共查询到20条相似文献，搜索用时 31 毫秒
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The ability of sensitive rainforest species to evolve in response to climate change is largely unknown. We show that the Australian tropical rainforest fly Drosophila birchii exhibits clinal variation in desiccation resistance, but the most resistant population lacks the ability to evolve further resistance even after intense selection for over 30 generations. Parent-offspring comparisons indicate low heritable variation for this trait but high levels of genetic variation for morphology. D. birchii also exhibits abundant genetic variation at microsatellite loci. The low potential for resistance evolution highlights the importance of assessing evolutionary potential in targeted ecological traits and species from threatened habitats. 相似文献
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近60a来玛纳斯河流域气候变化趋势及突变分析 总被引：1，自引：0，他引：1
[目的]气候变化是21世纪人类面临的最大环境问题之一.其中以干旱区较为明显,而新疆是最为突出的地区之一.[方法]以中亚典型冰川融化区玛纳斯河流域为例,运用线性回归及Mann - Kendall趋势检验方法分析其1956 ～2010年气温及降水资料的变化趋势和突变点.[结果]近60a来玛纳斯河流域经历了一个增温趋湿的过程,增加幅度分别在0.44℃/10 a和12.6mm/10 a;春、夏、秋、冬四季增温幅度分别为0.50、0.21、0.52和0.52℃/10 a,降水倾向率分别为2.44、3.22、2.76和3.64 mm/10 a;趋势突变检验分析表明:流域内年平均气温在1980s明显的增温过程,突变点在1989年,四季突变点分别发生在1995、1986、1996和1987年.年降水量突变也发生在1980s后期,四季降水量M-K检验表明秋冬突变点分别发生在1983和1997年,春夏没有发生突变.[结论]研究结果对全面认识及预测干旱区年际及季节气候变化有一定借鉴意义. 相似文献
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李晓明 《国家林业局管理干部学院学报》2013,12(1):33-37
针对共同但有区别责任的历史性,在2011年南非德班气候大会上西方发达国家又提出新的观点,即：根据排放当时的科学技术水平,二氧化碳会引起全球气候变暖从而威胁人类生存并不为人类所知,并且当时排放温室气体的主体已经消逝,所以由发达国家承担量化减排责任缺乏法律依据。发达国家这一论点的本质在于逃避发达国家在历史上所欠下的气候债。无论从正义论的角度还是从国际环境责任归责原则的角度出发,发达国家的论点都是无法成立的。解决气候变化问题,国家自愿、有限主权让渡应当代替国家间博弈。 相似文献
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Estimates of glacial-interglacial climate change in tropical Africa have varied widely. Results from a process-based vegetation model show how montane vegetation in East Africa shifts with changes in both carbon dioxide concentration and climate. For the last glacial maximum, the change in atmospheric carbon dioxide concentration alone could explain the observed replacement of tropical montane forest by a scrub biome. This result implies that estimates of the last glacial maximum tropical cooling based on tree- line shifts must be revised. 相似文献
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Lobell DB Burke MB Tebaldi C Mastrandrea MD Falcon WP Naylor RL 《Science (New York, N.Y.)》2008,319(5863):607-610
Investments aimed at improving agricultural adaptation to climate change inevitably favor some crops and regions over others. An analysis of climate risks for crops in 12 food-insecure regions was conducted to identify adaptation priorities, based on statistical crop models and climate projections for 2030 from 20 general circulation models. Results indicate South Asia and Southern Africa as two regions that, without sufficient adaptation measures, will likely suffer negative impacts on several crops that are important to large food-insecure human populations. We also find that uncertainties vary widely by crop, and therefore priorities will depend on the risk attitudes of investment institutions. 相似文献
