تجزیه و تحلیل هزینه - منفعت سیستم برق سبز در ژاپن با توجه به اثرات اقتصادی غیر مستقیم از طوفان گرمسیری

Global warming is likely to profoundly influence future weather patterns, and one consequence of this is the likelihood of an increase in tropical cyclone intensity. The present paper presents a cost-benefit analysis of introducing significant amounts of green energy in the electricity system in Japan in the light of the economic damage that an increase in tropical cyclone intensity could have on GDP growth between 2010 and 2085. Essentially the passage of a tropical cyclone will result not only in physical damage but also on a decrease in economic productivity due to precautionary cessation of the economic activity, which has an effect on GDP growth. By comparing the economic performance of different electricity system scenarios with the indirect economic damage of tropical cyclones from 2010 to 2085, based on the yearly economic data of green electricity, fossil fuel, GDP and population, it can be seen that the green scenarios are generally a cost-effective way of mitigating the effects of these weather systems, despite the large amount of initial investments necessary.

Global warming as a consequence of increased CO2 concentrations in the atmosphere is nowadays increasingly accepted as a scientific fact, and is considered one of the major challenges facing humanity in the 21st century. The 4th Intergovernmental Panel on Climate Change (4th IPCC) provides a well-established body of literature supporting this, and it is generally accepted that action must be taken to attempt to guard against the worst possible effects of climate change by reducing the emissions of CO2 and other greenhouse gases. These ideas were enshrined in the Kyoto Protocol, which committed major industrialised countries to the reduction of CO2 concentrations from the baseline 1990 levels. Japan, as one of the Annex 1 countries, is committed to these reductions, and Prime Minester Hatoyama pledged a 25% reduction in CO2 emissions by 2020 (BBC, 2009). Tropical cyclones can have devastating effects, especially in poor countries (Landsea et al., 2006). In Asia Cyclone Sidr was one of the strongest cyclones ever recorded, causing significant damage to Bangladesh in 2007 (Shibayama et al., 2009). However, the area most frequently affected by tropical cyclones is that of the western north Pacific Ocean, accounting for approximately one-third of these phenomena (Imamura and Van To, 1997). One of the worst affected places is Japan, which between 1980 and 2008 accounted for eight out of the ten costliest natural disasters in Asia (Elsner et al., 2008). A possible consequence of global warming is an increase in the frequency and intensity of tropical cyclones due to the warming of the sea (Emanuel, 1991 and Holland, 1997). Some evidence that this effect could already be happening has been given by Elsner et al. (2008) and Webster (2005). However, tropical cyclones are still not well understood and other research has argued that the data available is not reliable enough to make assertions about the relationship between climate change and tropical cyclones (Pielke et al., 2005 and Landsea, 2005). The present paper does not deal with the uncertainties regarding a possible increase in tropical cyclone intensity. Rather, the authors' would like to explore what would be the economical effects if this potential increase in intensity becomes a reality and if it would be cost-effective for Japan to mitigate them by increasing the uptake of renewable energy. Webersik (2010) points out that in the future the situation could reach a point where the costs of natural hazards may potentially outpace economic growth. This assertion has so far not been sufficiently explored in literature, specially a comparison of the costs that could be expected from a quick uptake in green technology. To try to understand how tropical cyclones are likely to be affected by an increase in global temperatures, a number of global climate models using powerful supercomputers have been carried out, as highlighted in the 4th IPCC. This report shows how although there is a general agreement that tropical cyclones are likely to increase in intensity, there is yet no consensus on the future frequency of these events. This increase in intensity will have profound effects on coastal areas, with wave heights expected to increase at both middle latitudes and the Antarctic Ocean (Mori et al., 2010). The damage that high waves can cause to coastal areas would be exacerbated by increases in the magnitude of storm surges, which become more severe as tropical cyclones increase in intensity (Kawai et al., 2006). These two effects would magnify the effects that sea level rise would have on coastal areas (Nobuoka, 2010). Measuring economic damage due to storms is a complex problem. This damage can broadly divided into two categories, the damage caused by the destruction of houses, infrastructure and other material objects (direct damage) and the loss in productivity due to temporary shutdown in production and because of prevention activities (indirect damage). Some research has been done on the possible effects of direct damage, such as that by Pielke (2007) and Hallegatte (2007), although it could be theoretically possible to increase the resilience of human societies (by improvement in building techniques, etc.) to reduce the exposure to direct damage. Hence the present paper will ignore this effect, as adaptation measures are likely to make countries more resilient to an increase in tropical cyclone intensity damage potential, and due to the fact that this effect is difficult to measure across different temporal domains. Regarding indirect damage, Hallegatte (2008) explains how this includes “business interruption in the event aftermath, production losses during the reconstruction period, and service losses in the housing sector”. This author found that the total losses due to a disaster affecting the area of Louisiana in the USA increase nonlinearly with respect to direct losses when the latter exceed $50 billion (for instance when direct losses exceed $200bn, total losses are twice as large as direct losses). The model given by Hallegatte (2008) attempts to reproduce the disruption in production that takes place after the event, and is useful to model the effects of high intensity events. However, in many countries in the Asia-Pacific, tropical cyclone related downtime is mostly due to low-intensity but high-frequency events. Hence, downtime is directly related to the duration of the event and as the tropical cyclones grow larger in the future the number of hours that a given area of a country will be affected by them will also increase. Esteban et al., 2009a and Esteban et al., 2009b thus analysed the effect of downtime on the economy due to an increase in the size of future tropical cyclones. However it is very difficult to adapt against this increase in downtime, and if anything, an increase in adaptation capacity would increase indirect economic losses. Pielke (2007) noted how “decision makers (including forecasters and emergency managers) have possibly become more risk averse over time and have used advance in the science of forecasting to reduce the chances of leaving part of the population unwarned. Of course, such strategies have costs in the form of a greater number of people warned unnecessarily”. The present paper will try to estimate economic effect of this increase in downtime in Japan and will then compare it to the cost of the mitigation measures (the cost of using green energy, which at present is generally more expensive than traditional forms of electricity production). This would thus highlight if it is Japan's economic interest to further increase the uptake in renewable energy and push for other countries to curb greenhouse gas emissions, through a successor to the Kyoto Treaty, for example.

