Beyond collapse: climate change and causality during the Middle Holocene Climatic Transition, 6400–5000 years before present

The twenty-first century is likely to be characterised by large changes in regional climatic and environmental conditions, with implications for the availability and distribution of key resources such as water and productive land. While the implications of such changes for human societies are potentially profound, the empirical evidence base for understanding human–environment interactions focuses largely on the relatively recent past, during which examples of rapid and severe climate change are lacking. While there are no precise past analogues for twenty-first century climate change, the Middle Holocene Climatic Transition (MHCT), from about 6400–5000?years before present, provides us with an example of a period of large-scale global climatic reorganisation, punctuated by episodes of rapid and severe climate change, at a time when human societies were beginning to resemble those of today. A survey of archaeological and palaeo-environmental data from the northern hemisphere subtropics and other regions provides us with evidence for linked climatic, environmental and societal change during the MHCT. This evidence, the strength of which varies with location, allows us to construct convincing narratives of linked climatic, environmental and societal changes that accommodate a variety of responses and outcomes, and that are much more nuanced than narratives of the proposed climate-induced collapse of individual societies. Such synthetic studies that compare contexts across time and space can help us understand human–environment interactions during times of climatic disruption, while allowing for diverse outcomes and avoiding the pitfalls of climatic determinism.     

Migration Within Mexico: A Data-based Exercise for Secondary Students

Abstract

People have been leaving rural environments and moving into urban environments. By 2007, the most people in the world will live in cities (United Nations 2002). Mexico illustrates this world trend closely. Mexico now publishes data on the Internet that can be used to study the movement of people within the country. A lesson is presented with selected new data connecting regional migration and job opportunities. Students create choropleth maps, analyze patterns, and make generalizations about patterns and processes.     

生态移民国外研究进展

随着环境变化对人类生产生活影响程度的逐渐加深,越来越多的学者投身于对生态难民及其相关领域的研究。本文对生态移民的定义与分类、生态移民的产生原因、生态移民的相关预测与评估、环境变化与移民之间的关联等方面进行了重点综述,并对环境难民的进～步应用进行了展望。提出要扩大生态移民的研究区域、转移生态移民的预测重点、加深关于生态移民影响效益的评估研究、探索更综合严谨的生态移民研究方法以及建立一套适合于生态移民的应对指导体系和可持续发展体系。     

试论未来极端气候事件发展趋势的不确定性

极端气候事件是在一定时间尺度上发生的不同于气候系统平均状态的气候突变.早第三纪的最热事件（PETM）,第四纪中国黄土高原古土壤S4、S5记录的暖湿事件,砂黄土L9、L15记录的干冷事件等都是在轨道时间尺度上发生的极端气候事件.末次冰消期的YD冷事件、全新世9次冷事件是在千—百年尺度上发生的极端气候事件.这些极端气候事件出现于地球气候系统不同的冷暖背景下,它们的成因机制和表现形式有很多不确定性.20世纪以来发生的干旱、洪水、飓风、雪灾、沙尘暴等极端气候事件,无法用持续增加的温室气体的变化来解释.关于极端气候事件发生频率和强度随＂全球变暖＂而增加的结论也存在一定程度的不确定性.因此,简单地将现代极端气候事件统统归因于＂气候变暖＂既不科学也不合理.深入研究各个时间尺度上发生的极端气候事件的波动性、周期性和不确定性特征,有助于科学预测未来气候变化背景下极端气候事件的发展趋势.     

水流注入方式和填料层高度对人工湿地流态的影响

流态模拟实验作为评价人工净化湿地系统运行状况、物质在其中停留时间的有效工具,在污水处理领域具有重要作用。罗丹明B背景浓度低、重现性好,被选为评价升流式、降流式和填料层高度对水力流态影响的示踪剂。实验使用罗丹明B和NaCl作为示踪剂,在湿地系统中进行流态实验,探究升流式、降流式和填料层高度对人工净化湿地流态的影响。实验结果表明,升流式人工湿地比降流式人工湿地处理效果好,示踪剂水力停留时间(hydraulic retention time,HRT)的体积利用率分别为82.0%和76.8%,升流式人工湿地无效体积中死区占更大比例,而降流式人工湿地滞留区占无效体积的比例更大;人工湿地填料层高度对示踪剂停留时间分布影响不大,体积利用率都在80%以上,但是,其死区和滞留区随着填料层高度的变化在无效体积中所占的比例有所差异,死区所占的比例随着填料层高度的增加先增加后减少,滞留区所占的比例则先减少后增加。     

20世纪末中国迁移人口空间分布格局——基于城市的视角

基于人口普查资料,对20世纪末中国迁移人口在不同行政级别、不同规模城市的分布格局进行分析,并运用探索性空间数据分析技术进一步对地级及以上城市迁移人口的空间分布特征进行研究。结果表明:地级及以上城市在迁移人口流动中占主要地位,其中百万规模级别以上城市在人口迁移中地位尤为显著;县级市间迁移人口规模差异显著,东部地区县级市平均迁移规模要大于西部和中部;省际迁移中城市空间分布大体呈现3个梯状层次;省内迁移中城市空间分布总体表现出极大的相似性,均以各省会城市作为省内迁移人口的第一流入地;不论是省内迁移还是省际迁移,东部沿海地区的珠三角和长三角地区城市群都是迁移人口的高度集聚地。     

Time and Practice: Learning to Become a Geographer

Abstract

Illustrated Dictionary of Place Names: United States and Canada. By Kelsie B. Harder. New York: Van Nostrand, 1976. Pp. xiv + 631, $18.95.

