共查询到20条相似文献，搜索用时 31 毫秒
1.
Daniel S. Wilks 《Climatic change》1992,22(1):67-84
While large-scale climate models (GCMs) are in principle the most appropriate tools for predicting climate changes, at present little confidence can be placed in the details of their projections. Use of tools such as crop simulation models for investigation of potential impacts of climatic change requires daily data pertaining to small spatial scales, not the monthly-averaged and large-scale information typically available from the GCMs. A method is presented to adapt stochastic weather generation models, describing daily weather variations in the present-day climate at particular locations, to generate synthetic daily time series consistent with assumed future climates. These assumed climates are specified in terms of the commonly available monthly means and variances of temperature and precipitation, including time-dependent (so-called transient) climate changes. Unlike the usual practice of applying assumed changes in mean values to historically observed data, simulation of meteorological time series also exhibiting changes in variability is possible. Considerable freedom in climate change scenario construction is allowed. The results are suitable for investigating agricultural and other impacts of a variety of hypothetical climate changes specified in terms of monthly-averaged statistics. 相似文献
2.
Farm-Level Adaptation to Climatic Variability and Change: Crop Diversification in the Canadian Prairies 总被引：4，自引：0，他引：4
Among other foci, recent research on adaptation to climatic variability and change has sought to evaluate the merit of adaptation generally, as well as the suitability of particular adaptations. Additionally, there is a need to better understand the likely uptake of adaptations. For example, diversification is one adaptation that has been identified as a potential farm-level response to climatic variability and change, but its adoption by farmers for this reason is not well understood. This paper serves two purposes. The first is to document the adoption of crop diversification in Canadian prairie agriculture for the period 1994–2002, reflect upon its strengths and limitations for managing a variety of risks, including climatic ones, and gauge its likely adoption by producers in response to anticipated climate change. The second purpose is to draw on this case to refine our current understanding of climate change adaptation more generally. Based upon data from over 15 000 operations, it was determined that individual farms have become more specialized in their cropping patterns since 1994, and this trend is unlikely to change in the immediate future, notwithstanding anticipated climate change and the known risk-reducing benefits of crop diversification. More broadly, the analysis suggests that suitable and even possible climate change adaptations need to be more rigorously assessed in order to understand their wider strengths and limitations. 相似文献
3.
Southern China is a major grain-producing area, but has been suffering from increasingly serious droughts caused by global warming. As a result, crop losses have become serious. To provide insights into these losses, we obtained data to support a systematic and comprehensive analysis of how agricultural drought has caused crop losses from 1961 to 2011 and of the relationship between these changes and the climatic factors responsible for the losses. We found an obvious increase in the loss of crops due to agricultural drought in southern China, with the greatest increase in crop loss in the southwest and smaller increases in the south and southeast. Moreover, because each crop growth stage is affected differently by climatic factors and because the values of these factors show an uneven seasonal distribution, the losses were greatest when changes in various climatic factors occurred during key crop developmental periods. The fittings of the relationship between crop loss and various climatic factors was often strongest based on data from key developmental periods rather than based on data for the whole year. In addition, we found improved prediction of losses using multiple regression, and developed a model for assessing crop losses. Our results provide a scientific reference for developing methods to evaluate the losses caused by agricultural drought in southern China.
相似文献4.
PNNLs Agriculture and Land Use is used to demonstrate the impact of potential changes in climate on agricultural production and land use in the United States. AgLU simulates production of four crop types in several world regions, in 15-yr time steps from 1990 to 2095. Changes in yield of major field crops in the United States, for 12 climate scenarios, are obtained from simulations of the EPIC crop growth model. Results from the HUMUS model are used to constrain crop irrigation, and BIOME3 model is used to simulate productivity of unmanaged ecosystems. Assumptions about changes in agricultural productivity outside the United States are treated on a scenario basis, either responding in the same way as in the United States, or not responding to climate. 相似文献
5.
