Almost as soon as the coronavirus pandemic began, experts began to notice that the global blockade seemed to lead to a sharp drop in global carbon emissions.
The idea spawned both memes for the destruction of humanity on the planet and well-meaning visions for a greener future. NASA scientists have now found that the blockade has led to a 20 percent global reduction in nitrogen dioxide emissions since February, according to a press release, a change that shocked them.
“In a way, I was surprised at how much it dropped,” project leader and NASA researcher Christoph Keller said in a statement. “Many countries have already done a very good job of lowering nitrogen dioxide concentrations in recent decades due to clean air regulations, but what our results clearly show is that there is still a significant contribution to human behavior.”
The problem with comparing air pollution levels before and after locking is that the numbers usually vary over time. So NASA scientists had to develop a model that could accurately predict global emissions of nitrogen dioxide – an air pollutant linked to transport and industry – this year, if the pandemic never happened.
They found that most cities reported between 20 and 50 percent lower nitrogen dioxide emissions than the business-as-usual model, and Milan, Italy, saw a staggering 60 percent reduction.
“We all knew that the blockages would affect air quality,” Keller said in a statement. “It also soon became clear that it would be difficult to quantify how much of this change was related to blocking measures compared to overall seasonality or variability in pollution.”
READ MORE: NASA model reveals how much COVID-related pollution levels deviate from the norm [NASA/Goddard Space Flight Center]
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