Summers will get much hotter and monsoons more intense as air pollution goes down amid lockdown, says study
The coronavirus pandemic has forced countries across the world to impose lockdowns and restrict movement in order to contain the spread of the infection. As a result, the air quality has dramatically improved with no pollution-causing agents such as transport and industries in operation. The inevitable reduction in polluting gases could increase the amount of sunlight that reached the earth's surface and affect the weather patterns, per scientists.
Air pollution caused by nitrogen oxide (the main pollutant emitted from vehicles) across major cities in Asia and the US has declined by at least 60 percent in the recent weeks, according to BBC. The skies are now devoid of haze and appear bluer than before, with people in northern India reporting they are now able to enjoy startling views of the Himalayas in almost three decades.
Scientists confirmed earlier in the year that cleaner skies in recent times have contributed to the well-being and brightening of the earth's surface. Satellite measurements show that Europe saw a surface dimming effect until the late 1980s, followed by a brightening effect as air-pollution regulatory measures were installed. China also followed a similar pattern in surface dimming but it wasn't until 2005 that the brightening set in. Now, it is likely that the lockdown has resulted in cleaner skies further intensifying the brightening effect. However, its impact on the weather pattern is hard to gauge, because the process is not straightforward.
“Aerosols can scatter and absorb radiation. They can also modify clouds to make them more reflective and longer lived,” Laura Wilcox, a climate scientist at the University of Reading told the Guardian. In contrast to carbon dioxide, aerosols can linger around in the atmosphere for a week, two weeks tops. This means that any reduction in pollution levels can be instantly recognized.
“With smaller amounts of aerosol in the atmosphere we will already be seeing more solar radiation reaching the surface, and thus potentially warmer surface temperatures in regions that usually have high levels of air pollution,” said Wilcox. However, detecting the effect of the pollution decline and inferencing the fluctuations in the climate will be extremely complex.
Computer simulations have illustrated that if the air quality improves rapidly, it will contribute to the rise in temperatures. Wilcox's new research also found that a reduction in air pollution in Asia will lead to heavier tropical monsoons, due to a larger disparity in temperatures of the land and ocean. In an unlikely scenario, with rapid increases in the air quality, the research findings suggest that the hottest day of the year shoot up by at least 39.2 degrees Fahrenheit by 2050, and one-third of that increase will be due to cleaner skies. If the drop in air pollution persists over time, it'll be more feasible to seeing the impact it will have on the climate.
“I will be watching India closely over the coming weeks. We would typically expect to see summer monsoon onset within the next four weeks, and would usually see both very hot temperatures and high aerosol levels ahead of monsoon onset,” Wilcox added.
The improvement in air quality over northern India could very well help fuel and intensify the monsoon showers, according to Wilcox. Her team will be on standby, ready to gather measurements so they can compare it with data from the previous years. Although cleaner skies are momentarily expediting climate change, the long-term effects and possible dangers associated with global warming are tremendous.