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The net balance of terrestrial biogenic greenhouse gases produced as a result of human activities and the climatic impact of this balance are uncertain; here the net cumulative impact of the three greenhouse gases, methane, nitrous oxide and carbon dioxide, on the planetary energy budget from 2001 to 2010 is a warming of the planet. Climate mitigation by nitrous oxide reduction The biogenic fluxes of individual greenhouse gases have extensively studied, but the net terrestrial biogenic greenhouse gas balance as a result of human activities and its climatic impact remains uncertain. Hanqin Tian et al . have quantified the net cumulative impact of three greenhouse gases — methane, nitrous oxide and carbon dioxide — on the planetary energy budget. From 2001 to 2010, they find a net positive (warming) cumulative impact and conclude that a reduction in agricultural methane and nitrous oxide emissions — in particular in Southern Asia — may help mitigate climate change. The terrestrial biosphere can release or absorb the greenhouse gases, carbon dioxide (CO 2 ), methane (CH 4 ) and nitrous oxide (N 2 O), and therefore has an important role in regulating atmospheric composition and climate 1 . 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 2 , 3 . The terrestrial biogenic fluxes of individual greenhouse gases have been studied extensively 4 , 5 , 6 , 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 CO 2 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.

Considerable amounts of the greenhouse gas methane leak from the U.S. oil and natural gas supply chain. Alvarez et al. reassessed the magnitude of this leakage and found that in 2015, supply chain emissions were ∼60% higher than the U.S. Environmental Protection Agency inventory estimate. They suggest that this discrepancy exists because current inventory methods miss emissions that occur during abnormal operating conditions. These data, and the methodology used to obtain them, could improve and verify international inventories of greenhouse gases and provide a better understanding of mitigation efforts outlined by the Paris Agreement. Science , this issue p. 186 Methane leakage from the U.S. oil and natural gas supply chain is much greater than previously estimated. Methane emissions from the U.S. oil and natural gas supply chain were estimated by using ground-based, facility-scale measurements and validated with aircraft observations in areas accounting for ~30% of U.S. gas production. When scaled up nationally, our facility-based estimate of 2015 supply chain emissions is 13 ± 2 teragrams per year, equivalent to 2.3% of gross U.S. gas production. This value is ~60% higher than the U.S. Environmental Protection Agency inventory estimate, likely because existing inventory methods miss emissions released during abnormal operating conditions. Methane emissions of this magnitude, per unit of natural gas consumed, produce radiative forcing over a 20-year time horizon comparable to the CO 2 from natural gas combustion. Substantial emission reductions are feasible through rapid detection of the root causes of high emissions and deployment of less failure-prone systems.

Across many cities, estimates of methane emissions from natural gas (NG) distribution and end use based on atmospheric measurements have generally been more than double bottom-up estimates. We present a top-down study of NG methane emissions from the Boston urban region spanning 8 y (2012 to 2020) to assess total emissions, their seasonality, and trends. We used methane and ethane observations from five sites in and around Boston, combined with a high-resolution transport model, to calculate methane emissions of 76 ± 18 Gg/yr, with 49 ± 9 Gg/yr attributed to NG losses. We found no significant trend in the NG loss rate over 8 y, despite efforts from the city and state to increase the rate of repairing NG pipeline leaks. We estimate that 2.5 ± 0.5% of the gas entering the urban region is lost, approximately three times higher than bottom-up estimates. We saw a strong correlation between top-down NG emissions and NG consumed on a seasonal basis. This suggests that consumption-driven losses, such as in transmission or end-use, may be a large component of emissions that is missing from inventories, and require future policy action. We also compared top-down NG emission estimates from six US cities, all of which indicate significant missing sources in bottom-up inventories. Across these cities, we estimate NG losses from distribution and end use amount to 20 to 36% of all losses from the US NG supply chain, with a total loss rate of 3.3 to 4.7% of NG from well pad to urban consumer, notably larger than the current Environmental Protection Agency estimate of 1.4% [R. A. Alvarez et al., Science 361, 186–188 (2018)].

