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

Sulfur hexafluoride (SF6) is a potent greenhouse gas. Here we use long-term atmospheric observations to determine SF6 emissions from China between 2011 and 2021, which are used to evaluate the Chinese national SF6 emission inventory and to better understand the global SF6 budget. SF6 emissions in China substantially increased from 2.6 (2.3-2.7, 68% uncertainty) Gg yr-1 in 2011 to 5.1 (4.8-5.4) Gg yr-1 in 2021. The increase from China is larger than the global total emissions rise, implying that it has offset falling emissions from other countries. Emissions in the less-populated western regions of China, which have potentially not been well quantified in previous measurement-based estimates, contribute significantly to the national SF6 emissions, likely due to substantial power generation and transmission in that area. The CO2-eq emissions of SF6 in China in 2021 were 125 (117-132) million tonnes (Mt), comparable to the national total CO2 emissions of several countries such as the Netherlands or Nigeria. The increasing SF6 emissions offset some of the CO2 reductions achieved through transitioning to renewable energy in the power industry, and might hinder progress towards achieving China's goal of carbon neutrality by 2060 if no concrete control measures are implemented.

CCl4 emissions in eastern China during 2021-2022 and exploration of potential new sources.

According to the Montreal Protocol, the production and consumption of ozone-layer-depleting CCl4 for dispersive applications was globally phased out by 2010, including China. However, continued CCl4 emissions were disclosed, with the latest CCl4 emissions unknown in eastern China. In the current study, based on the atmospheric measurements of ~12,000 air samples taken at two sites in eastern China, the 2021-2022 CCl4 emissions are quantified as 7.6 ± 1.7 gigagrams per year. This finding indicates that CCl4 emissions continued after being phased out for dispersive uses in 2010. Subsequently, our study identifies potential industrial sources (manufacture of general purpose machinery and manufacture of raw chemical materials, and chemical products) of CCl4 emissions.

Anthropogenic Chloroform Emissions from China Drive Changes in Global Emissions.

Emissions of chloroform (CHCl3), 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 CHCl3 from China were derived by atmospheric measurement-based "top-down" inverse modeling and a sector-based "bottom-up" inventory method. Top-down CHCl3 emissions grew from 78 (72-83) Gg yr-1 in 2011 to a maximum of 193 (178-204) Gg yr-1 in 2017, followed by a decrease to 147 (138-154) Gg yr-1 in 2018, after which emissions remained relatively constant through 2020. The changes in emissions from China could explain all of the global changes during the study period. The CHCl3 emissions in China were dominated by anthropogenic sources, such as byproduct emissions during disinfection and leakage from chloromethane industries. Had emissions continued to grow at the rate observed up to 2017, a delay of several years in Antarctic ozone layer recovery could have occurred. However, this delay will be largely avoided if global CHCl3 emissions remain relatively constant in the future, as they have between 2018 and 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 (CFCl3), CFC-12 (CF2Cl2), CCl4, HCFC-22 (CHClF2), HCFC-141b (C2H3Cl2F), HCFC-142b (C2H3ClF2), HFC-23 (CHF3), HFC-134a (C2H2F4), and CH3Cl. Results show that the ACE-FTS satellite observations can be used to derive the concentrations and emissions of these ODSs, HFCs, and CH3Cl, as they are consistent with those derived from the ground-based observations. Our findings imply that the changes in the concentrations and emissions of the ODSs and HFCs closely match the regulatory status of the MP, and satellite observations can be used to monitor the past and future progress of the MP.

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 PM2.5 aerosol constituents from the Rwanda Climate Observatory, serving as a regional receptor site. We find a strong seasonal cycle for all investigated chemical species, where the maxima coincide with large-scale upwind savanna fires. BC concentrations show notable interannual variability, with no clear long-term trend. The Δ14C and δ13C signatures of BC unambiguously show highly elevated biomass burning contributions, up to 93 ± 3%, with a clear and strong savanna burning imprint. We further observe a near-equal contribution from C3 and C4 plants, irrespective of air mass source region or season. In addition, the study provides improved relative emission factors of key aerosol components, organic carbon (OC), K+, and NO3-, in savanna-fires-influenced background atmosphere. Altogether, we report quantitative source constraints on Eastern Africa BC emissions, with implications for parameterization of satellite fire and bottom-up emission inventories as well as regional climate and chemical transport modeling.

