New York has a greenhouse gas accounting problem. The state broadly tracks its sources of air pollution, from energy production to transportation to waste management, but the books don’t always match what’s actually in the air. The amount of methane over New York City, for example, is puzzlingly higher than expected.
The challenge lies in reconciling the two, Commane says. “These models can be tweaked to make sure that they represent the atmosphere as we understand it now.” And the findings in New York City could inform similar efforts elsewhere, especially in places with comparable natural gas infrastructure.Commane compares atmospheric modeling to solving a complicated puzzle. “I’ve always enjoyed playing with numbers,” she says.
Moving to Columbia University in 2018 to start her own lab gave Commane the opportunity to help address emissions at their source. In addition to New York City’s status as the top source of greenhouse gas emissions in the United States, it ranks third worldwide. Commane wondered whether the trees might help explain why carbon emissions measured in the atmosphere were slightly lower than what the bottom-up models predicted. Using the latest high-resolution land cover maps to incorporate vegetation into their model, she and Dandan Wei, a postdoc in her lab, found that the city’s trees were absorbing“So the trees do really matter,” Commane says, and models need to account for them.
Then it’s a matter of hopping into a car or going on foot to measure and confirm the exact location of the emissions with portable sensors, Commane says.