Understanding the drivers of energy and material flows of cities is important for addressing global environmental challenges. Accessing, sharing, and managing energy and material resources is particularly critical for megacities, which face enormous social stresses because of their sheer size and complexity. Here we quantify the energy and material flows through the world’s 27 megacities with populations greater than 10 million people as of 2010. Collectively the resource flows through megacities are largely consistent with scaling laws established in the emerging science of cities. Correlations are established for electricity consumption, heating and industrial fuel use, ground transportation energy use, water consumption, waste generation, and steel production in terms of heating-degree-days, urban form, economic activity, and population growth. The results help identify megacities exhibiting high and low levels of consumption and those making efficient use of resources. The correlation between per capita electricity use and urbanized area per capita is shown to be a consequence of gross building floor area per capita, which is found to increase for lower-density cities. Many of the megacities are growing rapidly in population but are growing even faster in terms of gross domestic product (GDP) and energy use. In the decade from 2001–2011, electricity use and ground transportation fuel use in megacities grew at approximately half the rate of GDP growth.

Standard-Nutzungsbedingungen:Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden.Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen.Sofern die Verfasser die Dokumente unter Open-Content-Lizenzen (insbesondere CC-Lizenzen) zur Verfügung gestellt haben sollten, gelten abweichend von diesen Nutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte. The opinions expressed in this paper do not necessarily reflect the position of Fondazione Eni Enrico Mattei Terms of use: Documents in Back to Kyoto? US Participation and the Linkage between R&D and Climate Cooperation SummaryThe US decision not to ratify the Kyoto Protocol and the recent outcomes of the Bonn and Marrakech Conferences of the Parties drastically reduce the effectiveness of the Kyoto Protocol in controlling GHG emissions. The reason is not only the reduced emission abatement in the US, but also the spillover effects on technology and countries' relative bargaining power induced by the US decision. Therefore, it is crucial to analyse whether an incentive strategy exists that could induce the US to revise their decision and to comply with the Kyoto commitments. One solution, occasionally proposed in the literature and in actual policymaking, is to link negotiations on climate change control with decisions concerning international R&D cooperation. This paper explores this idea by analysing on the one hand the incentives for EU, Japan and Russia to adopt this strategy, and on the other hand the incentives for the US to join a coalition which cooperates both on climate change control and on technological innovation. The extended regime in which cooperation takes place on both dimensions (GHG emissions and R&D) will be examined from the view point of countries' profitability and freeriding incentives. Finally, after having assessed the effectiveness and credibility of the issue linkage strategy, we explore the economic and environmental benefits of a new, recently proposed regime, which aims at achieving GHG emission control by enhancing cooperation on technological innovation and diffusion (without targets on emissions).

The US decision not to ratify the Kyoto Protocol and the recent outcomes of the Bonn and Marrakech Conferences of the Parties have important implications for both the effectiveness and the efficiency of future climate policies. Among these implications, those related with technical change and with the functioning of the international market for carbon emissions are particularly relevant, because these variables have the largest impact on the overall abatement cost to be borne by Annex B countries in the short and in the long run. This paper analyses the consequences of the US decision to withdraw from the Kyoto/Bonn Protocol both on technological innovation and on the price of emission permits (and, as a consequence, on abatement costs). In particular, the analysis highlights mechanisms and feedbacks related to technological innovation, technological spillovers and R&D which could be relevant and which modify some policy relevant conclusions. First, we identify two feedback effects which explain why our results lead to a less significant fall in the price of permits than in most empirical analyses recently circulated. We show that the US defection from the Kyoto Protocol, by inducing a decline in the demand and price of emission permits, lowers the incentives to undertake energy-saving R&D. As a consequence, emissions increase and feed back on the demand and supply of permits, thus implying a lower decline in the price of permits than previously estimated. At the same time, as a result of the reduced R&D investments and the augmented emissions, climate change damages intensify and require an increase in investments that are again coupled with a growth of emissions. By thus again increasing the demand for permits and reducing their supply, this effect enhances the previous mechanism. Notwithstanding the lower decline in the price of permits, the paper still identifies a smaller price than would occur with a US participation. Therefore, we emphasise in a second step the crucial role of Russia in climate negotiations due to a large increase in Russia's bargaining power. JEL classification: H0; H4; O3

Microbiological quality represents the biggest concern to the reuse of treated wastewater. This paper reports and discusses the results of an international survey on the removal of indicators of microbiological contamination in surface-flow constructed wetlands. Constructed wetlands consistently provide a reduction of 90-99% (1-2 log-removal) in the concentration of indicators such as coliform bacteria and faecal streptococci. This removal is found in wetlands treating water from different types of pretreatment (primary sedimentation, activated sludge, trickling filter, maturation ponds). On the other hand, when the influent is of high microbiological quality, wetlands act as sources of pathogenic contamination. The final water quality, however, is still compatible with medium to no-contact recreational activities and other final water uses. High variability in the effluent quality and seasonality might limit the opportunities for reuse. The role of constructed wetlands in different treatment schemes and the remaining open questions concerning removal mechanisms and reference pathogens are discussed.

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