Extreme development of dragon fruit agriculture with nighttime lighting in Southern Vietnam

Dragon fruit is widely grown in Southeast Asia and other tropical or subtropical regions. As a high-value cash crop ideal for exportation, dragon fruit cultivation has boomed during the past decade in southern Vietnam. Light supplementing during the winter months using artificial lighting sources is a widely adopted cultivation technique to boost productivity in the major dragon fruit planting regions of Vietnam. The application of electric lighting at night leads to a significant increase of nighttime light (NTL) observable by satellite sensors. The strong seasonality signal of NTL in dragon fruit cultivation enables identifying dragon fruit plantations using NTL images. We employed Visible Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band (DNB) monthly nighttime imagery from 2012 to 2019 to extract the growing area of dragon fruit in Bình Thuan Province, the largest dragon fruit growing region of Vietnam. The Breakpoint for Additive Seasonal Trend (B-FAST) analysis was applied to calculate the seasonality of NTL inside the dragon fruit plantations and distinguish them from the background. The results indicated that the dragon fruit cultivation strongly increased after 2014 and reached a plateau after 2017. In recent years, dragon fruit cultivation has experienced a slight decrease due to market fluctuations. We applied a buffer analysis over the largest dragon fruit cultivation area in Bình Thuan to analyze the spatial trend of the expansion of dragon fruit planting. Our results suggest that the dragon fruit cultivation of Bình Thuan has expanded to cover most inter-hill plains, reaching a spatial extent capacity due to the topographical constraints, and thus has begun to encroach into the low-elevation foothill area. In the case of emergency lock-down orders in February 2020 during the COVID-19 pandemic, NTL used for dragon fruit cultivation changed heterogeneously in space and time, driven by market price and shipping limitations far away from the local restrictions. Under the dual rural-urban hot spot situation with strong and contemporary developments of both dragon fruit agriculture and the urban tourism industry, building structures were detected densely in the city and gradually dispersed well into the rural landscape in Bình Thuan. The outcomes of this study will be valuable for local policymakers to better understand of the available area for dragon fruit cultivation and achieve better-coordinated cultivation planning against future fluctuations of the global market while providing insights and new understanding into the dual hot-spot developments valuable for planning rural-urban change strategies. © Springer Nature Switzerland AG 2022. All rights reserved.

Tracking changes in atmospheric particulate matter at a semi-urban site in Central France over the past decade.

Nearly 10-year (2013-2022) data on atmospheric particulate matters (PMs) were collected to investigate the air quality in a suburban site of Orléans city (France). The PM10 concentration decreased slightly between 2013 and 2022. PMs concentrations showed a monthly variation with higher concentration in cold periods. PM10 presented a clear bimodal diurnal variation peaking at morning rush hour and midnight, whereas the fine PMs such as PM2.5 and PM1.0 only had significant peaks during nighttime. Further, PM10 had more pronounced week-end effect than other fine PMs. COVID-19 lockdown impact on PMs levels was further investigated, showing that the lockdown during cold season could result in an increase of PMs concentrations because of the enhanced household heating. We concluded that PM10 could originate from biomass burning and fossil fuel related activities, air parcels from the western Europe through Paris were also important source of PM10 in the investigated area. Fine PMs, such as PM2.5 and PM1.0, originated mainly from biomass burning in addition to secondary formation at the local scale. This study provides a long-term PMs measurement database to explore the sources and characterization of PMs in central France, which could support future regulation and formulation of air quality standards.

The systemic risk of US oil and natural gas companies

We analyse the evolution of the systemic risk impact of oil and natural gas companies since 2000. This period is characterised by several events that affected energy source markets: the real effect of the global financial crisis, the explosion of shale production and the diffusion of the Covid-19 pandemic. The price of oil and natural gas showed extreme swings, impacting companies' financial situations, which, accompanied by technological developments in shale production, had an impact on the debt issuance and on the overall risk level of the oil and natural gas sector. By studying the systemic impact of oil and natural gas companies on risk in the financial market, measured by the ΔCoVaR, we observe that in the most recent decade, their role is sensibly increasing compared to 2000–2010, even accounting for the possible effect associated with the increase in companies' sizes. In addition, our results show evidence of a decreasing relevance of traditional drivers of systemic risk, suggesting that additional factors might be present. Finally, when focusing on the impact of Covid-19, we document its relevant role in fuelling the increase in the oil and natural gas companies' systemic impact. © 2023 The Authors

