Four climate cycles of recurring deep and surface water destabilizations on the Iberian margin

Centennial climate variability over the last ice age exhibits clear bipolar behavior. High-resolution analyses of marine sediment cores from the Iberian margin trace a number of associated changes simultaneously. Proxies of sea surface temperature and water mass distribution, as well as relative biomarker content, demonstrate that this typical north-south coupling was pervasive for the cold phases of climate during the past 420,000 years. Cold episodes after relatively warm and largely ice-free periods occurred when the predominance of deep water formation changed from northern to southern sources. These results reinforce the connection between rapid climate changes at Mediterranean latitudes and century-to-millennial variability in northern and southern polar regions.     

Paleo-Indian remains from laguna de tagua tagua, central chile

Bone and stone tools associated with extinct fauna (horse and mastodon) place man's occupation in central Chile at 11,380 +/- 320 years ago.     

Sr-Nd-Pb isotope evidence for ice-sheet presence on southern Greenland during the Last Interglacial

To ascertain the response of the southern Greenland Ice Sheet (GIS) to a boreal summer climate warmer than at present, we explored whether southern Greenland was deglaciated during the Last Interglacial (LIG), using the Sr-Nd-Pb isotope ratios of silt-sized sediment discharged from southern Greenland. Our isotope data indicate that no single southern Greenland geologic terrane was completely deglaciated during the LIG, similar to the Holocene. Differences in sediment sources during the LIG relative to the early Holocene denote, however, greater southern GIS retreat during the LIG. These results allow the evaluation of a suite of GIS models and are consistent with a GIS contribution of 1.6 to 2.2 meters to the ≥4-meter LIG sea-level highstand, requiring a significant sea-level contribution from the Antarctic Ice Sheet.     

近20年山东省南四湖大风气候特征分析

根据南四湖畔4个陆面台站近20年的大风记录,对南四湖大风天气的基本气候特征进行了统计分析,结果表明:南四湖地区大风以西北风为主,春季出现大风日数最多,秋季最少。自90年代末大风日数呈逐渐减少趋势,南四湖大风频次逐年减少,造成该结果的原因除了大气环流背景方面的影响因素外,还可能与全球气候变暖、测站周围局地环境改变、人工防护林带面积扩大有关。     

CO2-forced climate and vegetation instability during Late Paleozoic deglaciation

The late Paleozoic deglaciation is the vegetated Earth's only recorded icehouse-to-greenhouse transition, yet the climate dynamics remain enigmatic. By using the stable isotopic compositions of soil-formed minerals, fossil-plant matter, and shallow-water brachiopods, we estimated atmospheric partial pressure of carbon dioxide (pCO2) and tropical marine surface temperatures during this climate transition. Comparison to southern Gondwanan glacial records documents covariance between inferred shifts in pCO2, temperature, and ice volume consistent with greenhouse gas forcing of climate. Major restructuring of paleotropical flora in western Euramerica occurred in step with climate and pCO2 shifts, illustrating the biotic impact associated with past CO2-forced turnover to a permanent ice-free world.     

鄱阳湖地区油菜生产气象条件分析与种植气候区划

针对鄱阳湖地区油菜生产的特点,对影响油菜生长和产量形成的气象条件进行分析,并建立油菜气候区划指标.根据鄱阳湖地区1961～2005年油菜生长季气候要素分析显示,影响该区油菜生长发育的主要气候要素为降水和日照条件,关键生长发育期为播种出苗期和开花结荚期.采用1: 5万数字高程模型(DEM)和GIS空间分析,将影响油菜生长的关键气候要素插值生成分布式数据,并根据建立的油菜气候区划指标对鄱阳湖地区油菜种植进行区划.结果表明,除鄱阳湖滨湖区及湖区的南部为油菜种植一般区外,其余地区均为油菜种植的最适区和较适区,尤其鄱阳湖地区北部,为油菜种植的最佳区.     

