Koichi Kuriyama

Statistical analysis for the development of national average weighting factors—visualization of the variability between each individual’s environmental thoughts

PurposeWeighting is one of the steps involved in life cycle impact assessment (LCIA). This enables us to integrate various environmental impacts and facilitates the interpretation of environmental information. Many different weighting methodologies have already been proposed, and the results of many case studies with a single index have been published. However, a number of problems still remain. Weighting factors should be based on the preferences of society as a whole so that the life cycle assessment (LCA) practitioner can successfully apply them to every product and service. However, most existing studies do not really measure national averages but only the average of the responses obtained from the people actually sampled. Measuring the degree of uncertainty in LCIA factors is, therefore, one of the most important issues in current LCIA research, and some advanced LCIA methods have tried to deal with the problem of uncertainty. However, few weighting methods take into account the variability between each individual’s environmental thoughts. LIME2, the updated version of life cycle impact assessment method based on endpoint modeling (LIME), has been developed as part of the second LCA national project of Japan. One of the aims of LIME2 is to develop new weighting factors which fulfill the following requirements: (1) to accurately represent the environmental attitudes of the Japanese public, (2) to measure the variability between each individual’s environmental thoughts and reflect them in the choice of suitable weighting factors.MethodsThis study adopted the technique of conjoint analysis, which is currently the most advanced methodology available in the field of environmental economics. Using a random sampling process, 1,000 individual responses were collected. Every response was based on an interview survey designed to minimize bias. We used a random parameter logit model to estimate the preferences of society. Statistical values based on this model can be considered to reflect the variability between each individual’s environmental thoughts. The calculated results can then be used to develop integration factors in LIME2, enabling us to express LCIA results as a single index, such as external cost.Results and discussionThe calculated values were significant statistically at the 1% level (all p values for the safeguard subject coefficients were less than 0.0001), with the exception of “social assets.” Based on the calculated results, two types of weighting factor, an economic valuation and a dimensionless index, were obtained. A relative comparison of importance among these four categories indicates that “biodiversity” receives the highest level of recognition, followed by “human health” and “primary production,” while the weight of “social assets” rate lower than the other safeguard subjects, in comparison. Using the calculated results produced by the RPL model, the probability density of the variables for individual preferences could then be derived and displayed. The coefficients of variance for the estimated weighting factors were relatively small (in the range from 0.1 to 0.3).ConclusionsAccurate weighting factors representing the environmental attitudes of the Japanese public are needed in order to conduct general-purpose LCA for Japanese products. Random, unbiased sampling throughout Japan and an interview survey carried out on 1,000 respondents enabled us to address and solve the problems found with past weighting methodologies. We confirmed that the results of comparisons carried out among safeguard subjects were statistically significant, and showed that the contents of the questionnaires were well understood by the respondents. This study succeeded in visualizing the variability between each individual’s environmental thoughts in order to improve the transparency of the weighting factors—expressing the difference in individual preferences within a certain range. This data can be used to develop integration factors with statistical values which can then be applied to uncertainty analysis in future LCA case studies.

Development of weighting factors for G20 countries. Part 2: estimation of willingness to pay and annual global damage cost

