Unprecedented decarbonization of China's power system in the post-COVID era (preprint)

In October of 2020, China announced that it aims to start reducing its carbon dioxide (CO2) emissions before 2030 and achieve carbon neutrality before 20601. The surprise announcement came in the midst of the COVID-19 pandemic which caused a transient drop in China's emissions in the first half of 2020. Here, we show an unprecedented de-carbonization of China's power system in late 2020: although China's power related carbon emissions were 0.5% higher in 2020 than 2019, the majority (92.9%) of the increased power demand was met by increases in low-carbon (renewables and nuclear) generation (increased by 9.3%), as compared to only 0.4% increase for fossil fuels. China's low-carbon generation in the country grew in the second half of 2020, supplying a record high of 36.7% (increased by 1.9% compared to 2019) of total electricity in 2020, when the fossil production dropped to a historical low of 63.3%. Combined, the carbon intensity of China's power sector decreased to an historical low of 519.9 tCO2/GWh in 2020. If the fast decarbonization and slowed down power demand growth from 2019 to 2020 were to continue, by 2030, over half (50.8%) of China's power demand could be provided by low carbon sources. Our results thus reveal that China made progress towards its carbon neutrality target during the pandemic, and suggest the potential for substantial further decarbonization in the next few years if the latest trends persist.

Global Daily CO$_2$ emissions for the year 2020 (preprint)

The diurnal cycle CO$_2$ emissions from fossil fuel combustion and cement production reflect seasonality, weather conditions, working days, and more recently the impact of the COVID-19 pandemic. Here, for the first time we provide a daily CO$_2$ emission dataset for the whole year of 2020 calculated from inventory and near-real-time activity data (called Carbon Monitor project: https://carbonmonitor.org). It was previously suggested from preliminary estimates that did not cover the entire year of 2020 that the pandemics may have caused more than 8% annual decline of global CO$_2$ emissions. Here we show from detailed estimates of the full year data that the global reduction was only 5.4% (-1,901 MtCO$_2$, ). This decrease is 5 times larger than the annual emission drop at the peak of the 2008 Global Financial Crisis. However, global CO$_2$ emissions gradually recovered towards 2019 levels from late April with global partial re-opening. More importantly, global CO$_2$ emissions even increased slightly by +0.9% in December 2020 compared with 2019, indicating the trends of rebound of global emissions. Later waves of COVID-19 infections in late 2020 and corresponding lockdowns have caused further CO$_2$ emissions reductions particularly in western countries, but to a much smaller extent than the declines in the first wave. That even substantial world-wide lockdowns of activity led to a one-time decline in global CO$_2$ emissions of only 5.4% in one year highlights the significant challenges for climate change mitigation that we face in the post-COVID era. These declines are significant, but will be quickly overtaken with new emissions unless the COVID-19 crisis is utilized as a break-point with our fossil-fuel trajectory, notably through policies that make the COVID-19 recovery an opportunity to green national energy and development plans.

De-carbonization of global energy use during the COVID-19 pandemic (preprint)

The COVID-19 pandemic has disrupted human activities, leading to unprecedented decreases in both global energy demand and GHG emissions. Yet a little known that there is also a low carbon shift of the global energy system in 2020. Here, using the near-real-time data on energy-related GHG emissions from 30 countries (about 70% of global power generation), we show that the pandemic caused an unprecedented de-carbonization of global power system, representing by a dramatic decrease in the carbon intensity of power sector that reached a historical low of 414.9 tCO2eq/GWh in 2020. Moreover, the share of energy derived from renewable and low-carbon sources (nuclear, hydro-energy, wind, solar, geothermal, and biomass) exceeded that from coal and oil for the first time in history in May of 2020. The decrease in global net energy demand (-1.3% in the first half of 2020 relative to the average of the period in 2016-2019) masks a large down-regulation of fossil-fuel-burning power plants supply (-6.1%) coincident with a surge of low-carbon sources (+6.2%). Concomitant changes in the diurnal cycle of electricity demand also favored low-carbon generators, including a flattening of the morning ramp, a lower midday peak, and delays in both the morning and midday load peaks in most countries. However, emission intensities in the power sector have since rebounded in many countries, and a key question for climate mitigation is thus to what extent countries can achieve and maintain lower, pandemic-level carbon intensities of electricity as part of a green recovery.

