古今气候略论     

水涛 《火山地质与矿产》2010,(3):169-175

自2009年入冬以来北半球经受了创记录的严寒侵袭,联合国IPCC报告的权威性受到质疑。地球气候变化趋向陷入纷争的境地。从地质学和考古学的视角,以更长的时间周期去认识和了解气候变化规律和成因机制,或许对将来气候的长期预报有所启示。地球在漫长的演化史中经历了以千万年计的＂地质气候旋回＂、千百年计的＂史前气候周期＂及近现代以百年计的＂世纪气候波动＂。不同级次的周期均为内在自然因素所制约,CO2含量在地球演化史中趋于波动下降过程,当代的CO2浓度和气温均处于地质史的低点。人类活动可能在百年尺度内存在对气候和生态环境的影响。自20世纪初开始至今近百年升温趋向中,令人关注的是在中国曾有1941年、1969年、2009~2010年之交极度低温的出现,＂低温节点＂时距约为30~40年,似与海洋存在数十年为变化周期之说相近。由此引发对人为因素导致持续增温的质疑。2009年入冬以来的严寒是否为近百年升温波动周期的终结抑或只是次级的突变因素所致,尚有待观察。但自然因素主导的周期波动规律不可逆转,不能被未经实证而被夸大了的＂人为因素＂所左右。  相似文献   

Spatial patterns and driving forces of land use change in China during the early 21st century     

LIU Jiyuan  ZHANG Zengxiang  XU Xinliang  KUANG Wenhui  ZHOU Wancun  ZHANG Shuwen  LI Rendong  YAN Changzhen  YU Dongsheng  WU Shixin  JIANG Nan 《地理学报》2010,20(4):483-494

Land use and land cover change as the core of coupled human-environment systems has become a potential field of land change science (LCS) in the study of global environmental change. Based on remotely sensed data of land use change with a spatial resolution of 1 km × 1 km on national scale among every 5 years, this paper designed a new dynamic regionalization according to the comprehensive characteristics of land use change including regional differentiation, physical, economic, and macro-policy factors as well. Spatial pattern of land use change and its driving forces were investigated in China in the early 21st century. To sum up, land use change pattern of this period was characterized by rapid changes in the whole country. Over the agricultural zones, e.g., Huang-Huai-Hai Plain, the southeast coastal areas and Sichuan Basin, a great proportion of fine arable land were engrossed owing to considerable expansion of the built-up and residential areas, resulting in decrease of paddy land area in southern China. The development of oasis agriculture in Northwest China and the reclamation in Northeast China led to a slight increase in arable land area in northern China. Due to the “Grain for Green” policy, forest area was significantly increased in the middle and western developing regions, where the vegetation coverage was substantially enlarged, likewise. This paper argued the main driving forces as the implementation of the strategy on land use and regional development, such as policies of “Western Development”, “Revitalization of Northeast”, coupled with rapidly economic development during this period.  相似文献   

20 世纪美国城市体系的演变及其对中国的启示   总被引：3，自引：1，他引：2  

谈明洪  李秀彬 《地理学报》2010,65(12):1488-1495

在快速城市化过程中,在规模不等的城市中城市人口将如何分布？这是制订中国社会经济发展战略必须考虑的一个重大基础问题。美国是世界上最大的发达经济体,城市体系成熟,100 年前的城市化水平和中国现在相当。研究20 世纪美国城市体系的演化特征,对中国会有所启发。采用美国人口普查数据,运用位序-规模法则等方法,分析了美国城市系统的演变过程。结果显示：在20 世纪前70 年美国城市化处于加速发展的中期阶段,大城市的人口增长明显快于中小城市,城市体系向非均衡化方向发展;20 世纪后30 年,美国城市化进入了稳定发展的后期阶段。与美国不同的是,处于城市化加速发展中期阶段的中国(1985-2000 年),小城市人口增长较快,城市体系趋于均衡。研究认为：未来我国大城市的人口集聚有较大潜力。  相似文献   

21世纪初中国土地利用变化的空间格局与驱动力   总被引：33，自引：15，他引：18  

刘纪远  张增祥  徐新良  匡文慧  周万村  张树文  李仁东  颜长珍  于东升  吴世新  江南 《地理学报(英文版)》2010,20(4):483-494

