Changing consumption patterns and reduced travel as nations closed their borders and citizens were forced to stay at home quickly led to lower levels of pollution during the early days of the coronavirus pandemic. By the middle of April 2020, global carbon dioxide emissions had decreased by 17 percent compared to mean levels for 2019.
Air pollution, which by World Health Organization estimates kills around seven million people each year, was particularly affected. In India between March and May of 2020, the major metropolises of Bengaluru, Chennai, Delhi, Kolkata, Mumbai, and Pune saw a 42 to 60 percent reduction in particulate matter and a 46 to 61 percent decrease in nitrogen dioxide, a potentially toxic air pollutant which can inflame the airways and exacerbate or even prompt respiratory diseases as it attacks the lungs.
The pattern was repeated worldwide. While there was little change in those places like Taipei and Rio de Janeiro which implemented few coronavirus restrictions, in New York and Milan nitrogen dioxide levels decreased by 30 to 40 percent during the early days of the pandemic, and in Wuhan the reduction even reached 60 percent.
Intense air pollution manifests as smog, a combination of nitrogen oxides with ground-level ozone and other airborne particles. In the Indian capital of Delhi, where the air quality index regularly reaches severe levels and even threatens to exceed the measurable scale, blue skies afforded rare perspectives on national landmarks like the India Gate.
Scientists cautioned however that the short-term decrease in global travel and industry was likely to have a limited impact on the steady buildup of atmospheric carbon. This week researchers from the Scripps Institution of Oceanography and the National Oceanic and Atmospheric Administration in the United States confirmed such impressions, reporting that the level of carbon dioxide in the atmosphere has reached its highest since accurate measurements began 63 years ago.
Concentrations of carbon dioxide in the atmosphere peaked in May, when they reached a monthly average of 419 parts per million. That represents a small increase on the figure of 417 parts per million which was recorded last year. Ralph Keeling, a geochemist at Scripps, whose father pioneered research into the rapid buildup of atmospheric carbon, said in a statement:
‘The ultimate control knob on atmospheric CO2 is fossil-fuel emissions. But we still have a long way to go to halt the rise, as each year more CO2 piles up in the atmosphere. We ultimately need cuts that are much larger and sustained longer than the COVID-related shutdowns of 2020.’
Atmospheric carbon dioxide is one of the primary greenhouse gases, which effectively serve to trap heat and increase the temperature on Earth. The highest average buildup typically occurs in May, before plants in the Northern Hemisphere begin to remove large quantities of carbon from the atmosphere. From autumn to spring, plants and soil in the Northern Hemisphere give off carbon dioxide, causing levels to rise.
In December the latest edition of the Emissions Gap Report was published by the United Nations. The report found that despite the drop in emissions caused by the coronavirus pandemic, the world remains on course for a temperature rise of 3.2 degrees Celsius by the end of the century, far in excess of the goals set out by the Paris Agreement.