A model was developed to try to understand the economic risks that an increase in tropical cyclone size would have on the Japanese economy by 2085. As any model that attempts to predict the effects of climate change, it is based on a number of assumptions, clearly stated, that try to be as conservative as possible while allowing for an understanding of the magnitude of the problem. A wide variety of scenarios are employed in the model, highlighting different assumptions relating to the future cost of electricity, the influence of the maximum wind intensity of the typhoon and the growth in its size, and GDP per capita growth levels for the Japanese economy. As a consequence of the wide range of these scenarios, different conclusions could be obtained from the present work, depending on the scenarios that the reader will choose to consider. The authors themselves would like to emphasise that they believe that the cost of conventional electricity is likely to increase in the future, driven by factors such as peak oil &gas, the increase competition for these resources, and the pressure that this would then place on coal. The present work thus shows how it would be much cheaper for a country such as Japan to enter into a binding international treaty on greenhouse gas emissions, and face an increased cost in the price of electricity in the immediate future, than face the consequences on inaction. Of course, the outcome of this calculation assumes that all countries would be acting together, and that there would be no “free-riders” in the system, which would destroy any incentive for Japan to enter into such a treaty. Three different green technology scenarios are presented in the paper, a full solar, full wind, and a Solar+Wind Scenario. While the scenarios presented might appear simplistic and conservative, the authors believe that in doing so the message given in the paper is unequivocal. More complex and optimistic green energy scenarios would only reinforce the message given in the present paper. The calculations carried out in the present paper, though detailed, only consider one aspect of the danger of tropical cyclone intensity, that of indirect damage, and clear do not represent the total effect of these phenomenon. If these events are indeed influenced by climate change, the full economic consequences of what is outlined on this paper would be a gross under-estimation of the total effect that they could haveon the economy.