Hydrogen plays part in global warming
Hydrogen has long been promoted as a potential solution to the climate crisis, offering a clean alternative to fossil fuels for transport and heavy industries because it only emits water vapor when used. However, a new study warns that hydrogen may also contribute, albeit indirectly, to global warming.
Published in the journal Nature, the research found that hydrogen emissions have played a small role in rising temperatures by allowing methane—a potent greenhouse gas—to persist longer in the atmosphere. Between 1990 and 2020, hydrogen emissions increased, contributing roughly 0.02°C to the nearly 1.5°C rise in global temperatures since the pre-industrial era.
“We need a deeper understanding of the global hydrogen cycle and its links to global warming to support a climate-safe and sustainable hydrogen economy,” said Rob Jackson, a Stanford University scientist and senior author of the paper.
The study, conducted by the Global Carbon Project, an international group of scientists, concluded that most of the increase in hydrogen comes from human activities. It is closely linked to rising methane emissions from fossil fuels, livestock, and landfills. The relationship between the two gases is complex: when methane breaks down in the atmosphere, it produces hydrogen. While hydrogen itself is not a pollutant, it indirectly contributes to warming by reducing the abundance of natural “detergents” in the atmosphere that would normally break down methane.
“More hydrogen means fewer detergents in the atmosphere, causing methane to persist longer and, therefore, warm the climate longer,” explained Zutao Ouyang, lead author and assistant professor of ecosystem modeling at Auburn University. The study also notes that hydrogen’s interactions with these atmospheric compounds can affect cloud formation and lead to the production of additional greenhouse gases, including ozone and stratospheric water vapor.
Other sources of hydrogen emissions since 1990 include leaks from industrial production. While hydrogen can be produced by splitting water into hydrogen and oxygen through electrolysis, most hydrogen today is made from natural gas or coal in processes that consume large amounts of energy and emit substantial carbon dioxide.
The long-term goal is to produce “green” hydrogen at scale using renewable energy, but the technology remains expensive and faces significant challenges. Understanding hydrogen’s indirect role in climate change will be essential as nations seek to expand its use in the transition to a low-carbon economy.
