what has driven oil prices since 2000 a structural change perspective abstract this paper characterizes weekly international oil price fundamentals since 2000 by analyzing the transformation of the market mechanism based on structural change perspective using endogenously determined break tests that allow for changes in both level and trend we divide the price fluctuations in the international oil market after 2000 into three stages relatively calm market period january 07 2000 to march 12 2004 the bubble accumulation period march 19 2004 to june 06 2008 and the global economic crisis period june 13 2008 to september 11 2009 the results show the existence of structural breaks refutes the utility of investigation of the full sample period as a whole and in different structural periods the main drivers of oil price changes and their way of influence and degree are significantly distinct then we demonstrate the evolving process of market mechanism since 2000 through establishing comparative models we also quantitatively measure the roles of speculation and episodic events in oil price fluctuations

evolution of population resource dynamics models abstract this paper provides a comprehensive analysis of brander and taylor s 1998 model and its descendants from the following perspectives population growth substitutability innovation capital accumulation property rights and institutional designs and modeling approach this survey aims to contribute to a better understanding of population and resource dynamics models in general and facilitate further application of the model framework to relevant circumstances although often treated as exogenous in optimal growth models making population growth an endogenous function allows us to analyze broader effects of economic activities on population the issues of substitutability innovation and capital accumulation are intertwined allowing a model to address the effect of an endogenous technological change on substitutability between natural and man made capital facilitates our analyses of sustainability issues to address internalizing inter generational externalities in resource use incorporating property right changes and institutional designs to this type of model is a useful exercise but careful attention is needed for the consistency between such an arrangement and the mathematical representation of the depicted economy finally although the common criticism regarding convenient mathematical assumptions applies to the existing bt type models the use of computer simulation can relax such assumptions to better represent the intended relationships between the relevant variables

demographic pressure and natural resources conservation abstract a field survey was carried out in the villages of nlobesse e at the western periphery of the dja biosphere reserve south cameroon to evaluate the various effects that the increase in the local populations exert on the conservation of the natural resources of the reserve survey results show that the population was increasing rapidly at 40 00 00 per annum with 61 54 of the total inhabitants originating from other parts of the country despite the rapid population growth the population of the kaka and baka ethnic groups also known as the pigmies who have been noted by ecofac ecosysteme forestiere d afrique centrale for having a marked negative impact on the conservation of the natural resources because they depend mostly on the natural resources of the reserve for their livelihood and practice very little or no agriculture were decreasing at a rate of 6 2 probably they sought better hunting gathering and collecting conditions elsewhere in the reserve animal proteins originating from the reserve provide most of the animal proteins consumed by the households and the entire population of nlobesse e demands 44 4 kg of bush meat per day it was also noted that the local population practiced very little agriculture in the reserve hunting and fishing activities that have been noted for having a negative influence on the conservation of biodiversity contributed 15 2 and 11 2 respectively of the total income of the households other sources of income included wages earned from the agro plantation that contributed 40 3 farming 24 2 commerce 3 and others 4 58 merchant middlemen also referred to as buyam sellam and individuals with no commercial interest were the two main relay agents responsible for transporting natural resources out of nlobesse e it would have been expected that the increasing population combined to the high incidence of poverty in the region per capita income of 225 fcfa or 0 3 per day would have exerted a high sustainability pressure on the conservation of reserve resources however this was not the case because of an agro plantation in the area that provided the local population with the necessary income to buy foodstuff and other needed resources from far away areas to maintain this trend it is recommended that other sources of income such as the creation of small scale enterprises and ecotourism should be encouraged in and around biospheres reserves

