PALEOCLIMATE: Taking the Temperature of Past Ocean Surfaces

Accurate reconstructions of past climatic conditions on Earth are important for modeling future climate change. Researchers use climate "proxies" from deep-sea sediments, corals, or ice cores to reconstruct these past climatic conditions, but as Nürnberg explains in this Perspective, different techniques often give different answers. A relatively new technique, Mg/Ca paleothermometry, is a particularly promising tool, especially in conjunction with oxygen isotope measurements on the same planktonic foraminiferal specimens. The power of this method is exemplified by the study by Lea et al.     

Comment on "Intensifying weathering and land use in Iron Age Central Africa"

Bayon et al. (Reports, 9 March 2012, p. 1219) interpreted unusually high aluminum-potassium ratio values in an Atlantic sediment core as indicating anthropogenic deforestation around 2500 years before the present (B.P.). We argue that there is no terrestrial evidence for forest destruction by humans and that the third millennium B.P. rainforest crisis can be clearly attributed mostly to climatic change.     

Forests of the past: a window to future changes

The study of past forest change provides a necessary historical context for evaluating the outcome of human-induced climate change and biological invasions. Retrospective analyses based on fossil and genetic data greatly advance our understanding of tree colonization, adaptation, and extinction in response to past climatic change. For instance, these analyses reveal cryptic refugia near or north of continental ice sheets, leading to reevaluation of postglacial tree migration rates. Species extinctions appear to have occurred primarily during periods of high climatic variability. Transoceanic dispersal and colonization in the tropics were widespread at geological time scales, inconsistent with the idea that tropical forests are particularly resistant to biological invasions.     

CLIMATE: A New Route Toward Limiting Climate Change?

Climate change mitigation strategies have focused on reductions in carbon dioxide and other long-lived greenhouse gases. Smith et al., investigate the viability of a different strategy, recently proposed by Hansen et al., which focuses on controlling short-lived pollutants such as soot and tropospheric ozone. They conclude that carbon dioxide must remain the primary focus of climate change mitigation strategies.     

Speciation and stasis in marine ostracoda: climatic modulation of evolution

Morphologic and paleozoogeographic analysis of Cenozoic marine Ostracoda from the Atlantic, Caribbean, and Pacific indicates that climatic change modulates evolution by disrupting long-term stasis and catalyzing speciation during sustained, unidirectional climatic transitions and, conversely, by maintaining morphologic stasis during rapid, high-frequency climatic oscillations. In the middle Pliocene, 4 to 3 million years ago, at least six new species of Puriana suddenly appeared as the Isthmus of Panama closed, changing oceanographic circulation and global climate. Since then morphologic stasis has characterized ancestral and descendant species during many glacial-interglacial cycles. The frequency and duration of climatic events have more impact on ostracode evolution than the magnitude of climatic changes.     

Hydrological impact of heinrich events in the subtropical northeast atlantic

Reconstructing the impact of Heinrich events outside the main belt of ice rafting is crucial to understanding the underlying causes of these abrupt climatic events. A high-resolution study of a marine sediment core from the Iberian margin demonstrates that this midlatitude area was strongly affected both by cooling and advection of low-salinity arctic water masses during the last three Heinrich events. These paleoclimatic time series reveal the internal complexity of each of the last three Heinrich events and illustrate the value of parallel studies of the organic and inorganic fractions of the sediments.     

Medicine. Communicating statistical information

Most people, experts included, have difficulties understanding and combining statistical information effectively. Hoffrage et al. demonstrate that these difficulties can be considerably reduced by communicating the information in terms of natural frequencies rather than in terms of probabilities. Several applications in medicine, legal decision-making, and education are discussed.     

Equatorial pacific seismic reflectors as indicators of global oceanographic events

The origin of a series of regionally correlatable seismic horizons in the Neogene sediments of the central equatorial Pacific is examined through seismic modeling and the detailed analyses of stratigraphic and physical property relationships in Deep Sea Drilling Project cores. These regionally traceable reflectors are synchronous; the younger reflectors are the direct result of carbonate dissolution events, the older ones of stratigraphically selective diagenetic processes. The changes in ocean chemistry associated with these events appear to be linked to global reorganizations of surface and bottom-water circulation patterns, the most dramatic of which are associated with reorganizations of North Atlantic bottom waters. These deepwater seismic horizons appear to correlate with the major events on the "relative sea-level" curve of Vail et al. for the Neogene.     

Comment on "Erosion of lizard diversity by climate change and altered thermal niches"

Using a regionally calibrated model, Sinervo et al. (Reports, 14 May 2010, p. 894) predicted potential climate change impacts on lizard populations and estimated that many extinctions are under way. We argue that this model is not sufficient for predicting global losses in lizard species in response to anthropogenic climate change.     

桂林动物物候对气候变化的响应分析

利用统计学方法,对桂林气候（1951—2008年）和3种动物物候（1983—2008年）的趋势变化特征进行了分析,并探讨了动物物候期与气温、降水、日照等气候因子的相关性及其对主要气候影响因子的响应情况。结果表明,在气候变化背景下,桂林市动物各个物候期发生了不同程度的变化,始鸣（见）期和绝鸣（见）期既有提前,又有推迟,始鸣（见）期以呈提前趋势为主,绝鸣（见）期以呈推迟趋势为主;始绝鸣（见）间隔日数,3种动物均一致延长。桂林市动物物候期与其发生时和发生前1～5个月的气候因子相关较显著。动物物候期变化对气温和降水量变化的响应最敏感,而对日照的反映不敏感,即动物物候期的变化主要是气温和降水变化共同作用的结果。     

