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Increasing atmospheric helium due to fossil fuel exploitation


Fossil fuels contain small amounts of helium, which are co-released into the atmosphere together with carbon dioxide. However, a clear build-up of helium in the atmosphere has not previously been detected. Using a high-precision mass spectrometry technique to determine the atmospheric ratio of helium-4 to nitrogen, we show that helium-4 concentrations have increased significantly over the past five decades. Obtaining a direct measure of the rise in atmospheric helium-4 is possible because changes in nitrogen are negligible. Using 46 air samples acquired between 1974 and 2020, we find that the helium-4 concentration increased at an average rate of 39 ± 3 billion mol per year (2σ). Given that previous observations have shown that the ratio between helium-3 and helium-4 in the atmosphere has remained constant, our results also imply that the concentration of helium-3 is increasing. The inferred rise in atmospheric helium-3 greatly exceeds estimates of anthropogenic emissions from natural gas, nuclear weapons and nuclear power generation, suggesting potential problems with previous isotope measurements or an incorrect assessment of known sources.

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Fig. 1: Atmospheric 4He/N2 change relative to the average of samples in 2020.
Fig. 2: Atmospheric 3He/4He trend and inferred 3He emissions.

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All data generated or analysed during this study are included in the Article. Source data are provided with this paper.


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We thank R. Beaudette, A. Seltzer, S. Shackleton, J. Morgan, J. Ng, J. Dohner, Y. Jin and E. Morgan for comments and insightful discussions during the development and troubleshooting of the He/N2 analysis method. We are grateful to S. Hatley, A. Cox and T. Lueker for locating many old cylinders and unearthing documentation of their history. This work would not have been possible without the support of C. Harth, who generously shared the AGAGE Essex tanks and advised on their use and history. We also thank B. Paplawsky and S. Clark for maintaining and operating the Ar/N2, O2/N2 and CO2 analysis systems in the Keeling laboratory. This work was supported by National Science Foundation grants MRI-1920369 (J.S.), OCE-1924394 (J.S.) and AGS-1940361 (R.F.K.).

Author information

Authors and Affiliations



B.B. carried out the measurements and data analysis with support from B.P., J.S. and R.F.K. B.B. prepared the manuscript, which was subsequently edited by all authors.

Corresponding author

Correspondence to Benjamin Birner.

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Competing interests

The authors declare no competing interests.

Peer review

Peer review information

Nature Geoscience thanks Yuji Sano, Christine Boucher and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Primary Handling Editor: Tom Richardson, in collaboration with the Nature Geoscience team.

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Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data

Extended Data Fig. 1 Cumulative global natural gas emissions from different sources.

Data for natural gas production and flaring are from the Global Carbon Budget [42,43]. Data for fugitive fossil CH4 emissions [44] were rescaled to bring them into agreement with observed mean fossil CH4 emissions in 2003-2012 reported by Hmiel et al. [45] and multiplied by 1.25 to account for carbon compounds other than CH4 present in natural gas. All emission records are extrapolated to 2021 using a smoothing spline.

Source data

Extended Data Fig. 2 Relationships between anomalies in O2/N2, 4He/N2, and Ar/N2.

Anomalies are defined as deviations from the true atmospheric history denoted as Δ(O2/N2), Δ(4He/N2), and Δ(Ar/N2). Relationships are shown between (a) Δ(O2/N2) and Δ(4He/N2), (b) Δ(Ar/N2) and Δ(4He/N2), and (c) Δ(Ar/N2) and Δ(O2/N2). Best fit lines are calculated using the method of York et al.41 and exclude data from Essex tanks (black circles). Magenta circles show results from test measurements of cylinders filled through 13X mole sieve which presumably was used as a drying agent at different times in the past.

Source data

Extended Data Fig. 3 Repeat analysis of the same sample and standard cylinder combination.

Cylinder ND33676 was first measured in January 2020 before the open split biases were calibrated (gray circles) and then analyzed regularly (black circles) to constrain measurement repeatability. Major changes to the analysis system were made at the end of May 2020 and previous performance was never fully recovered as highlighted on the graphic.

Source data

Extended Data Fig. 4 Relationship between pressure and the 4He/N2 anomaly.

The 4He/N2 anomaly is defined as the difference between the measured 4He/N2 in each sample and our estimate of the atmospheric change (that is, best fit line in Extended Data Figure 5). Essex tanks (black circles and diamonds) and high-pressure cylinders (gray circles) show no clear pressure dependence above 1.5 MPa. Two Essex tanks (magenta circles) with pressure below 1 MPa are clear outliers and their data are rejected. The 4He/N2 anomaly in Essex tanks does not vary systematically between tanks using all stainless-steel seals (SS, black circles) and tanks using Teflon tape seals on tapered threads (black diamonds).

Source data

Extended Data Fig. 5 Uncorrected timeseries of (a) He/N2, (b) Ar/N2, (c) O2/N2 and (d) CO2 in our samples.

Monthly means of flask observations from La Jolla (LJO) and Mauna Loa (MLO) are shown for comparison with a polynomial fit of the trend and a one harmonic seasonal cycle. Results from high-pressure cylinders (gray) and Essex tanks (black) are shown separately. Data were quality screen as described in the text and some samples rejected (magenta circles) if Ar/N2 deviated more than 200 per meg from the fit to flask data (black dotted line). Results from two laboratory tests of drying air with 13X molecular sieve are shown as red crosses.

Source data

Extended Data Table 1 Summary of experimental conditions for helium permeation experiments with high-pressure cylinders.


Extended Data Table 2 Contributions to the overall uncertainty in 4He/N2 (1σ).


Supplementary information

Supplementary Information

Supplementary Table 1.

Supplementary Data 1

Summary of sample properties.

Supplementary Data 2

Summary of all sample data.

Source data

Source Data Fig. 1

Fill date, material, He/N2 and uncertainty data for all reported samples.

Source Data Extended Data Fig. 1

Data compilation of natural gas emissions.

Source Data Extended Data Fig. 2

Tank type and atmospheric anomaly data for He/N2, O2/N2 and Ar/N2.

Source Data Extended Data Fig. 3

Repeat measurements of He/N2 on cylinder ND33676.

Source Data Extended Data Fig. 4

Pressure and atmospheric He/N2 anomaly for different tank types.

Source Data Extended Data Fig. 5

Uncorrected time series of He/N2, Ar/N2, O2/N2 and CO2 in the accepted and some rejected data.

Source Data Extended Data Table 1

Summary of conditions for helium permeation experiments.

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Birner, B., Severinghaus, J., Paplawsky, B. et al. Increasing atmospheric helium due to fossil fuel exploitation. Nat. Geosci. 15, 346–348 (2022).

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