Clinical features of COVID-19 patients with comorbid coronary heart disease (preprint)

Background: In addition to the lungs, the coronavirus disease 2019 (COVID-19) also affects multiple organs throughout the body. The relationship between COVID-19 infection and cardiovascular disease, and the mechanisms by which this disease causes damage to the cardiovascular system are unclear. Coronary heart disease (CHD) is one of the common comorbidities of COVID-19, but there is insufficient evidence for its clinical features and impact on clinical outcomes. The aim of this study was to analyze the clinical characteristics of COVID-19 patients with comorbid CHD and the possible risk factors for the occurrence of critical illness. Methods: A single-center, retrospective study was conducted to analyze COVID-19 patients admitted to the Sino-French New City Campus of Tongji Hospital in Wuhan, Hubei Province and treated by the Peking University National Medical Assistance Team between January 29 and March 10, 2020. Patients testing positive for SARS-CoV-2 viral nucleic acid in nasopharyngeal swab specimens and who had comorbid CHD, were included in the study. Clinical data and laboratory test results of eligible patients were collected, and the factors associated with the occurrence of critical illness among these patients were evaluated. Results: A total of 205 patients were enrolled in this study, including 20 CHD patients and 185 non-CHD patients. The mean age was 66.7 years. Compared to non-CHD patients, more CHD patients had comorbid hypertension and diabetes (P < 0.05). In terms of laboratory tests, the CHD group did not differ significantly from the non-CHD group in blood routine, blood chemistry, and various inflammatory cytokines. More CHD patients experienced myocardial injury (25% vs 8.1% P < 0.031) and CHD patients were more likely to progress to critical illness (40% vs 16.8%P = 0.012). Univariate logistic regression analysis indicated that a history of CHD, occurrence of myocardial injury, high white blood cell (WBC) count, low lymphocyte count, and elevated levels of Cr, ferritin, IL-2R, IL-8 at admission were factors associated with the occurrence of critical illness. Multivariate regression analysis found that a history of CHD（OR=3.529, 95% CI =1.032-12.075, P =0.044），high WBC count（OR=1.289, 95% CI =1.136-1.463, P＜0.001） and low lymphocyte count（OR=0.215, 95% CI =0.075-0.616, P =0.004）were independent factors for the occurrence of critical illness among COVID-19 patients. Conclusion: COVID-19 patients with comorbid CHD commonly exhibited myocardial injury and were prone to developing critical illness. Among COVID-19 patients, a history of CHD，high WBC count and low lymphocyte count were independent risk factors for the occurrence of critical illness. Greater attention and vigilance are needed in this regard during clinical practice.

The SARS-CoV-2 RNA with mild pulmonary consolidation lasts longer in non-severe COVID-19 patients: an observational study (preprint)

Background: Since December 2019, COVID-19 has rapidly swept the world. It is particularly important to understand the dynamic changes of the whole disease course of non-severe patients from the onset to the follow-up after discharge.Methods: On February 1, 2020, 18 cases of non-severe COVID-19 appeared in a hospital in Beijing. All patients were SARS-CoV-2 RNA positive by RT-PCR for pharyngeal swabs. We recorded the clinical information and viral dynamics of these patients from the onset of the disease to 2 months after discharge. According to the severity of lung consolidation, 18 patients were divided into two groups (mild pulmonary consolidation group [imaging score ≤10]; severe pulmonary consolidation group [imaging score >10]).Results: Eighteen patients (median age 43) were included, including 14 females. Fever (11/18) and cough (8/18) were the most common symptoms. The duration of SARS-CoV-2 RNA positive in mild pulmonary consolidation group was significantly longer than severe pulmonary consolidation group (the median time was 30 days and 13 days, respectively, P= 0.0031). Two months after discharge, almost all patients were followed up for IgM antibody disappearance and IgG antibody production.Conclusion: In non-severe COVID-19 patients, the positive duration of the SARS-CoV-2 RNA in patients with mild pulmonary consolidation was longer than the severe pulmonary consolidation. However, it is necessary for a large sample to verify our conclusions.