human and nature dynamics handy modeling inequality and use of resources in the collapse or sustainability of societies abstract there are widespread concerns that current trends in resource use are unsustainable but possibilities of overshoot collapse remain controversial collapses have occurred frequently in history often followed by centuries of economic intellectual and population decline many different natural and social phenomena have been invoked to explain specific collapses but a general explanation remains elusive in this paper we build a human population dynamics model by adding accumulated wealth and economic inequality to a predator prey model of humans and nature the model structure and simulated scenarios that offer significant implications are explained four equations describe the evolution of elites commoners nature and wealth the model shows economic stratification or ecological strain can independently lead to collapse in agreement with the historical record the measure carrying capacity is developed and its estimation is shown to be a practical means for early detection of a collapse mechanisms leading to two types of collapses are discussed the new dynamics of this model can also reproduce the irreversible collapses found in history collapse can be avoided and population can reach a steady state at maximum carrying capacity if the rate of depletion of nature is reduced to a sustainable level and if resources are distributed equitably

oil and gas markets in the uk evidence from a cointegrating approach the paper examines the relationship between uk wholesale gas prices and the brent oil price over the period 1996 2003 in order to investigate whether oil and gas prices decoupled during this period as orthodox gas market liberalisation theory suggests tests for unit roots and cointegration are carried out and it is discovered that a long run equilibrium relationship between uk gas and oil prices exists moreover this relationship pre dates the opening of the uk mainland europe interconnector following a recursive methodology hansen h and johansen s 1999 some tests for parameter constancy in cointegrated var models econometrics journal 2 306 333 it was found that the cointegrating relationship is present throughout the sample period however the long run solutions seem to be more volatile evidence is provided that the short run relationship is linear and impulse response functions are used to examine the effects that a shock in oil would have on gas these findings do not support the assumption that gas prices and oil prices decouple

international transmission of inflation among g 7 countries a data determined var analysis abstract we investigate the international transmission of inflation among g 7 countries using data determined vector autoregression analysis as advocated by swanson and granger swanson n granger c 1997 impulse response functions based on a causal approach to residual orthogonalization in vector autoregressions journal of the american statistical association 92 357 367 over the period 1973 2003 we find that unexpected changes in us inflation have large effects on inflation in other countries although they are not always the dominant international factor similarly shocks to some other countries also have a statistically and economically significant influence on us inflation moreover our evidence indicates that us inflation has become less vulnerable to foreign shocks since the early 1990s mainly because of the diminished influence from germany and france

the role of commodity prices in formulating monetary policy commodity prices often provide signals about the future direction of the economy especially inflation it has been argued therefore that the information in commodity prices should be used in formulating monetary policy this paper investigates whether a systematic monetary policy response to contemporaneous commodity price shocks would have helped stabilize the postwar u s economy the authors findings suggest that responding to unexpected commodity price movements would have lowered the average rate of inflation and reduced its variability while the path of real growth would be relatively unchanged copyright 1991 by mit press

energy transition towards economic and environmental sustainability feasible paths and policy implications this paper focuses on growth feasibility in an era of increasing scarcity of fossil fuels a stylised dynamic model illustrates the implications of investing in smooth technological progress in the field of renewable energy positive rates of gdp growth sustained by fossil fuels entail on the one hand more income available for r d in renewable energy sources and on the other an acceleration of the exhaustible resource depletion time our model explores such a trade off and highlights the danger of high growth rates policies should target low growth rates stimulate investment in alternative energy sources and discourage consumption growth

valuation of the operating flexibility of multinational corporations the returns to multinationality are estimated as the value of operating flexibility empirical measures of the return of multinationality require a precise specification of the extensiveness of the mnc s transnational network to measure the degree of multinationality this precise empirically grounded definition of multinationality has been absent from the academic literature to date we address this omission and we find that two characteristics of the transnational network its breadth number of foreign countries in which the mnc has operations and depth the concentration of foreign subsidiaries in a few countries are significant in explaining the value of operating flexibility in particular we find that the returns to multinationality are maximized for firms with networks that have breadth but not depth the role of market intangibles such as r d and advertising on mnc market valuation is shown to depend on the flexibility regime

