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Scientists mull stratospheric barrier to curb global warming
What to study?
- Static Part: What is Stratospheric Aerosol Injection (SAI)? What are Sulphur Aerosols and how they occur?
Context: Scientists have found that spraying sun-dimming chemicals high above the earth to slow global warming could be remarkably inexpensive costing about $2.25 billion a year over a 15-year period.
This geo-engineering technique known as stratospheric aerosol injection (SAI) could limit rising temperatures that are causing climate change.
What are Stratospheric Sulphur Aerosols?
Stratospheric sulfur aerosols are sulfur-rich particles which exist in the stratosphere region of the Earth’s atmosphere. The layer of the atmosphere in which they exist is known as the Junge layer, or simply the stratospheric aerosol layer.
These particles consist of a mixture of sulfuric acid and water. They are created naturally, such as by photochemical decomposition of sulfur-containing gases, e.g. carbonyl sulfide.
- Sulfur aerosols are common in the troposphere as a result of pollution with sulfur dioxide from burning coal, and from natural processes.
- Volcanoes are a major source of particles in the stratosphere as the force of the volcanic eruption propels sulfur-containing gases into the stratosphere.
What is Stratospheric Aerosol Injection (SAI)?
Under SAI delivery of precursor sulfide gases such as sulfuric acid, hydrogen sulfide (H2S) or sulfur dioxide (SO2) are sprayed by artillery, aircraft and balloons.
It would involve the use of huge hoses, cannons or specially designed aircraft to spray large quantities of sulphate particles into the upper layer of the atmosphere to act as a reflective barrier against sunlight.
- Total costs estimated to launch a hypothetical SAI effort 15 years from now would be $3.5 billion and average annual operating costs would be about $2.25 billion a year over 15 years.
- Discounting other methods of deployment because of cost and feasibility, the research assumes a special aircraft can be designed to fly at an altitude of about 20 km and carry a load of 25 tonnes.
This proposed method could counter most climatic changes, take effect rapidly, have very low direct implementation costs, and be reversible in its direct climatic effects.
Benefits of the SAI:
Mimics a natural process. It is technologically feasible. The method is economically feasible and efficient.
Possible side effects:
- Tropospheric Ozone depletion.
- Whitening of the sky.
- Tropopause warming and the humidification of the stratosphere.
- Involves Health effects.
- Stratospheric temperature rise and circulation change.
Sources: the hindu.