关键词： livestock   climate impacts   land use modeling   adaptation costs   production systems   GREENHOUSE-GAS EMISSIONS   GLOBAL CHANGE   CROP PRODUCTIVITY   FOOD SECURITY   MODEL   LAND   IMPACTS   CARBON   NITROGEN   GROWTH  

摘要： Livestock farming is the world's largest land use sector and utilizes around 60% of the global biomass harvest. Over the coming decades, climate change will affect the natural resource base of livestock production, especially the productivity of rangeland and feed crops. Based on a comprehensive impact modeling chain, we assess implications of different climate projections for agricultural production costs and land use change and explore the effectiveness of livestock system transitions as an adaptation strategy. Simulated climate impacts on crop yields and rangeland productivity generate adaptation costs amounting to 3% of total agricultural production costs in 2045 (i.e. 145 billion US$). Shifts in livestock production towards mixed crop-livestock systems represent a resource-and cost-efficient adaptation option, reducing agricultural adaptation costs to 0.3% of total production costs and simultaneously abating deforestation by about 76 million ha globally. The relatively positive climate impacts on grass yields compared with crop yields favor grazing systems inter alia in South Asia and North America. Incomplete transitions in production systems already have a strong adaptive and cost reducing effect: a 50% shift to mixed systems lowers agricultural adaptation costs to 0.8%. General responses of production costs to system transitions are robust across different global climate and crop models as well as regarding assumptions on CO2 fertilization, but simulated values show a large variation. In the face of these uncertainties, public policy support for transforming livestock production systems provides an important lever to improve agricultural resource management and lower adaptation costs, possibly even contributing to emission reduction.

关键词： climate change impacts   agricultural modeling   forestry modeling   mitigation scenarios   EPIC   MC1   FASOM-GHG   ATMOSPHERIC CARBON-DIOXIDE   UNITED-STATES   CO2   GROWTH   YIELD   ECOSYSTEMS   MARKETS   CROPS   WATER   FOOD  

摘要： Increasing atmospheric carbon dioxide levels, higher temperatures, altered precipitation patterns, and other climate change impacts have already begun to affect US agriculture and forestry, with impacts expected to become more substantial in the future. There have been numerous studies of climate change impacts on agriculture or forestry, but relatively little research examining the long-term net impacts of a stabilization scenario relative to a case with unabated climate change. We provide an analysis of the potential benefits of global climate change mitigation for US agriculture and forestry through 2100, accounting for landowner decisions regarding land use, crop mix, and management practices. The analytic approach involves a combination of climate models, a crop process model (EPIC), a dynamic vegetation model used for forests (MC1), and an economic model of the US forestry and agricultural sector (FASOM-GHG). We find substantial impacts on productivity, commodity markets, and consumer and producer welfare for the stabilization scenario relative to unabated climate change, though the magnitude and direction of impacts vary across regions and commodities. Although there is variability in welfare impacts across climate simulations, we find positive net benefits from stabilization in all cases, with cumulative impacts ranging from $32.7 billion to $54.5 billion over the period 2015-2100. Our estimates contribute to the literature on potential benefits of GHG mitigation and can help inform policy decisions weighing alternative mitigation and adaptation actions.

关键词： climate   agriculture   economics   yields   prices   trade   CROP PRODUCTION   FOOD DEMAND   LAND-USE   MODEL   PRODUCTIVITY   RESPONSES   FUTURE   GROWTH   TRADE  

摘要： Previous studies have combined climate, crop and economic models to examine the impact of climate change on agricultural production and food security, but results have varied widely due to differences in models, scenarios and input data. Recent work has examined (and narrowed) these differences through systematic model intercomparison using a high-emissions pathway to highlight the differences. This paper extends that analysis to explore a range of plausible socioeconomic scenarios and emission pathways. Results from multiple climate and economic models are combined to examine the global and regional impacts of climate change on agricultural yields, area, production, consumption, prices and trade for coarse grains, rice, wheat, oilseeds and sugar crops to 2050. Wefind that climate impacts on global average yields, area, production and consumption are similar across shared socioeconomic pathways (SSP 1, 2 and 3, as we implement them based on population, income and productivity drivers), except when changes in trade policies are included. Impacts on trade and prices are higher for SSP 3 than SSP 2, and higher for SSP 2 than for SSP 1. Climate impacts for all variables are similar across low to moderate emissions pathways (RCP 4.5 and RCP 6.0), but increase for a higher emissions pathway (RCP 8.5). It is important to note that these global averages may hide regional variations. Projected reductions in agricultural yields due to climate change by 2050 are larger for some crops than those estimated for the past half century, but smaller than projected increases to 2050 due to rising demand and intrinsic productivity growth. Results illustrate the sensitivity of climate change impacts to differences in socioeconomic and emissions pathways. Yield impacts increase at high emissions levels and vary with changes in population, income and technology, but are reduced in all cases by endogenous changes in prices and other variables.