基于SPEI的河北省南部棉花生长季干旱特征分析

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。     

Impact of climate change on maize yield in China from 1979 to 2016

Climate change severely impacts agricultural production, which jeopardizes food security. China is the second largest maize producer in the world and also the largest consumer of maize. Analyzing the impact of climate change on maize yields can provide effective guidance to national and international economics and politics. Panel models are unable to determine the group-wise heteroscedasticity, cross-sectional correlation and autocorrelation of datasets, therefore we adopted the feasible generalized least square(FGLS) model to evaluate the impact of climate change on maize yields in China from 1979–2016 and got the following results:(1) During the 1979–2016 period, increases in temperature negatively impacted the maize yield of China. For every 1°C increase in temperature, the maize yield was reduced by 5.19 kg 667 m–2(1.7%). Precipitation increased only marginally during this time, and therefore its impact on the maize yield was negligible. For every 1 mm increase in precipitation, the maize yield increased by an insignificant amount of 0.043 kg 667 m–2(0.014%).(2) The impacts of climate change on maize yield differ spatially, with more significant impacts experienced in southern China. In this region, a 1°C increase in temperature resulted in a 7.49 kg 667 m–2 decrease in the maize yield, while the impact of temperature on the maize yield in northern China was insignificant. For every 1 mm increase in precipitation, the maize yield increased by 0.013 kg 667 m–2 in southern China and 0.066 kg 667 m–2 in northern China.(3) The resilience of the maize crop to climate change is strong. The marginal effect of temperature in both southern and northern China during the 1990–2016 period was smaller than that for the 1979–2016 period.     

Pliocene paleoclimate and East antarctic ice-sheet history from surficial ash deposits

The preservation, age, and stratigraphic relation of an in situ ashfall layer with an underlying desert pavement in Arena Valley, southern Victoria Land, indicate that a cold-desert climate has persisted in Arena Valley during the past 4.3 million years. These data indicate that the present East Antarctic Ice Sheet has endured for this time and that average temperatures during the Pliocene in Arena Valley were no greater than 3 degrees C above present values. One implication is that the collapse of the East Antarctic Ice Sheet due to greenhouse warming is unlikely, even if global atmospheric temperatures rise to levels last experienced during mid-Pliocene times.     

京津冀地区气候类型划分及其动态变化

按照与现行全国气候分类或分区方案具有可比性和同时反映京津冀地区气候分类的特殊性原则,以京津冀地区56个气象站点1961—1990年和1981—2010年2个时段的累年月值和日值观测数据为基础,采用日平均气温稳定≥10℃的日数指标划分温度带,应用校正的FAO56-Penman-Monteith模型估算潜在蒸散量并计算年干燥度,采用年干燥度指标并参照地带性植被土壤分布界线划分干湿型。结果表明,研究区共划分6种气候类型。2个时段的气候类型时空变化表明,近30年来京津冀地区暖干化趋势明显,突出表现在,中温带南界明显北移,中温带范围缩小,而暖温带范围扩大。从局地尺度看,区域西北部和南部的邢台、邯郸变暖趋势最为明显,变暖趋势最小的是包括承德南部、唐山北部的燕山山地区;东部沿海地区变干趋势最为明显,其次是西北部地区,变化较小的是区域东北部和西南部。     

