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Atmospheric History of H 2 Over the Past Century Reconstructed From South Pole Firn Air
Abstract Molecular hydrogen (H 2 ) is an abundant and reactive constituent of Earth's atmosphere, with links to climate and air quality. Anthropogenic emissions of H 2 are expected to rise as the use of H 2 as an energy source increases. Documenting past variations in atmospheric H 2 will help...
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| Published in: | Geophysical research letters 2020-07, Vol.47 (14) |
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| Main Authors: | , , , , , |
| Format: | Article |
| Language: | English |
| Citations: | Items that this one cites Items that cite this one |
| Online Access: | Get full text |
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| Summary: | Abstract
Molecular hydrogen (H
2
) is an abundant and reactive constituent of Earth's atmosphere, with links to climate and air quality. Anthropogenic emissions of H
2
are expected to rise as the use of H
2
as an energy source increases. Documenting past variations in atmospheric H
2
will help to validate current understanding of the global H
2
budget. The modern instrumental record begins in the 1980s; there is little information about atmospheric H
2
prior to that time. Here, we use firn air measurements from a 2001 South Pole campaign to reconstruct atmospheric H
2
levels over the 20th century. Inversion of the measurements indicates that H
2
over South Pole has increased from 350–540 ppb from 1910–2000. A biogeochemical box model indicates that the atmospheric burden of H
2
increased by 37% over that time. The rise in H
2
is consistent with increasing H
2
emissions from fossil fuel combustion and increasing atmospheric production from methane oxidation.
Plain Language Summary
Hydrogen (H
2
) is an atmospheric trace gas with both natural and anthropogenic sources. In the atmosphere, photochemical reactions of H
2
can contribute to air pollution and influence climate. Future use of hydrogen as a possible replacement for fossil fuels will likely lead to increased emissions and atmospheric levels. Here we use measurements of hydrogen in South Pole firn air to reconstruct atmospheric hydrogen levels over the 20th century. We find that atmospheric H
2
increased by about 40% over that time. This increase is consistent with estimates of emissions of hydrogen and hydrogen precursors from fossil fuel burning.
Key Points
South Pole firn air was used to reconstruct atmospheric levels of H
2
during the 20th century
H
2
levels at South Pole increased from 340 to 540 ppb from 1910 to 2000
The increase in atmospheric H
2
is consistent with increasing anthropogenic emissions and methane oxidation |
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| ISSN: | 0094-8276 1944-8007 |
| DOI: | 10.1029/2020GL087787 |