slowed the CO2 accumulation in the atmosphere, it may not reduce the overall atmospheric concentration of the element. "In New Delhi and Mumbai the story is somewhat more mixed. The CO2 enhancements are smaller or almost the same in February, reflecting the large role of natural processes, such as year-to-year differences in CO2 uptake and release by forests and crops," said the taskforce.
The taskforce observed a significant drop in nitrogen dioxide (NO2) levels that coincide with reduced traffic and industrial activity. (Shutterstock)
NASA’s Orbiting Carbon Observatory-2 (OCO-2) satellite and Japan’s Greenhouse gases
Observing SATellite (GOSAT) tracked changes in CO2 emission in Mumbai, Beijing, Tokyo, and New York. The results show small, about 0.5 parts per million, or 0.125 per cent reductions in CO2 over each region.
Significant improvement in air quality
The taskforce observed a significant drop in nitrogen dioxide (NO2) levels that coincide with reduced traffic and industrial activity during three months of lockdown.
Satellite data shows a reduction of 40-50 per cent in NO2 levels in Delhi and Mumbai between March 25 and April 20. However, the reductions were not consistent throughout India. "Observations over India also showed less air pollution during lockdowns in selected cities, such as New Delhi and Mumbai," the taskforce said.
Northeast India showed nearly constant NO2 levels due to coal-based power plants, which did not reduce electric power generation significantly during the lockdown.
A notice put up at a barricade reads, 'India Gate closed due to coronavirus', to prevent mass gathering of tourists and locals amid fear of spread of the virus, at India Gate in New Delhi.
Similarly, in Madrid, Milan, Rome, and Paris, satellite data showed about a 50 per cent reduction in NO2 from March 13-April 13, 2020 compared to the same months the year before. These reductions coincide with the implementation of strict quarantine measures across Europe.
"Understanding the extent of any such changes would be important in maintaining global and local markets and food security as the world recovers from the pandemic," Zurbuchen said.
The taskforce used the Tropospheric Monitoring Instrument (TROPOMI) on ESA's Copernicus Sentinel-5P satellite and the joint NASA-Royal Netherlands Meteorological Institute (KNMI) Ozone Monitoring Instrument (OMI) on the Aura satellite to study the changes.