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Climatic Reconstruction (climatic + reconstruction)

Distribution by Scientific Domains
Earth and Environmental Science75%

Selected Abstracts

Coherence of climatic reconstruction from historical documents in China by different studies

INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 8 2008
Quansheng Ge
Abstract Much effort has been spent in the last few decades to reconstruct the climate over China using a variety of historical documents. However, differences in the results of reconstructions exist even when people are using similar documents. In order to address this issue, 14 published temperature series by different studies were analyzed for coherence and mutual consistency. The analyses on their temporal fluctuations indicate that for the individual time series (standardized) on the 10-years time scales, 57 of the 91 correlation coefficients reach the significance level of 99%. The spatial patterns among the different time series also show high coherency. In addition, consistency also exhibit when comparing the reconstructions with other available natural climate change indicators. Above information was subsequently used to synthesize the temperature series for the last 500 and 1000 years. Copyright © 2007 Royal Meteorological Society [source]

Pilot study of latewood-width of conifers as an indicator of variability of summer rainfall in the North American monsoon region

INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 6 2001
David M. Meko
Abstract The variability of the North American Monsoon System (NAMS) is important to the precipitation climatology of Mexico and the southwestern United States. Tree-ring studies have been widely applied to climatic reconstruction in western North America, but as yet, have not addressed the NAMS. One reason is the need for highly resolved seasonal dendroclimatic information. Latewood-width, the portion of the annual tree ring laid down late in the growing season, can potentially yield such information. This paper describes a pilot study of the regional summer precipitation signal in latewood-width from a network of five Pseudotsuga menziesii chronologies developed in the heart of the region of NAMS influence in Arizona, USA. Exploratory data analysis reveals that the summer precipitation signal in latewood is strong, but not equally so over the full range of summer precipitation. Scatter in the relationship increases toward higher levels of precipitation. Adjustment for removal of inter-correlation with earlywood-width appears to strengthen the summer precipitation signal in latewood-width. To demonstrate a possible application to climatic reconstruction, the latewood precipitation signal is modelled using a nonlinear model,a binary recursive classification tree (CT) that attempts to classify summers as dry or not dry from threshold values of latewood-width. The model identifies narrow latewood-width as an effective predictor of a dry summer. Of 14 summers classified dry by latewood-width for the period 1868,1992, 13 are actually dry by the instrumental precipitation record. The results suggest that geographical expansion of coverage by latewood-width chronologies and further development of statistical methods may lead to successful reconstruction of variability of the NAMS on century time scales. Copyright © 2001 Royal Meteorological Society [source]

Reconstructing the demise of Tethyan plants: climate-driven range dynamics of Laurus since the Pliocene

GLOBAL ECOLOGY, Issue 6 2008
Francisco Rodríguez-Sánchez
ABSTRACT Aim Climate changes are thought to be responsible for the retreat and eventual extinction of subtropical lauroid species that covered much of Europe and North Africa during the Palaeogene and early Neogene; little is known, however, of the spatial and temporal patterns of this demise. Herein we calibrate ecological niche models to assess the climatic requirements of Laurus L. (Lauraceae), an emblematic relic from the Tethyan subtropical flora, subsequently using these models to infer how the range dynamics of Laurus were affected by Plio-Pleistocene climate changes. We also provide predictions of likely range changes resulting from future climatic scenarios. Location The Mediterranean Basin and Macaronesian islands (Canaries, Madeira, Azores). Methods We used a maximum-entropy algorithm (Maxent) to model the relationship between climate and Laurus distribution over time. The models were fitted both to the present and to the middle Pliocene, based on fossil records. We employed climatic reconstructions for the mid-Pliocene (3 Ma), the Last Glacial Maximum (21 ka) and a CO2 -doubling future scenario to project putative species distribution in each period. We validated the model projections with Laurus fossil and present occurrences. Results Laurus preferentially occupied warm and moist areas with low seasonality, showing a marked stasis of its climatic niche. Models fitted to Pliocene conditions successfully predicted the current species distribution. Large suitable areas existed during the Pliocene, which were strongly reduced during the Pleistocene, but humid refugia within the Mediterranean Basin and Macaronesian islands enabled long-term persistence. Future climate conditions are likely to re-open areas suitable for colonization north of the current range. Main conclusions The climatic requirements of Laurus remained virtually unchanged over the last 3 Myr. This marked niche conservatism imposed largely deterministic range dynamics driven by climate conditions. This species's relatively high drought tolerance might account for the survival of Laurus in continental Europe throughout the Quaternary whilst other Lauraceae became extinct. Climatic scenarios for the end of this century would favour an expansion of the species's range towards northern latitudes, while severely limiting southern populations due to increased water stress. [source]

Coleoptera from the Late Weichselian deposits at Nřrre Lyngby, Denmark and their bearing on palaeoecology, biogeography and palaeoclimate

BOREAS, Issue 1 2000
GEOFFREY RUSSELL COOPE
The freshwater sediments exposed on the cliffs at Nřrre Lyngby northern Jutland has long been a classical locality for the study of Danish Quaternary geology, palaeontology and archaeology. These deposits date from the latter part of the Allerřd period (i.e. G I-1). Samples for insect analysis have been taken from both the northern and southern exposures of these deposits. Ninety-five- taxa of Coleoptera (beetles) were obtained, of which 69 could be named to species. Of the latter, 23 are not found living in Denmark today. Most of these are still living in northern Fennoscandia but one species is now confined to Mongolia. These assemblages have enabled a detailed picture of the local environment to be reconstructed, showing that the basin-like profile of the deposits represents a section through a channel with slowly moving water. It has been possible to quantify the thermal climate of the time using the Mutual Climatic Range method indicating that mean July temperatures were about 10°C and mean January temperatures were about , 12°C. These figures are considered in the context of Lateglacial climatic reconstructions obtained from coleopteran assemblages elsewhere in northwestern Europe. [source]