Scientists question atmospheric methane removal technology

New research shows proposed climate interventions could worsen air quality while delivering minimal benefits

A new study by University of Utah researchers raises serious concerns about proposed climate interventions that would spray hydrogen peroxide into the atmosphere to combat global warming. The study, published in Environmental Science and Technology, found that large-scale deployment of the technology would be needed to have a meaningful impact on methane levels, which could have unintended consequences for air quality.

“Our work shows that the efficiency of the proposed technology is quite inefficient, meaning that widespread adoption of the technology would be needed to have any meaningful impact on CH4 in the atmosphere,” said lead author, a postdoctoral researcher at the university’s Wilkes Center. Alfred W. Mayhew said. “Then our results suggest that if this technology is adopted on a large scale, then we can start to see some negative impacts on air quality, particularly particulate air pollution in the winter.”

The study focuses on a patented technology that proposes using 600-meter-tall towers to release hydrogen peroxide (H2O2) into the atmosphere during the day. This chemical then reacts with sunlight to produce hydroxyl radicals, which break down the methane into less harmful compounds.

Using a complex atmospheric model, the researchers studied three scenarios with varying numbers of towers and emission rates. Their results show that even if 50 towers were operated at recommended emission rates, the technology would only reduce annual anthropogenic methane emissions by about 0.01%.

Numbers tell a sobering story

The study calculated that to achieve a 50% reduction in anthropogenic methane emissions, approximately 352,000 towers would be needed, a scale that raises serious practical and environmental concerns. Even if emissions rates increase, tens of thousands of towers will still be needed to have a significant impact.

Even more troubling are the findings regarding the impact on air quality. Research shows that large-scale deployments could lead to significant increases in particulate matter pollution, especially in winter. In some areas, the 95th percentile of PM2.5 concentrations has increased by up to 3.6 μg/m3, a change that may cause some areas to fall out of compliance with air quality regulations.

Chemical complexity creates challenges

Jessica D. Haskins, assistant professor of atmospheric sciences and co-author of the study, explained that hydroxyl groups oxidize double-bonded molecules more easily than methane does, making the process inherently inefficient. Competition between methane and other atmospheric compounds for OH reactions greatly reduces the effectiveness of this technology.

The research comes at a critical time, as methane has 81.2 times the warming potential of carbon dioxide over 20 years and is responsible for nearly one-third of the rise in global temperatures since the Industrial Revolution. Although methane only lasts in the atmosphere for about nine years, its powerful warming effect makes it a target for climate intervention strategies.

A cautionary tale about geoengineering

The study highlights broader concerns about geoengineering approaches to climate change. “There can be a lot of feedback in climate. You change one thing and you think it’s going to do this, but it might actually have the opposite effect in one place versus another,” Haskins said. “You have to be very careful and make those kinds of assessments.”

While the researchers did not completely rule out the possibility of targeted use of the technology, they stressed that any implementation would require careful consideration of local conditions and timing. “Future studies could potentially show that placing these towers near point sources of methane has little impact on air quality if they are activated at certain times of the year and are located away from large population centers,” Mayhew noted. “

expect

The study, funded by the Wilkes Center for Climate Science and Policy at the University of Utah, is the first comprehensive assessment of the impact of atmospheric methane removal technologies on air quality. Its findings suggest that while the search for technological solutions to climate change should continue, careful assessment of potential side effects must be prioritized.

As the world grapples with the challenge of reducing greenhouse gas emissions, the study is a reminder that there are no simple solutions to climate change. The most effective approach may still be to reduce methane emissions at the source, rather than trying to remove the gas after it enters the atmosphere, the researchers suggest.