Decarbonization of electricity generation can support climatechange mitigation and presents an opportunity to address pollution resulting from fossil-fuel combustion. Generally, renewable technologies require higher initial investments in infrastructure than fossil-based power systems. To assess the tradeoffs of increased up-front emissions and reduced operational emissions, we present, to our knowledge, the first global, integrated lifecycle assessment (LCA) of long-term, wide-scale implementation of electricity generation from renewable sources (i.e., photovoltaic and solar thermal, wind, and hydropower) and of carbon dioxide capture and storage for fossil power generation. We compare emissions causing particulate matter exposure, freshwater ecotoxicity, freshwater eutrophication, and climate change for the climate-change-mitigation (BLUE Map) and business-as-usual (Baseline) scenarios of the International Energy Agency up to 2050. We use a vintage stock model to conduct an LCA of newly installed capacity year-by-year for each region, thus accounting for changes in the energy mix used to manufacture future power plants. Under the Baseline scenario, emissions of air and water pollutants more than double whereas the low-carbon technologies introduced in the BLUE Map scenario allow a doubling of electricity supply while stabilizing or even reducing pollution. Material requirements per unit generation for low-carbon technologies can be higher than for conventional fossil generation: 11-40 times more copper for photovoltaic systems and 6-14 times more iron for wind power plants. However, only two years of current global copper and one year of iron production will suffice to build a low-carbon energy system capable of supplying the world's electricity needs in 2050.land use | climate-change mitigation | air pollution | multiregional input-output | CO 2 capture and storage

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Technology-rich integrated assessment models (IAMs) address possible technology mixes and future costs of climate change mitigation by generating scenarios for the future industrial system. Industrial ecology (IE) focuses on the empirical analysis of this system. We conducted an in-depth review of five major IAMs (AIM/CGE, GCAM, IMAGE, REMIND, and MESSAGE) from an IE perspective, and revealed differences between the two fields regarding the modelling of linkages in the industrial system. Most IAMs ignore material cycles and recycling, incoherently describe the life-cycle impacts of technology, and miss linkages regarding buildings and infrastructure. Adding IE system linkages to IAMs adds new constraints and allows for studying new mitigation options, both of which may lead to more robust and policy-relevant mitigation scenarios.

A rapid and deep decarbonization of power supply worldwide is required to limit global warming to well below 2 °C. Beyond greenhouse gas emissions, the power sector is also responsible for numerous other environmental impacts. Here we combine scenarios from integrated assessment models with a forward-looking life-cycle assessment to explore how alternative technology choices in power sector decarbonization pathways compare in terms of non-climate environmental impacts at the system level. While all decarbonization pathways yield major environmental co-benefits, we find that the scale of co-benefits as well as profiles of adverse side-effects depend strongly on technology choice. Mitigation scenarios focusing on wind and solar power are more effective in reducing human health impacts compared to those with low renewable energy, while inducing a more pronounced shift away from fossil and toward mineral resource depletion. Conversely, non-climate ecosystem damages are highly uncertain but tend to increase, chiefly due to land requirements for bioenergy.

18Climate change mitigation demands large-scale technological change on a global level and, if 19 successfully implemented, will significantly affect how products and services are produced and 20 consumed. In order to anticipate the life cycle environmental impacts of products under climate 21 mitigation scenarios, we present the modelling framework of an integrated hybrid life cycle 22 assessment model covering nine world regions. Life cycle assessment databases and multi-23 regional input-output tables are adapted using forecasted changes in technology and resources 24 up to 2050 under a 2°C scenario. We call the result of this modelling "Technology Hybridized 25Environmental-economic Model with Integrated Scenarios" (THEMIS). As a case study, we 26 apply THEMIS in an integrated environmental assessment of concentrating solar power. Life-27 cycle greenhouse gas emissions for this plant range from 33 to 95 g CO2/kWh across different 28 world regions in 2010, falling to 30-87 g CO2/kWh in 2050. Using regional life cycle data 29 yields insightful results. More generally, these results also highlight the need for systematic 30 life cycle frameworks that capture the actual consequences and feedback effects of large-scale 31 policies in the long-term. 32 Introduction 33A 2°C global average temperature increase is considered the threshold above which global 34 warming consequences on human health, ecosystems, and resources might be disastrous. 35Pathways incorporating a combination of a shift towards low-carbon energy technologies, 36 efficiency improvements, and a decrease in final consumption present various ways to reduce 37 greenhouse gas emissions as means to reach climate targets. In effect, climate change 38 mitigation demands large-scale technology change on a global level and, if successful, will 39 significantly affect how products and services are produced and consumed. Understanding the 40 3 future life cycle implications of this substantial change requires a modeling of technological 41 deployments in the global economy. 42In general, life cycle assessment (LCA) studies provide static snapshots of systems at a given 43 moment in the past or in a hypothetical future for a given region. In contrast, energy scenario 44 models trace fuel chains, and do not account for the life cycle aspects related to the energy 45 systems' infrastructure. This paper demonstrates a methodology that combines these 46 approaches to overcome the shortcomings of each. Depending on the large scale impact of a 47 certain technology's deployment, the whole life cycle impact of any given product may be 48 affected. Modifications predicted in climate change mitigation roadmaps address all sectors of 49 the economy, from electricity generation through transportation to cement production. It is 50 therefore essential to assess these modifications based on a model that contains all life cycle 51 phases of both existing and emerging technologies. We illustrate this approach in the present paper by applying the resulting model on...