easter island historical anecdote or warning for the future two standard solutions for the malthusian trap involve institutional reforms and technological progress using easter island as an example we investigate the hypothetical role that technological progress and population management reform might have played in preventing the collapse of the island s civilization the model includes a composite manufactured good and a composite harvested renewable resource fertility is assumed to rise with per capita income the resource s carrying capacity and intrinsic growth rate as well as labor s harvesting productivity are subject to technological progress fertility is subject to population management reform the model yields a system of two simultaneous nonlinear non autonomous differential equations we first study the system s steady states the system is then parameterized for easter island and its comparative dynamics are investigated in simulations we find that technological progress can generate large fluctuations in population renewable resources and per capita utility sometimes resulting in system collapse with high fertility rates the population and the resource vanish none of the simulations investigated here exhibit a constantly growing per capita utility over time finally we evaluate the applicability of these results to contemporary societies 2000 elsevier science b v all rights reserved

oil exploitation and the environmental kuznets curve abstract this study refers to a panel estimation of an environmental kuznets curve ekc for oil to determine the factors most affecting oil exploitation in 38 oil producing countries during 1990 2000 control variables such as oil reserves oil price population political rights and the gini index were used to determine its contribution to the main ekc model the empirical results fully support the existence of an ekc for oil exploitation furthermore the result indicates that the proved oil reserves has a significant and positive role in oil production but oil price and population do not significantly affect crude oil production also increased freedoms and a better income distribution will reduce the rate of oil exploitation thus policies aiming at enhancing democratic society and better income distribution would be more compatible with sustainability

modeling global and local dependence in a pair of commodity forward curves with an application to the us natural gas and heating oil markets abstract the goal of this paper is to present a model for the joint evolution of correlated commodity forward curves each forward curve is directed by two state variables namely slope and level and the model is meant to capture both the local and global dependence structures between slopes and levels our framework can be interpreted as an extension of the concept of cointegration to forward curves the model is applied to a us database of heating oil and natural gas futures prices over the period february 2000 february 2009 we find the long run slope and level relationships between natural gas and heating oil markets analyze the lead and lag properties between the two energy commodities the volatilities and correlations between their daily co movements and evaluate the robustness of these observations to the turmoil experienced by energy markets since 2003

the effect of subsistence on collapse and institutional adaptation in population resource societies abstract we extend the brander taylor model of population and resource development in an isolated society by adding a resource subsistence requirement to people s preferences this improves plausibility amplifies population overshoot and collapse and can destabilize the steady state and allows for complete cessation of non harvesting activities in line with archaeological evidence for many societies we then use bifurcation techniques to give a global analysis of four types of institutional adaptation an ad valorem resource tax and quotas on total resource harvest total harvest effort and per capita effort in all cases we find that a higher subsistence requirement makes it harder or often impossible for adaptation to avoid overshoot and collapse

non linear dynamics of population and natural resources the emergence of different patterns of development abstract this paper studies the long term dynamic interaction between the exploitation of natural resources and population growth brander and taylor brander j a and taylor m s 1998 the simple economics of easter island a ricardo malthus model of renewable resource use american economic review 88 1 119 138 started a sequence of papers which sought to deduce from historical and archaeological studies some stylized links between ecological and economic systems in this strand of literature all the services of the natural environment are aggregated in an ecological complex which is characterized by a simple logistic dynamics given such assumptions these models show a unique long term steady state the aim of this paper is to obtain a more general framework that could account for the heterogeneity of environmental development paths followed by past societies two new assumptions are introduced i the disaggregation of the ecological complex into two different resources ii irreversibility namely an inexorable tendency to exhaustion when the renewable resource stock is below a certain threshold analysis of the dynamic properties of the system shows a multiplicity of steady states which makes it possible to consider the effects of technical progress cultural and climate changes on the resilience of the existing development path

have oil and gas prices got separated abstract this paper applies vector error correction models that show that oil and natural gas prices decoupled around 2009 before 2009 us and uk gas prices had a long term equilibrium with crude prices to which gas prices always reverted after exogenous shocks both us and uk gas prices adjusted to the crude oil price individually and departure from the equilibrium gas price on one continent resulted in a similar departure on the other after an exogenous shock the adjustment between us and uk gas prices took approximately 20 weeks on average and the convergence was mediated mainly by crude oil with a necessary condition that arbitrage across the atlantic was possible after 2009 however the uk gas price has remained integrated with oil price but the us gas price decoupled from crude oil price and the european gas price as the atlantic arbitrage has halted the oversupply from shale gas production has not been mitigated by north american export as there has been no liquefying and export capacity

