Integrating diverse methods to understand climate-land interactions in East Africa   总被引：3，自引：0，他引：3  

Jennifer M. Olson  Gopal Alagarswamy 《Geoforum》2008,39(2):898-911

The questions of how land use change affects climate, and how climate change affects land use, require examination of societal and environmental systems across space at multiple scales, from the global climate to regional vegetative dynamics to local decision making by farmers and herders. It also requires an analysis of causal linkages and feedback loops between systems. These questions and the conceptual approach of the research design of the Climate-Land Interaction Project (CLIP) are rooted in the classical human-environment research tradition in Geography.This paper discusses a methodological framework to quantify the two-way interactions between land use and regional climate systems, using ongoing work by a team of multi-disciplinary scientists examining climate-land dynamics at multiple scales in East Africa. East Africa is a region that is undergoing rapid land use change, where changes in climate would have serious consequences for people’s livelihoods, and requiring new coping and land use strategies. The research involves exploration of linkages between two important foci of global change research, namely, land use/land cover (LULC) and climate change. These linkages are examined through modeling agricultural systems, land use driving forces and patterns, the physical properties of land cover, and the regional climate. Both qualitative and quantitative methods are being used to illustrate a diverse pluralism in scientific discovery.  相似文献   

Effective livelihood adaptation to climate change disturbance: Scale dimensions of practice in Mozambique   总被引：2，自引：0，他引：2  

Henny Osbahr  Chasca Twyman  W. Neil Adger  David S.G. Thomas 《Geoforum》2008,(6):1951-1964

Natural resource-dependent societies in developing countries are facing increased pressures linked to global climate change. While social-ecological systems evolve to accommodate variability, there is growing evidence that changes in drought, storm and flood extremes are increasing exposure of currently vulnerable populations. In many countries in Africa, these pressures are compounded by disruption to institutions and variability in livelihoods and income. The interactions of both rapid and slow onset livelihood disturbance contribute to enduring poverty and slow processes of rural livelihood renewal across a complex landscape. We explore cross-scale dynamics in coping and adaptation response, drawing on qualitative data from a case study in Mozambique. The research characterises the engagements across multiple institutional scales and the types of agents involved, providing insight into emergent conditions for adaptation to climate change in rural economies. The analysis explores local responses to climate shocks, food security and poverty reduction, through informal institutions, forms of livelihood diversification and collective land-use systems that allow reciprocity, flexibility and the ability to buffer shocks. However, the analysis shows that agricultural initiatives have helped to facilitate effective livelihood renewal, through the reorganisation of social institutions and opportunities for communication, innovation and micro-credit. Although there are challenges to mainstreaming adaptation at different scales, this research shows why it is critical to assess how policies can protect conditions for emergence of livelihood transformation.  相似文献   

Linkages between Alaskan sockeye salmon abundance, growth at sea, and climate, 1955–2002     

G.T. Ruggerone  J.L. Nielsen  J. Bumgarner 《Deep Sea Research Part II: Topical Studies in Oceanography》2007,54(23-26):2776

We tested the hypothesis that increased growth of salmon during early marine life contributed to greater survival and abundance of salmon following the 1976/1977 climate regime shift and that this, in turn, led to density-dependent reductions in growth during late marine stages. Annual measurements of Bristol Bay (Bering Sea) and Chignik (Gulf of Alaska) sockeye salmon scale growth from 1955 to 2002 were used as indices of body growth. During the first and second years at sea, growth of both stocks tended to be higher after the 1976–1977 climate shift, whereas growth during the third year and homeward migration was often below average. Multiple regression models indicated that return per spawner of Bristol Bay sockeye salmon and adult abundance of western and central Alaska sockeye salmon were positively correlated with growth during the first 2 years at sea and negatively correlated with growth during later life stages. After accounting for competition between Bristol Bay sockeye and Asian pink salmon, age-specific adult length of Bristol Bay salmon increased after the 1976–1977 regime shift, then decreased after the 1989 climate shift. Late marine growth and age-specific adult length of Bristol Bay salmon was exceptionally low after 1989, possibly reducing their reproductive potential. These findings support the hypothesis that greater marine growth during the first 2 years at sea contributed to greater salmon survival and abundance, which in turn led to density-dependent growth during later life stages when size-related mortality was likely lower. Our findings provide new evidence supporting the importance of bottom-up control in marine ecosystems and highlight the complex dynamics of species interactions that continually change as salmon grow and mature in the ocean.  相似文献   

Modelling and forecasting long-term dynamics of Western Baltic macrobenthic fauna in relation to climate signals and environmental change   总被引：1，自引：0，他引：1  