Nanomedicine and Drug Delivery Systems: Roles, Advantages and Disadvantages

Nanotechnology is a new and rapidly evolving subject in the pharmacological and therapeutic professions. Nanoparticles have many advantages as medication delivery systems, including increased efficacy and fewer adverse drug reactions. This study investigated the roles of nanomedicine and drug delivery systems in the pharmaceutical industry, as well as the advantages and disadvantages of nanotechnology. The study used a qualitative research technique, with online survey questionnaires sent to medical professionals and experts in the field of nanomedicine. These surveys comprised open-ended questions that enabled respondents to record their responses in whatever way they deemed fit. The ten respondents were from a variety of medical and health institutes, as well as medical consulting firms. In terms of results, the research established that nanomedicine had been used in medical care for therapy and diagnostic purposes. They are being explored in clinical trials for several reasons. Nanoparticles are used to treat renal disease, Tuberculosis, skin problems, Alzheimer's disease, and various types of cancer and to create COVID-19 vaccines. Further information about the study findings may be found in the results and discussion chapter.Copyright © 2022 Dr. Yashwant Research Labs Pvt. Ltd.. All rights reserved.

SUSTAINABLE ENERGY DELIVERY FOR AFRICA'S CHANGING CLIMATE: AN ECONOMIC ASSESSMENT

This paper assesses Africa's energy future in a changing global climate to inform development policy. In the midst of economic and energy challenges, coupled with COVID-19 pandemic recovery, Africa is expected to meet global climate obligations. While it makes sense to develop climate resilient economies, Africa appears stuck in its pre-climate change energy delivery systems. The economic, social and environmental consequences of this stagnation are suboptimal for the continent, calling for urgent transition to more sustainable energy delivery. The study analyzed fossil fuel use in Africa from 1960 to 2016, based on a modified Hotelling Rule. Through time series data, the sustainable marginal cost of energy for Africa was estimated. The study further derived the optimal point in time when Africa should switch from fossil fuels as a main source of electricity generation to renewable energy, due to climate change. The study finds more than 70 percent increase in the marginal cost of fossil fuel compared to a cumulative reduction of 80 percent in the marginal cost of solar photovoltaic over the study period. Also, the switch point to renewable energy as the main source of electricity in Africa was found to be 2003. For sustainable delivery of energy in Africa, the study recommends policies to internalize the externalities of fossil fuel, backed by recovery subsidies to make up for the loss of welfare from fossil fuel use, and to create an enabling environment for a speedy energy transition in Africa's changing climate. © 2020 AESS Publications. All Rights Reserved.

Fossil fuels subsidy removal and the EU carbon neutrality policy

The complexity of the EU carbon neutrality policy is addressed by evaluating the impacts of the interaction among different policy instruments. An energy-economic dynamic CGE model based on GTAP utilities is developed for simulating different policy scenarios starting from a business as usual case where the economic impacts related to the COVID-19 pandemic and recovery measures are included. The instruments tested as part of the EU climate strategy are the removal of fossil-fuel consumption subsidies, a carbon pricing mechanism and the public support to clean energy technologies. The modelling approach is based on a revenue recycling mechanism to finance clean energy technologies. We find that the simultaneous implementation of all instruments under the EU climate strategy including the removal of subsidies to fossil fuels and the reuse of revenues to foster the technological transition of the energy system is a win-win solution for a sustainable and decarbonised EU economy. © 2023 The Author(s)

Vulnerability of Renewable and Fossil Fuel Energy from COVID-19

COVID-19 has hurt the world economy since its global spread. So various economic sectors, particularly the energy sector, have been impacted negatively. Statistical analysis has been used in numerous research to assess the effects and repercussions of COVID-19 on the energy sector. However, the influence of its interaction with other sectors, such as households and businesses, on the energy sector has not been studied. The DSGE model provides a framework for analyzing the effect of COVID-19 on the energy sector in dealing with households, businesses, government, and central bank policymakers. The energy sector is separated into two parts in this paper: renewable energy and fossil fuel energy. The impact of COVID-19 on consumption, production, investment in renewable energy, and investment in fossil fuels was then studied using the DSGE framework. The results indicated a decline in production and investment in these two sectors, as well as a rise in consumption. The results also indicate that the fossil fuel energy sector has had a greater decline in production, a greater increase in production costs, a greater loss in investment, and a greater increase in consumption than the renewable energy sector. © Azam Ahmadyan.