五大连池火山蒙古栎和紫椴径向生长对气候变化的响应

研究不同气候因子利用策略的蒙古栎和紫椴径向生长与气候变化的关系,进而为气候变暖后,该区域火山森林生态系统管理和利用提供基础数据。以蒙古栎和紫椴为研究对象,采用树木年代学方法分析了蒙古栎和紫椴径向生长对气候变化的响应,揭示蒙古栎和紫椴径向生长-气候的关系对气温突变的响应差异。结果表明:1)五大连池火山6-7月的月平均最高气温和干燥指数与蒙古栎和紫椴年轮指数均呈显著负相关(P<0.05),这表明同一区域树木生长-气候关系具有一定的相似性,也表明6-7月的月平均最高气温和干燥指数是该地区蒙古栎和紫椴径向生长的主要限制因子。2)蒙古栎和紫椴年轮指数在突变增温(1981年)前后与气候的响应关系呈现明显的变化,气温明显变暖后与气侯的响应更加敏感; 突变增温后,南北坡向蒙古栎和紫椴树木生长-气候响应差异显著,南坡蒙古栎径向生长的趋势与温度升高的趋势相同,而北坡紫椴径向生长则呈现出随着温度升高而降低的现象。升温造成的干旱胁迫可能是2树种生长响应差异及北坡紫椴出现生长对温度变化响应的“分离现象”的重要原因。如果未来增温趋势持续或者加重,紫椴的生长可能会因干旱胁迫加剧而衰退,蒙古栎生长增长的趋势快速下降或也出现生长对温度变化响应的“分离现象”。     

Multiple thermal maxima during the holocene

The astronomical theory of climatic change provides an alternative to the traditional chronology for Holocene climatic change, which calls for one thermal maximum about 6000 years ago. The theory predicts a series of maxima during the Holocene, one for each season. Because the relation of the perihelion to the spring equinox changes with a 22,000-year period, late summer insolation would have been greatest 5000 years ago, whereas early summer insolation would have been greatest 13,000 years ago. Climatic reconstructions based on the response of ecosystems to late summer climate indicate a later Holocene thermal maximum than paleoclimatic data sensitive to early summer climate. In southern Idaho, three different vegetation types indicate thermal maxima at different times during the Holocene, depending on the climatic variable controlling each type.     

豫南雨养区夏玉米产量与气象因子的关系

根据豫南雨养区方城、西平两县1995-2008年的夏玉米单产和同期气象资料,分析了该区生长期间气温、降水量、日照时数等气象因子对夏玉米气象产量的影响。结果表明,水分影响夏玉米生育的全过程,与光照时数相比,气温显著影响产量,6月、8月的降水量、7月的气温是影响夏玉米产量的关键气象因子。     

气象因子对南疆地区骏枣果实品质的影响

为了了解新疆南疆地区气象因子对骏枣果实品质的影响,分析了2015-2016年南疆地区阿克苏、和田及库尔勒三个地区的温度、日照量、降雨量、相对湿度和风速等气象数据,研究了气候变化情况对骏枣果实品质的作用规律。通过对比两年内12项气象因子对单果重、Vc和可溶性总糖含量等骏枣果实品质的影响,发现南疆气候条件对骏枣果实品质有明显影响,不同品质指标的气象影响因子有所不同。结果表明对骏枣品质的关键指标（单果重、蛋白质、Vc和可溶性总糖含量）影响较大的气象因子分别为平均气温、平均最高温度、日照时数和降水量。其中Vc和可溶性总糖受空气平均最低温度的影响最明显。     

夏季哈德莱环流强度变化与亚洲季风区经向水汽输送的关系

采用NCEP/NCAR再分析资料,计算了夏季哈德莱环流(H.C.)强度,分析了夏季H.C.强度年际、年代际变化特征,以及亚洲季风区夏季水汽输送的气候特征,并研究了夏季哈德莱环流强度与亚洲季风区水汽输送的关系。结果表明,1979~2010年夏季南半球H.C.强度有明显增强趋势,同时也有明显的年际变化。索马里东部洋面和印尼东部洋面是南半球水汽北转输入亚洲的重要区域;夏季南半球哈德莱环流强度与索马里东部洋面和印尼东部洋面的经向水汽输送呈显著的正相关关系,与在我国中东部—南海南部、阿拉伯海东南部的经向水汽输送呈显著的负相关关系。     

Stable Isotopic Evidence for a Pedogenic Origin of Carbonates in Trench 14 near Yucca Mountain, Nevada