Joachim Grger  Heye Rumohr 《Journal of Sea Research》2006,55(4):266-277

Long-term macrobenthos data from Kiel Bight in the Western Baltic collected between 1968 and 2000 have been correlated with the winter NAO index (North Atlantic Oscillation Index) and other environmental data such as temperature, salinity and oxygen content in the bottom water in order to detect systematic patterns related to so far unexplained abiotic signals in the dynamics of zoobenthic species assemblages. The benthos data come from a cluster of five stations (Süderfahrt/ Millionenviertel) in Kiel Bay. Our investigations concentrated on the macrobenthic dynamics with a focus on the number of species m^− 2 (species richness). Using logarithms and the time series analysis approach of Box/Jenkins (ARIMA modelling, transfer function modelling) it was shown that species richness was strongly influenced by the winter NAO (adjusted for a linear time trend within the 1968-2000 period) and salinity (with a shift/lag of four years). Bootstrapping experiments (i.e. sampling from the error process) and analysis of prediction power (by means of the one- or more-years leaving-out method) showed that the parameter estimates behaved in a stable way, leading to a relatively robust model.  相似文献   

Using the Mellor–Yamada mixing scheme in seasonally ice-covered seas—Corrigendum to: Parameterization of vertical mixing in the Weddell Sea [Ocean Modelling 6 (2004) 83–100]     

Ralph Timmermann  Martin Losch 《Ocean Modelling》2005,10(3-4):369-372

A coding error in the s-Coordinate Primitive Equation Model (SPEM) has led to misleading statements about the behaviour of the Mellor–Yamada level 2 parameterization of vertical mixing. It has been claimed that the scheme removes static instability only very slowly and preserves statically unstable stratifications for an unrealistic long time. This note corrects this statement by demonstrating that the Mellor–Yamada mixing scheme, if implemented correctly, tends to overestimate rather than underestimate vertical mixing in seasonally ice-covered seas. Similar to other mixing schemes with the same behaviour, this leads to spurious open ocean deep convection, an unrealistic homogenization of the water column, and a significant reduction of sea ice volume.  相似文献   

The Bering Sea—A dynamic food web perspective     

Kerim Aydin  Franz Mueter   《Deep Sea Research Part II: Topical Studies in Oceanography》2007,54(23-26):2501

The Bering Sea is a high-latitude, semi-enclosed sea that supports extensive fish, seabird, marine mammal, and invertebrate populations and some of the world's most productive fisheries. The region consists of several distinct biomes that have undergone wide-scale population variation, in part due to fisheries, but also in part due to the effects of interannual and decadal-scale climatic variation. While recent decades of ocean observation have highlighted possible links between climate and species fluctuations, mechanisms linking climate and population fluctuations are only beginning to be understood. Here, we examine the food webs of Bering Sea ecosystems with particular reference to some key shifts in widely distributed, abundant fish populations and their links with climate variation. Both climate variability and fisheries have substantially altered the Bering Sea ecosystem in the past, but their relative importance in shaping the current ecosystem state remains uncertain.  相似文献   

三峡及邻区晚第三纪以来构造应力场特征探讨     

贾永刚  单红仙 《海洋科学》1995,19(2):36-41

用三峡及邻区（东经１０８°～１１３°，北纬２９°～３３°）地质资料，地震资料，现 场地应力测量资料论证三峡及邻区晚第三纪以来构造应力场稳定性及其分区特 征。  相似文献   

Geographical distribution of fish catches and temperature variations in the northeast Atlantic since 1945     

Rögnvaldur Hannesson 《Marine Policy》2007

Warming of the northeast Atlantic is expected to affect the location and productivity of fish stocks. It is examined whether variations in catches of cod, herring, mackerel, anchovy and sardines in the ICES statistical areas are related to variations in ocean temperature. Temperatures at certain locations along the Norwegian coast are taken as proxies for temperatures in the Norwegian Sea and the North Sea. It is found that the catches of cod in the North Sea are inversely correlated with temperature and that recruitment and catches of cod in the Norwegian Sea and the Barents Sea are positively related to temperature. There is also some indication of a positive correlation between temperature and the catches of mackerel in the North Sea and the Norwegian Sea, and between temperature and the catches of sardines in the North Sea.  相似文献   

北极海冰减少的气候效应研究   总被引：2，自引：0，他引：2  

魏立新  张海影 《海洋预报》2005,22(Z1):56-61

本文采用了OSU两层大气环流模式对特定的北极海冰进行数值模拟,研究北极海冰减少的气候效应.试验中海温一律取为气候平均值,北极海冰作为外强迫源影响大气,大气响应完全是环流内部调整的结果.本文对北极海冰减少后的大气环流特征进行了分析,特别是与中国的气温和降水之间的关系.  相似文献   

呼伦湖的近期扩张及其与全球气候变化的关系   总被引：10，自引：0，他引：10  

秦伯强  王苏民 《海洋与湖沼》1994,25(3):280-287

通过近２０多年湖泊水量平衡分析发现，湖泊水位变化主要由湖盆内径流补给量的丰枯决定。进一步分析揭示，呼伦湖地区乃至整个东北地区，本世纪以来随气温升高，随水有增加的趋势。降水增加导致入湖径流量，湖水位上升，呼伦湖本世纪以来的扩张与内蒙古东部地区其他内陆湖泊的变化一致，但这在我国乃至整个亚洲内陆干旱或半干旱区是独一无二的，为此成为这一地区气候变化的指示器。  相似文献