Green Fiscal Stimulus in Indonesia and Vietnam: A Reality Check of Two Emerging Economies

The COVID-19 pandemic has caused economic and social upheaval across countries. The global economy suffered its biggest slump in four decades while the decades of progress in poverty reduction are now in reverse. However, the pandemic presents a window of opportunity for a greener world. In contrast to fossil fuel, renewable energy showed resilience throughout the pandemic, where the demand and investment in this sector continued to increase. The opportunity for a post-COVID-19 green recovery also comes from billions of government fiscal measures in response to COVID-19. Using the case of two emerging economies, Indonesia and Vietnam, this paper investigates whether the stimulus plans align with a country's sustainable energy and climate targets. This study finds that despite ambitious country targets for green energy transition, these countries may miss opportunities for a green future due to limited fiscal measures directed to green recovery. The pandemic has exacerbated public fiscal budgets that may further limit the capacity to fund green projects. Amidst the uncertainty and challenges brought by the pandemic, it is critical to balance between promoting economic recovery and achieving sustainable energy and climate targets. To this end, the authors suggest several policy recommendations to achieve these targets amid uncertainty brought by the COVID-19 pandemic for emerging economies. © 2023 by the authors.

Near-real-time estimation of fossil fuel CO2 emissions from China based on atmospheric observations on Hateruma and Yonaguni Islands, Japan.

We developed a near-real-time estimation method for temporal changes in fossil fuel CO2 (FFCO2) emissions from China for 3 months [January, February, March (JFM)] based on atmospheric CO2 and CH4 observations on Hateruma Island (HAT, 24.06° N, 123.81° E) and Yonaguni Island (YON, 24.47° N, 123.01° E), Japan. These two remote islands are in the downwind region of continental East Asia during winter because of the East Asian monsoon. Previous studies have revealed that monthly averages of synoptic-scale variability ratios of atmospheric CO2 and CH4 (ΔCO2/ΔCH4) observed at HAT and YON in JFM are sensitive to changes in continental emissions. From the analysis based on an atmospheric transport model with all components of CO2 and CH4 fluxes, we found that the ΔCO2/ΔCH4 ratio was linearly related to the FFCO2/CH4 emission ratio in China because calculating the variability ratio canceled out the transport influences. Using the simulated linear relationship, we converted the observed ΔCO2/ΔCH4 ratios into FFCO2/CH4 emission ratios in China. The change rates of the emission ratios for 2020-2022 were calculated relative to those for the preceding 9-year period (2011-2019), during which relatively stable ΔCO2/ΔCH4 ratios were observed. These changes in the emission ratios can be read as FFCO2 emission changes under the assumption of no interannual variations in CH4 emissions and biospheric CO2 fluxes for JFM. The resulting average changes in the FFCO2 emissions in January, February, and March 2020 were 17 ± 8%, - 36 ± 7%, and - 12 ± 8%, respectively, (- 10 ± 9% for JFM overall) relative to 2011-2019. These results were generally consistent with previous estimates. The emission changes for January, February, and March were 18 ± 8%, - 2 ± 10%, and 29 ± 12%, respectively, in 2021 (15 ± 10% for JFM overall) and 20 ± 9%, - 3 ± 10%, and - 10 ± 9%, respectively, in 2022 (2 ± 9% for JFM overall). These results suggest that the FFCO2 emissions from China rebounded to the normal level or set a new high record in early 2021 after a reduction during the COVID-19 lockdown. In addition, the estimated reduction in March 2022 might be attributed to the influence of a new wave of COVID-19 infections in Shanghai. Supplementary Information: The online version contains supplementary material available at 10.1186/s40645-023-00542-6.

Evolutionary Challenges to Humanity Caused by Uncontrolled Carbon Emissions: The Stockholm Paradigm.

