رشد اقتصادی و بازبینی مصرف انرژی- شواهدی از علیت گرنجر خطی و غیر خطی

The relationship between energy consumption and economic growth is considered as an imperative issue in energy economics. Previous studies have ignored the nonlinear behavior which could be caused by structural breaks. In this study, both linear and nonlinear Granger causality tests are applied to examine the causal relationship between energy consumption and economic growth for a sample of Asian newly industrialized countries as well as the U.S. This study finds evidence supporting a neutrality hypothesis for the United States, Thailand, and South Korea. However, empirical evidence on Philippines and Singapore reveals a unidirectional causality running from economic growth to energy consumption while energy consumption may have affected economic growth for Taiwan, Hong Kong, Malaysia and Indonesia. Policy implications are also discussed.

Economists have been debating about the issues related to global warming and policies have been designed and implemented to address the global warming issue. For this purpose, the Kyoto Protocol has been enacted in 2005. According to the Protocol, 39 developed and developing countries in the world have to reduce their CO2 emission to 5% of their 1999 levels by 2012. To protect economic development, no CO2 reduction promise is required for the first commitment period of 2005–2012 for other developing countries. Some of these countries produce a considerably large share of the world's total emission due to high level of industrial development. For example, South Korea, Taiwan and Singapore rank high on the list of CO2 emission: 9th, 22nd and 39th, respectively. Therefore, these countries are considered to be the candidates to reduce their CO2 emissions in the following period. The issue of the possible impact of emission reduction on economic growth inevitably arises due to the possible connection between emission and energy consumption, and energy consumption and economic growth. Due to the importance of the possible connection between energy consumption and economic growth, there is a growing literature in this area. In general, studies find evidence of correlation between these two variables for countries with different economic structure and at different stages of economic development. Studies on the bi-directional relationships can be traced back to Kraft and Kraft (1978). They applied the Granger causality test to U.S. data for the period of 1947–1974, and found that a unidirectional causality runs from economic growth to energy consumption, thus suggesting that an energy conservation policy is feasible. Since Kraft and Kraft (1978), there has been a vast body of studies contributing to this literature. Table 1 summarizes related studies. One observation from the table is that these studies yield mixed and often conflicting results for both developed and developing countries due to different methods, sample periods, and model specifications being employed. Furthermore, it is worth noting that most previous studies are limited in scope to the applications of linear models. However, economic events and regime changes such as changes in economic environment, changes in energy policy and fluctuations in energy price can cause structure changes in the pattern of energy consumption for a given time period under study. This creates a room for a nonlinear rather than linear relationship between energy consumption and economic growth (Lee and Chang, 2005).Looking at the time trends of energy consumption for sampled Asian developing countries as in Fig. 1, one can observe one or more possible breaks. Some studies considered these possible structure changes in the time series. For example, Lee and Chang (2005) used the cointegration test to examine the structural breaks in the Taiwanese energy consumption for the period of 1954–2003, and identified the points of structure break in energy consumption and GDP. Given the evidence of structural breaks within the series, a nonlinear relation has to be taken into account when one investigates the relationship between energy consumption and economic growth. The Granger causality test (Granger, 1969) is based on the assumption of linear relationships between variables, and is therefore not able to explore the nonlinear causal relationship. Baek and Brock (1992) proposed a nonlinear Granger causality test to deal with the nonlinearity issue. Through using Monte Carlo simulation, they showed that forecasting performance of linear models decreases in the presence of nonlinearity, and the forecasting performance of nonlinear models is better than that of linear models. For this reason, the nonlinear Granger causality test has been widely employed in many fields such as macroeconomics and finance (Hiemstra and Jones, 1994). In order to apply the nonlinear causality test, linear dependence is removed. For this purpose, this study applies a VAR model to remove any linear dependencies and then uses the BDS test by Brock et al. (1987) to test any nonlinear dependencies among the residuals. Our study focuses on Asian developing countries in a hope to provide more definitive evidence between energy consumption and economic growth to aid their policy design and implementation.

The causal relation between energy consumption and economic growth has been a well-studied topic. Energy is one of essential factors for any country's economic development and therefore plays an important role in economy activities. On the other hand, higher level of economic development could induce more energy consumption. Facing the goal of emission reduction set by Kyoto protocol to mitigate global warming, energy policies for many countries have more or less been impacted by the protocol. Hence, the impact of corresponding changes in energy policy and energy consumption on economic growth, especially for developing countries, deserves more careful studies. This study centered on the energy consumption–economic growth relationship and empirically investigated a sample of nine Asia developing countries, taking into account the nonlinearity of time series. Different from previous studies, this study employed the nonlinear Granger causality test in addition to linear Granger causality test to examine the relations between energy consumption and economic growth for the sample countries. The results reveal that five countries (Taiwan, Hong Kong, Singapore, Indonesia and Philippines) had nonlinear causal relations between energy consumption and economic growth. The existence of nonlinearity might owe to the structural breaks caused by some significant economic events such as the Asian financial crisis or oil crisis etc. Ignoring the nonlinearity, therefore, the linear model cannot fully explore all information. The neutrality hypothesis, i.e. no causal relation between energy consumption and economic growth, is supported by both the linear and nonlinear tests for the United States, South Korea and Thailand. However, the unidirectional nonlinear Granger causality running from economic growth to energy is evident for Philippines and Singapore. In term of policy implication, due to the neutrality or unidirectional causality for above countries, implementing energy conservation policies and strategies to mitigate global warming in the Kyoto protocol such as reducing CO2 emissions would not significantly impact economic growth in these countries. On the other hand, the causality running from energy consumption to economic growth is found evident for Taiwan, Hong Kong, Malaysia and Indonesia. More specifically, the bi-directional causality exists for Malaysia and Indonesia, while unidirectional causality exists for Taiwan and Hong Kong. For these countries, therefore, implementing energy conservation policy might lead to a significantly negative impact on economic growth. Facing continuously rising oil price and coping with the pressure of environmental protection, the above countries should actively seek other energy-related strategies such as enhancing efficiency of energy consumption and developing alternative energy resources to sustain economic growth. Due to the topical importance of the relationship between energy consumption and economic growth and the lack of uniformity in empirical findings, however, we caution that government of these countries need to be extra careful in implementing relevant policies and the policies should be based on sound economic analyses. In this regard, our study represents one step closer to economic truth, but further studies utilizing newer samples and newer methodologies are clearly warranted.