Layered carbonate and silica encrust fault fractures exposed in Trench 14 near Yucca Mountain, site of the proposed high-level nuclear waste repository in southern Nevada. Comparison of the stable carbon and oxygen isotopic compositions of the fracture carbonates with those of modern soil carbonates in the area shows that the fracture carbonates are pedogenic in origin and that they likely formed in the presence of vegetation and rainfall typical of a glacial climate. Their isotopic composition differs markedly from that of carbonate associated with nearby springs. The regional water table therefore remained below the level of Trench 14 during the time that the carbonates and silica precipitated, a period probably covering parts of at least the last 300,000 years.     

气候和土壤类型对湿地松人工林生长和材质的影响

湿地松人工林林分生长和材质在不同气候和土壤类型条件下差异的比较分析表明:生长在南亚热带山地黄红壤上的湿地松人工林林分的胸径和树高以及木材密度和力学强度大于生长在中亚热带山地黄红壤上的,而木材尺寸稳定性表现则相反;生长在南亚热带滨海沙地林分的胸径和树高以及木材密度和力学强度均小于生长在南亚热带山地黄红壤上的,木材尺寸稳定性则表现相反。差异显著性t检验的结果表明:气候和土壤类型极显著或显著影响湿地松人工林林分胸径和树高以及木材密度、干缩性和力学强度。     

Southern Hemisphere water mass conversion linked with North Atlantic climate variability

Intermediate water variability at multicentennial scales is documented by 340,000-year-long isotope time series from bottom-dwelling foraminifers at a mid-depth core site in the southwest Pacific. Periods of sudden increases in intermediate water production are linked with transient Southern Hemisphere warm episodes, which implies direct control of climate warming on intermediate water conversion at high southern latitudes. Coincidence with episodes of climate cooling and minimum or halted deepwater convection in the North Atlantic provides striking evidence for interdependence of water mass conversion in both hemispheres, with implications for interhemispheric forcing of ocean thermohaline circulation and climate instability.     

1951-2010年南方晚稻气候适宜度时空变化特征分析

气候变化引起作物气候适宜度,为了明确1951—2010年南方晚稻气候适宜度的时空演变特征,研究依据南方稻区196个站点的1951—2010年逐日气象数据和作物生育期数据,采用现有的气候适宜度评估模型,分1951—1980年、1981—2010年2个时段对南方稻区晚稻生育期内气候适宜度的时空演变特征进行分析。结果表明,南方稻区晚稻气候适宜度呈下降趋势,且1981年以后下降趋势较为明显;其中,研究区内晚稻的温度适宜度总体呈增加趋势,而降水适宜度则呈先增加后降低的趋势,光照适宜度则总体呈显著的下降趋势。晚稻气候适宜度、光照适宜度及温度适宜度皆呈由东向西逐渐递减空间分布特征,降水适宜度空间分布特征不明显。从生育期来看,晚稻抽穗开花期的温度、降水适宜度均较低,为此,晚稻抽穗开花期应注意温度与水分的管理。文章的结果可为南方晚稻的田间管理提供理论参考。     

Mediterranean moisture source for an early-Holocene humid period in the northern Red Sea

Paleosalinity and terrigenous sediment input changes reconstructed on two sediment cores from the northernmost Red Sea were used to infer hydrological changes at the southern margin of the Mediterranean climate zone during the Holocene. Between approximately 9.25 and 7.25 thousand years ago, about 3 per thousand reduced surface water salinities and enhanced fluvial sediment input suggest substantially higher rainfall and freshwater runoff, which thereafter decreased to modern values. The northern Red Sea humid interval is best explained by enhancement and southward extension of rainfall from Mediterranean sources, possibly involving strengthened early-Holocene Arctic Oscillation patterns and a regional monsoon-type circulation induced by increased land-sea temperature contrasts. We conclude that Afro-Asian monsoonal rains did not cross the subtropical desert zone during the early to mid-Holocene.