This review paper discusses the Stockholm Paradigm (SP) as a theoretical framework and practical computational instrument for studying and assessing the risk of emerging infectious diseases (EIDs) as a result of climate change. The SP resolves the long-standing parasite paradox and explains how carbon emissions in the atmosphere increase parasites' generalization and intensify host switches from animals to humans. The SP argues that the growing rate of novel EID occurrence caused by mutated zoonotic pathogens is related to the following factors brought together as a unified issue of humanity: (a) carbon emissions and consequent climate change; (b) resettlement/migration of people with hyper-urbanization; (c) overpopulation; and (d) human-induced distortion of the biosphere. The SP demonstrates that, in an evolutionary way, humans now play a role migratory birds once played in spreading parasite pathogens between the three Earth megabiotopes (northern coniferous forest belt; tropical/equatorial rainforest areas; and hot/cold deserts), i.e., the role of "super-spreaders" of parasitic viruses, bacteria, fungi and protozoa. This makes humans extremely vulnerable to the EID threat. The SP sees the +1.0-+1.2 °C limit as the optimal target for the slow, yet feasible curbing of the EID hazard to public health (150-200 years). Reaching merely the +2.0 °C level will obviously be an EID catastrophe, as it may cause two or three pandemics each year. We think it useful and advisable to include the SP-based research in the scientific repository of the Intergovernmental Panel on Climate Change, since EID appearance and spread are indirect but extremely dangerous consequences of climate change.

Novel research methods on evaluating the nexus between environment and energy use: evaluating the role of tourism in the pre-COVID period

Since the fossil fuels are the principal energy sources across the globe, it is considered as the major reason for environmental degradation. Although, the fossil fuel consumption contributes to maintain industrial production, which is a key factor of economic growth, yet tourism is also among the key sources of revenue for China in the pre-Covid-19 pandemic. However, after the emergence of this novel pandemic, both fossil fuel consumption and tourism are severely affected that slowdowns China's economic progress and could have influence on environmental quality. This study investigates the impact of traditional fossil fuel, economic growth, and tourism on carbon emissions level in China over the period 1995–2020. Using time series estimating approaches, all the variables are found stationary at first difference. Due to irregular distribution of data, this study employed the novel Quantile-on-Quantile regression. The estimated results reveal that consumption of fossil fuel significantly enhances the level of carbon emissions in China. Whereas the impact of economic growth and tourism on carbon emission is mixed. The influence of both the variables is found positive in the lower and medium quantiles, while negative in the upper quantiles. This study also employed the pairwise Granger causality test, that validates two-way causal nexus between fossil fuel consumption—carbon emission and economic growth—carbon emissions. While one way causality from tourism to carbon emissions is evident in the empirical results. This study suggests lowering of fossil fuel consumption by using the alternative energy sources and increase tourism stringent environmental regulations for environmentally destructive tourism activities. © 2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.

Emissions of black carbon and polycyclic aromatic hydrocarbons: Potential implications of cultural practices during the Covid-19 pandemic

Emissions of black carbon (BC) and polycyclic aromatic hydrocarbons (PAHs) from various anthropogenic activities are often reported, yet cultural practices such as the multi-day Diwali festival and its influences on the emissions of these compounds are often overlooked. Major activities during this festival include burning rows of oil-filled earthen lamps (diyas) and fireworks (bursting of crackers). A comprehensive field investigation was conducted to document the role of Diwali celebrations on the releases of BC and PAHs during the ongoing Covid pandemic. The results show that large-scale releases of BC and PAHs were observed on the first day of Diwali compared to the remaining four days. BC and PM2.5 mass concentrations throughout the monitoring period ranged from 3.24 to 27.64 µg m−3 and 83.33 to 288.13 µg m−3, respectively. The source apportionment was performed based on the calculated backward trajectories. The results show that the contribution of fossil fuel emission at Adityapur (ADP), Sakchi (SAK), and Gamharia (GMA) was approximately 36.1 %, 34.4 %, and 55.56 %, while biomass burning contribution was approx. 56.9 %, 59.9 %, 41.67 %, respectively. The result showed that fossil fuel emissions were lower compared to biomass combustion during Diwali. Simultaneously, PAHs diagnostic ratio showed that vehicular discharge and coal burning significantly contributed to PAHs at these study sites. © 2022 The Author(s)

Effects of emission sources on the particle number size distribution of ambient air in the residential area