朝阳地区2013年春季极端天气气候特征及对农业的影响分析

为了加强适应气候变化特别是应对极端气候事件能力建设、降低灾害风险,利用朝阳地区7个观测站的降水和气温历史资料,通过气候统计和95(5)百分位等方法,分析了朝阳地区春季天气气候变化规律。结果表明,2013年4—5月朝阳地区气候出现异常变化,发生了温度极端冷气候事件和降水极端偏少事件,对朝阳地区的种植业、畜牧业等产生了较大的负面影响。     

近40年烟台蒸发皿蒸发量变化特征

蒸发作为大气水分和热量平衡的主要因子,也是地球水循环受气候变化影响的重要指标。进行蒸发量变化的研究,对更深入地了解区域气候变化、实现水资源可持续利用有着重要意义。利用烟台1971～2010年期间逐月蒸发皿(口径20 cm)蒸发量资料,采用主成份分析法,得出烟台蒸发皿蒸发量近40年变化较大,年代特征明显。近40年蒸发皿蒸发量呈总体下降趋势,蒸发量气候倾向率为-55.7 mm/10a,其绝对值高于全国平均变化速率-30.7 mm/10a的绝对值。不同季节蒸发皿蒸发量变化趋势不同,蒸发量下降主要在春季和秋季,夏季不明显,而冬季蒸发量呈上升趋势。     

吕梁山地形对气候的影响分析

本研究以中尺度区域气候差异与地形的关系为研究方向,对吕梁山东、西两侧近同一纬度区域的气候要素数据进行分析。以榆林市、原平市、延安市、介休市为研究样区,收集30年(1989—2018年)的年均气温和年均降水量数据,采用Mann-Kendall检验方法进行气候变化趋势分析和气候突变检验。结果表明,北段、南段的东西侧气候变化趋势和气候突变具有差异性,但南北段东西两侧气候变化不同步。由于南北段的东西侧研究区域纬度地带性和经度地带性影响很小,可见吕梁山地形对吕梁山东、西两侧的气候产生了一定的影响。通过本研究,对于如何根据吕梁山具体地形条件分析气候变化,进一步合理配置农、林、牧、副和旅游等产业具有重要意义。     

Cell biology. ER-to-Golgi traffic--this bud's for you

How do protein-transporting vesicles, which bud from the endoplasmic reticulum (ER), specifically dock to, and fuse with, the Golgi apparatus? In their Perspective, Brittle and Waters discuss new work (Allan et al.) suggesting that some vesicle-associated docking and fusion proteins are "programmed" during vesicle budding from the ER and direct downstream events that occur during fusion of these transport vesicles with the membranes of the Golgi.     

气候变化与对荆州市粮食安全影响的思考

运用二次多项式回归方法,模拟分析出荆州市近54年来逐年平均气温呈整体上升趋势.气候变暖;揭示了荆州市在全球气候变暖的大背景下,近年极端天气气候事件频发,阶段性的低温冷害也时有发生的区域气候变化事实;提出了应时气候变化,保障荆州粮食安全的必要措施.     

Planetary science. The weather on Titan

When the Voyager 1 spacecraft returned images in 1980, the dense atmosphere of Saturn's moon Titan was assumed to be bland and featureless. As Lorenz discusses in his Perspective, recent ground-based spectroscopy, and images from the Hubble Space Telescope, are changing this perception. Observations such as the short-lived clouds in Titan's atmosphere reported by Griffith et al. suggest that although average precipitation is likely to be low, individual precipitation events may be heavy enough to cause deep valleys on Titan's surface.     

Climatic change: are we on the brink of a pronounced global warming?

If man-made dust is unimportant as a major cause of climatic change, then a strong case can be made that the present cooling trend will, within a decade or so, give way to a pronounced warming induced by carbon dioxide. By analogy with similar events in the past, the natural climatic cooling which, since 1940, has more than compensated for the carbon dioxide effect, will soon bottom out. Once this happens, the exponential rise in the atmospheric carbon dioxide content will tend to become a significant factor and by early in the next century will have driven the mean planetary temperature beyond the limits experienced during the last 1000 years.     

气候变化对青藏高原陆地生态系统的影响研究进展

气候变化对陆地生态系统的影响及其反馈是当前全球变化研究的重要内容,青藏高原是全球气候变化的敏感区和启动区,气候变化对青藏高原陆地生态系统的影响是当前全球气候变化的重要研究领域。系统总结了目前关于气候变化对青藏高原陆地生态系统的影响与反馈的相关研究,最后根据当前研究中存在的问题,讨论了未来的研究方向。     

Long-distance dispersal of plants

Long-distance dispersal (LDD) of plants poses challenges to research because it involves rare events driven by complex and highly stochastic processes. The current surge of renewed interest in LDD, motivated by growing recognition of its critical importance for natural populations and communities and for humanity, promises an improved, quantitatively derived understanding of LDD. To gain deep insights into the patterns, mechanisms, causes, and consequences of LDD, we must look beyond the standard dispersal vectors and the mean trend of the distribution of dispersal distances. "Nonstandard" mechanisms such as extreme climatic events and generalized LDD vectors seem to hold the greatest explanatory power for the drastic deviations from the mean trend, deviations that make the nearly impossible LDD a reality.     

Comment on "A global map of human impact on marine ecosystems"

Halpern et al. (Reports, 15 February 2008, p. 948) integrated spatial data on 17 drivers of change in the oceans to map the global distribution of human impact. Although fishery catches are a dominant driver, the data reflect activity while impacts occur at different space and time scales. Failure to account for this spatial disconnection could lead to potentially misleading conclusions.