Some scientists might chalk this finding up to the law of unintended consequences. Others might call it climate change whack-a-mole. But a new study offers an answer to a puzzling air pollution event that occurred during the COVID-19 pandemic. The pandemic shutdown forced people out of their cars and into their homes. This then triggered a drop in carbon dioxide (CO2) and other greenhouse gases in the atmosphere. Yet, methane is Earth’s most potent planet warming pollutant. And methane spiked. Why? The answer: because the decline in CO2 emissions also cut chemical “cleaning agents” that destroy methane. So says a study by a Beijing University research team. It was published in the journal Science. The agents are “hydroxyl (OH) radicals.” They're formed by a reaction between pollutants, such as nitrogen oxides, and sunlight. It changes methane into less potent gases. But OH radicals don’t linger in the air long. So what happened when people sharply curtailed their driving habits during the pandemic? There were fewer of these agents to destroy methane. The scientists relied on satellite data for their research. They observed that 83% of the methane spike came from a weakened atmospheric “sink.” It was tied to the pandemic effect instead of increased methane emissions. OH is a "cleanup" tool, Euen Nisbet told Live Science. Nisbet's a Royal Holloway University of London Earth sciences professor. "It oxidizes all the nasties," Nisbet said. OH transforms carbon monoxide into CO2, he said. It also bonds hydrogens to change methane into CO2. Nisbet was not involved in the study. But Nisbet authored commentary on its findings. The results don’t mean humans need to keep pumping CO2 into the air to curb methane, scientists say. Rather, they must find better ways to target both at the same time. "We've got to work twice as hard," Nisbet said. Reflect: When people try to fix one environmental problem and it accidentally causes another, how do you think decisions should be made about what to change next?
