Solar radiation management (SRM)

Context
The United States is eyeing a controversial tool to counter global warming: Solar radiation management (SRM), which involves reflecting a small fraction of sunlight into space. What is solar radiation management (SRM)?
Aerosols are tiny particles suspended in a gas form which reduce the heat intensity.
 The Solar radiation management (SRM) is part of a controversial concept called ‘geoengineering’.
  • SRM aims at injecting the atmosphere with aerosols or using giant mirrors to reflect the sunlight back.
  • By reducing the load of greenhouse gas (GHG) emissions, the SRM is being sold as a futuristic technology that will reduce soaring temperatures in Africa to make it relatively cooler.
  • Popular theoretical ideas for SRM include:
    • modifying cloud structures
    • spraying aerosols into the stratosphere
What is Geoengineering?
  • ‘Geoengineering’ literally means interventions that change the way the Earth’s systems work.
  • Category: Geoengineering is broadly divided into two categories —
    • technologies for capturing carbon (carbon dioxide removal)
    • methods for managing how much of the Sun’s heat reaches the Earth
      • preventing the Sun from heating up the Earth (solar radiation management)
      • removing heat from the Earth’s atmosphere into space (Earth radiation management) 
Marine Cloud Brightening (MCB)
  • Clouds are natural umbrella (white), they reflect sunlight, keeping the Earth cool.
  • Clouds that are present above the oceans cool the surface below substantially.
  • There are proposals to further “whiten” these clouds and expand their cover, through a process called marine cloud brightening (MCB). 
 What is the need?
  • The call to pursue geoengineering is spurred by the urgency of tackling the fallout of climate change.
  • As the world continues to heat, with no end in sight for fossil fuel emissions, solar and other forms of geoengineering are starting to occupy more mainstream space in climate discussions.
Is it regulated?
  • Ideas associated with geoengineering have not been tested or executed yet.
  • A draft EU report had flagged the risks associated with geoengineering and called for talks towards an international framework to govern such technologies.
How would it impact?
  • This is not only dangerous but also frightening and inequitable.
  • By dimming the incoming sunlight can upset the anthropogenic equilibrium and, thereby, have a devastating impact by way of:
    • disrupting monsoons
    • altering cropping patterns
    • causing unforeseen problems for the local and regional biodiversity
    • extended droughts and incessant rains
Major processes of natural SRM
  • Planting more plants, especially suitable ones with lighter coloured leaves
  • Increasing the coverage of water ice. Sea ice is the best-known natural surface for reflecting light and heat, sending back nearly 90 percent of energy.

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