Middle America: Its Lands and Peoples. 2nd ed. By Robert C. West and John P. Augelli. Englewood Cliffs, N.J.: Prentice-Hall, 1976. Pp. xvii + 494, $14.95.

Contemporary Africa: Geography and Change. Edited by C. Gregory Knight and James L. Newman. Englewood Cliffs, N.J.: Prentice-Hall, 1976. Pp. xiv + 546, $14.95.

Atlas of Mexico. By Stanley A. Arbingast et al. 2nd ed. Austin, Tex.: Bureau of Business Research, University of Texas, 1975. Pp. ix + 165, $15.00.

Readings in Social Geography. Edited by Emrys Jones. London: Oxford University Press, 1975. Pp. 328, $18.50 and $6.95.

California: Patterns on the Land. 5th ed. By Robert Durrenberger and Robert Johnson. A California Council for Geographic Education Publication. Palo Alto, Calif.: Mayfield Publishing, 1976. Pp. viii + 134, $6.95.

Studying China in Elementary and Secondary Schools, Studying India in Elementary and Secondary Schools, and Studying Japan in Elementary and Secondary Schools. By Leonard S. Ken-worthy. World Affairs Guides. New York: Teachers College Press, 1975. Pp. 68, iii + 67, and iii + 65, $2.75 each.

World Regional Geography: A Question of Place. By Paul Ward English and James Andrew Miller. Harper &; Row Series in Geography. New York: Harper &; Row, 1977. Pp. xiii + 591, $15.95.

Census Data: Geographic Significance and Classroom Utility. Edited by Borden D. Dent. Tualatin, Oreg.: Geographic and Area Study Publications, 1976. Pp. ix + 277.

The Middle East: A Geographical Study. By Peter Beaumont, Gerald H. Blake, and Malcolm J. Wagstaff. London: John Wiley &; Sons, 1976. Pp. xvii + 572, $25.50 and $14.95.

Man's Economic Environment. By Edgar C. Conklingand Maurice Yeates. New York: McGraw-Hill Book Co., 1976. Pp. xi + 308, $11.95.

Applied Climatology: An Introduction. 2nd ed. By John F. Griffiths. New York/London: Oxford University Press, 1976. Pp. xiii + 136, $9.00.

Man and the Environment: Regional Perspectives. Edited by J. H. Holmes. Hawthorn, Victoria: Longman Australia Pty Limited, 1976. Pp. vi + 261, $7.95.

Introduction to Cultural Geography. 5th ed. By Henry M. Kendall, Robert M. Glendinning, Clifford H. MacFadden, and Craig H. MacFadden. New York: Harcourt Brace Jovanovich, 1976. Pp. xx + 449, $12.95.

Interpretation of Aerial Photographs. 3rd ed. By Thomas Eugene Avery. Minneapolis, Minn.: Burgess Publishing Company, 1977. Pp. xi + 392, $14.95.

Geography of the U.S.S.R. 3rd ed. By Paul Lydolph. New York: John Wiley &; Sons, 1977. Pp. xi + 495, $18.95.     

基于小波与R/S方法的汉江中下游流域降水量时间序列分析

基于汉江中下游流域9个国家气象站1961～2006年的降水数据,综合采用Morlet小波分析、小波分解和R/S分析方法,对流域降水量周期和未来趋势进行分析及预测。研究结果表明:汉江中下游流域年降水量存在5年左右的短周期和10～15年的中长周期;部分气象站可能存在40年左右长周期,需要更长的时间序列验证。基于通过小波分解提取的历史降水量变化趋势,进一步结合R/S分析表明,汉江中下游流域降水量时间序列总体上存在比较明显的赫斯特现象,未来该流域面临较大的防洪压力。     

模糊时间序列模型在短期气候预测中的应用

将模糊时间序列模型引入短期气候预报,利用重庆34个地面气象观测站的逐日观测资料(1971—2007年)和重庆市旱涝灾害监测预警决策服务系统计算的干旱指数和洪涝指数等资料,运用模糊时间序列模型分别对2001—2007年重庆市城口县1月降水、1月平均气温的预报结果(年度预测)和重庆市春旱指数的预报结果(年度预测)进行了模糊时间序列分析,预测了2004—2007年的发展趋势,用2004—2007年实测值与预测结果进行了比较,并与加权集成、人工神经网络集成、数据挖掘集成等模型进行了精度比较和分析.结果表明:模糊时间序列模型各项精度评定指标优良,并且计算简单,具有一定的实用价值.     

日本Mw9.0地震前GRACE卫星重力变化

利用GRACE重力卫星月重力场数据,通过去相关与高斯滤波等方法获取日本大地震震前震源区周缘年度、季度和年度差分重力变化,以及若干点位时间序列重力变化;分析结果表明:日本大地震前5年内在震源区周边出现了比较明显的卫星重力异常正负交替和迁移现象,至震前1－2年,震区周边形成了明显正负异常区,正重力异常区重力增加现象明显;点位重力时间序列分布指出了日本MW9.0级地震前存在与1976年唐山地震类似的重力变化现象。这些结果反映了日本大地震震前震源区周边地下物质运动、质量迁移和能量积累等问题,为研究该地震的孕育过程提供了证据。