Particle size distribution is a major factor in the health and climate effects of ambient aerosols, and it shows a large variation depending on the prevailing atmospheric emission sources. In this work, the particle number size distributions of ambient air were investigated at a suburban detached housing area in northern Helsinki, Finland, during a half-year period from winter to summer of 2020. The measurements were conducted with a scanning mobility particle sizer (SMPS) with a particle size range of 16–698 nm (mobility diameter), and the events with a dominant particle source were identified systematically from the data based on the time of the day and different particle physical and chemical properties. During the measurement period, four different types of events with a dominant contribution from either wood-burning (WB), traffic (TRA), secondary biogenic (BIO), or long-range transported (LRT) aerosol were observed. The particle size was the largest for the LRT events followed by BIO, WB, and TRA events with the geometric mean diameters of 72, 62, 57, and 41 nm, respectively. BIO and LRT produced the largest particle mode sizes followed by WB, and TRA with the modes of 69, 69, 46, and 25 nm, respectively. Each event type had also a noticeably different shape of the average number size distribution (NSD). In addition to the evaluation of NSDs representing different particle sources, also the effects of COVID-19 lockdown on specific aerosol properties were studied as during the measurement period the COVID-19 restrictions took place greatly reducing the traffic volumes in the Helsinki area in the spring of 2020. These restrictions had a significant contribution to reducing the concentrations of NOx and black carbon originating from fossil fuel combustion concentration, but insignificant effects on other studied variables such as number concentration and size distribution or particle mass concentrations (PM1, PM2.5, or PM10). © 2022 The Authors

Nearly five-year continuous atmospheric measurements of black carbon over a suburban area in central France

Atmospheric black carbon (BC) concentration over a nearly 5 year period (mid-2017–2021) was continuously monitored over a suburban area of Orléans city (France). Annual mean atmospheric BC concentration were 0.75 ± 0.65, 0.58 ± 0.44, 0.54 ± 0.64, 0.48 ± 0.46 and 0.50 ± 0.72 μg m−3, respectively, for the year of 2017, 2018, 2019, 2020 and 2021. Seasonal pattern was also observed with maximum concentration (0.70 ± 0.18 μg m−3) in winter and minimum concentration (0.38 ± 0.04 μg m−3) in summer. We found a different diurnal pattern between cold (winter and fall) and warm (spring and summer) seasons. Further, fossil fuel burning contributed >90 % of atmospheric BC in the summer and biomass burning had a contribution equivalent to that of the fossil fuel in the winter. Significant week days effect on BC concentrations was observed, indicating the important role of local emissions such as car exhaust in BC level at this site. The behavior of atmospheric BC level with COVID-19 lockdown was also analyzed. We found that during the lockdown in warm season (first lockdown: 27 March–10 May 2020 and third lockdown 17 March–3 May 2021) BC concentration were lower than in cold season (second lockdown: 29 October–15 December 2020), which could be mainly related to the BC emission from biomass burning for heating. This study provides a long-term BC measurement database input for air quality and climate models. The analysis of especially weekend and lockdown effect showed implications on future policymaking toward improving local and regional air quality as well. © 2022 Elsevier B.V.

Nitrogen dioxide as proxy indicator of air pollution from fossil fuel burning in New Delhi during lockdown phases of COVID-19 pandemic period: impact on weather as revealed by Sentinel-5 precursor (5p) spectrometer sensor.

There has been a long-lasting impact of the lockdown imposed due to COVID-19 on several fronts. One such front is climate which has seen several implications. The consequences of climate change owing to this lockdown need to be explored taking into consideration various climatic indicators. Further impact on a local and global level would help the policymakers in drafting effective rules for handling challenges of climate change. For in-depth understanding, a temporal study is being conducted in a phased manner in the New Delhi region taking NO2 concentration and utilizing statistical methods to elaborate the quality of air during the lockdown and compared with a pre-lockdown period. In situ mean values of the NO2 concentration were taken for four different dates, viz. 4th February, 4th March, 4th April, and 25th April 2020. These concentrations were then compared with the Sentinel (5p) data across 36 locations in New Delhi which are found to be promising. The results indicated that the air quality has been improved maximum in Eastern Delhi and the NO2 concentrations were reduced by one-fourth than the pre-lockdown period, and thus, reduced activities due to lockdown have had a significant impact. The result also indicates the preciseness of Sentinel (5p) for NO2 concentrations.

Forecasting oil, coal, and natural gas prices in the pre-and post-COVID scenarios: Contextual evidence from India using time series forecasting tools.