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Berner RA 《Science (New York, N.Y.)》1993,261(5117):68-70
Changes in solar radiation, as it affects the rate of weathering of silicates on the continents, and other changes involving weathering and the degassing of carbon dioxide (CO(2)) have been included in a long-term carbon-cycle model. These additions to the model show that the major controls on CO(2) concentrations during the Paleozoic era were solar and biological, and not tectonic, in origin. The model predictions agree with independent estimates of a large mid-Paleozoic (400 to 320 million years ago) drop in CO(2) concentrations, which led to large-scale glaciation. This agreement indicates that variations in the atmospheric greenhouse effect were important in global climate change during the distant geologic past. 相似文献
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Rule S Brook BW Haberle SG Turney CS Kershaw AP Johnson CN 《Science (New York, N.Y.)》2012,335(6075):1483-1486
Giant vertebrates dominated many Pleistocene ecosystems. Many were herbivores, and their sudden extinction in prehistory could have had large ecological impacts. We used a high-resolution 130,000-year environmental record to help resolve the cause and reconstruct the ecological consequences of extinction of Australia's megafauna. Our results suggest that human arrival rather than climate caused megafaunal extinction, which then triggered replacement of mixed rainforest by sclerophyll vegetation through a combination of direct effects on vegetation of relaxed herbivore pressure and increased fire in the landscape. This ecosystem shift was as large as any effect of climate change over the last glacial cycle, and indicates the magnitude of changes that may have followed megafaunal extinction elsewhere in the world. 相似文献
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Weathering of uplifted continental rocks consumes carbon dioxide and transports cations to the oceans, thereby playing a critical role in controlling both seawater chemistry and climate. However, there are few archives of seawater chemical change that reveal shifts in global tectonic forces connecting Earth ocean-climate processes. We present a 68-million-year record of lithium isotopes in seawater (δ(7)Li(SW)) reconstructed from planktonic foraminifera. From the Paleocene (60 million years ago) to the present, δ(7)Li(SW) rose by 9 per mil (‰), requiring large changes in continental weathering and seafloor reverse weathering that are consistent with increased tectonic uplift, more rapid continental denudation, increasingly incongruent continental weathering (lower chemical weathering intensity), and more rapid CO(2) drawdown. A 5‰ drop in δ(7)Li(SW) across the Cretaceous-Paleogene boundary cannot be produced by an impactor or by Deccan trap volcanism, suggesting large-scale continental denudation. 相似文献
