Prelims: Environment (Technologies for Climate Change mitigation), Stratospheric Aerosol Intervention, Stratosphere
Mains: General Studies-III Conservation, Environmental Pollution and Degradation, Environmental Impact Assessment.
Why in the News ?
A recent study looked at the impact of stratospheric aerosol intervention (SAI) in mitigating global warming effects in West Asia (also known as Middle East) and North Africa (MENA).
Source: DTE
📌 FYI on Prelims
Stratosphere
- It is the layer of Earth’s atmosphere lying between the troposphere and the mesosphere.
- The stratosphere extends from the tropopause at about 10 to 17 km (about 6 to 11 miles) altitude to its upper boundary (the stratopause) at about 50 km (30 miles).
- It’s characterized by a highly stable temperature gradient that cools from top to bottom.
- It also contains the ozone layer.
- Commercial jet aircraft fly in the lower stratosphere to avoid turbulence and increased atmospheric drag, which are common in the troposphere below.
- This layer holds 19 percent of the atmosphere’s gases but very little water vapor
About:
Stratospheric Aerosol Intervention (SAI)
- Stratospheric Aerosol Intervention (SAI), also known as Stratospheric Aerosol Injection, is a geoengineering or climate engineering approach that uses tiny reflective particles or aerosols to reflect sunlight into space in order to cool the planet and reverse or stop global warming.
- It aims to mimic the cooling effects of volcanic eruptions by injecting sulfur dioxide (SO2) directly into the stratosphere, where it forms sunlight-reflecting sulfate aerosols.
- The 1991 eruption of Mount Pinatubo in the Philippines, often cited as the inspiration for this concept, deposited massive amounts of particulate matter and sulfur dioxide (SO2) into the atmosphere.
- This aerosol layer was reported to have lowered average temperatures around the world by about 0.5 °C (0.9 °F) over the following few years.
- It is believed that as more radiation is scattered in the stratosphere by aerosols, less would be absorbed by the troposphere, the lower level of the atmosphere where weather primarily occurs.
- The production of such an artificial aerosol layer could be accomplished by shooting sulfur particles into the stratosphere with cannons or dispersing them from balloons or other aircraft.
Aerosols
- They are tiny solid or liquid particles suspended in air or a gas.
- Aerosols can be natural, such as fog or gas from volcanic eruptions, or artificial, such as smoke from burning fossil fuels.
- Aerosol particles are either emitted directly into the atmosphere (primary aerosols) or produced in the atmosphere from precursor gases (secondary aerosols).
- Aerosol particles are tiny, but numerous, and often comprise a number of inorganic and organic substances.
- True aerosol particles range in diameter from a few millimicrometres to about 1 micrometre (equal to 10-4 cm).
- Particles with a diameter of less than 0.1 micrometer are sometimes referred to as Aitken nuclei.
- Visible forms of atmospheric aerosol plumes include smoke, smog, haze, and dust.
UPSC CSE EXAMS Corner
Prelims: PYQ/FAQ
Q. Consider the following:
- Aerosols
- Foam agents
- Fire retardants
- Lubricants
In the making of how many of the above are hydrofluorocarbons used?
a) Only one
b) Only two
c) Only three
d) All four
Explaination:
- Hydrofluorocarbons (HFCs) are synthetic chemicals that are used as refrigerants, blowing agents, firefighting agents, solvents, and propellants. They are non-flammable, chemically stable, and non-reactive.
- HFCs are potent greenhouse gases, with global warming potentials (GWPs) that are hundreds to thousands of times greater than carbon dioxide (CO2) per unit of mass. They are also short-lived climate pollutants (SLCPs), meaning that they have atmospheric lifetimes of less than 30 years.
- HFCs were introduced in the late 1980s to replace ozone-depleting substances, such as chlorofluorocarbons (CFCs). However, their use has become increasingly regulated in the 21st century due to their impact on climate change.
- The Kigali Amendment to the Montreal Protocol is a global agreement to phase down HFC production and consumption. Under the Kigali Amendment, all countries have agreed to reduce their HFC consumption by 85% by 2050.
- There are a number of alternatives to HFCs that are available and being developed. These alternatives have lower GWPs and are often more energy-efficient. Some examples of HFC alternatives include:
- Hydrofluoroolefins (HFOs)
- Natural refrigerants, such as carbon dioxide (CO2), ammonia, and propane
- Hydrocarbon blends
- Water
- HFCs are entirely man-made. They are primarily produced for use in refrigeration, air-conditioning, insulating foams and aerosol propellants, with minor uses as solvents and for fire protection. HFCs are not used for making lubricants.
