- March 11, 2022
- Posted by: OptimizeIAS Team
- Category: DPN Topics
Context- Scientists say that accurately modelling the intensity of aerosol effects on climate change is vital to humanity’s future but aerosol complexity makes it difficult to model and understand.
- Aerosols are fine particulates that float in the atmosphere.
- While there has not been significant change in presence of natural aerosols, human-caused aerosols have increased rapidly.
- An immense aerosol cloud regularly swirls over India, China and Southeast Asia, fed by particles of ash, soot and organic carbon compounds.
- Aerosols are a mixed bag of substances, liquid and solid, that differ from their gassy brethren.
- They tend to hang in the atmosphere near their source, or move as localised or regional masses via air currents.
- They range in size from a few atoms across to the width of a human hair.
- They include:
- crystals of sulphate,
- balls of almost pure black carbon (commonly, though not entirely accurately, called soot),
- droplets of nitric or sulfuric acid, spores of pollen.
- They may be salt freed from the crests of breaking waves, or desert sand whipped up by the wind.
- Natural Aerosols: One of the largest natural sources of aerosols are plankton, which breathe out dimethyl sulphide (DMS), a strong-smelling chemical that gives the sea it’s familiar pungent odour.
- DMS reacts with oxygen to produce clouds of sulfuric acid.
- Sulphur dioxide released by volcanoes does the same.
- Ninety percent of aerosols in the atmosphere are naturally occurring, but their levels have remained relatively constant over time.
- Anthropogenic Aerosols: On the other hand anthropogenic, or human-made aerosols are emitted from:
- vehicle exhausts;
- the smokestacks of factories,
- ships and coal-burning powerplants;
- by farmers burning field stubble and land grabbers clearing Amazon forest with fire;
- by gas flares on oil rigs and discarded plastic shopping bags.
- Even tumble driers release microplastic fibres that float skyward.
- These sources have increased dramatically over the industrial period, roughly in step with greenhouse gases.
- Most aerosols help cool the planet by reflecting sunlight back out into space, reducing the amount of radiant energy that reaches Earth’s surface.
- They also help create clouds or brighten existing clouds, by acting as condensation nuclei around which water vapor condenses.
- Aerosols first came to public attention in the 1970s, not so much because of their cooling impact, but due to acid rain.
- The worst aerosols are very fine particulates that can penetrate deep into the lungs and may even enter the blood stream exacerbating respiratory and cardiovascular conditions.