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厘清饱和水汽压差(VPD)的年际动态特征有助于深入理解大气干湿程度对气候变化的响应。本研究基于我国西南地区105个台站1982—2015年的气象观测资料,利用Mann-Kendall突变检验分析VPD的突变特征,基于统计分析探讨突变点前后的VPD变化趋势及影响因素。研究结果表明,西南地区1982—2015年VPD变化以2000年为突变年,增速由0.001 kPa/a变为0.005 kPa/a,并且VPD呈增加趋势的站点在2000年后增多。VPD在时间动态上出现变化的主要原因是在2000—2015年间相对湿度下降幅度增加,导致西南地区出现更干燥的气候特征。作为大气主要水汽来源的外来水汽通量和局地实际蒸散发在2000年后表现为增长趋势,但由于2000年后更高的空气温度引起饱和水汽压比实际水汽压增幅更大,即大气中实际水汽增加远低于饱和水汽容量增加,进而导致VPD增幅更大。本研究表明在突变点后西南地区VPD显著变化的原因主要是温度上升对相对湿度的影响,研究结果有助于深入理解中国西南地区的气候变化,明晰VPD变化背后的相关机制,为该地区的生态系统构建和未来气候变化应对提供参考。 相似文献
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非洲农业产量对气候变化响应与适应研究进展 总被引：1，自引：0，他引：1
非洲是全世界气候变化最脆弱的地区,而非洲农业受气候变化的影响最为敏感。气候变化已经并将继续对非洲农业和粮食安全产生较大的负面影响。提高气候变化对非洲作物产量影响的理解,揭示非洲农业对气候变化的响应规律,是及时、正确和有效适应气候变化的关键。本文综述了非洲农业对气候变化的响应与适应的研究进展,总结了作物机理模型、统计模型和经济模型目前研究这一问题的三大主要方法,系统阐述了非洲农业对过去和未来气候变化的响应程度及适应措施。未来气候变化对非洲农业的可能影响,不同的研究在不同时间尺度和空间尺度上,随着气候情景、研究方法和作物种类的不同,影响程度的结论差异性较大：作物机理模型方法显示的影响范围是-84%-62%;统计方法评价的影响范围则是-57%-30%;而用计量经济学方法研究显示的影响范围是-100%-168%。随着气候变化对非洲农业的影响得到公认,非洲农业对气候变化的适应问题得到了越来越多的研究。选育抗旱品种、发展保护性农业、完善灌溉设施、调整技术管理等适应措施将有可能对粮食安全带来更大的益处。另外,加强极端气候事件的监测和预警、增强气候预报、有效结合气候变化制定农业生产种植和管理措施、调整作物布局、发挥区域和国际组织（世界气象组织WMO、联合国粮农组织FAO等）在非洲应对气候变化影响方面的合作和对非洲的援助等措施均可提高非洲农业对气候变化的适应能力。本文进一步讨论了研究中存在的不确定性因素,包括数据、方法、结果的不确定性以及气候变化的间接影响、缺乏综合研究等问题,并指出了未来的发展趋势。本文有助于更好地理解非洲农业产量对气候变化的响应与适应,为解决非洲粮食安全问题和消除非洲贫困提供科技支撑,同时也为中国农业应对气候变化提供借鉴。 相似文献
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【目的】科学探明世界第二大洲--非洲的耕地资源禀赋、准确揭示2000-2010年耕地动态变化规律和过程,服务全球粮食安全。【方法】采用全球首套30 m空间分辨率地表覆盖数据GlobeLand30 的 2000年和 2010年耕地数据产品,在不同分析指标和空间尺度上分析10年间非洲耕地利用格局的总体变化、地理差异特征及其生态环境背景。【结果】2000-2010 年,非洲耕地总面积增加了1 540.63×104 hm2,变化率为 7.42%;5个区域10年间耕地面积变化率从大到小依次是：中非（10.42%）、东非（9.49%）、西非（7.55%）、北非（6.74%）和南部非洲（4.86%）;耕地面积数量增加排在前10位的国家是尼日利亚、坦桑尼亚、苏丹、肯尼亚、莫桑比克、乍得、阿尔及利亚、赞比亚、津巴布韦和布基纳法索;耕地面积数量减少排在前10位的国家是科特迪瓦、马里、安哥拉、加纳、马拉维、突尼斯、布隆迪、卢旺达、刚果（金）和南非。2010年,非洲耕地复种指数为98.11%,10年间变化率为13.54%;2010年,5个区域的复种指数从大到小依次是西非（163.75%）、中非（148.01%）、东非（76.64%）、北非（75.20%）和南部非洲（57.56%）。耕地空间格局变化区域差异明显,耕地在各经纬度带上以增加为主,以东半球和北半球面积增加较多;新增耕地主要由林地、草地和灌木地等植被类型开发利用转入,分别占转出总量的 15.19%、66.37%和 11.20%,减少耕地主要转成为林地、草地和灌木地,转出面积分别占转出总量的 21.15%、61.19%和11.78%,新增的耕地面积远大于减少的面积。从耕地变化与生态环境因子之间的关系来看,耕地增减变化主要发生在年均温度为20-30℃区域和年均降水为600-1 200 mm的区域,以及500-1 000 m高原区间和坡度小于2°的平缓地带。【结论】2000-2010年,非洲耕地面积数量和空间变化剧烈,不同区域和国家的耕地变化存在明显差异。研究结果揭示了非洲耕地空间分布及时空变化特征,不仅可为分析全球耕地空间分布格局、揭示其地域差异和时空波动规律提供重要基础参考,也可为耕地增减变化比较集中的区域的政策导向、土地产权制度调整提供科学依据,服务全球粮食安全问题解决。 相似文献
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旨在为棉花干旱灾害的监测、预报预警及防御提供理论依据。利用河北省南部8个气象站点1962—2020年的逐月气温、降水量数据，采用标准化降水蒸散指数(SPEI)，通过回归分析、Mann-Kendall检验等方法，分析了河北省南部棉花生长季（4—10月）干旱变化特征。结果表明，河北南部棉花全生育期的干旱频率为25%，其中重旱以上发生频率为6.8%;播种期、苗期、蕾期、花铃期和吐絮期干旱频率分别为35.6%、30.5%、32.2%、30.5%和32.2%;苗期气候在1976年发生干湿变化突变，1976年后呈显著湿润化趋势;蕾期气候在1968年发生干湿突变，1968年后呈显著湿润化趋势;棉花花铃期气候1982年后呈干旱化趋势，变化趋势越来越显著;棉花吐絮期气候1989年后呈干旱化趋势;棉花全生育期气候1982年后呈现持续干旱化趋势。20世纪90年代以来，棉花苗期、蕾期气候呈湿润化趋势，花铃期呈干旱化趋势，作物品种培育和栽培技术措施改进应重视这种变化趋势。 相似文献
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By modifying habitats and creating bridges and barriers between landmasses, climate change and tectonic events are believed to have important consequences for diversification of terrestrial organisms. Such consequences should be most evident in phylogenetic histories of groups that are ancient, widespread, and diverse. The squirrel family (Sciuridae) is one of very few mammalian families endemic to Eurasia, Africa, and North and South America and is ideal for examining these issues. Through phylogenetic and molecular-clock analyses, we infer that arrival and diversification of squirrels in Africa, on Sunda Shelf islands, across Beringea, and across the Panamanian isthmus coincide in timing and location with multiple well-documented sea-level, tectonic, and paleontological events. These precise correspondences point to an important role for global change in the diversification of a major group of mammals. 相似文献
