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Wildfires are becoming more frequent due to the global climate change. Large amounts of greenhouse gases emitted by wildfires can lead to increases in extreme climate events. Accurately estimating the greenhouse gas carbon dioxide (CO2) emissions from wildfires is important for mitigation of climate change. In this paper, we develop a novel method to estimate wildfire CO2 emissions from the relationship between local CO2 emissions and XCO2 anomalies. Our method uses the WRF-Chem assimilation system from OCO-2 XCO2 retrievals which coupled with Data Assimilation Research Testbed (DART). To validate our results, we conducted three experiments evaluating the wildfire CO2 emissions over the conterminous United States. The four-month average wildfire emissions from July to October in 2015∼2018 were estimated at 4.408 Tg C, 1.784 Tg C, 1.514 Tg C and 2.873 Tg C, respectively. Compared to the average of established inventories CT2019B, FINNv1.5 and GFASv1.2 fire emissions, our estimates fall within one standard deviation, except for 2017 due to lacking of OCO-2 XCO2 retrievals. These results suggest that the regional carbon assimilation system, such as WRF-Chem/DART, using OCO-2 XCO2 retrievals has a great potential for accurately tracking regional wildfire emissions. [ABSTRACT FROM AUTHOR]

Limiting global warming well below 2 °C requires substantial increase in the installation of low-carbon electricity generation technologies (EGTs). EGTs however require several critical materials and materials associated with considerable energy, water and CO 2 emissions. This paper assesses the implications of materials and energy efficiencies for climate change mitigation potential of global energy transition scenarios (GETS). The analysis is carried out using a dynamic material flow-stock model for 21 materials and 15 scenarios combining GETS developed by international organizations including International Energy Agency (IEA) and Greenpeace (GP), materials scenarios, and energy, water, and emissions intensities scenarios. Materials related CO 2 emissions are expected to constitute between 4% and 14% the emissions reported in the IEA Sustainable Development scenario, while expected to be between 10% and 28% in GP Advanced Revolution scenario. Increasing material efficiency and reducing emissions intensities (driven by increasing energy efficiency, renewable technologies in energy supply mix, and recycling) reduce cumulative emissions by 73.2% and 26.3% respectively, while both reduce emissions by 79.5%. Increasing materials efficiency in EGT, energy and water efficiency in mining activities mainly for iron, aluminium, and nickel, and recycling, combined with careful selection of EGTs are significant to realize the full potential of GETS in climate change mitigation. • Materials and energy efficiencies implications for climate change mitigation potential of energy scenarios are assessed. • Dynamic material flow-stock model for 21 materials and 15 combined materials and energy scenarios are used. • Materials related CO 2 emissions constitute between 4% and 14% of emissions reported in IEA Sustainable Development scenario. • Increasing material efficiency and reducing emission intensities reduce cumulative emissions by 79.5%. • Increasing materials efficiency and recycling, and careful selection of EGT are significant for climate change mitigation. [ABSTRACT FROM AUTHOR]