Palaeoclimatic cycles and new glacial periods induced by the impact of extraterrestrial bodies

THE consequence of "nuclear winter" induced by nuclear war and climatic catastrophe induced by extraterrestrial impact were widely studied for fear of the potential danger of the basic nuclear war (the totalexplosive equivalent 5 000Mt TNT). Using zero-dimensional energy balance model authors reportedthe short-term climatic effect induced by six huge Cenozoic bolide-impact events (65, 34, 15, 2.4,1.1, 0.73 MaBP). However, only the direct climatic effect of dusts yielded by the impact was considered in the previous study. In this note, based on the previous simulation results the effect of variance ofglobal reflectance with temperature on the long-term climatic change was further taken into consideration.Combined with the strata records of palaeoclimatic change the relationship of impact energy with its in-

Glacial reconstruction and periglacial dynamics at the end of Late Pleistocene on the surface of Cofre de Perote volcano,México:a climatological retrospective

Despite being within the intertropical region of the planet,the Mexican territory still has glacier-covered mountains.In recent decades,important advances have been made in studies on glaciology and periglacial environment in Mexico both for current and past conditions.However,in spite of Cofre de Perote volcano(4200 m a.s.l.)being a strategically located mountain,it has not yet been studied in regards to the glacial and periglacial processes;in fact,those dynamics have modified the mountain massifs in the past.To complement the series of studies on glacial history in the high mountain environment of México,this study reconstructs the glacial cover and the periglacial environment of the volcano surface during the final stage of the Late Pleistocene based on climatic retrospective and through the identification of geomorphological features.The findings indicate the existence of a large glacier(ice cap)that covered the northern,western,and southern slopes of the mountain;while in the eastern sector there were two small glaciers,one being of cirque type,and the other of valley type.The current temperature conditions prevent the occurrence of permanent ice bodies;at the same time,it was found that the periglacial blockfields of the slopes is a legacy of the climatic conditions that prevailed at the end of Late Pleistocene.

Palaeoclihlatic Indicators of China's Quaternary Saline Lake Sediments and Hydrochemistry

In this paper the authors classify saline lake sediments into the cold, warm and eurythermal phases, reveal the consistency between the zoning of hydrochemical types of modern saline lake water and climatic zoning and give climatic parameters under the conditions of typical cold phase (mirabilite and natron), warm phase (thenar-dite) and slightly warm phase (bloedite) saline lake deposition.

VEGETATION AND ENVIRONMENT OF EASTERN CHINA IN THE COLD STAGES OF THE QUATERNARY

In the cold stages of the Quaternary,steppe vegetation was dominant over eastern China as a consequence of long-term aridity.Steppe,forest-steppe and tundra might span conterminously from southern Europe to East Asia.In the South China floral region,subtropical coniferous forests extended widely over plains and hills.Many taxa of hydrophilic and/or thermophilic plants have survived in sanctuaries.The impact of cold climate in the Quaternary might be limited in severity and extent in eastern China.

Solar Activity and Climate Change Hazards

This paper discusses that the global worming caused by the green-house gases effect will be equal or less than that of the global cooling resulting from the solar activities. In this respect, we refer to the MDM （Modern Dalton Minimum） which stated that starting from 2005 to the next 40 years; the earth＇s surface temperature will become cooler than nowadays. However, the degree of cooling, previously mentioned in old Dalton Minimum （c. 210 year ago）, will be minimized by building-up of green-house gases effect during MDM period. Regarding to the periodicities of solar activities, it is clear that we have a new solar cycle of around 210 years now.

Implications for soil environment from uranium isotopes of stalagmites

By analyzing U and Th isotopic compositions of 41 samples in two stalagmites from Hulu Cave, Nanjing, we first discovered that variations of 238U and δ234U0 along the stalagmite growth-sequence (covering a period from 75 to 18 kaBP) are in high similarity to summer insolation curve at 33°N and δ18O-based climate record of the studied stalagmites. The concentration of 238U is mainly controlled by content of organic matter in the soil above the cave. This mechanism can be used to explain our result that 238U curve of stalagmites is in phase with fluctuation of the δ18O record of the same stalagmites and summer insolation at cave locality. However, 238U concentration curve vs. age is, in amplitude, inconsistent with the climatic curves, possibly due to complex processes of soil-water-rock interaction. δ234U0 indicates pedogenic intensity of soil profile above the cave and sensitively reflects alternations of pedogenesis and aeolian accumulation processes of Xiashu loess in Nanjing. Consequently,

Calcareous nannoplankton dating of the Late Quaternary deposits in Greece and the eastern Mediterranean: Case studies from terrestrial and marine sites

The distribution and abundance of Emiliania huxleyi（E. huxleyi） assemblages in the marine sediments of the Aravonitsa Plateau, Greece, and from the eastern Mediterranean are used（1） to evaluate the calcareous nannoplankton NN21 a and NN21 b biozones and the NN21a/NN21 b boundary, and（2） to analyze the palaeoenvironmental and palaeoclimatic conditions prevailing in this interval. The sediment succession displays varied E. huxleyi assemblages and these are interpreted as reflecting climatic variability during marine isotope stages MIS 1-8.