coupled societies are more robust against collapse a hypothetical look at easter island inspired by the challenges of environmental change and the resource limitations experienced by modern society recent decades have seen an increased interest in understanding the collapse of past societies modelling efforts so far have focused on single isolated societies while multi patch dynamical models representing networks of coupled socio environmental systems have received limited attention we propose a model of societal evolution that describes the dynamics of a population that harvests renewable resources and manufactures products that have positive effects on population growth collapse is driven by a critical transition that occurs when the rate of natural resource extraction passes beyond a certain point for which we present numerical and analytical results applying the model to easter island gives a good fit to the archaeological record subsequently we investigate what effects emerge from the movement of people goods and resources between two societies that share the characteristics of easter island we analyse how diffusive coupling and wealth driven coupling change the population levels and their distribution across the two societies compared to non interacting societies we find that the region of parameter space in which societies can stably survive in the long term is significantly enlarged when coupling occurs in both social and environmental variables

modelling futures price volatility in energy markets is there a role for financial speculation this paper models volatility in four energy futures markets adopting garch models the variance equation is enriched with alternative measures of speculation based on cftc data the market share of non commercial traders the working s t index and the percentage of net long positions of non commercials over total open interest in future markets it also includes a control for market liquidity we consider four energy commodities light sweet crude oil heating oil gasoline and natural gas over the period 2000 2014 analysed at weekly frequency we find that speculation presents a negative and significant sign the robustness exercise shows that i results remain unchanged through different model specifications garch in mean egarch and tarch ii results are robust to different specifications of the mean and variance equation

poverty trap and global indeterminacy in a growth model with open access natural resources abstract in this paper we use global analysis techniques to analyze an economic growth model with environmental negative externalities giving rise to a three dimensional dynamic system the framework is the one introduced by wirl 1997 53 the dynamics of our model admits a locally attracting stationary state p 1 which is in fact a poverty trap coexisting with another stationary state p 2 possessing saddle point stability global dynamical analysis shows that under some conditions on the parameters if the initial values of the state variables are close enough to the coordinates of p 1 then there exists a continuum of equilibrium trajectories approaching p 1 and one trajectory approaching p 2 therefore our model exhibits global indeterminacy since either p 1 or p 2 can be selected according to agent expectations moreover we prove that conditions guaranteeing the attractivity of p 1 also imply the saddle point stability of p 2 however when p 1 is not attractive numerical simulations show the possible existence of one or two limit cycles an attractive one surrounding p 1 and one endowed with a two dimensional stable manifold surrounding p 2

market conditions trader types and price volume relation in energy futures markets we investigate the asymmetric relations between trading volume and price changes and trading volume and price volatility of energy futures contracts across maturities and under different market conditions using a relatively long sample of daily observations we examine whether the impact of trading volume on returns and volatility of futures contracts can be time varying and dependent on the market condition we differentiate the market condition based on the slope of the forward curve into backwardation and contango the results indicate that trading volume and returns are positively related when the market is in backwardation and negatively related when the market is in contango in addition the positive relation between changes in trading volume and volatility of futures contracts seem to be stronger when the market is in backwardation than when it is in contango finally the results indicate that to a certain extent trade participation and trading activities of agents in energy futures markets can be explained by the slope of the forward curve which reflects the market condition and sentiment

what drives natural gas prices a structural var approach abstract in this study we develop a structural vector autoregressive model var for the german natural gas market our setup allows us to analyze the determinants of the natural gas price in a comprehensive framework in particular we illustrate the usefulness of our approach by disentangling the effects of different fundamental influences on gas prices during three recent supply interruptions the russian ukrainian gas dispute of january 2009 the libyan civil war in 2011 and the withheld russian exports in february 2012 our results show that the natural gas price is affected by temperature storage and supply shortfalls in the short term while the long term development is closely tied to both crude oil and coal prices capturing the economic climate and the substitution relationship between the different energy commodities

