Rethinking time-lagged emissions and abatement potential of fluorocarbons in the post-Kigali Amendment era.

The Montreal Protocol has been successful in safeguarding the ozone layer and curbing climate change. However, accurately estimating and reducing the time-lagged emissions of ozone-depleting substances or their substitutes, such as produced but not-yet-emitted fluorocarbon banks, remains a significant challenge. Here, we use a dynamic material flow analysis model to characterize the global stocks and flows of two fluorocarbon categories, hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs), from 1986 to 2060.

Component-Level Residential Building Material Stock Characterization Using Computer Vision Techniques.

Residential building material stock constitutes a significant part of the built environment, providing crucial shelter and habitat services. The hypothesis concerning stock mass and composition has garnered considerable attention over the past decade. While previous research has mainly focused on the spatial analysis of building masses, it often neglected the component-level stock analysis or where heavy labor cost for onsite survey is required.

Uncovering the Carbon Emission Intensity and Reduction Potentials of the Metro Operation Phase: A Case Study in Shenzhen Megacity.

The huge energy consumption of metro operations has become a significant challenge faced by the urban public transportation sector to achieve low-carbon development. Using Shenzhen as an example, this study has made efforts to quantify the metro's energy consumption and carbon emission intensity during the operation phase by using the Life Cycle Assessment approach. Furthermore, this study evaluates the actions that can be taken to reduce energy consumption and emissions.

High-Resolution Mapping of the Urban Built Environment Stocks in Beijing.

Improving our comprehension of the weight and spatial distribution of urban built environment stocks is essential for informing urban resource, waste, and environmental management, but this is often hampered by inaccuracy and inconsistency of the typology and material composition data of buildings and infrastructure. Here, we have integrated big data mining and analytics techniques and compiled a local material composition database to address these gaps, for a detailed characterization of the quantity, quality, and spatial distribution (in 500 m × 500 m grids) of the urban built environment stocks in Beijing in 2018. We found that 3621 megatons (140 ton/cap) of construction materials were accumulated in Beijing's buildings and infrastructure, equaling to 1141 Mt of embodied greenhouse gas emissions.

Product and Metal Stocks Accumulation of China's Megacities: Patterns, Drivers, and Implications.

The rapid urbanization in China since the 1970s has led to an exponential growth of metal stocks (MS) in use in cities. A retrospect on the quantity, quality, and patterns of these MS is a prerequisite for projecting future metal demand, identifying urban mining potentials of metals, and informing sustainable urbanization strategies. Here, we deployed a bottom-up stock accounting method to estimate stocks of iron, copper, and aluminum embodied in 51 categories of products and infrastructure across 10 Chinese megacities from 1980 to 2016.