J. Neumann 《Climatic change》1985,7(4):441-454
A search was made of the classical Greek and Roman literature for references to climatic change, irrespective whether facts of observation or views. It was found that several scholars/scientists of the classical antiquity made pronouncements on the subject and their statements are either summarized or quoted verbatim in this paper. From the Greek literature we quote Plato, Aristotle and Theophrastus; Herodotus is also quoted for an indirect reference to the topic. From the Roman literature we cite the agricultural writer Columella and the scientist Pliny the Elder; actually, Columella quotes the distinguished writers on husbandry, the Sasernas, father and son.Aristotle's statement is relevant to a degree to the Mycenaean drought (~ 1200 B.C.) problem. The Columella-Saserna pronouncement relates to the astronomical theory of climatic change, while Theophrastus discusses man-made climatic changes.Appendix I gives a statistics of storms, as gleaned from the classical literature, covering approximately the months April–October. Further, it lists some pointers to the relative coolness of the era 850/800–400/300 B.C. in some areas of the Mediterranean. Appendix II offers a few examples for the usefulness of the ancient literature from the point of view of environmental data or events.Now visiting with the Department of Meteorology, The University of Helsinki, Helsinki, Finland. 相似文献
6.
Increasing concentrations of carbon dioxide and other infrared absorbing gases are widely proposed as a mechanism for a global surface warming over the next several decades. Various methods have been used to anticipate the regional climatic changes which might result. In earlier papers Pittock has concluded that for Australia an increase in the extent of the summer rainfall regime is likely, with a decrease in winter rainfall. This is similar to a change which took place over much of Australia in the 1940's.In this paper a climate scenario, roughly corresponding to the climate which might be expected to occur by about the middle of the twenty-first century, has been used as the input into the Miami Model of net primary productivity due to Lieth. Results show that about half of Australia might experience productivity increases in excess of 20%. A small area in the extreme south-west of Australia shows a small decrease in productivity.The direct response of plants to higher ambient carbon dioxide concentrations, and many other possible effects such as changes in the incidence of plant diseases, pests, and soil erosion have not been assessed.Whether or not increasing carbon dioxide will lead to further climatic change in the next few decades, the results show that Australian primary productivity is quite sensitive to climatic variations within the range found in the historical records. 相似文献
7.
分别统计分析了上海、合肥、金华、武汉、长沙、南昌、吉安、衡阳等站生长季热量（﹥10 ℃积温及持续日数）和越冬期低温（﹤０℃负积温及极端最低气温）变化特征。运用谱分析方法，提出长江中下游地区气候冷暖变化的周期及长期波动趋势。同时，预测本世纪末，长江中下游地区气候冷暖波动对建立高产、优质、高效的现代农业可能是一种潜在威胁；指出在长江中下游地区农业生产过程中必须重视气候投入，突破传统农业经验，优化农业耕作轮作栽培制度，建设对气候变化具有强的调控功能的新的农业生态系统。 相似文献
8.
USE OF A STOCHASTIC WEATHER GENERATOR IN THE DEVELOPMENT OF CLIMATE CHANGE SCENARIOS 总被引：14，自引：0，他引：14
Climate change scenarios with a high spatial and temporal resolution are required in the evaluation of the effects of climate change on agricultural potential and agricultural risk. Such scenarios should reproduce changes in mean weather characteristics as well as incorporate the changes in climate variability indicated by the global climate model (GCM) used. Recent work on the sensitivity of crop models and climatic extremes has clearly demonstrated that changes in variability can have more profound effects on crop yield and on the probability of extreme weather events than simple changes in the mean values. The construction of climate change scenarios based on spatial regression downscaling and on the use of a local stochastic weather generator is described. Regression downscaling translated the coarse resolution GCM grid-box predictions of climate change to site-specific values. These values were then used to perturb the parameters of the stochastic weather generator in order to simulate site-specific daily weather data. This approach permits the incorporation of changes in the mean and variability of climate in a consistent and computationally inexpensive way. The stochastic weather generator used in this study, LARS-WG, has been validated across Europe and has been shown to perform well in the simulation of different weather statistics, including those climatic extremes relevant to agriculture. The importance of downscaling and the incorporation of climate variability are demonstrated at two European sites where climate change scenarios were constructed using the UK Met. Office high resolution GCM equilibrium and transient experiments. 相似文献
9.