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 (CH2Cl2). The emissions grew from 231 (213-245) Gg yr-1 in 2011 to 628 (599-658) Gg yr-1 in 2019, with an average annual increase of 13 (12-15) %, primarily from eastern China. The overall increase in CH2Cl2 emissions from China has the same magnitude as the global emission rise of 354 (281-427) Gg yr-1 over the same period. If global CH2Cl2 emissions remain at 2019 levels, they could lead to a delay in Antarctic ozone recovery of around 5 years compared to a scenario with no CH2Cl2 emissions.

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-1 after 2013 (based upon measured atmospheric concentrations and an assumed atmospheric lifetime). These findings heighten the need to understand processes that could affect the CFC-11 lifetime, including ocean fluxes. We evaluate how ocean uptake and release through 2300 affects CFC-11 lifetimes, emission estimates, and the long-term return of CFC-11 from the ocean reservoir. We show that ocean uptake yields a shorter total lifetime and larger inferred emission of atmospheric CFC-11 from 1930 to 2075 compared to estimates using only atmospheric processes. Ocean flux changes over time result in small but not completely negligible effects on the calculated unexpected emissions change (decreasing it by 0.4 ± 0.3 Gg ⋅ yr-1). Moreover, it is expected that the ocean will eventually become a source of CFC-11, increasing its total lifetime thereafter. Ocean outgassing should produce detectable increases in global atmospheric CFC-11 abundances by the mid-2100s, with emission of around 0.5 Gg ⋅ yr-1; this should not be confused with illicit production at that time. An illustrative model projection suggests that climate change is expected to make the ocean a weaker reservoir for CFC-11, advancing the detectable change in the global atmospheric mixing ratio by about 5 yr.

A decline in global CFC-11 emissions during 2018-2019.

The atmospheric concentration of trichlorofluoromethane (CFC-11) has been in decline since the production of ozone-depleting substances was phased out under the Montreal Protocol1,2. Since 2013, the concentration decline of CFC-11 slowed unexpectedly owing to increasing emissions, probably from unreported production, which, if sustained, would delay the recovery of the stratospheric ozone layer1-12. Here we report an accelerated decline in the global mean CFC-11 concentration during 2019 and 2020, derived from atmospheric concentration measurements at remote sites around the world. We find that global CFC-11 emissions decreased by 18 ± 6 gigagrams per year (26 ± 9 per cent; one standard deviation) from 2018 to 2019, to a 2019 value (52 ± 10 gigagrams per year) that is similar to the 2008-2012 mean. The decline in global emissions suggests a substantial decrease in unreported CFC-11 production. If the sharp decline in unexpected global emissions and unreported production is sustained, any associated future ozone depletion is likely to be limited, despite an increase in the CFC-11 bank (the amount of CFC-11 produced, but not yet emitted) by 90 to 725 gigagrams by the beginning of 2020.

A decline in emissions of CFC-11 and related chemicals from eastern China.

Emissions of ozone-depleting substances, including trichlorofluoromethane (CFC-11), have decreased since the mid-1980s in response to the Montreal Protocol1,2. In recent years, an unexpected increase in CFC-11 emissions beginning in 2013 has been reported, with much of the global rise attributed to emissions from eastern China3,4. Here we use high-frequency atmospheric mole fraction observations from Gosan, South Korea and Hateruma, Japan, together with atmospheric chemical transport-model simulations, to investigate regional CFC-11 emissions from eastern China. We find that CFC-11 emissions returned to pre-2013 levels in 2019 (5.0 ± 1.0 gigagrams per year in 2019, compared to 7.2 ± 1.5 gigagrams per year for 2008-2012, ±1 standard deviation), decreasing by 10 ± 3 gigagrams per year since 2014-2017. Furthermore, we find that in this region, carbon tetrachloride (CCl4) and dichlorodifluoromethane (CFC-12) emissions-potentially associated with CFC-11 production-were higher than expected after 2013 and then declined one to two years before the CFC-11 emissions reduction. This suggests that CFC-11 production occurred in eastern China after the mandated global phase-out, and that there was a subsequent decline in production during 2017-2018. We estimate that the amount of the CFC-11 bank (the amount of CFC-11 produced, but not yet emitted) in eastern China is up to 112 gigagrams larger in 2019 compared to pre-2013 levels, probably as a result of recent production. Nevertheless, it seems that any substantial delay in ozone-layer recovery has been avoided, perhaps owing to timely reporting3,4 and subsequent action by industry and government in China5,6.

