International Institute for Applied Systems Analysis

About: International Institute for Applied Systems Analysis is a nonprofit organization based out in Laxenburg, Austria. It is known for research contribution in the topics: Population & Greenhouse gas. The organization has 1369 authors who have published 5075 publications receiving 280467 citations. The organization is also known as: IIASA.

A dynamical system for neighborhoods inplant communities

Abstract: How should plant ecologists scale up from the fine-scale events affecting individual plants in small neighborhoods to the coarse-scale dynamics of plant communities? We give here a dynamical system, derived from an individual-based model, that captures the main effects of spatial structure. The individual-based model describes a multispecies plant community, living in a spatial domain, containing plants that (1) reproduce and die with rates that depend on other individuals in a specified neighborhood, and (2) move through seed dispersal and clonal growth. Over the course of time, substantial spatial structure can build up in such a community due to local interactions and dispersal. The dynamical system describes how the structure of local neighborhoods changes over time, using the first and second spatial moments of the individual-based model. We show, by means of an example of two competing species, that the dynamical system gives a close approximation to the behavior of the underlying individual-based model, and that the chang- es in local spatial structure as time progresses have fundamental effects on the dynamics.

Financial instruments for disaster risk management and climate change adaptation

Abstract: The International Panel on Climate Change (IPCC) has called for a new balance between reducing the risks from climate extremes and transferring them (for example, through insurance) as means for effectively preparing for and managing disaster impacts in a changing climate. This paper elaborates on this balance with an overview of disaster risk financing mechanisms and how they contribute to disaster risk reduction and climate change adaptation in developing countries. We suggest a risk management approach that targets risk reduction and risk financing to different layers of risk, including a layer that represents a possible limit to adaptation. By reviewing traditional post-disaster financial arrangements, such as government compensation, and non-traditional pre-disaster instruments, such as index-based insurance, we show how risk financing can complement and stimulate risk reduction. We discuss the benefits of financial instruments, including the provision of post-disaster finances for recovery and pre-disaster security necessary for climate adaptation and poverty reduction. These benefits come at a cost, and we discuss the risks, challenges, and future prospects of risk financing in developing countries.

Sexual Conflict and the Tragedy of the Commons

Abstract: It is widely understood that the costs and benefits of mating can affect the fecundity and survival of individuals. Sexual conflict may have profound consequences for populations as a result of the negative effects it causes males and females to have on one another’s fitness. Here we present a model describing the evolution of sexual conflict, in which males inflict a direct cost on female fitness. We show that these costs can drive the entire population to extinction. To males, females are an essential but finite resource over which they have to compete. Population extinction owing to sexual conflict can therefore be seen as an evolutionary tragedy of the commons. Our model shows that a positive feedback between harassment and the operational sex ratio is responsible for the demise of females and, thus, for population extinction. We further show that the evolution of female resistance to counter harassment can prevent a tragedy of the commons. Our findings not only demonstrate that sexual conflic...

Adaptation in integrated assessment modeling: where do we stand?

Abstract: Adaptation is an important element on the climate change policy agenda. Integrated assessment models, which are key tools to assess climate change policies, have begun to address adaptation, either by including it implicitly in damage cost estimates, or by making it an explicit control variable. We analyze how modelers have chosen to describe adaptation within an integrated framework, and suggest many ways they could improve the treatment of adaptation by considering more of its bottom-up characteristics. Until this happens, we suggest, models may be too optimistic about the net benefits adaptation can provide, and therefore may underestimate the amount of mitigation they judge to be socially optimal. Under some conditions, better modeling of adaptation costs and benefits could have important implications for defining mitigation targets.

Land use and soil erosion in the upper reaches of the Yangtze River: some socio‐economic considerations on China's Grain‐for‐Green Programme

Abstract: Soil erosion in the upper reaches of the Yangtze River in China is a major concern and the Central Government has initiated the Grain-for-Green Programme to convert farmland to forests and grassland to improve the environment. This paper analyses the relationship between land use and soil erosion in Zhongjiang, a typical agricultural county of Sichuan Province located in areas with severe soil erosion in the upper reaches of the Yangtze River. In our analysis, we use the ArcGIS spatial analysis module with detailed land-use data as well as data on slope conditions and soil erosion. Our research shows that the most serious soil erosion is occurring on agricultural land with a slope of 10 similar to 25 degrees. Both farmland and permanent crops are affected by soil erosion, with almost the same percentage of soil erosion for corresponding slope conditions. Farmland with soil erosion accounts for 86.2 per cent of the total eroded agricultural land. In the farmland with soil erosion, 22.5 per cent have a slope of 10 degrees. On gentle slopes with less than 5 degrees inclination, some 6 percent of the farmland had strong (5000 similar to 8000 t km(-2) y(-1)) or very strong (8000 similar to 15000 t km(-2) y(-1)) erosion. However, on steep slopes of more than 25 degrees, strong or very strong erosion was reported for more than 42 per cent of the farmland. These numbers explain why the task of soil and water conservation should be focused on the prevention of soil erosion on farmland with steep or very steep slopes. A Feasibility Index is developed and integrated socio-economic assessment on the feasibility of improving sloping farmland in 56 townships and towns is carried out. Finally, to ensure the success of the Grain-for-Green Programme, countermeasures to improve sloping farmland and control soil erosion are proposed according to the values of the Feasibility Index in the townships and towns. These include: (1) to terrace sloping farmland on a large scale and to convert farmland with a slope of over 25 degrees to forests or grassland; (2) to develop ecological agriculture combined with improving the sloping farmland and constructing prime farmland and to pay more attention to improving the technology for irrigation and cultivation techniques; and (3) to carry out soil conservation on steep-sloping farmland using suggested techniques. In addition, improving ecosystems and the inhabited environment through yard and garden construction for households is also an effective way to prevent soil erosion. Copyright (c) 2006 John Wiley & Sons, Ltd.