The Total Carbon Column Observing Network (TCCON) measures column-average mole fractions of several greenhouse gases (GHGs), beginning in 2004, from over 30 current or past measurement sites around the world using solar absorption spectroscopy in the near-infrared (near-IR) region. TCCON GHG data have been used extensively for multiple purposes, including in studies of the carbon cycle and anthropogenic emissions, as well as to validate and improve observations from space-based sensors. Here, we describe an update to the retrieval algorithm used to process the TCCON near-IR solar spectra and to generate the associated data products. This version, called GGG2020, was initially released in April 2022. It includes updates and improvements to all steps of the retrieval, including but not limited to the conversion of the original interferograms into spectra, the spectroscopic information used in the column retrieval, post hoc air mass dependence correction, and scaling to align with the calibration scales of in situ GHG measurements. All TCCON data are available through https://tccondata.org/ (last access: 22 April 2024) and are hosted on CaltechDATA (https://data.caltech.edu/, last access: 22 April 2024). Each TCCON site has a unique DOI for its data record. An archive of all the sites' data is also available with the DOI https://doi.org/10.14291/TCCON.GGG2020 (Total Carbon Column Observing Network (TCCON) Team, 2022). The hosted files are updated approximately monthly, and TCCON sites are required to deliver data to the archive no later than 1 year after acquisition. Full details of data locations are provided in the “Code and data availability” section.

Methane emissions from the oil and gas (O&G) industry play a major role in the global methane budget. The MethaneSAT space-based mission, which operated between March 2024 and June 2025, was designed to provide high-quality data on O&G methane emissions, from regional fluxes to high-emitting point sources. This was enabled by MethaneSAT's measurements in the 1598–1683 nm window with a high spectral resolution (0.25 nm), medium spatial sampling (100×400 m2 at nadir), and wide-area coverage (about 200 km at nadir). In this work, we showcase the potential of MethaneSAT to survey high-emitting point sources across O&G basins. We first assess MethaneSAT's performance for the detection, quantification and attribution of methane plumes through the analysis of key observation-related parameters, including wind speed, surface albedo and spatial sampling. We estimate a minimum detection limit of about 500 kg h−1 for a bright surface and low wind conditions, and an average detection limit around 1300 kg h−1 corresponding to an ensemble of sites with different observation conditions. We analyzed selected MethaneSAT datasets from the main O&G methane hotspots in the world. We observe particularly strong and persistent sources in the Turkmenistan's South Caspian basin and in the Midland sub-basin of the US Permian Basin, and reveal major super-emissions in Maturin (Venezuela) and Zagros Foldbelt and Widyan (Iran), and the Appalachian basin. We also present other examples of strong methane sources at high latitudes (West Siberia), in offshore platforms in the Gulf of Mexico, and from the waste sector. Our results illustrate the potential of MethaneSAT data to map methane emissions from hotspot regions and super-emitters around the planet.

Arctic terrestrial ecosystems are major global sources of methane (CH₄); hence, it is important to understand the seasonal and climatic controls on CH₄ emissions from these systems. Here, we report year-round CH₄ emissions from Alaskan Arctic tundra eddy flux sites and regional fluxes derived from aircraft data. We find that emissions during the cold season (September to May) account for ≥50% of the annual CH₄ flux, with the highest emissions from noninundated upland tundra. A major fraction of cold season emissions occur during the “zero curtain” period, when subsurface soil temperatures are poised near 0 °C. The zero curtain may persist longer than the growing season, and CH₄ emissions are enhanced when the duration is extended by a deep thawed layer as can occur with thick snow cover. Regional scale fluxes of CH₄ derived from aircraft data demonstrate the large spatial extent of late season CH₄ emissions. Scaled to the circumpolar Arctic, cold season fluxes from tundra total 12 ± 5 (95% confidence interval) Tg CH₄ y⁻¹, ∼25% of global emissions from extratropical wetlands, or ∼6% of total global wetland methane emissions. The dominance of late-season emissions, sensitivity to soil environmental conditions, and importance of dry tundra are not currently simulated in most global climate models. Because Arctic warming disproportionally impacts the cold season, our results suggest that higher cold-season CH₄ emissions will result from observed and predicted increases in snow thickness, active layer depth, and soil temperature, representing important positive feedbacks on climate warming.

This study quantitatively estimates the spatial distribution of anthropogenic methane sources in the United States by combining comprehensive atmospheric methane observations, extensive spatial datasets, and a high-resolution atmospheric transport model. Results show that current inventories from the US Environmental Protection Agency (EPA) and the Emissions Database for Global Atmospheric Research underestimate methane emissions nationally by a factor of ∼1.5 and ∼1.7, respectively. Our study indicates that emissions due to ruminants and manure are up to twice the magnitude of existing inventories. In addition, the discrepancy in methane source estimates is particularly pronounced in the south-central United States, where we find total emissions are ∼2.7 times greater than in most inventories and account for 24 ± 3% of national emissions. The spatial patterns of our emission fluxes and observed methane–propane correlations indicate that fossil fuel extraction and refining are major contributors (45 ± 13%) in the south-central United States. This result suggests that regional methane emissions due to fossil fuel extraction and processing could be 4.9 ± 2.6 times larger than in EDGAR, the most comprehensive global methane inventory. These results cast doubt on the US EPA’s recent decision to downscale its estimate of national natural gas emissions by 25–30%. Overall, we conclude that methane emissions associated with both the animal husbandry and fossil fuel industries have larger greenhouse gas impacts than indicated by existing inventories.