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). No purposeful end-use is known for any of these compounds. We find that HCFC-132b appeared in the atmosphere 20 y ago and that its global emissions increased to 1.1 Gg⋅y-1 by 2019. Regional top-down emission estimates for East Asia, based on high-frequency measurements for 2016-2019, account for ∼95% of the global HCFC-132b emissions and for ∼80% of the global HCFC-133a emissions of 2.3 Gg⋅y-1 during this period. Global emissions of HCFC-31 for the same period are 0.71 Gg⋅y-1 Small European emissions of HCFC-132b and HCFC-133a, found in southeastern France, ceased in early 2017 when a fluorocarbon production facility in that area closed. Although unreported emissive end-uses cannot be ruled out, all three compounds are most likely emitted as intermediate by-products in chemical production pathways. Identification of harmful emissions to the atmosphere at an early stage can guide the effective development of global and regional environmental policy.

A comprehensive quantification of global nitrous oxide sources and sinks.

Nitrous oxide (N2O), like carbon dioxide, is a long-lived greenhouse gas that accumulates in the atmosphere. Over the past 150 years, increasing atmospheric N2O concentrations have contributed to stratospheric ozone depletion1 and climate change2, with the current rate of increase estimated at 2 per cent per decade. Existing national inventories do not provide a full picture of N2O emissions, owing to their omission of natural sources and limitations in methodology for attributing anthropogenic sources. Here we present a global N2O inventory that incorporates both natural and anthropogenic sources and accounts for the interaction between nitrogen additions and the biochemical processes that control N2O emissions. We use bottom-up (inventory, statistical extrapolation of flux measurements, process-based land and ocean modelling) and top-down (atmospheric inversion) approaches to provide a comprehensive quantification of global N2O sources and sinks resulting from 21 natural and human sectors between 1980 and 2016. Global N2O emissions were 17.0 (minimum-maximum estimates: 12.2-23.5) teragrams of nitrogen per year (bottom-up) and 16.9 (15.9-17.7) teragrams of nitrogen per year (top-down) between 2007 and 2016. Global human-induced emissions, which are dominated by nitrogen additions to croplands, increased by 30% over the past four decades to 7.3 (4.2-11.4) teragrams of nitrogen per year. This increase was mainly responsible for the growth in the atmospheric burden. Our findings point to growing N2O emissions in emerging economies-particularly Brazil, China and India. Analysis of process-based model estimates reveals an emerging N2O-climate feedback resulting from interactions between nitrogen additions and climate change. The recent growth in N2O emissions exceeds some of the highest projected emission scenarios3,4, underscoring the urgency to mitigate N2O emissions.

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. We also assess the impacts (and costs) of controls on ODS consumption and emissions on the ozone layer (in terms of CFC-11-equivalent) and climate (in CO2-equivalent). In addition, we show that while China's future ODS emissions are likely to be defined as long as there is full compliance with the Montreal Protocol; its HFC emissions through 2050 are very uncertain. Our findings imply that HFC controls over the next decades that are more stringent than those under the Kigali Amendment to the Montreal Protocol would be beneficial in mitigating global climate change.

Toward a consistent modeling framework to assess multi-sectoral climate impacts.