renewable resources property rights regimes and endogenous growth abstract we extend brander and taylor s brander j a taylor m s 1998 the simple economics of easter island a ricardo malthus model of renewable resource use am econ rev 88 119 138 model of feast and famine cycles on easter island using galor and weil s gailor o weil d n 2000 population technology and growth from malthusian stagnation to the demographic transition and beyond am econ rev 90 806 28 model of endogenous technological advance where technological change is related to the population we note that different property rights regimes will influence the relative direction of technological advance whether that advance is in harvesting technologies or in technologies that influence the growth rate of some renewable biological resource property rights regimes that favor biological growth rates over harvest rates tend to dampen feast famine cycles while those that favor harvest efficiency worsen such cycles

what drives natural gas prices in the united states a directed acyclic graph approach abstract this study investigates the impacts of driving factors for natural gas prices during the period from 1999 to 2017 a data driven approach namely the directed acyclic graph dag is first employed to disclose the contemporaneous relations among natural gas crude oil and various factors the main results indicate that there is a stable contemporaneous causal flow from crude oil to natural gas unlike most of the previous research we found a long term equilibrium relationship between crude oil and natural gas returns when additional factors were taken into account however the impact of oil price returns on natural gas price volatility has decreased after the 2008 global financial crisis finally storage and seasonality factors can never be ignored when analysing natural gas prices while the impact of speculative activity on natural gas volatility is relatively weak

separated influence of crude oil prices on regional natural gas import prices this paper analyses the impact of global economic activity and international crude oil prices on natural gas import prices in three major natural gas markets using the panel cointegration model it also investigates the shock impacts of the volatility and the increase and decrease of oil prices on regional natural gas import prices the results show that both global economic activity and international crude oil prices have significant long term positive effects on regional natural gas import prices the volatility of international crude oil prices has a negative impact on regional natural gas import prices the shock impact is weak in north america lags in europe and is most significant in asia which is mainly determined by different regional policies for price formation in addition the response of natural gas import prices to increases and decreases in international crude oil prices shows an asymmetrical mechanism of which the decrease impact is relatively stronger

the message in north american energy prices how similar is the price behavior of north american natural gas fuel oil and power prices using current state of the art econometric methodology we explore the degree of shared trends across north american energy markets across these markets there appear to be effective arbitraging mechanisms for the price of natural gas and fuel oil but not for the price of electricity

gas and lng trading hubs hub indexation and destination flexibility in east asia abstract in the east asian gas markets issues like gas trading hubs hub indexed pricing and destination flexibility are being debated this paper examines the impact of a change in east asia s pricing benchmark and contract flexibility on the regional and global gas markets the paper uses the nexant world gas model a linear program with global cost minimization as the objective to our knowledge this study on hub competition price benchmark change and contract flexibility improvement in east asia will be the first in the literature and have real policy relevance the results show that both price benchmark change and contract flexibility improvements will create an overall benefit for the world and east asia importers but the impacts are different among exporters and importers however there is no evidence of competition among different benchmark hubs and no evidence that destination restrictions cause the asia premium it implies that removal of destination clauses has higher priority than the change to hub indexation for japan korea and chinese taipei but both should be treated equally in china the study also suggests that east asian importers should cooperate among themselves and with exporters to facilitate the hub creation and contract changes in east asia

contagion around the october 1987 stock market crash abstract this study investigates financial contagion among seven international stock markets around the october 19 1987 crash building on a recent advance in vector autoregression analysis by swanson n granger c w j 1997 impulse response functions based on a causal approach to residual orthogonalization in vector autoregression journal of the american statistical association 92 357 367 data determined historical decompositions are conducted to provide a day by day picture of price fluctuation transmission which is crucial to explore the financial contagion pattern characterized by rich dynamics the results clearly show that the crash originated in the us market and that an upward movement in the japanese market after the crash helped the recovery in the us market which has not yet been empirically documented in the literature