Unexplained high and persistent methyl bromide emissions in China.

Methyl bromide (CHBr) is an important ozone-depleting substance whose use is regulated under the Montreal Protocol. Quantifying emissions on the national scale is required to assess compliance with the Montreal Protocol and thereby ensure the timely recovery of the ozone layer. However, the spatial-temporal patterns of China's national CHBr emissions remain unclear.

Increases in Global and East Asian Nitrogen Trifluoride (NF) Emissions Inferred from Atmospheric Observations.

Nitrogen trifluoride (NF) is a potent and long-lived greenhouse gas that is widely used in the manufacture of semiconductors, photovoltaic cells, and flat panel displays. Using atmospheric observations from eight monitoring stations from the Advanced Global Atmospheric Gases Experiment (AGAGE) and inverse modeling with a global 3-D atmospheric chemical transport model (GEOS-Chem), we quantify global and regional NF emission from 2015 to 2021. We find that global emissions have grown from 1.

Substantial increase in perfluorocarbons CF (PFC-14) and CF (PFC-116) emissions in China.

The perfluorocarbons tetrafluoromethane (CF, PFC-14) and hexafluoroethane (CF, PFC-116) are potent greenhouse gases with near-permanent atmospheric lifetimes relative to human timescales and global warming potentials thousands of times that of CO. Using long-term atmospheric observations from a Chinese network and an inverse modeling approach (top-down method), we determined that CF emissions in China increased from 4.7 (4.

Rising Perfluorocyclobutane (PFC-318, -CF) Emissions in China from 2011 to 2020 Inferred from Atmospheric Observations.

Global atmospheric emissions of perfluorocyclobutane (-CF, PFC-318), a potent greenhouse gas, have increased rapidly in recent years. Combining atmospheric observations made at nine Chinese sites with a Lagrangian dispersion model-based Bayesian inversion technique, we show that PFC-318 emissions in China grew by approximately 70% from 2011 to 2020, rising from 0.65 (0.

Sustained growth of sulfur hexafluoride emissions in China inferred from atmospheric observations.

Sulfur hexafluoride (SF) is a potent greenhouse gas. Here we use long-term atmospheric observations to determine SF emissions from China between 2011 and 2021, which are used to evaluate the Chinese national SF emission inventory and to better understand the global SF budget. SF emissions in China substantially increased from 2.

Anthropogenic Chloroform Emissions from China Drive Changes in Global Emissions.

Emissions of chloroform (CHCl), a short-lived halogenated substance not currently controlled under the Montreal Protocol on Substances that Deplete the Ozone Layer, are offsetting some of the achievements of the Montreal Protocol. In this study, emissions of CHCl from China were derived by atmospheric measurement-based "top-down" inverse modeling and a sector-based "bottom-up" inventory method. Top-down CHCl emissions grew from 78 (72-83) Gg yr in 2011 to a maximum of 193 (178-204) Gg yr in 2017, followed by a decrease to 147 (138-154) Gg yr in 2018, after which emissions remained relatively constant through 2020.

Historical trend of ozone-depleting substances and hydrofluorocarbon concentrations during 2004-2020 derived from satellite observations and estimates for global emissions.

Global concentrations (or mole fractions) and emissions of ozone-depleting substances (ODSs) and their hydrofluorocarbon (HFCs) substitutes that are controlled by the Montreal Protocol and its Amendments and adjustments (MP) are of great interest to both the scientific community and public. Previous studies on global concentrations and emissions have mostly relied on ground-based observations. Here, we assess the global concentrations and emissions of eight MP controlled substances and methyl chloride from ACE-FTS (Atmospheric Chemistry Experiment high-resolution infrared Fourier transform spectrometer) satellite observations: CFC-11 (CFCl), CFC-12 (CFCl), CCl, HCFC-22 (CHClF), HCFC-141b (CHClF), HCFC-142b (CHClF), HFC-23 (CHF), HFC-134a (CHF), and CHCl.

Atmospheric Black Carbon Loadings and Sources over Eastern Sub-Saharan Africa Are Governed by the Regional Savanna Fires.

