Aerosols are tiny particles suspended in the air. Some occur naturally, originating from volcanoes, dust storms, forest and grassland fires, living vegetation, and sea spray.
Human activities, such as the burning of fossil fuels and the alteration of natural surface cover, also generate aerosols.
Averaged over the globe, aerosols made by human activities currently account for about 10 percent of the total amount of aerosols in our atmosphere. Most of that 10 percent is concentrated in the Northern Hemisphere, especially downwind of industrial sites, slash-and-burn agricultural regions, and overgrazed grasslands.
Injecting aerosols in the upper atmosphere is believed to be a method that can quickly counter global warming, new research revealed. Solar- radiation management could not only reduce rainfall in the long term, but its effects will also vary across regions. Some places will be over- cooled by atmospheric changes, which are too minor to be effective for their neighbours.
The gases under consideration are sulphur compounds that would produce sulphate aerosols in the upper atmosphere. Reengineering advocates have suggested injecting large quantities of these materials into the stratosphere, either by shooting them up in artillery shells or releasing them from high-flying aeroplanes. Once there, they would disperse into a thin, bright haze that would reflect enough sunlight back into space to partially or completely offset global warming.
According to the new study, it is quite easy to design sulphate-injection scenarios that keep the temperature stable until 2080. But, the change in sunlight alters other weather patterns. It changes the distribution of energy in the troposphere so that it becomes more convectively stable.
Regional effects are also important. Researchers demonstrate that levels of sulphate that kept China closest to its baseline climate were so high that they made India cold and wet. Those that were best for India raised the mercury levels in China. However, both countries fared better either way than under a no-geoengineering policy. The researchers also found that all of these effects get worse with time.
This type of geoengineering is at best a temporary fix – something people working in the field had always known because it does nothing to prevent the accumulation of C02 and the resulting acidification of the oceans.
Impact of Aerosols on Air Pollution:
i. Aerosols affect human health
ii. Aerosols reduce visibility
iii. Aerosols contribute to acid deposition, affecting forests and lake
iv. Aerosols reflect solar light and hence influence climate change
v. Aerosols contribute eutrophication, affecting water quality
vi. Aerosols catalyze stratospheric ozone loss/ Antarctic ozone hole