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The renewal of old bridges is sometimes restricted to avoid the high carbon emissions caused by materials and construction, which however might not be conductive to climate change mitigation due to their insufficient functions. In order to facilitate the optimization of renewal timing and strategy from the perspective of reducing the comprehensive global warming impacts, we put forward the low-carbon bridge renewal decision method referring to the ideas of consequential life cycle assessment (LCA) and dynamic LCA. In the proposed method, a comparative system boundary matching the bridge renewal characteristics is constructed, where the carbon emission reduction owing to the traffic efficiency improvement by functional updating is incorporated as the low-carbon benefits of renewal, and three types of time-dependent factors, i.e., time-dependent characterization factor, trend factors and changes of traffic demands, are introduced to characterize the influence of renewal timing. The proposed method provided guidance for the renewal of Maogang Bridge, the first long-span cable-stayed bridge in Shanghai. Results illustrate that the global warming impacts of renewal construction activities and the low-carbon benefits from functional updating decrease with the renewal timing. For Maogang Bridge, the rapidly increasing traffic demands inevitably advocated renewal in advance, and the reduction of global warming impacts from emission reduction or carbon uptake could be manifested for renewal in advance. Adopting material recycling in the disposal of old bridge helped reconstructing a new bridge while deconstructing the old one in 2019 becoming the finally selected low-carbon renewal strategy, which is expected to reduce 15.04 kt CO 2 e-2019 compared to the essential renewal in 2050 with the landfill disposal method. The robustness of the strategy choice has been justified, given the variations of analytical time horizon, expected emission trends and repair emissions. In this way, the low-carbon renewal decision method could build a quantitative basis for judging the urgency of functional updating and verifying the low-carbon benefits of immediate concrete recycling in up-coming urban renewals. • Low-carbon bridge renewal decision optimizes renewal timing and strategy. • System boundary is expanded for quantifying benefits from functional updating. • Emission trends and time-dependent characterization factors are explored. [ABSTRACT FROM AUTHOR]

Efforts to avoid the acceleration of global warming have tended to focus on countries with high CO 2 emissions levels and large populations, with a high level of economic development or industrialization. African countries, which often do not conform to such criteria, are more vulnerable to climate change due to their dependence on climate-sensitive industries and their limited infrastructure and technological capacity to cope with its impacts. The long-term economic growth rates projected for Africa's rapid development period will, further, make Africa a potential emission hotspot in the near future. Here, for the first time, we built an energy-related emissions inventory for 19 African countries for 2010–2019, which addresses emissions from 47 economic sectors and 5 energy types, making it the most comprehensive of its kind. The degree of decoupling of economy and emissions, and drivers of CO 2 emission changes are also examined. Most African countries experienced rapid growth in CO 2 emissions, with an average annual growth rate of 5.5% for fossil fuel-related CO 2 emissions and 6.0% for unsustainable biomass-related CO 2 emissions. Only two countries, South Africa and Tanzania, have achieved a strong decoupling of economic growth from CO 2 emissions. Economic and population are the most important drivers of emissions, while energy intensity has been identified as a key factor in mitigating CO 2 emissions, especially for those countries that have reached strong or weak decoupling. The findings from this study provide essential insights that could guide the development of low-carbon policies and strategies in Africa. • We provide energy-related emission inventories for 19 African countries from 2010 to 2019. • African countries experienced rapid growth in CO2 emissions. • Two countries achieved strong decoupling of GDP from CO2 emissions. • Economic and population growth are the most important drivers of emissions. [ABSTRACT FROM AUTHOR]

This study developed a climatic-economic-technological integrated assessment model named CIECIA-TD-F. Based on model, the implementation effects of low carbon technology financing on climate mitigation, technology promotion, and economic development in the context of climate change cooperation were studied. The results indicate that carbon reduction, under the current pledged climate financing scale, is limited. Global surface warming in 2100 is still around 2.38 °C even when the technologies are globally shared. Low carbon technology financing improves technology R&D and absorptive capacities of the least developed countries. Their carbon reduction rates reach 50 percent under the capacity principle. However, donations impair the R&D inputs of developed countries and delay their advanced technological progress, leading to 1 percent more carbon emissions. This limits the imitations of China and Russia in turn by decreasing their imitation numbers by 1–2 percent. Collecting 800 billion USD per year from 2030 to 2100 is a climatically effective means. It holds global warming to 1.99 °C. However, the donors suffer more than 1 percent of economic losses. That indicates the economic feasibility of this means is weak. On this basis, we proposed a Pareto-improvement scheme which combines financing with technology sharing and national R&D improvements. This policy mix both achieves the 2 °C goal and protect the economic benefits of all countries. Thus, policy mix combining different measures will be more suitable for improving reduction effects and achieving multiple goals. Compared with sole technology financing, it has more significant global carbon governance meanings and is noteworthy in future climate negotiations. • Nine combinations of typical collection and dispensation principles were assessed. • The current scale of climate financing pledge was insufficient. • 2 °C goal can be achieved by improving financing scale dramatically in short term. • Advanced technology innovation was delayed for the economic losses of the funding donors. • A Pareto improving scheme was proposed. [ABSTRACT FROM AUTHOR]