PurposeThis paper is the second part of a series of articles presenting the results of research on monetary weighting factors (MWFs) for the G20 countries, which together account for approximately 90% of the global GDP. We developed their MWFs with regard to Life Cycle Impact Assessment (LCIA) and evaluated them via a large-scale questionnaire survey. We estimated the economic value of one unit of damage caused by human activities.MethodsTo ensure that the MWFs covered all areas of protection as defined by the LCIA method based on Endpoint Modeling (human health, social assets, biodiversity, and primary production), we conducted a choice experiment in all G20 countries. We conducted face-to-face interviews to minimize survey bias and ensure that the questions were understood by the emerging G20 countries’ respondents. Internet surveys were adopted to collect samples from the developed G20 countries’ respondents, where Internet diffusion rates are generally high. We obtained response data from 200 to 250 and 500 to 600 households of all the emerging and all the developed G20 countries, respectively. We gathered 6400 responses in all. We estimated preference intensities using the random parameter logit model. We calculated MWFs based on each respondent’s willingness to pay.Results and discussionWe devised MWFs providing the costs of damage to four safeguard subjects. All the estimated values are statistically significant at the 1% level, with the exception of monetary attributes from Mexico. The MWFs for the G20 are 23,000 USD for human health (per year), 2.5 USD for social assets (per USD of resources), 11 billion USD for biodiversity (per species), and 5.6 billion USD for primary production (per 100 million tons). The differences between the developed and emerging G20 countries are considerable, with the values generally being smaller for the latter in purchasing power parity (USD) terms. The estimated global total economic annual impact was approximately 5.1 trillion USD (6.7% of the world’s total GDP).ConclusionsWe obtained reasonable and conservative global-scale MWFs compared with previous studies. Moreover, the cross-country heterogeneity in this study potentially helps extrapolate future/global value developments from current/local estimates. The variations in human health and social asset MWFs are small enough within developed countries to allow international transfers among them, while significant variations in biodiversity and primary production MWFs are a caveat to up-front international transfers even within developed countries.

How many broadleaved trees are enough in conifer plantations? The economy of land sharing, land sparing and quantitative targets

Summary For biodiversity conservation to be an effective and significant social investment, non-marketed values of biodiversity conservation and its associated opportunity costs should be evaluated in monetary terms. In this study, we measured the willingness to pay (WTP) for bird abundance using a choice experiment (CE) based on the random utility model. We performed a cost–benefit analysis to identify the optimal proportion of broadleaved trees in conifer plantations on a volume basis to maximize the social benefits of bird conservation and wood production. The results suggested that respondents to the CE were not satisfied with their current situation and preferred an increase in bird abundance. However, the estimated WTP indicated diminishing returns of bird conservation. More specifically, WTP first greatly increased before gradually experiencing decreasing marginal values, reaching its peak and finally decreasing slightly with increasing bird abundance. Optimization analyses indicated that when the relationship between bird abundance and broadleaved tree proportion was convex, semi-natural plantations with nonzero broadleaved tree proportion (0·02–0·22) were always optimal options. When the relationship was linear, optimal broadleaved tree proportion ranged from 0 to 0·78 and was greatly affected by wood values. When the relationship was concave, there were only two optimal broadleaved tree proportions: a very high proportion (approximately 0·90) and the lowest possible proportion (0). When the convex and concave relationships approached the linear form, comparable benefits could be attained across broad ranges of broadleaved tree proportion both within and across the relationships. In such cases, it would be useful to increase the likelihood of a feasible land-use strategy of either land sparing or land sharing in order to be successful. Synthesis and applications. It can be difficult to set quantitative targets in biodiversity conservation solely on an ecological basis, and social benefits of biodiversity conservation can create diminishing returns in many situations. The framework we propose shows how to reconcile resource production and biodiversity conservation in the real world.

Efficiency analysis of thinning based on daily reports of forest operations: the case of Hiyoshi, Japan

ABSTRACT A new requirement has emerged to improve efficiency in forest management in Japan. However, few empirical studies assess the efficiency of forest management using data from several sites and examine long-term forest management. The objective of this research is to assess the efficiency of thinning by examining daily operational data on the districts in Hiyoshi provided by the Hiyoshi’s Forest Owners’ Cooperative. Using data envelopment analysis, we find that even within the same organization, differences can be seen among forest plots. In addition, from the econometric analysis, we find that efficiency significantly depends on natural conditions such as tree diameter at breast height or number of felled trees left in forests (rather than extracted). The results indicate that Hiyoshi’s Forest Owners’ Cooperative, which applies relatively advanced forest management, can still improve efficiency by working with trees with large enough diameters at breast height, implementing thinning that will lead to such larger diameters, and introducing an adequate machine that will decrease the number of felled trees left in forests.