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Weighting of impacts is frequently applied to enable the prioritization of life cycle assessment (LCA) results for the support of decision making. Most Distance-to-Target (DtT) weighting approaches consider policy targets, whereas potential is seen in the weighting of environmental impacts on a more scientific basis. This study aims at the comparison of science-based (SB) to policy-based (PoB) DtT weighting approaches as well as the application in a comparative case study for the domestic footprint of the European Union. The developed approaches integrated SB targets from ten environmental impact categories into the DtT weighting method of the Ecological Scarcity Method in an effort to derive SB eco-factors. In addition to SB eco-factors based on existing weighting factors for Europe from the literature, weighting factors for the European Union were developed. The application of the eco-factors in the case study showed that the SB approach led to three times higher absolute weighting results in contrast to PoB results. SB weighting was dominated by the impact category climate change with the strictest weighting factors in all approaches considered and a share of 87–92%. For the remaining impact categories, common PoB weighting factors were generally stricter. PoB results showed a more balanced distribution, with shares of 64% for climate change, 10% for photochemical ozone formation, 7% for acidification, and 7% for terrestrial eutrophication. Science-based targets can not replace conventional PoB weighting approaches but should be integrated into the weighting step to provide a more comprehensive view of the environmental performance of product systems. SB weighting results are an additional source of information on environmental sustainability regarding environmental carrying capacity that can broaden the basis for decision making. • Comparison of targets based on science and policy via distance-to-target weighting. • Development of weighting sets for comparative application to EU domestic footprint. • Science-based results are dominated by the impact category climate change. • Lower results in policy-based weighting due to less strict climate policy targets. • Analysis of EU policy regarding effectiveness to stay within carrying capacities. [ABSTRACT FROM AUTHOR]

Although many of today's ecological, climatic and socio-economic problems seem unprecedented, similar events have occurred in the past. As such, historic periods of climatic and economic volatility can be used as a way of developing frameworks for analyzing today's predicament. Western Europe's “middle ages” (circa 11–14th century) may be one such case. By the 12th century, medieval Europe had shifted from the subsistence agrarian economy that emerged following the collapse of the Roman Empire to one where spatially dispersed trade in agricultural commodities helped support a complex society that devoted considerable resources to cultural works. This shift was facilitated by new institutional arrangements centred on monastic orders that provided access to both new agricultural and food processing technologies as well as trade routes. These institutional arrangements contributed to population growth and land clearing. All of these factors increased the wealth of society but also concentrated this wealth in a small number of communities that were dependent on an ever-increasing and exploited hinterland for resources. Ultimately, this created a tightly coupled continent-wide subsistence system that was vulnerable to the weather, economic and disease shocks of the 14th century when Europe's population declined by perhaps 50%. In exploring this history, the goal of this paper is to draw on a diverse theoretical body of literature (that includes resiliency theory, landscape ecology, political science and ecological economics) to develop a series of hypotheses about how large-scale complex civilizations can become vulnerable to climate change. [Copyright &y& Elsevier]