Historical ice records, such as freeze and breakup dates and the total duration of ice cover, can be used as a quantitative indicator of climatic change if long homogeneous records exist and if the records can be calibrated in terms of climatic changes. Lake Mendota, Wisconsin, has the longest uninterrupted ice records available for any lake in North America dating back to 1855. These records extend back prior to any reliable air temperature data in the midwestern region of the U.S. and demonstrate significant warming of approximately 1.5 °C in fall and early winter temperatures and 2.5 °C in winter and spring temperatures during the past 135 years. These changes are not completely monotonie, but rather appear as two shorter periods of climatic change in the longer record. The first change was between 1875 and 1890, when fall, winter, and spring air temperatures increased by approximately 1.5 °C. The second change, earlier ice breakup dates since 1979, was caused by a significant increase in winter and early spring air temperatures of approximately 1.3 °C. This change may be indicative of shifts in regional climatic patterns associated with global warming, possibly associated with the Greenhouse Effect.With the relationships between air temperature and freeze and break up dates, we can project how the ice cover of Lake Mendota should respond to future climatic changes. If warming occurs, the ice cover for Lake Mendota should decrease approximately 11 days per 1 °C increase. With a warming of 4 to 5 °C, years with no ice cover should occur in approximately 1 out of 15 to 30 years. 相似文献
10.
The potential equilibrium response of Canadian vegetation under two doubled-CO2 climatic scenarios was investigated at three levels in the vegetation mosaic using the rule-based, Canadian Climate-Vegetation Model (CCVM) and climatic response surfaces. The climatic parameters employed as model drivers (i.e., degree-days, minimum temperature, snowpack, actual evapotranspiration, and soil moisture deficit) have a more direct influence on the distribution of vegetation than those commonly used in equilibrium models. Under both scenarios, CCVM predicted reductions in the extent of the tundra and subarctic woodland formations, a northward shift and some expansion in the distributions of boreal and the temperate forest, and an expansion of the dry woodland and prairie formations that was especially pronounced under one of the scenarios. Results of the response surface analysis suggest the potential for significant changes in the probability of dominance for eight boreal tree species. A dissimilarity coefficient was used to identify forest-types under the future climatic scenarios that were analogous to boreal forest-types derived from cluster analysis of the current probabilities of species dominance. All of the current forest-types persisted under the doubled-CO2 scenarios, but no-analog areas were also identified within which an empirically derived threshold of the distance coefficient was exceeded. Maps showing the highest level in the vegetation hierarchy where change was predicted suggest the relative impact of the response under the two climatic scenarios. 相似文献
11.
Charles Weiss Jr. 《Climatic change》1989,15(1-2):299-307
Land prices, insurance rates, future markets, mortgage terms, and other market mechanisms may be expected to guide short-term economic response to climatic change as its effects become apparent to investors. On the other hand, the pervasive influence of discount rates on investment decisions makes it unlikely that the market will give satisfactory guidance to investments that must be undertaken long before the appearance of the climatic effect they are intended to mitigate. For this reason, only government is likely to undertake such long-term investments as large civil works intended to modify hydrology (irrigation, seawall dikes), and research and development in agriculture or other technologies which need to be adapted to new climatic conditions, while the effects of climate change are still distant and uncertain.Decisions regarding very large macroprojects, as well as decisions which determine the siting of installations that have long-term consequences for the environment (e.g., dump sites for disposal of long-term hazardous wastes) should carefully consider the effects of climate change regardless of current market signals. Strategic planners for government and industry should take steps now to identify those decisions for which planning is now beginning, and which need to take into account the effects of long-term climate change. 相似文献
12.