Decarbonization is a process that transforms economies to lower greenhouse gas (GHG) emissions per unit of economic output, aiming towards net-zero GHG emissions. This process could also reduce short-lived climate pollutant (SLCP) emissions, including black carbon and methane. They have relatively short atmospheric lifetimes but have large radiative forcing and impact human health. Therefore, reducing SLCPs can improve air pollution and help mitigate climate change. Costa Rica was one of the first countries to have a decarbonization plan, and many others have stated their goal to reach net-zero emissions by around mid-century. However, reducing SLCP emissions as an economy decarbonizes is not guaranteed, and few examples in the literature have assessed how decarbonization impacts SLCPs. This paper estimates the SLCP emission reductions from Costa Rica's decarbonization plan. Through a value chain analysis and the identification of implementation barriers, the paper also evaluates which policy instruments can advance SLCP mitigation in multiple sectors, creating implementation synergy. We find that mitigation measures, by 2050, in the transport, agricultural, solid waste, and industrial sectors avoid 25.2 kt of black carbon emissions (23 times the 2018 emissions) and 2167 kt of methane (15 times the 2018 emissions). However, the country faces financial and governance challenges in each sector that will need overcoming to implement the intended mitigation measures. We identify a comprehensive environmental tax reform, the overhauling of urban regulatory plans, the strengthening of institutional capabilities, and low-carbon investment with favorable financing as crucial cross-sectoral policy synergies that will advance the implementation of SLCP mitigation. • Decarbonizing can reduce and avoid short-lived climate pollutant (SLCP) emissions. • Black carbon and methane (two SLCPs) cause global warming and poor air quality. • Some policy instruments can reduce SLCPs in multiple sectors, causing synergy. • Improved urban planning can favor the mitigation in transport and waste sectors. • Institutional strength and favorable financing are needed to advance mitigation. [ABSTRACT FROM AUTHOR]

• Current national policies are not sufficient to meet the Paris Agreement goals. • Collective increase in climate action is needed to stabilize warming at safe levels. • Good practice policies can bridge the emissions gap to a below 2 °C world. • These policies can create a bridge trajectory in key major-emitting countries. One key aspect of the Paris Agreement is the goal to limit the global average temperature increase to well below 2 °C by the end of the century. To achieve the Paris Agreement goals, countries need to submit, and periodically update, their Nationally Determined Contributions (NDCs). Recent studies show that NDCs and currently implemented national policies are not sufficient to cover the ambition level of the temperature limit agreed upon in the Paris Agreement, meaning that we need to collectively increase climate action to stabilize global warming at levels considered safe. This paper explores the generalization of previously adopted good practice policies (GPPs) to bridge the emissions gap between current policies, NDCs ambitions and a well below 2 °C world, facilitating the creation of a bridge trajectory in key major-emitting countries. These GPPs are implemented in eleven well-established national Integrated Assessment Models (IAMs) for Australia, Brazil, Canada, China, European Union (EU), India, Indonesia, Japan, Russia, South Korea, and the United States, that provide least-cost, low-carbon scenarios up to 2050. Results show that GPPs can play an important role in each region, with energy supply policies appearing as one of the biggest contributors to the reduction of carbon emissions. However, GPPs by themselves are not enough to close the emission gap, and as such more will be needed in these economies to collectively increase climate action to stabilize global warming at levels considered safe. [ABSTRACT FROM AUTHOR]

• Prior beliefs and demographics affect reading accuracy and knowledge gains from scenarios. • In contrast, effects from different visualization formats analyzed are relatively minor. • Graphs with steep slope are disadvantageous over tables and graphs with gradual slope. • Tailoring formats to demographic and country differences to some extent reduces adverse effects. While scenarios are used extensively for communication about climate change mitigation, little is known about the interpretation of these scenarios by citizens. We conducted a cross-country empirical evaluation of scenario visualizations for global mitigation, using online surveys in Germany (N = 379), Poland (N = 223), and France (N = 225). Each respondent received visualizations of the required changes in global carbon dioxide emissions and composition of electricity supply (fossil fuels, nuclear, and renewable sources) for limiting global warming to 1.5 °C. We evaluated the effects of respondents' demographics, prior beliefs, numeracy, and graph literacy on the reading accuracy and knowledge gains from the visualizations. We also included an experimental between-groups design on visualization format, where four groups received different graph formats (steep or gradual graphs with depictions of uncertainty ranges or scenario ensembles) and the fifth group received a table. Results showed that higher education level, numeracy, and graph literacy increased reading accuracy in all countries, while age reduced them. Respondents with prior beliefs about climate change mitigation that matched the information in the visualizations had also higher reading accuracy and knowledge gains. While the effects of different visualization formats were comparatively minor, customizing formats according to demographic and country differences was used to reduce adverse effects from these differences. These results emphasize the need to design visualizations that match characteristics of the intended audience and could inform better communication of climate change mitigation scenarios to non-expert audience. [ABSTRACT FROM AUTHOR]