Atmospheric hydrogen increases, which can be a problem for the climate

The levels of hydrogen in the atmosphere jumped 60% since pre -industrial times, highlighting the dramatic impact, the combustion of fossil fuels had on the atmospheric composition of the planet. Although hydrogen is not a greenhouse gas, it has an indirect warming effect by reactions with other molecules.

The results come from the very first long -term recording of atmospheric hydrogen, compiled using data from ice nuclei extracted from Greenland in 2024. “The Core Ice record is incredible,” said Alex Archibald at the University of Cambridge.

Hydrogen is a small light molecule that escapes easily in the atmosphere. This means that hydrogen has generally disclosed ice nuclei before samples come back to laboratories – which are often thousands of kilometers – which makes the compilation of a long -term chronological series of its atmospheric levels very difficult.

To overcome this problem, John Patterson at the University of California, Irvine and his colleagues took their laboratory equipment in the field, analyzing ice cores immediately after extraction. “We took instruments on the ice, and as soon as we drilled our samples, we worked to clean them and have them seal in our fusion rooms so that we can do our analysis right on the ice,” he said.

The team was therefore able to constitute a long -term record of atmospheric hydrogen dating back 1100 years. It marks an enormous advance on the longest time series of approximately 100 years, which depended on the observation recordings and the analysis of snowfall. “It is really impressive from a logistical point of view, to get these measures out,” said David Stevenson at the University of Edinburgh, in the United Kingdom.

The hydrogen concentrations went from around 280 parts per billion at the beginning of the 19th century to around 530 parts per billion today, the team noted. According to Patterson, this is not surprising, given the steep increase in the combustion of fossil fuels from the pre -industrial era. Hydrogen is released in the form of a by-product when fossil fuels or biomass are burned.

Patterson and his colleagues combined the information from Clearit Ice recordings with modeling to try to build an image of the reasons why the hydrogen levels fluctuated during the last millennium. “Our data gives us how the atmosphere has changed, but it does not tell us why the atmosphere has changed,” explains Patterson. “So we try to use these biogeochemical models to explore why it could have changed.”

For example, ice nucleus recordings reveal hydrogen levels in the atmosphere lowered by 16% during the small glacial period, a period of lower temperatures between the 16th and 19th centuries. A reduction in forest fire emissions during this period does not fully explain this sharp drop in hydrogen concentrations, says Patterson. “This tells us that the natural biogeochemistry of hydrogen changes with the climate in a way that we do not really understand, [and] We didn’t really expect it, ”he says.

In the atmosphere, hydrogen competes with methane to react with hydroxyl radicals, crucial molecules to eliminate methane molecules warming the planet from the atmosphere. “The more hydrogen in the atmosphere there is, the less hydroxyl to react with methane,” explains Patterson, prolonging the warming effect of methane in the atmosphere. “At the moment, there is about half a part per million hydrogen in the atmosphere. Based on our best estimates, which provides something like 2% of the total anthropogenic warming effect.”

A better understanding of the hydrogen cycle is crucial to judge whether the mass adoption of hydrogen fuel in the future in the context of a distance from fossil fuels could provide unexpected consequences. A sharp increase in atmospheric hydrogen concentrations could, for example, amplify the heating effect of methane. Methane emissions have been increasing regularly since 2007 due to the production of fossil fuels, agriculture and warming temperatures triggering its release from wetlands and permafrosts.

“Methane is the great reason why we hesitate to take the path of the economy of hydrogen, because in the end, we will disclose a little hydrogen in the atmosphere,” explains Archibald. “If we disclose hydrogen in the atmosphere, we will exacerbate the methane crisis.”

This could be an argument to use hydrogen sparingly where renewable power cannot replace the use of fossil fuels, suggests Archibald. But Patterson and other experts emphasize that the effects of warming the increased use of hydrogen are still probably minimal compared to the enormous warming effect of fossil fuels. “I don’t want to scare people away from the energy of hydrogen, because it’s so much better than the alternative,” explains Patterson.