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Olivieri A Achilli A Pala M Battaglia V Fornarino S Al-Zahery N Scozzari R Cruciani F Behar DM Dugoujon JM Coudray C Santachiara-Benerecetti AS Semino O Bandelt HJ Torroni A 《Science (New York, N.Y.)》2006,314(5806):1767-1770
Sequencing of 81 entire human mitochondrial DNAs (mtDNAs) belonging to haplogroups M1 and U6 reveals that these predominantly North African clades arose in southwestern Asia and moved together to Africa about 40,000 to 45,000 years ago. Their arrival temporally overlaps with the event(s) that led to the peopling of Europe by modern humans and was most likely the result of the same change in climate conditions that allowed humans to enter the Levant, opening the way to the colonization of both Europe and North Africa. Thus, the early Upper Palaeolithic population(s) carrying M1 and U6 did not return to Africa along the southern coastal route of the "out of Africa" exit, but from the Mediterranean area; and the North African Dabban and European Aurignacian industries derived from a common Levantine source. 相似文献
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High-resolution holocene environmental changes in the thar desert, northwestern india 总被引：2，自引：0，他引：2
Enzel Y Ely LL Mishra S Ramesh R Amit R Lazar B Rajaguru SN Baker VR Sandler A 《Science (New York, N.Y.)》1999,284(5411):125-128
Sediments from Lunkaransar dry lake in northwestern India reveal regional water table and lake level fluctuations over decades to centuries during the Holocene that are attributed to changes in the southwestern Indian monsoon rains. The lake levels were very shallow and fluctuated often in the early Holocene and then rose abruptly around 6300 carbon-14 years before the present (14C yr B.P.). The lake completely desiccated around 4800 (14)C yr B.P. The end of this 1500-year wet period coincided with a period of intense dune destabilization. The major Harrapan-Indus civilization began and flourished in this region 1000 years after desiccation of the lake during arid climate and was not synchronous with the lacustral phase. 相似文献
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气候变化通过改变环境禀赋影响作物间的比较优势。在2019年中央"一号文件"提出"大豆振兴计划"背景下,农户会根据气候变化情况调整种植结构还是调整生产资料投入?如何影响大豆播种面积?其作用机理是什么?本文基于1998—2017年3560份地级市数据,运用动态面板差分广义矩模型(DIF-GMM),考察了气候变化对大豆播种面积占比的影响。研究发现:日照、气温和降水均会影响大豆播种面积占比,进一步作用机制分析发现,气候变化主要是通过影响大豆单位面积产量,进而影响其播种面积占比。农户的适应性行为在气候变化对大豆播种面积占比的影响中起调节作用,其中,灌溉、地膜和化肥在气温对大豆播种面积占比的影响具有正向调节作用,调节降水变化的要素主要是灌溉。同时,进口量、相对收益以及生产成本也是影响大豆播种面积占比变化的重要因素。在此基础上,本文还运用面板向量自回归模型(PVAR)对未来十年气候变化及农户适应性行为对大豆播种面积占比的动态影响路径和影响程度进行了预测分析,发现化肥和农药施用量可在短期内缓解气候变化对大豆播种面积占比的影响,而日照、降水、灌溉和地膜将对大豆播种面积占比具有长期持续冲击。 相似文献
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