Carbon Monitor: a near-real-time daily dataset of global CO2 emission from fossil fuel and cement production (preprint)

We constructed a near-real-time daily CO2 emission dataset, namely the Carbon Monitor, to monitor the variations of CO2 emissions from fossil fuel combustion and cement production since January 1st 2019 at national level with near-global coverage on a daily basis, with the potential to be frequently updated. Daily CO2 emissions are estimated from a diverse range of activity data, including: hourly to daily electrical power generation data of 29 countries, monthly production data and production indices of industry processes of 62 countries/regions, daily mobility data and mobility indices of road transportation of 416 cities worldwide. Individual flight location data and monthly data were utilised for aviation and maritime transportation sectors estimates. In addition, monthly fuel consumption data that corrected for daily air temperature of 206 countries were used for estimating the emissions from commercial and residential buildings. This Carbon Monitor dataset manifests the dynamic nature of CO2 emissions through daily, weekly and seasonal variations as influenced by workdays and holidays, as well as the unfolding impacts of the COVID-19 pandemic. The Carbon Monitor near-real-time CO2 emission dataset shows a 7.8% decline of CO2 emission globally from Jan 1st to Apr 30th in 2020 when compared with the same period in 2019, and detects a re-growth of CO2 emissions by late April which are mainly attributed to the recovery of economy activities in China and partial easing of lockdowns in other countries. Further, this daily updated CO2 emission dataset could offer a range of opportunities for related scientific research and policy making.

The phenotypic changes of γδ T cells in COVID-19 patients (preprint)

A novel pneumonia-associated respiratory syndrome named coronavirus disease-2019 (COVID-19), which caused by SARS-CoV-2 and broken in Wuhan, China in the end of 2019. Unfortunately, there is no specific antiviral agent or vaccine available to treat SARS-CoV-2 infections. Also, information regarding the immunological characteristics in COVID-19 patients remains limited. Here we collected the blood samples from 18 healthy donors (HD) and 38 COVID-19 patients to analyze changes in {gamma}{delta} T cells. In comparison to HD, the {gamma}{delta} T cells percentage was decreased. {gamma}{delta} T cells are able to immediately respond to SARS-CoV-2 infection and upregulate the activation marker CD25. In addition, the increased expression of CD4 in {gamma}{delta} T cells may serve as a biomarker for the assessment of SARS-CoV-2 infection.

Analysis of adaptive immune cell populations and phenotypes in the patients infected by SARS-CoV-2 (preprint)

Coronavirus disease-2019 (COVID-19), caused by SARS-CoV-2, has rapidly spread to most of countries in the world, threatening the health and lives of many people. Unfortunately, information regarding the immunological characteristics in COVID-19 patients remains limited. Here we collected the blood samples from 18 healthy donors (HD) and 38 COVID-19 patients to analyze changes in the adaptive immune cell populations and phenotypes. In comparison to HD, the lymphocyte percentage was slightly decreased, the percentages of CD4 and CD8 T cells in lymphocytes are similar, whereas B cell percentage increased in COVID-19 patients. T cells, especially CD8 T cells, showed an enhanced expression of late activation marker CD25 and exhaustion marker PD-1. Importantly, SARS-CoV-2 induced an increased percentage of T follicular helpher (Tfh)- and germinal center B-like (GCB-like) cells in the blood. However, the parameters in COVD-19 patients remained unchanged across various age groups. Therefore, we demonstrated that the T and B cells can be activated normally and exhibit functional features. These data provide a clue that the adaptive immunity in most people could be primed to induce a significant immune response against SARS-CoV-2 infection upon receiving standard medical care.

COVID-19 infection induces readily detectable morphological and inflammation-related phenotypic changes in peripheral blood monocytes, the severity of which correlate with patient outcome (preprint)

Background: Excessive monocyte/macrophage activation with the development of a cytokine storm and subsequent acute lung injury, leading to acute respiratory distress syndrome (ARDS) is a feared consequence of infection with COVID-19. The ability to recognize and potentially intervene early in those patients at greatest risk of developing this complication could be of great clinical utility. Methods: We performed detailed flow cytometric analysis of peripheral blood samples from 28 COVID-19 patients treated at Xian No.8 Hospital and the First Affiliated Hospital of Xian Jiaotong University in early 2020 in an attempt to identify factors that could help predict severity of disease and patient outcome. Findings: While we did not detect significant differences in the number of monocytes between patients with COVID-19 and normal healthy individuals,we did identify significant morphological and functional differences, which are more pronounced in patients requiring prolonged hospitalization and ICU admission. Patients with COVID-19 have larger than normal monocytes, easily identified on forward scatter, side scatter analysis by routine flow cytometry,with the presence of a distinct population of monocytes with high forward scatter (FSC-high). On more detailed analysis, these FSC-high monocytes are CD11b+, CD14+, CD16+, CD68+, CD80+, CD163+, CD206+ and secrete IL-6, IL-10 and TNF-alpha, consistent with an inflammatory phenotype. Conclusions: The detection and serial monitoring of this subset of inflammatory monocytes using flow cytometry could be of great help in guiding the prognostication and treatment of patients with COVID-19 and merits further evaluation.