MEAN AND VARIANCE CHANGE IN CLIMATE SCENARIOS: METHODS, AGRICULTURAL APPLICATIONS, AND MEASURES OF UNCERTAINTY 总被引：12，自引：2，他引：10
Our central goal is to determine the importance of including both mean and variability changes in climate change scenarios in an agricultural context. By adapting and applying a stochastic weather generator, we first tested the sensitivity of the CERES-Wheat model to combinations of mean and variability changes of temperature and precipitation for two locations in Kansas. With a 2°C increase in temperature with daily (and interannual) variance doubled, yields were further reduced compared to the mean only change. In contrast, the negative effects of the mean temperature increase were greatly ameliorated by variance decreased by one-half. Changes for precipitation are more complex, since change in variability naturally attends change in mean, and constraining the stochastic generator to mean change only is highly artificial. The crop model is sensitive to precipitation variance increases with increased mean and variance decreases with decreased mean. With increased mean precipitation and a further increase in variability Topeka (where wheat cropping is not very moisture limited) experiences decrease in yield after an initial increase from the 'mean change only case. At Goodland Kansas, a moisture-limited site where summer fallowing is practiced, yields are decreased with decreased precipitation, but are further decreased when variability is further reduced. The range of mean and variability changes to which the crop model is sensitive are within the range of changes found in regional climate modeling (RegCM) experiments for a CO2 doubling (compared to a control run experiment). We then formed two types of climate change scenarios based on the changes in climate found in the control and doubled CO2 experiments over the conterminous U. S. of RegCM: (1) one using only mean monthly changes in temperature, precipitation, and solar radiation; and (2) another that included these mean changes plus changes in daily (and interannual) variability. The scenarios were then applied to the CERES-Wheat model at four locations (Goodland, Topeka, Des Moines, Spokane) in the United States. Contrasting model responses to the two scenarios were found at three of the four sites. At Goodland, and Des Moines mean climate change increased mean yields and decreased yield variability, but the mean plus variance climate change reduced yields to levels closer to their base (unchanged) condition. At Spokane mean climate change increased yields, which were somewhat further increased with climate variability change. Three key aspects that contribute to crop response are identified: the marginality of the current climate for crop growth, the relative size of the mean and variance changes, and timing of these changes. Indices for quantifying uncertainty in the impact assessment were developed based on the nature of the climate scenario formed, and the magnitude of difference between model and observed values of relevant climate variables. 相似文献
13.
This paper concerns the impact of human-induced global climate change on the River Rhine discharge. For this purpose a model for climate assessment, named ESCAPE, is coupled to a water balance model, named RHINEFLOW. From climate scenarios, changes in regional annual water availability and seasonal discharge in the River Rhine Basin are estimated. The climate scenarios are based on greenhouse gases emissions scenarios. An assessment is made for best guess seasonal discharge changes and for changes in frequencies of low and high discharges in the downstream reaches of the river. In addition, a quantitative estimation of the uncertainties associated with this guess is arrived at.The results show that the extent and range of uncertainty is large with respect to the best guess changes. The uncertainty range is 2–3 times larger for the Business-as-Usual than for the Accelerated Policies scenarios. This large range stems from the doubtful precipitation simulations from the present General Circulation Models. This scenario study showed the precipitation scenarios to be the key-elements within the present range of reliable climate change scenarios.For the River Rhine best guess changes for annual water availability are small according to both scenarios. The river changes from a present combined snow-melt-rain fed river to an almost entirely rain fed river. The difference between present-day large average discharge in winter and the small average discharge in autumn should increase for all scenarios. This trend is largest in the Alpine part of the basin. Here, winter discharges should increase even for scenarios forecasting annual precipitation decreases. Summer discharge should decrease. Best guess scenarios should lead to increased frequencies of both low and high flow events in the downstream (Dutch) part of the river. The results indicate changes could be larger than presently assumed in worst case scenarios used by the Dutch water management authorities. 相似文献
14.