关键词： 气候变化   中国农业   农业生产  

摘要： 近年来世界各国经济得以快速发展,但却给大气环境带来了严重的负面作用,尤其最近几年,气候变化较大,温室效应、城市热岛效应经常发生,严重影响到社会经济建设,特别是对我国农业生产影响较大,使我国农业面临严峻挑战。通过实践研究得知,气候变化对我国农业的影响不仅局限于诱发病虫害。

关键词： 气候变冷   重农   亩产   晁错   贵粟论  

摘要： 中国古代气候寒冷(或变冷)时期的重农理论较温暖(或变暖)时期更为丰富,并非出于偶然。汉初的案例表明,气候变冷带来的农业生产率下降造成(局部)生产危机,这种经济冲击导致社会内在的变革要求,促使以晁错为代表的重农思想家革新陈旧理论及其所指导的政策以应对新挑战。长期而言,重农理论的发展史上存在着一个"气候变冷——粮食减产(农民受灾)——重农理论(政策批判)产生"的理论催化机制。这是因为,有生命力的思想和理论总是试图为更多事实提供解释和指导,而特殊时期的现实危机却使传统理论失去解释力或指导意义,这促使学者通过对平常和特殊情况的综合总结,提出新的解决办法。

关键词： 东北地区   气候变化   农业热量资源   响应   界限温度  

摘要： 气候变暖背景下,系统研究我国东北地区农业热量资源对气候变化的响应仍具有重要的现实意义。根据1961-2010年东北地区64个气象台站的逐日资料,采用公认的农业气象指标,分析了80%保证率下东北地区稳定通过10℃农业热量资源的时空变化特征及演变趋势,探讨了近50a东北地区农业热量资源对气候变化的响应规律。结果表明:从1960-2010年,东北地区农业热量资源存在年代际变化,且80年代到90年代是该地区农业热量资源增加最快的时期。以1980年为界线,≥10℃初日出现的日期先推迟再提前,终日出现的日期推迟,持续日数先减少后增加,积温呈持续增多趋势;近50a东北地区热量资源增加趋势明显。东北地区农业热量资源地域差异明显。热量资源较丰富的是辽宁省西部和南部,较匮乏的是黑龙江省的大兴安岭地区,且由南向北随纬度增大呈初日出现日期延迟、终日出现日期提前、持续日数减少、积温减少的变化规律。

关键词： 气候变化   农业生产转型   农业产业链  

摘要： 以增温为主要特征的气候变化是当今世界各国共同面临的严峻挑战。本文在对气候变化与农业生产间相互影响的关系进行分析的基础上,重点对当前中国应对气候变化的农业生产转型的内涵、路径和农业产业链上不同主体参与农业生产转型行为的研究及其进展进行了梳理、归纳和述评,指出了当前研究存在的一些不足:学科隔阂较为明显,导致关于气候变化对农业生产影响的评估存在偏差;未区分不同主体适应气候变化行为的差异,缺少微观与宏观数据的有效对接;定性研究农户应对气候变化行为的文献居多,量化分析及其方法研究不足;研究视角较为单一,缺少农业生产转型视角的研究。本文最后对未来相关研究的重点做出了展望:第一,探索更全面的分析路径,优化模拟模型;第二,结合新型农业经营主体的特点,建立正确的适应机制假设;第三,综合利用面板数据和横截面数据,开展动态研究;第四,改进测评方法,区分不同主体适应气候变化的差异;第五,加强交叉学科研究,探索建立能有效结合微观调查数据和宏观统计数据的模型。