中国不同气候区河川径流对气候变化的敏感性

利用一个简单的月水量平衡模型,模拟了位于中国不同气候区的21个典型流域的径流量过程,采用假定的气候情景,分析了河川径流量对不同气候变化的敏感性。结果表明,所采用的月水量平衡模型能够较好地模拟不同气候区的月流量过程,21个典型流域的Nash-Sutcliffe模型效率系数大多超过65%,水量平衡误差也均控制在1%以内。黄河以北干旱半干旱地区的典型流域径流量对气温和降水变化的响应敏感,其次为华中、华南半湿润区和湿润区,西部高寒山区径流对气候变化的响应最弱。因此,中国适应气候变化的重点应集中在干旱半干旱地区。     

Biogeography and climatic change as a context to human dispersal out of Africa and within Eurasia

The dispersal of the genus Homo occurred against a background of continuous environmental change. Here, dispersals of large mammals through the Levantine Corridor and into Western Europe and Java are studied and compared to existing records of climatic change and dispersals of early humans and lithic industry.The first human dispersal (with Oldowan lithic industry) out of Africa, around or shortly before 1.8 Ma may have been triggered by biological evolution and increased social organisation, rather than environmental change. After that event, increasing aridity led to decreased faunal exchange between Africa and Eurasia and may have isolated the human populations of Africa and Africa. Southern (Java) and Eastern Asia (China) also seem to have been isolated. Human dispersal into Western Europe may have been limited by closed environments in Central Europe until about 1.2 Ma ago, when faunal dispersal into Europe suggests the cyclic spread of open environments to the west. Acheulean technology originated in Africa, some 1.6–1.5 Ma ago, but its dispersal into Eurasia may have been obstructed by an arid Southwest Asia, until broadly about 0.9 Ma ago, when faunal exchange suggests that the area became temporarily less dry. By 0.6–0.5 Ma ago it reached Europe.     

Lower Devonian conodont zonation in arctic regions of Eurasia

The evolution of viewpoints on the Lower Devonian conodont zonal stratigraphy in Arctic regions of Eurasia is considered. The morphophylogenetic analysis of the Early Devonian conodonts is used to elaborate the Lower Devonian conodont zonation.     

Unravelling the evidence of climatic change

Book reviewed in this article:
Mörner, N-A. & Karlén, W. (eds.) 1984: Climatic Changes on a Yearly to Millennial Basis .     

Energy sector policies in Botswana and their implications for global climate change

Like most African countries, Botswana contributes almost insignificantly to global greenhouse emissions (GHGs). In this context, some have argued that energy policy and legislative measures to regulate emissions in Botswana should not be accorded high priority. This is a misguided view when one considers that each country, no matter how under-industrialized, contributes to the overall global emission problem. Moreover, the least developed countries will have to industrialize in order to meet the increasing economic and social needs of their growing populations. For rapidly growing economies like Botswana, whose annual energy demand is projected to increase by about 4% for the next ten years, the importance of compiling accurate inventories of sources and sinks of GHGs and formulating environmentally-friendly policies can hardly be over- emphasized. The United Nations Framework Convention on Climate Change (UNFCCC) provides the ideal basis for the country-by-country investigations and management of global climatic change; specifically its nature, properties, directionality, characteristics and probable consequences. Botswana was a founding signatory of UNFCCC in 1992 and ratified the Convention in 1994. The country is also involved in regional cooperation efforts, within the Southern African Development Community, to enforce regulatory mechanisms to minimize GHG emissions from the energy sector. There exist certain energy-related institutions, policies, and regulations in the country which could mitigate the impact of GHG emissions on global warming. This paper, based on government and other relevant documentation, critically analyses Botswana's energy sector policies in as far as they affect climate change. It is clear that much still needs to be done about energy policies in terms of proper formulation, monitoring, co-ordination, energy pricing and the exploration of energy alternatives to mitigate potentially negative impacts on climate change.     

Nondeterministic theories of climatic change

A basic assumption in some climatic theories is that, given the physical properties of the atmosphere and the underlying ocean and land, specified environmental parameters (amount of solar heating, etc.) would determine a unique climate and that climatic changes therefore result from changes in the environment. The possibility that no such unique climate exists and that nondeterministic factors are wholly or partly responsible for long-period fluctuations of the atmosphere-ocean-earth system, is considered. A simple difference equation is used to illustrate the phenomena of transitivity, intransitivity, and almost-intransitivity. Numerical models of moderate size suggest that almost-intransitivity might lead to persistence of atmospheric anomalies for a whole season. The effect of this persistence could be to allow substantial anomalies to build up in the underlying ocean or land, perhaps as abnormal temperatures or excessive snow or ice. These anomalies could subsequently influence the atmosphere, leading to long-period fluctuations. The implications of this possibility for the numerical modeling of climate, and for the interpretation of the output of numerical models, are discussed.     

