Study explaining the reason for the sudden increase in methane emissions during pandemic lockdown

Thanks to a recent study, scientists have been able to unravel the cause of a mysterious spike in methane emissions into the atmosphere that is causing the planet’s temperature to rise in 2020.

The rise of the boom, despite strict shutdowns as a result of Covid-19, which has reduced many sources of human-caused methane gas, can be explained by increasing emissions from nature and a sudden drop in air pollution, scientists said.

Methane remains in the atmosphere only as part of carbon dioxide, but it retains heat more efficiently and is responsible for almost 30% of global warming today.

Powerful greenhouse gases emitted into the atmosphere by oil, gas, waste and agriculture, as well as biological processes in wetlands, are the main target of efforts to limit global warming.

But a new study published in the journal Nature suggests that cutting methane production may be more difficult and urgent than is currently thought.

Researchers from China, France, the US and Norway have found that efforts to reduce carbon dioxide emissions and air pollution will affect the atmospheric process that cleans the air of methane. This means that the planet’s heating gases will linger longer and build up faster.

Philippe Siat, who co-led the study at the French Laboratory for Climate and Environmental Sciences (LSCE), explained that if the world wants to solve the problem of keeping temperature rises below 2°C since pre-industrial times, “we’ll have to move on.” faster and with more force” to reduce the amount of methane.

The researchers focused on the 2020 atmospheric methane concentration puzzle, which recorded the biggest increase on record, even as carbon emissions declined due to Covid-19 closures.

Study co-author Marielle Sonois of the French Laboratory for Climate and Environmental Sciences said they found likely two pieces of “bad news” about climate change.

First, they looked at inventories estimating fossil fuel and agricultural methane emissions and found that anthropogenic sources of methane did decline slightly in 2020.

They then used ecosystem models to estimate that warmer, wetter conditions in parts of the Northern Hemisphere caused an increase in emissions from wetlands.

This is worrisome and confirms other studies that say the more methane is released, the greater the warming, which can create a feedback loop largely beyond human control.

The researchers found that this is only half the story.

The researchers also looked at changes in atmospheric chemistry, as this provides a “sink” for methane, effectively scavenging it from the air in a relatively short period, turning it into water and carbon dioxide when it reacts with hydroxyl (OH) radicals.

These hydroxyl radicals are present in small amounts and have a lifetime of less than a second, but they remove about 85% of the methane from the atmosphere.

The researchers modeled changes in hydroxyl using anthropogenic sources of emissions of carbon monoxide, hydrocarbons and nitric oxide, which together influence the production and loss of hydroxyl radicals in the atmosphere.

They found that the concentration of hydroxyl radicals decreased by about 1.6% in 2020 compared to the previous year, mainly due to lower emissions of nitrogen oxides (NOx) caused by COVID-19 lockdowns.

Nitric oxide is mainly released into the air when fuel is burned.

“Reducing nitrogen oxides by 20 percent could increase methane emissions twice as fast,” Sayes said at a news briefing, adding: “We were very surprised.”

The researchers explained that their study helps unravel the mystery of rising atmospheric methane in 2020. But they acknowledged that more work is needed to answer the following mystery: why did methane concentrations hit a new record in 2021?

Source: phys.org.