Stock market price prediction is considered a critically important issue for designing future investments and consumption plans. Besides, given the fact that the COVID-19 pandemic has adversely impacted stock markets worldwide, especially over the past two years, investment decisions have become more challenging for risky. Hence, we propose a two-phase framework for forecasting prices of oil, coal, and natural gas in India, both for pre-and post-COVID-19 scenarios. Notably, the Autoregressive Integrated Moving Average, Simple Exponential Smoothing, and K- Nearest Neighbor approaches are utilized for analyses using data from January 2020 to May 2022. Besides, the various outcomes from the analytical exercises are matched with root mean squared error and mean absolute and percentage errors. Overall, the empirical outcomes show that the Autoregressive Integrated Moving Average method is appropriate for predicting India's oil, coal, and natural gas prices. Moreover, the predictive precision of oil, coal, and natural gas in the pre-COVID-19 period seems to be better than in that the post-COVID-19 stage. Additionally, prices of these energy resources are forecasted to increase through the year 2025. Finally, in line with the findings, significant policy recommendations are made.

Fossil fuels subsidy removal and the EU carbon neutrality policy

The complexity of the EU carbon neutrality policy is addressed by evaluating the impacts of the interaction among different policy instruments. An energy-economic dynamic CGE model based on GTAP utilities is developed for simulating different policy scenarios starting from a business as usual case where the economic impacts related to the COVID-19 pandemic and recovery measures are included. The instruments tested as part of the EU climate strategy are the removal of fossil-fuel consumption subsidies, a carbon pricing mechanism and the public support to clean energy technologies. The modelling approach is based on a revenue recycling mechanism to finance clean energy technologies. We find that the simultaneous implementation of all instruments under the EU climate strategy including the removal of subsidies to fossil fuels and the reuse of revenues to foster the technological transition of the energy system is a win-win solution for a sustainable and decarbonised EU economy.

Black carbon over tropical Indian coast during the COVID-19 lockdown: inconspicuous role of coastal meteorology.

Black carbon (BC) aerosols critically impact the climate and hydrological cycle. The impact of anthropogenic emissions and coastal meteorology on BC dynamics, however, remains unclear over tropical India, a globally identified hotspot. In this regard, we have performed in situ measurements of BC over a megacity (Chennai, 12° 59' 26.5″ N, 80° 13' 51.8″ E) on the eastern coast of India during January-June 2020, comprising the period of COVID-19-induced strict lockdown. Our measurements revealed an unprecedented reduction in BC concentration by an order of magnitude as reported by other studies for various other pollutants. This was despite having stronger precipitation during pre-lockdown and lesser precipitation washout during the lockdown. Our analyses, taking mesoscale dynamics into account, unravels stronger BC depletion in the continental air than marine air. Additionally, the BC source regime also shifted from a fossil-fuel dominance to a biomass burning dominance as a result of lockdown, indicating relative reduction in fossil fuel combustion. Considering the rarity of such a low concentration of BC in a tropical megacity environment, our observations and findings under near-natural or background levels of BC may be invaluable to validate model simulations dealing with BC dynamics and its climatic impacts in the Anthropocene.

Reductions in California's Urban Fossil Fuel CO2 Emissions During the COVID-19 Pandemic

Fossil fuel carbon dioxide (CO2) emissions (ffCO2) constitute the majority of greenhouse gas emissions and are the main determinant of global climate change. The COVID-19 pandemic caused wide-scale disruption to human activity and provided an opportunity to evaluate our capability to detect ffCO2 emission reductions. Quantifying changes in ffCO2 levels is especially challenging in cities, where climate mitigation policies are being implemented but local emissions lead to spatially and temporally complex atmospheric mixing ratios. Here, we assess ffCO2 emission patterns associated with pandemic-induced changes to human activity using direct observations of on-road CO2 mole fractions in the Los Angeles (LA) urban area and analyses of the radiocarbon (14C) content of annual grasses collected by community scientists throughout California, USA. With COVID-19 mobility restrictions in place in 2020, we observed a significant reduction in ffCO2 levels across California, especially in urban centers. In LA, on-road CO2 enhancements were 60 ± 16% lower than the corresponding period of 2019 and rebounded to pre-pandemic levels by 2021. Plant 14C analysis indicated ffCO2 reductions of 5 ± 10 ppm in 2020 relative to pre-pandemic observations in LA. However, ffCO2 emission trajectories varied substantially by region and sector as COVID-related restrictions were relaxed. Further development of these techniques could aid efforts to monitor decarbonization in cities, especially in developing countries without established CO2 monitoring infrastructure. © 2022. The Authors.