Regionality of climatic change in East Asia

Regional differences in climatic change are of importance in order to establish the counter-measures for the damage by anomalous climate to agricultural production. It is not unusual for some regions to suffer floods while droughts occur in nearby regions at the same time. This paper deals mainly with the regionality of climatic change in E Asia during recent years, using the year-climate method expressed by the Köppen's system of climatic classification. Occurrence frequencies of BW, BS, Cf, Cw, Dwa, Dwb, and Dwc-type showed striking regionalities, which were obtained from the data at the 134 observatories over E Asia during the period from 1951 to 1970. The distribution of climatic types in each year shows various tendencies: Wet and cold as in 1954 and 1957 shows a pattern in which the boundary between C-type and D-type runs south and the Cfa-zone is broad, extending from middle E China to SW Japan. In contrast, in dry and warm years like 1965, the Dwa regions disappear in the N of E China and the BS region is located just north of the Cwa region, which is distributed broadly from China to Japan. Occurrence frequencies of year climate during the last 100 years were calculated for the 4 stations: Hong Kong, Manila, Shanghai and Tokyo. The results were compared with the distribution types of winter temperature and summer precipitation in China. It seems that the precipitation conditions in summer were reversed between the Philippines and China. Summarizing the results obtained, a schema of the regionality of climatic fluctuation in E and SE Asia was given in relation to the upper air streams. The position of the subtropical jet stream in winter shows a close relationship to the N limit of the Aw and Am year climate regions and in summer with the S limit of Dw region in NE China and North Korea. The Cw and Cf year climate regions in E Asia are located roughly in the regions bounded by the axes of subtropical jet streams in winter and in summer. The Dw year climate region in the E of the Tibetan Plateau reflects the altitudinal effect of the Cw climate of SE China. The N of E China has the variable BS year climate, which may related to the summer and winter jet stream conditions. Finally, the interannual change of the agricultural production index was dealt with in relation to the occurrence frequency of year climate types over E Asia during the years 1967–1970. As far as this period is concerned, the drier conditions are more effective than the wetter conditions in reducing agricultural production.     

Renaissance of the astronomical theory of climatic change

Book reviewed in this article:
Berger, A., Imbrie, J., Hays, J., Kukla, G. and Saltzman, B. (eds.) 1984: Milankovitch and Climate. Understanding the Response to Astronomical Forcing .     

青藏高原中部湖泊岩芯记录的第四纪湖平面变化及气候意义

通过对羌塘地区中部羌D1井长181·6m第四系岩芯的研究,分析湖泊沉积记录的岩相旋回和Fe/Mn和Sr/Ba等微量元素古环境参数的变化,结合样品的热释光(TL)测年数据,讨论晚更新世该区湖泊扩张和湖面升降变化过程。结果表明,晚更新世以来该区湖泊环境的演化,经历了二次湖进过程,二次湖平面上升期之间出现了一次广泛的干化低水位时期。其中15~7万年期间的湖泛事件可以在区域上进行追踪对比,它对应于深海氧同位素的第5阶段,可以作为高原中央气候转型期的标志。     

Physical evidence of Quaternary climatic change

Changes of climate have characterized parts, and at times apparently all, of Earth's surface. Changes that have occurred during the Quaternary period have special significance because, being comparatively recent, they are revealed by physical geologic features that are still at or near the surface, as yet little damaged by erosion. Although some of these features can be interpreted in terms that are broadly quantitative, most are still only qualitative in that they are limited to specifying climatic parameters that are positive or negative relative to those prevailing today in the same area. The common parameters indicated by the physical evidence include temperature (mean annual or summer) and precipitation (mean annual or seasonal). More rarely directions and minimum speeds of effective winds can be specified. A useful basis for reconstructions of former climates is a checklist of the relict geologic features from which climatic inferences can be drawn. Such a list is given here.     