Efforts to estimate the physical and economic impacts of future climate change face substantial challenges. To enrich the currently popular approaches to impact analysis-which involve evaluation of a damage function or multi-model comparisons based on a limited number of standardized scenarios-we propose integrating a geospatially resolved physical representation of impacts into a coupled human-Earth system modeling framework. Large internationally coordinated exercises cannot easily respond to new policy targets and the implementation of standard scenarios across models, institutions and research communities can yield inconsistent estimates. Here, we argue for a shift toward the use of a self-consistent integrated modeling framework to assess climate impacts, and discuss ways the integrated assessment modeling community can move in this direction. We then demonstrate the capabilities of such a modeling framework by conducting a multi-sectoral assessment of climate impacts under a range of consistent and integrated economic and climate scenarios that are responsive to new policies and business expectations.

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 (CH4) 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. Here, we infer India's CH4 emissions for the period 2010-2015 using a combination of satellite, surface and aircraft data. We apply a high-resolution atmospheric transport model to simulate data from these platforms to infer fluxes at sub-national scales and to quantify changes in rice emissions. We find that average emissions over this period are 22.0 (19.6-24.3) Tg yr-1, which is consistent with the emissions reported by India to the United Framework Convention on Climate Change. Annual emissions have not changed significantly (0.2 ± 0.7 Tg yr-1) between 2010 and 2015, suggesting that major CH4 sources did not change appreciably. These findings are in contrast to another major economy, China, which has shown significant growth in recent years due to increasing fossil fuel emissions. However, the trend in a global emission inventory has been overestimated for China due to incorrect rate of fossil fuel growth. Here, we find growth has been overestimated in India but likely due to ruminant and waste sectors.India's methane emissions have been quantified using atmospheric measurements to provide an independent comparison with reported emissions. Here Ganesan et al. find that derived methane emissions are consistent with India's reports and no significant trend has been observed between 2010-2015.

Role of atmospheric oxidation in recent methane growth.

The growth in global methane (CH4) 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 CH4 sink, in the recent CH4 growth. We also examine the influence of systematic uncertainties in OH concentrations on CH4 emissions inferred from atmospheric observations. We use observations of 1,1,1-trichloroethane (CH3CCl3), which is lost primarily through reaction with OH, to estimate OH levels as well as CH3CC3 emissions, which have uncertainty that previously limited the accuracy of OH estimates. We find a 64-70% probability that a decline in OH has contributed to the post-2007 methane rise. Our median solution suggests that CH4 emissions increased relatively steadily during the late 1990s and early 2000s, after which growth was more modest. This solution obviates the need for a sudden statistically significant change in total CH4 emissions around the year 2007 to explain the atmospheric observations and can explain some of the decline in the atmospheric 13CH4/12CH4 ratio and the recent growth in C2H6 Our approach indicates that significant OH-related uncertainties in the CH4 budget remain, and we find that it is not possible to implicate, with a high degree of confidence, rapid global CH4 emissions changes as the primary driver of recent trends when our inferred OH trends and these uncertainties are considered.

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

Molecular hydrogen (H2 ) 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 H2 in various ecosystems are sparse, resulting in large uncertainties in the global H2 budget. Constraining the H2 cycle is critical to understanding its role in atmospheric chemistry and climate. We measured H2 fluxes at high frequency in a temperate mixed deciduous forest for 15 months using a tower-based flux-gradient approach to determine both the soil-atmosphere and the net ecosystem flux of H2 . We found that Harvard Forest is a net H2 sink (-1.4 ± 1.1 kg H2  ha-1 ) with soils as the dominant H2 sink (-2.0 ± 1.0 kg H2  ha-1 ) and aboveground canopy emissions as the dominant H2 source (+0.6 ± 0.8 kg H2  ha-1 ). Aboveground emissions of H2 were an unexpected and substantial component of the ecosystem H2 flux, reducing net ecosystem uptake by 30% of that calculated from soil uptake alone. Soil uptake was highly seasonal (July maximum, February minimum), positively correlated with soil temperature and negatively correlated with environmental variables relevant to diffusion into soils (i.e., soil moisture, snow depth, snow density). Soil microbial H2 uptake was correlated with rhizosphere respiration rates (r = 0.8, P < 0.001), and H2 metabolism yielded up to 2% of the energy gleaned by microbes from carbon substrate respiration. Here, we elucidate key processes controlling the biosphere-atmosphere exchange of H2 and raise new questions regarding the role of aboveground biomass as a source of atmospheric H2 and mechanisms linking soil H2 and carbon cycling. Results from this study should be incorporated into modeling efforts to predict the response of the H2 soil sink to changes in anthropogenic H2 emissions and shifting soil conditions with climate and land-use change.