Vast black carbon (BC) emissions from sub-Saharan Africa are perceived to warm the regional climate, impact rainfall patterns, and impair human respiratory health. However, the magnitudes of these perturbations are ill-constrained, largely due to limited ground-based observations and uncertainties in emissions from different sources. This paper reports multiyear concentrations of BC and other key PM aerosol constituents from the Rwanda Climate Observatory, serving as a regional receptor site.

A renewed rise in global HCFC-141b emissions between 2017-2021.

Global emissions of the ozone-depleting gas HCFC-141b (1,1-dichloro-1-fluoroethane, CHCClF) derived from measurements of atmospheric mole fractions increased between 2017 and 2021 despite a fall in reported production and consumption of HCFC-141b for dispersive uses. HCFC-141b is a controlled substance under the Montreal Protocol, and its phase-out is currently underway, after a peak in reported consumption and production in developing (Article 5) countries in 2013. If reported production and consumption are correct, our study suggests that the 2017-2021 rise is due to an increase in emissions from the bank when appliances containing HCFC-141b reach the end of their life, or from production of HCFC-141b not reported for dispersive uses.

Rapid increase in dichloromethane emissions from China inferred through atmospheric observations.

With the successful implementation of the Montreal Protocol on Substances that Deplete the Ozone Layer, the atmospheric abundance of ozone-depleting substances continues to decrease slowly and the Antarctic ozone hole is showing signs of recovery. However, growing emissions of unregulated short-lived anthropogenic chlorocarbons are offsetting some of these gains. Here, we report an increase in emissions from China of the industrially produced chlorocarbon, dichloromethane (CHCl).

On the effects of the ocean on atmospheric CFC-11 lifetimes and emissions.

The ocean is a reservoir for CFC-11, a major ozone-depleting chemical. Anthropogenic production of CFC-11 dramatically decreased in the 1990s under the Montreal Protocol, which stipulated a global phase out of production by 2010. However, studies raise questions about current overall emission levels and indicate unexpected increases of CFC-11 emissions of about 10 Gg ⋅ yr after 2013 (based upon measured atmospheric concentrations and an assumed atmospheric lifetime).

Unexpected nascent atmospheric emissions of three ozone-depleting hydrochlorofluorocarbons.

Global and regional atmospheric measurements and modeling can play key roles in discovering and quantifying unexpected nascent emissions of environmentally important substances. We focus here on three hydrochlorofluorocarbons (HCFCs) that are restricted by the Montreal Protocol because of their roles in stratospheric ozone depletion. Based on measurements of archived air samples and on in situ measurements at stations of the Advanced Global Atmospheric Gases Experiment (AGAGE) network, we report global abundances, trends, and regional enhancements for HCFC-132b ([Formula: see text]), which is newly discovered in the atmosphere, and updated results for HCFC-133a ([Formula: see text]) and HCFC-31 ([Formula: see text]ClF).

A comprehensive quantification of global nitrous oxide sources and sinks.

Nitrous oxide (NO), like carbon dioxide, is a long-lived greenhouse gas that accumulates in the atmosphere. Over the past 150 years, increasing atmospheric NO concentrations have contributed to stratospheric ozone depletion and climate change, with the current rate of increase estimated at 2 per cent per decade. Existing national inventories do not provide a full picture of NO emissions, owing to their omission of natural sources and limitations in methodology for attributing anthropogenic sources.

Changes in Emissions of Ozone-Depleting Substances from China Due to Implementation of the Montreal Protocol.

The ozone layer depletion and its recovery, as well as the climate influence of ozone-depleting substances (ODSs) and their substitutes that influence climate, are of interest to both the scientific community and the public. Here we report on the emissions of ODSs and their substitute from China, which is currently the largest consumer (and emitter) of these substances. We provide, for the first time, comprehensive information on ODSs and replacement hydrofluorocarbon (HFC) emissions in China starting from 1980 based on reported production and usage.

Deriving Global OH Abundance and Atmospheric Lifetimes for Long-Lived Gases: A Search for CHCCl Alternatives.