Mitigating anthropogenic methane emissions is widely recognized as an effective strategy to reduce near-term climate warming. Here, we use satellite observations from MethaneSAT (2024–2025) to characterize methane emissions from six oil and gas producing regions as a demonstration of MethaneSAT data capabilities. MethaneSAT was designed to address a gap in quantitative data of spatially-resolved emissions, by providing high-resolution area emissions (∼4km×4km) with a wide-swath (220–440 km). The native pixel resolution of MethaneSAT is ∼110m×400m (at nadir) at which the column-averaged dry-air mole fraction of methane is retrieved before atmospheric inversion-based methane emissions data are produced. We analyze emissions data across six oil and gas producing regions: the Permian (USA), San Joaquin (USA), Eagle Ford (USA/Mexico), Amu Darya (Turkmenistan and Uzbekistan), and the Zagros Foldbelt (Iran/Iraq). Regional oil and gas emissions span more than an order of magnitude, ranging from 408 t h−1 (95 % c.i.: 303–516 t h−1) for the Permian basin to 30 t h−1 (95 % c.i.: 20–41 t h−1) in the San Joaquin basin. Methane intensities also vary substantially by more than an order of magnitude in both gas-production-normalized and energy-normalized metrics. These differences reflect diverse factors, including oil versus gas production, infrastructure age, lower-producing wells, and emission mitigation controls. Across individual jurisdictions, including counties/districts, we find consistent underestimation by gridded EPA-GHGI and EDGAR bottom-up inventories relative to MethaneSAT-derived emissions. Overall, MethaneSAT data provide basin-wide and sub-regional insights into methane emissions and intensities, offering critical scientific and policy-relevant information to support targeted emission quantification and mitigation strategies.

Significance Most recent analyses of the environmental impact of natural gas have focused on production, with very sparse information on emissions from distribution and end use. This study quantifies the full seasonal cycle of methane emissions and the fractional contribution of natural gas for the urbanized region centered on Boston. Emissions from natural gas are found to be two to three times larger than predicted by existing inventory methodologies and industry reports. Our findings suggest that natural-gas–consuming regions may be larger sources of methane to the atmosphere than is currently estimated and represent areas of significant resource loss. Methane emissions from natural gas delivery and end use must be quantified to evaluate the environmental impacts of natural gas and to develop and assess the efficacy of emission reduction strategies. We report natural gas emission rates for 1 y in the urban region of Boston, using a comprehensive atmospheric measurement and modeling framework. Continuous methane observations from four stations are combined with a high-resolution transport model to quantify the regional average emission flux, 18.5 ± 3.7 (95% confidence interval) g CH ₄⋅m ⁻²⋅y ⁻¹. Simultaneous observations of atmospheric ethane, compared with the ethane-to-methane ratio in the pipeline gas delivered to the region, demonstrate that natural gas accounted for ∼60–100% of methane emissions, depending on season. Using government statistics and geospatial data on natural gas use, we find the average fractional loss rate to the atmosphere from all downstream components of the natural gas system, including transmission, distribution, and end use, was 2.7 ± 0.6% in the Boston urban region, with little seasonal variability. This fraction is notably higher than the 1.1% implied by the most closely comparable emission inventory.

High-latitude ecosystems have the capacity to release large amounts of carbon dioxide (CO₂) to the atmosphere in response to increasing temperatures, representing a potentially significant positive feedback within the climate system. Here, we combine aircraft and tower observations of atmospheric CO₂ with remote sensing data and meteorological products to derive temporally and spatially resolved year-round CO₂ fluxes across Alaska during 2012–2014. We find that tundra ecosystems were a net source of CO₂ to the atmosphere annually, with especially high rates of respiration during early winter (October through December). Long-term records at Barrow, AK, suggest that CO₂ emission rates from North Slope tundra have increased during the October through December period by 73% ± 11% since 1975, and are correlated with rising summer temperatures. Together, these results imply increasing early winter respiration and net annual emission of CO₂ in Alaska, in response to climate warming. Our results provide evidence that the decadal-scale increase in the amplitude of the CO₂ seasonal cycle may be linked with increasing biogenic emissions in the Arctic, following the growing season. Early winter respiration was not well simulated by the Earth System Models used to forecast future carbon fluxes in recent climate assessments. Therefore, these assessments may underestimate the carbon release from Arctic soils in response to a warming climate.