The earliest well-dated archeological site in the hyper-arid Tarim Basin and its implications for prehistoric human migration and climatic change

The routes and timing of human occupation of the Tibetan Plateau (TP) are crucial for understanding the evolution of Tibetan populations and associated paleoclimatic conditions. Many archeological sites have been found in/around the Tarim Basin, on the northern margin of the Tibetan Plateau. Unfortunately, most of these sites are surface sites and cannot be directly dated. Their ages can only be estimated based on imprecise artifact comparisons. We recently found and dated an archeological site on a terrace along the Keriya River. Our ages indicate that the site was occupied at ~ 7.0–7.6 ka, making it the earliest well-dated archeological site yet identified in the Tarim Basin. This suggests that early human foragers migrated into this region prior to ~ 7.0–7.6 ka during the early to mid-Holocene climatic optimum, which may have provided the impetus for populating the region. We hypothesize that the Keriya River, together with the other rivers originating from the TP, may have served as access routes onto the TP for early human foragers. These rivers may also have served as stepping stones for migration further west into the now hyper-arid regions of the Tarim Basin, leading ultimately to the development of the Silk Road.     

Permafrost features as evidence of climatic change

Permafrost features indicate certain upper limits for annual air and ground temperatures, with the air temperatures being usually the lower because of insulating snow and vegetation. The following features generally imply mean annual air temperatures no higher than those indicated and commonly lower: permafrost itself, large sorted forms of patterned ground, palsas, and rock glaciers, 0°C; ice-wedge polygons and well-developed soil-wedge polygons, ?5°C; open-system pingos, ?2°C; closed system pingos, ?6°C; the implication of cryoplanation terraces remains to be established, with estimates ranging from near 0° to ?12°C.Use of fossil permafrost features as temperature indicators is complicated by problems of correct identification and dating, soil type, and local and regional environmental variables such as precipitation and vegetation. Nevertheless the fact that certain maximum paleotemperatures can be reasonably established in places warrants expanded research in former periglacial areas to evaluate temperature increases to the present. The majority of determinations in Europe, where most of the work has been done to date, indicate minimum air temperature increases of 13°–18° since the maximum of the last glaciation.     

Recent climatic change and unusual weather in the Northern Hemisphere

Occurrence frequency of unusual weather caused by anomalous synoptic patterns has its peaks in the middle latitude regions and the subtropical regions. Height anomaly patterns at the 500 mb level for the last three decades show the expansion of negative area in the northern hemisphere, resulting in increase of variability in space and time.     

Holocene climatic change in the northern Midwest: Pollen-derived estimates

Mapping of Holocene pollen data in the midwestern United States has revealed several broadscale vegetational changes that can be interpreted in climatic terms. These changes include (1) the early Holocene northward movement of the spruce-dominated forest and its later southward movement after 3000 yr B.P. and (2) the eastward movement of the prairie/forest border into southwestern Wisconsin by 8000 yr B.P. and its subsequent westward retreat after 6000 yr B.P. When certain basic assumptions are met, multiple regression models can be derived from modern pollen and climate data and used to transform the pollen record of these vegetational changes into quantitative estimates of temperature or precipitation. To maximize the reliability of the regression equations, we followed a sequence of procedures that minimize violations of the assumptions that underlie regression analysis. Reconstructions of precipitation during the Holocene indicated that from 9000 to 6000 yr B.P. precipitation decreased by 10 to 25% over much of the Midwest, while mean July temperature increased by 0.5° to 2.0°C. At 6000 yr B.P. precipitation was less than 80% of its modern values over parts of Wisconsin and Minnesota. After 6000 yr B.P. precipitation generally increased, while mean July temperature decreased in the north, and increased in the south. The time of the maximum temperature varies within the Midwest and is earlier in the north and later in the south.     

Gigantic volcanic eruptions and climatic change in the early Eocene

23 layers of altered volcanic ash (bentonites) originating from the North Atlantic Igneous Province have been recorded in early Eocene deposits of the Austrian Alps, about 1,900 km away from the source area. The Austrian bentonites are distal equivalents of the “main ash-phase” in Denmark and the North Sea basin. We have calculated the total eruption volume of this series as 21,000 km³, which occurred in 600,000 years. The most powerful single eruption of this series took place 54.0 million years ago (Ma) and ejected ca. 1,200 km³ of ash material, which makes it one of the largest basaltic pyroclastic eruptions in geological history. The clustering of eruptions must have significantly affected the incoming solar radiation in the early Eocene by the continuous production of stratospheric dust and aerosol clouds. This hypothesis is corroborated by oxygen isotope values, which indicate a global decrease of sea surface temperatures between 1 and 2°C during this major phase of explosive volcanism.     

Evaluation of climatic change through harmonic analysis

In the present work, a precipitation and temperature series from Barcelona (Spain) are analysed in order to detect the possible existence of climatic changes or cycles. The analysis is carried out both from the temporal and spectral standpoints. The techniques used range from the classical periodogram and Blackman-Tukey method through to the Maximum Entropy method. The results do not show the existence of climatic cycles, though they do show a clear tendency toward increased precipitation and decreased temperature, since the last years of series.