An accurate estimate of global hydroxyl radical (OH) abundance is important for projections of air quality, climate, and stratospheric ozone recovery. As the atmospheric mixing ratios of methyl chloroform (CHCCl) (MCF), the commonly used OH reference gas, approaches zero, it is important to find alternative approaches to infer atmospheric OH abundance and variability. The lack of global bottom-up emission inventories is the primary obstacle in choosing a MCF alternative.

Atmospheric observations show accurate reporting and little growth in India's methane emissions.

Changes in tropical wetland, ruminant or rice emissions are thought to have played a role in recent variations in atmospheric methane (CH) concentrations. India has the world's largest ruminant population and produces ~ 20% of the world's rice. Therefore, changes in these sources could have significant implications for global warming.

Role of atmospheric oxidation in recent methane growth.

The growth in global methane (CH) concentration, which had been ongoing since the industrial revolution, stalled around the year 2000 before resuming globally in 2007. We evaluate the role of the hydroxyl radical (OH), the major CH sink, in the recent CH growth. We also examine the influence of systematic uncertainties in OH concentrations on CH emissions inferred from atmospheric observations.

Ecosystem fluxes of hydrogen in a mid-latitude forest driven by soil microorganisms and plants.

Molecular hydrogen (H ) is an atmospheric trace gas with a large microbe-mediated soil sink, yet cycling of this compound throughout ecosystems is poorly understood. Measurements of the sources and sinks of H in various ecosystems are sparse, resulting in large uncertainties in the global H budget. Constraining the H cycle is critical to understanding its role in atmospheric chemistry and climate.

Hydrofluorocarbon (HFC) Emissions in China: An Inventory for 2005-2013 and Projections to 2050.

Many hydrofluorocarbons (HFCs) that are widely used as substitutes for ozone-depleting substances (now regulated under the Montreal Protocol) are very potent greenhouse gases (GHGs). China's past and future HFC emissions are of great interest because China has emerged as a major producer and consumer of HFCs. Here, we present for the first time a comprehensive inventory estimate of China's HFC emissions during 2005-2013.

Reconciling reported and unreported HFC emissions with atmospheric observations.

We infer global and regional emissions of five of the most abundant hydrofluorocarbons (HFCs) using atmospheric measurements from the Advanced Global Atmospheric Gases Experiment and the National Institute for Environmental Studies, Japan, networks. We find that the total CO2-equivalent emissions of the five HFCs from countries that are required to provide detailed, annual reports to the United Nations Framework Convention on Climate Change (UNFCCC) increased from 198 (175-221) Tg-CO2-eq ⋅ y(-1) in 2007 to 275 (246-304) Tg-CO2-eq ⋅ y(-1) in 2012. These global warming potential-weighted aggregated emissions agree well with those reported to the UNFCCC throughout this period and indicate that the gap between reported emissions and global HFC emissions derived from atmospheric trends is almost entirely due to emissions from nonreporting countries.

Global emissions of refrigerants HCFC-22 and HFC-134a: unforeseen seasonal contributions.

HCFC-22 (CHClF2) and HFC-134a (CH2FCF3) are two major gases currently used worldwide in domestic and commercial refrigeration and air conditioning. HCFC-22 contributes to stratospheric ozone depletion, and both species are potent greenhouse gases. In this work, we study in situ observations of HCFC-22 and HFC-134a taken from research aircraft over the Pacific Ocean in a 3-y span [HIaper-Pole-to-Pole Observations (HIPPO) 2009-2011] and combine these data with long-term ground observations from global surface sites [National Oceanic and Atmospheric Administration (NOAA) and Advanced Global Atmospheric Gases Experiment (AGAGE) networks].

Consumption of atmospheric hydrogen during the life cycle of soil-dwelling actinobacteria.

Microbe-mediated soil uptake is the largest and most uncertain variable in the budget of atmospheric hydrogen (H2 ). The diversity and ecophysiological role of soil microorganisms that can consume low atmospheric abundances of H2 with high-affinity [NiFe]-hydrogenases is unknown. We expanded the library of atmospheric H2 -consuming strains to include four soil Harvard Forest Isolate (HFI) Streptomyces spp.