Showing papers by "International Institute for Applied Systems Analysis published in 1994"

Climate change and world food supply, demand and trade: Who benefits, who loses?

Abstract: This paper summarizes the findings of a major interdisciplinary research effort by scientists in 25 countries. The study examined the potential biophysical responses of major food crops to changing atmospheric composition and climate, and projected potential socioeconomic consequences. In a first step crop models were used to estimate how changing climatic conditions might alter yields of major crops at a number of sites representing both major production areas and vulnerable regions at low, mid and high latitudes. Then a dynamic recursive national-level model of the world food system was used to assess socio-economic impacts for the period 1990 up to year 2060.

On "badly behaved" dynamics (Some applications of generalized urn schemes to technological and economic change)

Abstract: Adaptive (path dependent) processes of growth modeled by urn schemes are important for several fields of applications: biology, physics, chemistry, economics. In this paper we present a general introduction to urn schemes, together with some new results. We review the studies that have been done in the technological dynamics by means of such schemes. Also several other domains of economic dynamics are analysed by the same machinery and its new modifications allowing to tackle non-homogeneity of the phase space. We demonstrate the phenomena of multiple equilibria, different vonvergence rates for different limit patterns, locally positive and locally negative feedbacks, limit behavior associated with non-homogeneity of economic environment where producers (firms) are operating. It is also shown that the above urn processes represent a natural and convenient stochastic replicator dynamics which can be used in evolutionary games.

A cross-diffusion model of forest boundary dynamics

Abstract: A simple mathematical model of mono-species forest with two age classes which takes into account seed production and dispersal is presented in the paper. This reaction — diffusion type model is then reduced by means of an asymptotic procedure to a lower dimensional reaction — cross-diffusion model. The existence of standing and travelling wave front solutions corresponding to the forest boundary is shown for the later model. On the basis of the analysis, possible changes in forest boundary dynamics caused by antropogenic impacts are discussed.

The Greenhouse Gas Methane (CH4): Sources and Sinks, the Impact of Population Growth, Possible Interventions

Abstract: Methane (CH4) is one of the trace gases in the atmosphere that is considered to play a major role in what is called the “greenhouse effect.” There are six major sources of atmospheric methane: emission from anaerobic decomposition in (1) natural wetlands; (2) paddy rice fields; (3) emission from livestock production systems (including intrinsic fermentation and animal waste); (4) biomass burning (including forest fires, charcoal combustion, and firewood burning); (5) anaerobic decomposition of organic waste in landfills; and (6) fossil methane emission during the exploration and transport of fossil fuels. Obviously, human activities play a major role in increasing methane emissions from most of these sources. Especially the worldwide expansion of paddy rice cultivation, livestock production and fossil fuel exploration have increased the methane concentration in the atmosphere. Several data sets help estimate atmospheric methane concentration up to 160,000 years back. Major sources and sinks of present-day methane emission and their relative contribution to the global methane balance demonstrate great uncertainties in the identification and quantification of individual sources and sinks. Most recent methane projections of the Intergovernmental Panel on Climate Change (IPCC) for 2025 and 2100 are discussed and used to estimate the contribution of population growth to future methane emission. Finally the paper discusses options and restrictions of reducing anthropogenic methane emissions to the atmosphere.

Emission Trading in Europe with an Exchange Rate

Abstract: This paper explores the analytical and empirical properties of a new method for emission trading according to a fixed exchange rate. The exchange rate is based on the ratios of the marginal costs of abatement in the optimal solution in order to account for the impact of the location of emission sources on the deposition. It is shown that, generally, this system will not achieve the optimal solution and does not guarantee that environmental deposition constraints are not violated, although total abatement costs are always reduced. A routine was developed to mimic trading as a bilateral, sequential process, subject to an exchange rate. In the example used, results for SO2 emissions in Europe show that, starting from a uniform reduction, exchange-rate trading achieves higher cost savings than one-to-one trading, without achieving the cost minimum. Sulfur deposition targets are not violated since the initial emission allocation overfulfilled targets at many places. The results are sensitive to: pre-trade emission levels, the transaction costs, the availability of information on potential cost savings and assumptions made on the behavior of trading partners.

An economic analysis of potential impacts of climate change in Egypt

Abstract: Projections of climate impacts on crop yields simulated for different General Circulation Model (GCM) scenarios are used, in a recursively dynamic general equilibrium framework, to account for potential economy-wide impacts of climate change in Egypt. Comparing these impact projections to those obtained under a reference, business-as-usual, scenario assuming some moderate changes in the political, economic or technological spheres, indicates that global warming has potentially negative effects. The analysis is based on a global assessment of potential climate change-induced variations in world commodity production and trade. The Egyptian agricultural sector, and the non-agricultural sector to a lesser extent, are projected to be increasingly less self-sufficient. Specific potential adverse impacts are identified. The simulation results show that high-cost adaptation measures involving major changes in the agricultural system and practices may mitigate these adverse impacts. Stimulating economic development of the rural areas and creating appropriate conditions for effective diffusion and development of technologies — particularly for the agricultural sector — would seem a desirable strategy. Perhaps, more importantly, the simulation results show that the assumption of exogenously determined technological progress may be inappropriate, in which case the potential adverse impacts of a future warming of the global climate are likely to be fewer than is indicated in this study — if prevailing constraints on productivity growth in the major food and feed grains are ‘released’ by endogenous advances in technology.