Uwe Radok 《Climatic change》1992,20(2):155-167
Changes in climate are generally defined as differences between means. The autocorrelation usually encountered in geophysical series and the implied persistence, or reduced number of independent observations, tend to render significance tests of mean differences inconclusive until a considerable amount of data has accumulated, by which time a climatic change could be well under way. A more efficient alternative approach is provided by small-sample variances. Under slightly idealized conditions their frequency distribution is of the chi-square type with a number of degrees of freedom that measures the persistence in the series and can be monitored on a short time scale with a sequential sampling procedure.Also at homein CIRES, Campus Box 449, University of Colorado, Boulder, CO 80309, U.S.A. 相似文献
15.
The increasing CO2 concentration in the atmosphere and its implication on agricultural productivity 总被引：1，自引：0，他引：1
Norman J. Rosenberg 《Climatic change》1981,3(3):265-279
The increasing concentration of CO2 in the atmosphere should result in a general increase in the net primary productivity of most cultivated species and forest species, assuming no counterproductive climatic changes occur. The photosynthetic rate of C3 plants is most responsive to increasing concentration of CO2 in the ambient air. C4 plants demonstrate a stomatal closure that causes reduced transpiration. In the case of both types of plants, the water use efficiency (photosynthesis/transpiration) is likely to be improved.It has been suggested that photosynthetic production may be limited today more by shortages of water and nutrients than by shortages of carbon dioxide. The author speculates that the inadvertant CO2-fertilization now occurring could, in itself, cause a moderate release from these constraints.Physiological responses to an increased atmospheric CO2 concentration are easily demonstrated in controlled environment studies. Because of the difficulty in maintaining artifically enriched air near the crop against the forces of turbulent transfer, studies in the open field have been inconclusive. The observation of decreased photosynthetic rate in a perennial crop during that part of the growing season when CO2 concentration is naturally low suggests a technique by which it may be possible to infer what will happen in the real world of agricultural fields if a CO2-rich environment, such as is predicted in the coming decades, materializes. Inferences from the very limited set of data available support the view that net photosynthetic production will be increased.Published as Paper No. 6123, Journal Series, Nebraska Agricultural Experiment Station. The work reported was conducted under Regional Research Project 11–33 and Nebraska Agricultural Experiment Station Project 1149.George Holmes Professor of Agricultural Meteorology, Center for Agricultural Meteorology and Climatology, Institute of Agriculture and Natural Sources, University of Nebraska-Lincoln, Lincoln, NE 68583, U.S.A. 相似文献
16.
The evaluation of the impact of climate change on deltaic systems implies studying a multi-component system in which the complexity of links is high enough to present doing it as a whole. Because of this, it is a reasonable approach to study separately the behaviour of each element, to be afterwards linked into a general conceptual model for deltaic behaviour. Moreover, in the case of largely regulated deltas, the main impacts of climatic change will be marine-related since those related to the catchment areas will be severely damped by river regulation and management policies. This fact implies that coastal fringes may become the main frontier between the delta and climatic change effects. In this context, a methodology to study climatic change impacts on deltaic coastal fringes is here presented. It will be further developed on two companion papers dealing with the study of driving terms and coastal response. As coastal processes act at different time and space scales, determining the reference – initial – situation must be done taking into account the inherent system dynamics. It is thus unrealistic to characterize the initial stage as a static one. In order to avoid this simplistic approach, a comprehensive approach to the coastal system must be employed, with three different scales (long-term/large scale, medium term/scale and episodic). 相似文献
17.
Climate Change Effects on Plant Growth, Crop Yield and Livestock 总被引：1，自引：0，他引：1
A review is given of the state of knowledge in the field of assessing climate change impacts on agricultural crops and livestock. Starting from the basic processes controlling plant growth and development, the possible impacts and interactions of climatic and other biophysical variables in different agro-environments are highlighted. Qualitative and quantitative estimations of shifts in biomass production and water relations, inter-plant competition and crop species adaptability are discussed. Special attention is given to the problems encountered when scaling up physiological responses at the leaf- and plant level to yield estimates at regional to global levels by using crop simulation models in combination with geo-referenced, agro-ecological databases. Some non-linear crop responses to environmental changes and their relations to adaptability and vulnerability of agro-ecosystems are discussed. 相似文献
18.