Deriving Global OH Abundance and Atmospheric Lifetimes for Long-Lived Gases: A Search for CH3CCl3 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 (CH3CCl3) (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. We illustrate that global emissions of long-lived trace gases can be inferred from their observed mixing ratio differences between the Northern Hemisphere (NH) and Southern Hemisphere (SH), given realistic estimates of their NH-SH exchange time, the emission partitioning between the two hemispheres, and the NH versus SH OH abundance ratio. Using the observed long-term trend and emissions derived from the measured hemispheric gradient, the combination of HFC-32 (CH2F2), HFC-134a (CH2FCF3, HFC-152a (CH3CHF2), and HCFC-22 (CHClF2), instead of a single gas, will be useful as a MCF alternative to infer global and hemispheric OH abundance and trace gas lifetimes. The primary assumption on which this multispecies approach relies is that the OH lifetimes can be estimated by scaling the thermal reaction rates of a reference gas at 272 K on global and hemispheric scales. Thus, the derived hemispheric and global OH estimates are forced to reconcile the observed trends and gradient for all four compounds simultaneously. However, currently, observations of these gases from the surface networks do not provide more accurate OH abundance estimate than that from MCF.

The terrestrial biosphere as a net source of greenhouse gases to the atmosphere.

The terrestrial biosphere can release or absorb the greenhouse gases, carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), and therefore has an important role in regulating atmospheric composition and climate. Anthropogenic activities such as land-use change, agriculture and waste management have altered terrestrial biogenic greenhouse gas fluxes, and the resulting increases in methane and nitrous oxide emissions in particular can contribute to climate change. The terrestrial biogenic fluxes of individual greenhouse gases have been studied extensively, but the net biogenic greenhouse gas balance resulting from anthropogenic activities and its effect on the climate system remains uncertain. Here we use bottom-up (inventory, statistical extrapolation of local flux measurements, and process-based modelling) and top-down (atmospheric inversions) approaches to quantify the global net biogenic greenhouse gas balance between 1981 and 2010 resulting from anthropogenic activities and its effect on the climate system. We find that the cumulative warming capacity of concurrent biogenic methane and nitrous oxide emissions is a factor of about two larger than the cooling effect resulting from the global land carbon dioxide uptake from 2001 to 2010. This results in a net positive cumulative impact of the three greenhouse gases on the planetary energy budget, with a best estimate (in petagrams of CO2 equivalent per year) of 3.9 ± 3.8 (top down) and 5.4 ± 4.8 (bottom up) based on the GWP100 metric (global warming potential on a 100-year time horizon). Our findings suggest that a reduction in agricultural methane and nitrous oxide emissions, particularly in Southern Asia, may help mitigate climate change.

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. Results show a rapid increase in HFC production, consumption, and emissions in China during the period and that the emissions of HFC with a relatively high global warming potential (GWP) grew faster than those with a relatively low GWP. The proportions of China's historical HFC CO2-equivalent emissions to China's CO2 emissions or global HFC CO2-equivalent emissions increased rapidly during 2005-2013. Using the "business-as-usual" (BAU) scenario, in which HFCs are used to replace a significant fraction of hydrochlorofluorocarbons (HCFCs) in China (to date, there are no regulations on HFC uses in China), emissions of HFCs are projected to be significant components of China's and global future GHG emissions. However, potentials do exist for minimizing China's HFC emissions (for example, if regulations on HFC uses are established in China). Our findings on China's historical and projected HFC emission trajectories could also apply to other developing countries, with important implications for mitigating global GHG emissions.

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. However, our measurement-based estimates of individual HFC species suggest that emissions, from reporting countries, of the most abundant HFC, HFC-134a, were only 79% (63-95%) of the UNFCCC inventory total, while other HFC emissions were significantly greater than the reported values. These results suggest that there are inaccuracies in the reporting methods for individual HFCs, which appear to cancel when aggregated together.