Industrialization as a historical phenomenon

Abstract: Industrialization is shown as a time-specific and spatially heterogeneous process. The description of industrialization paths uses two concepts along a functional/temporal and a spatial dimension: Technology clusters, i.e., a set of interrelated technological, institutional and social innovations, drive particular (historical) periods of industrial output and productivity growth. A spatial taxonomy reflects the different degrees of development and intensiveness of industrialization among core, rim, and periphery. In an inductive approach, industrial growth is described through the prism of changes in technology clusters and the spatially heterogeneous diffusion of industrialization on a global scale. "Industrialization paths" are discussed on the basis of the USA, Western Europe, Russia and Japan. The quantitative description focuses on macro-level indicators of industrial output, and the evolution of the productivity of factor inputs labor and energy. Energy intensiveness and carbon emissions are used as metric to assess changes in the environmental impacts of various industrialization paths, concluding that improvements in the efficiency of factor input use are part of the inherent incentive structure of industrial evolution. However, historical improvement rates will have to be considerably accelerated to lower absolute levels of industrial emissions. Finally, the implications of industrial productivity growth and its distribution in the form of rising incomes (consumption) and free time (leisure) are discussed inter alia from an environmental perspective.

An atmosphere-ocean model for integrated assessment of global change

Abstract: This paper describes the atmosphere-ocean system of the integrated model IMAGE 2.0. The system consists of four linked models, for atmospheric composition, atmospheric climate, ocean climate and for ocean biosphere and chemistry. The first model is globally averaged, the latter are zonally averaged with additional resolution in the vertical. The models reflect a compromise between describing the physical, chemical and biological processes and moderate computational requirements. The system is validated with direct observations for current conditions (climate, chemistry) and is consistent with results from General Circulation Model experiments. The system is used in the integrated setting of the IMAGE 2.0 model to give transient climate projections. Global surface temperature is simulated to increase by 2.5 K over the next century for socio-economic scenarios with continuing economic and population growth. In a scenario study with reduced ocean circulation, the climate system and the global C cycle are found to be appreciably sensitive to such changes.

Differential inclusions with stable subinclusions

Abstract: wherexER”,tE[tO,T]andF:R”x[tO,T] G. R" is a set-valued mapping with compact and convex images. An absolutely continuous function x(m) is a solution of (1) if it satisfies (1) for a.e. t E [to, T]. Thus, a differential inclusion generalizes an ordinary differential equation by permitting a set-valued right-hand side. Differential equations containing either control/ uncertain parameters or discontinuity in the right-hand side can be transformed into the framework of (1) [l, 21. A well-known and very useful result due to Filippov [3] estimates the uniform distance from an arbitrary absolutely continuous function x( -) to the set of solutions of (1) starting from x(t,) by means of constant times the “deviation”

PAHAP: A Pairwise Aggregated Hierarchical Analysis of Ratio‐Scale Preferences

Abstract: In this paper, we present a Pairwise Aggregated Hierarchical Analysis of Ratio-Scale Preferences (PAHAP), a new method for solving discrete alternative multicriteria decision problems. Following the Analytic Hierarchy Process (AHP), PAHAP uses pairwise preference judgments to assess the relative attractiveness of the alternatives. By first aggregating the pairwise judgment ratios of the alternatives across all criteria, and then synthesizing based on these aggregate measures, PAHAP determines overall ratio scale priorities and rankings of the alternatives which are not subject to rank reversal, provided that certain weak consistency requirements are satisfied. Hence, PAHAP can serve as a useful alternative to the original AHP if rank reversal is undesirable, for instance when the system is open and criterion scarcity does not affect the relative attractiveness of the alternatives. Moreover, the single matrix of pairwise aggregated ratings constructed in PAHAP provides useful insights into the decision maker's preference structure. PAHAP requires the same preference information as the original AHP (or, altematively, the same information as the Referenced AHP, if the criteria are compared based on average (total) value of the alternatives). As it is easier to implement and interpret than previously proposed variants of the conventional AHP which prevent rank reversal, PAHAP also appears attractive from a practitioner's viewpoint.

Parametric ordering of complex systems

Abstract: Cellular automata (CA) dynamics are ordered in terms of two global parameters, computable a priori from the description of rules. While one of them (activity) has been used before, the second one is new; it estimates the average sensitivity of rules to small configurational changes. For two-well-known families of rules, the Wolfram complexity classes cluster satisfactorily. The observed simultaneous occurrence of sharp and smooth transitions from ordered to disordered dynamics in CA can be explained with the two-parameter diagram.

