter in the book discusses details of an abatement strategy, that of planting new forests to sequester carbon dioxide and so reduce the annual atmospheric increase. Beyond the discussion of forests, the only consideration of abatement is in a chapter on the use of an economic model to project future carbon dioxide emissions.

Preparing the erosion productivity impact calculator (EPIC) model to simulate crop response to climate change and the direct effects of CO2

The adaptation of a crop simulation model to deal with the impacts of rising CO2 and climate change is described in this paper. Algorithms that represent the direct effects of atmospheric CO2 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.

Spatial scales of climate information for simulating wheat and maize productivity: the case of the US Great Plains

Abstract The spatial aggregation of climate and soils data for use in site-specific crop models to estimate regional yields is examined. The purpose of this exercise is to determine the optimum spatial resolution of observed climate and soils data for simulating major crops grown in the central Great Plains (maize, wheat), beginning at a scale of 2.8°×2.8° (T42), which is close to that of the European Centre for Medium-Range Forecasting (ECMWF) general circulation model (GCM) grid cell and progressively disaggregating climate and soils data to finer spatial scales. Using the Erosion Productivity Impact Calculator (EPIC) crop model, observed crop yields for the period 1984–1992 are compared with yields simulated with observed 1984–1992 climate. The goal is to identify the spatial resolution of climate and soils data which minimizes statistical error between observed and modeled yields. Agreement between simulated and observed maize and wheat was greatly improved when climate data was disaggregated to approximately 1°×1° resolution. No disaggregation results for hay were statistically significant. Disaggregation of climate data finer than the 1°×1° resolution gave no further improvement in agreement. Disaggregation of soils data gave no additional improvement beyond that of the disaggregation of climate data.

Why regional studies are needed in the development of full-scale integrated assessment modelling of global change processes

Abstract Full-scale integrated assessment models (lAMs) allow many components of the global climate change problem to be examined in one framework. The chief advantage of the IAM approach over less complete modelling frameworks is that the socio-economic and environmental consequences of policy choices aimed at abating or adapting to climate change can be evaluated in their totality. However, the highly aggregate functional forms that lAMs currently embed are lacking in sufficient regional and sectoral detail to be totally credible. In this paper, ten reasons why regional studies are needed in support of the development of full-scale lAMs are given. A strategic cyclical scaling exercise involving regional and global integrated modelling frameworks is proposed.