Temperature and precipitation effects on wheat yield across a European transect: a crop model ensemble analysis using impact response surfaces

This study explored the utility of the impact response surface (IRS) approach for investigating model ensemble crop yield responses under a large range of changes in climate. IRSs of spring and winter wheat Triticum aestivum yields were constructed from a 26-member ensemble of process-based crop simulation models for sites in Finland, Germany and Spain across a latitudinal transect. The sensitivity of modelled yield to systematic increments of changes in temperature (-2 to +9°C) and precipitation (-50 to +50%) was tested by modifying values of baseline (1981 to 2010) daily weather, with CO2 concentration fixed at 360 ppm. The IRS approach offers an effective method of portraying model behaviour under changing climate as well as advantages for analysing, comparing and presenting results from multi-model ensemble simulations. Though individual model behaviour occasionally departed markedly from the average, ensemble median responses across sites and crop varieties indicated that yields decline with higher temperatures and decreased precipitation and increase with higher precipitation. Across the uncertainty ranges defined for the IRSs, yields were more sensitive to temperature than precipitation changes at the Finnish site while sensitivities were mixed at the German and Spanish sites. Precipitation effects diminished under higher temperature changes. While the bivariate and multi-model characteristics of the analysis impose some limits to interpretation, the IRS approach nonetheless provides additional insights into sensitivities to inter-model and inter-annual variability. Taken together, these sensitivities may help to pinpoint processes such as heat stress, vernalisation or drought effects requiring refinement in future model development.

Pollen abundances, and temperature and precipitation reconstruction for the Eocene to Oligocene transition in northern high latitudes

A profound global climate shift took place at the Eocene-Oligocene transition (~33.5 million years ago) when Cretaceous/early Palaeogene greenhouse conditions gave way to icehouse conditions (Zachos et al., 2001, doi:10.1126/science.1059412; Coxall et al., 2005, doi:10.1038/nature03135; Lear et al., 2008, doi:10.1130/G24584A.1). During this interval, changes in the Earth's orbit and a long-term drop in atmospheric carbon dioxide concentrations (Pagani et al., 2005, doi:10.1126/science.1110063; Pearson and Palmer, 2000, doi:10.1038/35021000; DeConto and Pollard, 2003, doi:10.1038/nature01290) resulted in both the growth of Antarctic ice sheets to approximately their modern size (Coxall et al., 2005, doi:10.1038/nature03135; Lear et al., 2008, doi:10.1130/G24584A.1) and the appearance of Northern Hemisphere glacial ice (Eldrett et al., 2007, doi:10.1038/nature05591; Moran et al., 2006, doi:10.1038/nature04800). However, palaeoclimatic studies of this interval are contradictory: although some analyses indicate no major climatic changes (Kohn et al., 2004, doi:10.1130/G20442.1; Grimes et al., 2005, doi:10.1130/G21019.1), others imply cooler temperatures (Zanazzi et al., 2007, doi:10.1038/nature05551), increased seasonality (Ivany et al., 2000, doi:10.1038/35038044; Terry, 2001, doi:10.1016/S0031-0182(00)00248-0) and/or aridity (Ivany et al., 2000, doi:10.1038/35038044; Terry, 2001, doi:10.1016/S0031-0182(00)00248-0; Sheldon et al., 2002, doi:10.1086/342865; Dupont-Nivet et al., 2007, doi:10.1038/nature05516). Climatic conditions in high northern latitudes over this interval are particularly poorly known. Here we present northern high-latitude terrestrial climate estimates for the Eocene to Oligocene interval, based on bioclimatic analysis of terrestrially derived spore and pollen assemblages preserved in marine sediments from the Norwegian-Greenland Sea. Our data indicate a cooling of ~5 °C in cold-month (winter) mean temperatures to 0-2 °C, and a concomitant increased seasonality before the Oi-1 glaciation event. These data indicate that a cooling component is indeed incorporated in the d18O isotope shift across the Eocene-Oligocene transition. However, the relatively warm summer temperatures at that time mean that continental ice on East Greenland was probably restricted to alpine outlet glaciers.

United States historical climatology network (HCN) serial temperature and precipitation data /

Twenty-eight microfiches (11 x 15 cm.) in pocket mounted on cover p. [3]. Header title: Historical climate network--temperature and precipitation data plots.

Atlas of frequency distribution, auto-correlation and cross-correlation of daily temperature and precipitation at stations in the U.S., 1948-1991 (in English units) /

"September 1993."

毛乌素沙地优势植物对全球气候变化的响应研究

毛乌素沙地是中国半干旱地区典型沙地，这里的干旱生态系统对全球的水热配合格局的变化具有很灵敏的响应。随着未来全球气候变化，如温度和降水量变化，将给这里的陆地生态系统分布格局和生产力以及水分平衡带来巨大影响。故本文人工控制157. 5mm、315. Omm、472. 5mm和630. Omm4种施水量水平以及25/20℃和28/23℃（白天／晚上）两种温度，来研究与模拟毛乌素沙地优势植物对水分和温度变化的响应。 以沙柳、杨柴和油蒿幼苗为研究对象，人工控制4种降水量水平来探讨它们的水分平衡对全球变化中降水量变化的响应。结果表明，随着施水量的增加，沙地贮水量及其它的变化量、湿度、蒸发量和蒸腾量均逐渐增大。并且157. 5mm和315. Omm施水量的植物沙地出现水分亏缺现象。相同施水量下，沙地蓄水量和湿度均杨柴沙地>沙柳沙地>油蒿沙地，而植物蒸腾量却油蒿>沙柳>杨柴。 以沙柳和油蒿幼苗为研究对象，人工控制4种降水量水平来探讨植物气体交换过程对全球变化中降水量变化的响应。结果表明，施水量的增加显著提高了两种植物的净光合速率、蒸腾速率、气孔导度和光能利用效率，并且显著降低了叶片温度。同时，157. 5mm施水量造成沙柳和油蒿的净光合速率和蒸腾速率具有显著的“午睡”现象，而充足施水却有效的解除或缓解这种“午睡”现象。 以沙柳、杨柴、油蒿和柠条幼苗为研究对象，人工控制4种降水量水平来探讨植物叶绿素荧光对全球变化中降水量变化的响应。结果表明，不同施水量对这4种植物的初始荧光、最大荧光、可变荧光和PSII光化学效率均具有显著影响。157. 5mm施水量的沙柳、杨柴、油蒿和柠条以及630. Omm施水量的柠条出现明显的光抑制现象。 以沙柳、杨柴、油蒿和柠条幼苗为研究对象，人工控制4种降水量水平来探讨植物生长对全球变化中降水量变化的响应。结果表明，施水量的增加对沙柳、油蒿和杨柴枝叶形态和生物量等都具有显著正效应。而157. 5mm和630. Omrn的施水量对柠条生长具有负作用。另外，沙柳、杨柴和油蒿根冠生物量比随着施水量增加均逐渐减小，而不同施水量的油蒿根冠生物量比之间差异不显著。 以柠条、杨柴和油蒿幼苗为研究对象，人工控制两种温度水平来探讨植物形态、生物量和气候交换特征对增温的响应。结果表明，增温显著提高了柠条和杨柴株高、叶数、叶面积、生物量、净光合速率、蒸腾速率和气孔导度，却显著降低了水分利用效率。增温对油蒿叶数、叶大小、叶面积、生物量、蒸腾速率和气孔导度没有显著影响，却显著提高了油蒿的树高和净光合速率。柠条、杨柴和油蒿之间的种间生长和生理特征均有显著差异。