Guranteed state estimation for dynamical systems: Ellipsoidal techniques

Abstract: This paper gives a concise description of effective solutions to the guaranteed state estimation problems for dynamic systems with uncertain items being unknown but bounded. It indicates a rather unconventional, rigorous theory for these problems based on the notion of evolution equations of the ‘funnel’ type which could be further transformed - through exact ellipsoidal representations - into algorithmic procedures that allow effective simulation, particularly with computer graphics. the estimation problem is also interpreted as a problem of tracking a partially known system under incomplete measurements. Mathematically, the technique described in this paper is based on a theory of set-valued evolution equations with the approximation of solutions formulated in terms of set-valued calculus by ellipsoidal-valued functions.

A systems approach to immunology and cancer

Abstract: The application of system theory to immunology, cancer, and disease in general is presented Particular results from US-Russian research collaboration depict the potential role of such systematic analysis for more effective health care and disease control In particular, some emphasis is given to tumor control After a brief systematic overview of immunology, various potential immunotherapies are studied The recent clinical results of tumor exacerbation and interleukin treatment are systematically explained for the first time Also, the analysis provides a base for more systematic experimental planning >

Tatonnement procedures for linearly constrained convex optimization

Abstract: The emphasis in this article is to exploit the fact that precision requirements for solutions of most economic models in practice are moderate only. A simple approach is introduced for solving linearly constrained partial equilibrium models based on an iterative scheme similar to the simplex method. It allows large-scale models to be solved, within a practical tolerance, efficiently even in a micro computer environment. Extensions to linearly constrained convex optimization problems are presented. Finally, a set of computational tests on 68 linear programs from the NETLIB library is reported. Comparison of our approach with the simplex method using MINOS 5.1 and with Karmarkar's algorithm is reported. For moderate precision requirements these preliminary results are highly encouraging.

The equilibrium distribution for a class of multi-dimensional random walks

Abstract: In previous papers, it has been proved that the equilibrium distribution of homogeneous, nearest-neighboring random walks on a two-dimensional grid can be constructed explicitly through a compensation procedure if and only if there are no transitions to the North, North-East and East for points in the interior. In the present paper the extension to N-dimensional random walks is investigated. It appears that for higher dimensions the same condition should be satisfied for each plane in the grid space. Since induction with respect to the dimension is applied. the step from dimension 2 to dimension 3 is worked out in detail. For the proof of the if-part the condition is added that the random walk satisfies the so-called projection property on the boundaries. For 3-dimensional random walks, the eqUilibrium distribution appears to be the sum of six alternating series of binary trees of product forms. These analytic results make it possible to develop efficient numerical procedures. Such procedures are sketched in the paper. As a numerical illustration, the procedures are applied to the model of a 2 x 3 switch.

The radii inversion problem associated with the Hg capillary pressure experiment

Abstract: Today's practice of interpreting Hg capillary pressure curves — a widespread method in porosimetry — is generally unsatisfactory. This has already been demonstrated by Fatt. First, the saturation branch of such a curve is interpreted using the concept of a pore space model in which essential features of a network structure are disregarded. Second, the data provided by the desaturation branch are not used. Distributions of radii of capillaries within porous materials derived by this technique are usually incorrect in that the frequencies of occurrence of the greater radii turn out too small, those of the smaller radii too large. We present a more reliable approach which constrains radii frequency ranges for the Hg saturated pore space and for both the part of the pore space that desaturates and the part that traps mercury when Hg pressure is released. The pore space may be of an arbitrary geometrical structure, the radii distribution may be continuous. Also, the Hg desaturation may enable one to distinguish experimentally between structural and contact angle hysteresis.

Output Decline and the Demise of the CMEA and the USSR. The Case of Hungary

Abstract: The direct effect of market losses in CMEA on Hungarian output was 4%, out of the 18% decline registered in gross output in 1988–1992. Total (direct and indirect) effects amounted to 8%. In the same period Hungary's export expansion in western markets led to direct and total effects equivalent to 2.9% and 5.6% of the 1988 output, respectively. The share of reorientation within this switch from east to west was not negligible, it amounted to 19% of respective trade volumes. The 1991 price explosion of imported inputs inhibited the activity of Hungarian firms only moderately, due to earlier realistic domestic prices. In 1991 Hungary suffered a 26% terms of trade loss, and could have experienced an income terms of trade loss of USD 1400 to 1600 million, had the trade volume of 1990 been repeated. Since adjustments in 1991, much smaller income losses accrued. Due to earlier special tax arrangements, much of the burden of terms of trade losses had to be born by the budget.

Small Perturbations in Nonlinear Age-Structured Population Equations

Abstract: A non-linear age-structured population dynamic model described by partial integro-differential equations is considered, where the non-linear term reflects the interaction among individuals. This non-linear model is interpreted as a perturbed linear one. An approximation method based on the ideas of averaging, of a slow time transformation and a power series expansion is suggested. The asymptotic properties of the approximate solution are analyzed. It is shown that the approximate solution remains close to the true solution ast → ∞.