It is observed by NASA that there is a significant reduction of pollutants in the air. Since Covid 19 pandemic began, space and ground-based observations have shown the Earth’s atmosphere has seen changes in the level of air pollution. However, Scientist wanted to know how much the graph of pollution have been declined and can be attributed to changes in human activity during pandemic related shutdowns versus how much you have occurred in a pandemic free 2020.
Using computer models to generate a COVID-free 2020 for comparison, NASA researchers found that since February, pandemic restrictions have reduced global nitrogen dioxide concentrations by nearly 20%. The results were presented at the 2020 International Conference for high-Performance computing, networking, storage, and analysis. Nitrogen dioxide is an air pollutant that is primarily produced by the combustion of fossil fuels used by industry and transportation—both of which were significantly reduced during the height of the pandemic to prevent the novel coronavirus from spreading. Nitrogen dioxide levels often dip during Lunar New Year celebrations in China and much of Asia and then rebound. But no rebound was evident this year over Wuhan, China where the virus was first reported, and nitrogen dioxide levels remained much lower than in 2019. NASA's model reveals how COVID-related pollution levels deviated from the norm.
No two years are exactly alike. Normal variations in weather and atmospheric circulation change the make-up and chemistry of Earth’s atmosphere. Comparing 2020 nitrogen dioxide concentrations with data from 2019 or 2018 alone would not account for year-to-year differences. But, because the NASA model projections account for these natural variations, scientists can use them to parse how much of the 2020 atmospheric composition change was caused by the COVID-19 containment measures. Even with models, there was no predicting the sudden, drastic shifts in human behavior as the novel coronavirus—and the regulations attempting to control it—spread rapidly. Instead of trying to re-program their model with this unexpected event, Keller and his colleagues accounted for COVID-19 by having the model ignore the pandemic altogether. The model simulation and machine learning analysis took place at the NASA Center for climatesimulation. Its “business as usual” scenario showed an alternate reality version of 2020 one that did not experience any unexpected changes in human behavior brought on by the pandemic. From there it is simple subtraction. The difference between the model simulated values and the measured ground observations represents the change in emissions due to the pandemic response. The researchers received data from 46 countries—a total of 5,756 observation sites on the ground—relaying hourly atmospheric composition measurements in near-real-time. On a city-level, 50 of the 61 analyzed cities show nitrogen dioxide reductions between 20-50%.
In some ways, I was surprised by how much it dropped. Many countries have already done a very good job in lowering their nitrogen dioxide concentrations over the last decades due to clean air regulations, but what our results clearly show is that there is still a significant human behavior-driven contribution.