The use of general circulation models in the analysis of the ecosystem impacts of climatic change 总被引：4，自引：0，他引：4
W. Lawrence Gates 《Climatic change》1985,7(3):267-284
The use of general circulation models in the estimation of the impact of climatic change on the global ecosystem is seen to depend primarily on their ability to reliably depict the seasonal and geographical distribution of the changes in surface climate variables. While present GCMs generally simulate the observed distribution of surface air temperature reasonably well, they show significantly different changes in the equilibrium temperature as a result of doubled CO2, for example. These disagreements are attributed to differences in the model's resolution and parameterization of subgrid-scale processes. Such model-dependent errors notwithstanding, much more information of possible use in impact analysis can be extracted from general circulation model simulations than has generally been done so far. The completeness, consistency and experimental possibilities offered by simulated data sets permit the systematic extraction of a wide variety of statistics important to the surface ecosystem, such as the length of the growing season, the duration of rainless periods, and the surface moisture stress.Assuming further model improvements, the elements of a model-assisted methodology for climate impact analysis are seen to be: (1) the determination of the seasonal and geographical distribution of that portion of simulated climatic changes which are both statistically and physically significant; (2) the transformation of the (significant) large-scale climatic changes onto the local scale of impact (the climate inversion problem); and (3) the design of specific statistical parameters or functions relevant to local ecosystem impacts. 相似文献
19.
Mechanisms of shrubland expansion: land use,climate or CO2? 总被引：11，自引：0，他引：11
Encroachment of trees and shrubs into grasslands and the thicketization of savannas has occurred worldwide over the past century. These changes in vegetation structure are potentially relevant to climatic change as they may be indicative of historical shifts in climate and as they may influence biophysical aspects of land surface-atmosphere interactions and alter carbon and nitrogen cycles. Traditional explanations offered to account for the historic displacement of grasses by woody plants in many arid and semi-arid ecosystems have centered around changes in climatic, livestock grazing and fire regimes. More recently, it has been suggested that the increase in atmospheric CO2 since the industrial revolution has been the driving force. In this paper we evaluate the CO2 enrichment hypotheses and argue that historic, positive correlations between woody plant expansion and atmospheric CO2 are not cause and effect.Please direct all correspondence to the senior author. 相似文献
20.
An EPIC model-based wheat drought risk assessment using new climate scenarios in China 总被引：1，自引：0，他引：1
There is considerable research interest in future agro-drought risk assessment, since the increasing severity of climate change-related hazards poses a great threat to global food security. Wheat is the most important staple crop in the world, and China’s wheat production has long been impacted by drought. The frequency, intensity, and duration of droughts may increase due to climate change and stressing the need for robust assessment methods for drought risk, as well as adaptation and mitigation strategies. This paper investigates a method for assessing future wheat drought risk using climate scenarios and a crop model. We illustrate the utility of such an approach by assessing the risk of wheat drought under climate change scenarios in China using the Environmental Policy Integrated Climate model. Results show that the risk level of wheat drought is highest under scenario RCP8.5, followed by RCP4.5, RCP6.0, and RCP2.6, in descending order. If current climate change trends continue, wheat drought risk in China will be at risk levels between RCP6.0 and RCP8.5 by the end of the twenty-first century. The wheat drought risk assessment shows a “low-risk, high-risk, low-risk” spatial pattern starting in the spring wheat-planting regions in northern China and progressing to the winter wheat-planting regions in southern China. Significant differences were observed across regions, but in all RCP scenarios, the relative high-risk zones are the Huang-Huai Winter Wheat Region and the North Winter Wheat Region. In addition, wheat drought risk mitigation and adaptation strategies in China are proposed. 相似文献