Land use and land cover change as the core of coupled human-environment systems has become a potential field of land change science (LCS) in the study of global environmental change. Based on remotely sensed data of land use change with a spatial resolution of 1 km × 1 km on national scale among every 5 years, this paper designed a new dynamic regionalization according to the comprehensive characteristics of land use change including regional differentiation, physical, economic, and macro-policy factors as well. Spatial pattern of land use change and its driving forces were investigated in China in the early 21st century. To sum up, land use change pattern of this period was characterized by rapid changes in the whole country. Over the agricultural zones, e.g., Huang-Huai-Hai Plain, the southeast coastal areas and Sichuan Basin, a great proportion of fine arable land were engrossed owing to considerable expansion of the built-up and residential areas, resulting in decrease of paddy land area in southern China. The development of oasis agriculture in Northwest China and the reclamation in Northeast China led to a slight increase in arable land area in northern China. Due to the "Grain for Green" policy, forest area was significantly increased in the middle and western developing regions, where the vegetation coverage was substantially enlarged, likewise. This paper argued the main driving forces as the implementation of the strategy on land use and regional development, such as policies of "Western Development", "Revitalization of Northeast", coupled with rapidly economic development during this period.  相似文献   

气体水合物未来的能源   总被引：1，自引：0，他引：1  

张立生 《四川地质学报》1999,(1)

由水分子和甲烷等天然气体组成的笼形包合物气体水合物,是一种冰雪状的白色结晶物质,是新近发现的一种能源矿产,产出于大洋底的水下沉积物和陆上极地冻土带中。气体水合物是一种高密度的能源矿产,储量巨大,各大洋中都有,被称为２１世纪的能源,倍受各国政府和学者们的重视。  相似文献   

Geographic EducationResearch and the Changing Institutional Structure of American Education     

Fred M. Shelley 《The Professional geographer》1999,51(4):592-597

Professional geographers are paying increasing attention to the development of a research agenda concerning geographic education. In doing so, it is essential that geographers pay close attention to fundamental changes in the structure of education itself. Traditional educational methods and procedures associated with industrial society are being replaced by new and innovative modes of education that are linked to post-industrial social organization. This article explores the implications of these changes for understanding the teaching and learning of geography in the future.  相似文献   

地震灾情因社会发展而加重--20世纪全球地震灾害综述   总被引：2，自引：1，他引：1  

赵荣国  张洪由 《国际地震动态》1999,(6):1-10

２０世纪中国是世界上地震灾害最严重的国家。地震造成的经济损失最严重的是日本,美国,中国居第二,三位。全世界地震灾情有逐世纪加重的趋势。地震减灾研究有两点进展;１．中国有一次成功的临震预报;２．日本抗震建筑有效。全世界的未来地震灾情形势依然严峻。  相似文献   

20世纪上半叶西辽河流域巴林左旗聚落空间演变特征分析   总被引：7，自引：0，他引：7  

韩茂莉  张暐伟 《地理科学》2009,29(1)

从1918年放垦,巴林左旗经历了近百年的聚落兴建与农业开垦历程,以20世纪30年代初为转折点,此前聚落分布以空间扩展为主,以后转为密度增加,在聚落空间分布形式变化的同时,聚落高程也表现出从400～600m高程区这一自然条件具有优势的区域向其它高程扩展.在人口的推动下,巴林左旗聚落空间演变与环境选择经历了由疏至密、由优至劣的过程,并随着农业发展,农田扩展与资源的有限性构成了人地关系的矛盾焦点.  相似文献   

广西近百年气温和降水序列的多时间尺度分析   总被引：3，自引：0，他引：3  

黄雪松  况雪源  覃峥嵘  黄梅丽  林开平 《气候变化研究进展》2007,3(6):362-367

对广西近百年平均气温及降水量变化进行了多时间尺度的层次结构研究,并与Nino3区的海温距平进行奇异交叉谱分析。结果表明：平均气温有较强上升趋势并伴有明显的准两年周期振荡;降水则呈下降趋势,主要周期为32 a左右及准两年振荡。1884至1910年代初,广西处于干冷期;1910年代初至1930年前后,处于湿冷期;1930年前后至1950年代后期,处于湿暖期;1950年代后期至1990年代前期,处于干暖期。ENSO事件3~7 a的周期对广西平均气温及降水影响显著,赤道太平洋海温变化对广西气温的影响主要表现在年代际变化上,对降水的影响主要体现在年际变化上。  相似文献   

辽宁省海岸带主要河口区近百年沉积速率变化规律     

邴智武 《地质与资源》2016,25(1):74-78

基于¹³⁷Cs法和²¹⁰Pb法的相互校验,利用13孔岩心663个样品,定量分析了辽宁省海岸带主要河口区近百年沉积速率变化规律.研究表明,辽宁海岸带不同地区、不同时间段沉积速率是不同的.辽河河口区沉积最快,为23.66 mm/a,属于中高速沉积区;辽西海岸带沉积最慢,且总的趋势是沉积速率逐渐减小.随深度增加,辽西海岸带沉积速率逐渐加大,辽东湾大辽河、大凌河入海口沉积速率出现多个峰值,辽东半岛黄海西北岸沉积速率则逐渐减少.  相似文献