Molecular hydrogen levels (H2) in the atmosphere have increased in modern times due to human activity, according to new research.
When scientists analyzed air samples trapped in perforated cores of Antarctic ice, they found that atmospheric hydrogen had increased by 70 percent over the course of the 20th century.
Although recent air pollution laws have tried to curb fossil fuel emissions, hydrogen emissions have continued to rise with no signs of slowing down. And there is a possibility that the leak is to blame.
Molecular hydrogen is a natural component of our atmosphere due to the degradation of formaldehyde, but it is also a byproduct of the combustion of fossil fuels, especially from car exhaust and biomass combustion.
Although hydrogen does not trap heat in the atmosphere alone, it can indirectly affect the distribution of methane and ozone. After carbon dioxide, these are the two most important greenhouse gases, which means that global hydrogen levels can also disrupt the climate.
Nevertheless, sources and sinks of atmospheric hydrogen are rarely studied. We don’t even have a good estimate of how much humans have emitted since industrial times.
The current study is the first to offer a solid figure. Between 1852 and 2003, air samples from the South Pole of Antarctica suggest that atmospheric hydrogen jumped from 330 parts per billion to 550 parts per billion.
“Aged air gets trapped in the perennial snow on a layer of ice and sampling provides us with a very accurate account of atmospheric composition over time,” explains Earth scientist John Patterson of the University of California Irvine.
“Our paleoatmospheric reconstruction of H2 levels has greatly improved our understanding of anthropogenic emissions since the beginning of the industrial revolution. “
The news is not exactly good. It turns out that we may have been significantly underestimating our hydrogen emissions.
Some outlet pipe emissions have been mitigated in recent years with the use of catalytic converters, and ideally we would have seen hydrogen emissions decrease or even plateaus.
However, hydrogen levels have continued to rise in the atmosphere, almost without interruption.
“[W]We’re probably underestimating non-automotive gas sources, ”Patterson says.
Instead, there must be another source that grows rapidly and compensates for our progress in the auto industry: we just don’t know where it comes from.
This is not the only data set that identifies this discrepancy. Previous research has also shown a steady increase in hydrogen since 2000 and 2015, different from trends in other forms of exhaust pollution.
In terms of human-caused emissions, hydrogen emissions are believed to come primarily from the exhaust of the automobile, but hydrogen leakage from industrial processes is rarely taken into account.
No one has directly measured the amount of hydrogen leakage from these processes, but early estimates suggest it could be significant.
A 10% leakage rate between 1985 and 2005 would account for about half of the increase in recent hydrogen emissions, according to the researchers.
They may not be sure where hydrogen comes from (hydrogen emissions from coal combustion are also being seriously studied), but the authors argue that it is worth investigating them further.
Especially since green hydrogen processes, which split hydrogen from water to create carbon-free energy, could also produce substantial leaks if they are ever expanded, as some climate scientists and environmentalists expect.
It is not a new concern. It is a concern that scientists have been pointing out for years.
If one day hydrogen escapes from industrialized hydrogen gas plants, experts worry, it can increase the life of methane in our atmosphere, a greenhouse gas 20 times more potent than carbon dioxide.
Although, even with a small percentage of leaks, a global hydrogen economy would likely have much lower climate impacts than our fossil fuel-based energy system, according to the researchers.
Now scientists are looking for the mysterious source of hydrogen that we seem to be missing all the time. If at least some turn out to be leaks, the future of green hydrogen may have a problem that needs to be solved.
The study was published in PNAS.