It is well known that Covid-19 forced shutdowns in various countries have resulted in lower greenhouse gas (GHG) emissions and air pollution. Now, in a study published in Nature Climate Change on August 6, researchers from the University of Leeds and the University of York analyzed global emission reductions from February to June 2020 and made a prediction of the change in global temperatures.
What does the study say?
The researchers said a reduction in greenhouse gas emissions and air pollutants was seen as countries began to impose lockdowns on their residents and restrict their movement.
- Referring to mobility data from Google and Apple, they argued that a decrease in mobility of around 10% was observed in all but one of the 125 countries registered.
- They observed a reduction in mobility of up to 80 percent in five or more countries.
- Furthermore, mobility data from Google and Apple indicate that more than 50% of the world's population cut their trips by more than half in April 2020.
- In fact, Google mobility trends indicate that more than 80% of the population of 114 countries (approximately 4 billion people) reduced their movements by more than 50%.
So, are the drops in pollution levels permanent?
This does not appear to be the case. The researchers said the drop is expected to be temporary, as pollution levels are already returning to normal levels in many parts of Asia. However, considering that social distancing measures will be the new normal for another two years, the researchers speculate that the drop in emissions may remain at around 66% of their June 2020 levels by the end of 2021.
- A published study At the end of June he said that while the Covid-19 shutdowns were cleaning the air when a multitude of economic activities came to a halt, ozone pollution exploded during that time.
- This is because ozone pollution is known to increase during warmer months and accumulate in cleaner areas.
How does this affect temperatures?
According to the study, a decrease in nitrogen oxide (NOx) levels of up to 30% will contribute to a short-term cooling down to 0.01 degrees Celsius during the period 2020-2025 “almost exclusively due to depletion of ozone at level ground”. But in general, the effect of the immediate restrictions related to Covid-19 is close to “insignificant and lasting effects, if any, they will only be the result of the recovery strategy adopted in the medium term,” according to the study.
“These results underscore that without an underlying long-term decarbonization of economies across the system, even massive changes in behavior only lead to modest reductions in the rate of warming,”study says
What are the limits on the use of mobility data by Google and Apple?
One of the limitations is the representativeness of these data in relation to national behavior in general, since the use and penetration of the telephone vary by country and region. For example, the study mentions that while Apple's driving mobility has declined by more than 80 percent in India, it may not be a complete picture, as it likely represents that part of the population that can work from home. Therefore, estimates based on this data should be seen as an overestimate of the change in emissions induced by Covid-19.