Shankar IAS Summary: Climate Change- 2 | Famous Books for UPSC Exam (Summary & Tests) PDF Download

• Climate "forcings" influence the climate system, either intensifying or lessening its impact.
• Excess greenhouse gases, considered positive forcings, lead to Earth's warming.
• Negative forcings, like aerosols from volcanic eruptions, result in cooling effects on the planet.
• Types of Atmospheric Aerosols:
  • Volcanic dust
  • Soot from fossil fuel combustion
  • Particles from burning forests
  • Mineral dust
    
    Role of Atmospheric Aerosols
• Dark carbon-rich particles, such as diesel engine soot:
  • Absorb sunlight
  • Contribute to atmospheric warming
• Light aerosols, like those from high-sulfur coal or oil:
  • Reflect sunlight back to space
  • Induce a cooling effect
• Natural aerosols from volcanic eruptions:
  • Contribute to atmospheric cooling
  • Large eruptions can lower temperatures until sulfate particles settle out.

Changing the Energy Balance

• The ability of a process to influence the climate is measured by its "radiative forcing," which represents the alteration in the Earth's energy balance caused by that process.
• Climate forcings can be positive, contributing to global warming, or negative, leading to cooling. Some forcings, like those from increased CO₂ concentrations, are well understood, while others, like those from aerosols, are more uncertain.
  

Natural Forcings

• Natural forcings involve variations in the Sun's emitted energy, slow changes in Earth's orbit, and volcanic eruptions.
• Since the Industrial Revolution, the only significant natural forcing has been a slight increase in solar energy reaching Earth. However, this change alone cannot explain the current warming trend.

Human-Induced Forcings

• Human activities can also cause climate forcing, including greenhouse gas and aerosol emissions from burning fossil fuels, as well as modifications to the land surface like deforestation.

Human-Generated Greenhouse Gases

• Greenhouse gases act as a positive climate forcing, contributing to warming. Carbon dioxide from fossil fuel combustion is the largest single climate forcing agent, responsible for over half of the total positive forcing since 1750.
  
  Fossil Fuel Combustion

Human-Generated Aerosols

• Burning fossil fuels releases aerosols into the atmosphere, comprising tiny particles such as water, ice, ash, mineral dust, or acidic droplets. Aerosols can reflect the Sun's energy and influence cloud formation and longevity. Aerosols act as a negative forcing, exerting a cooling effect.

Causes of Climate Change

• Although natural forcings exist, they are insufficient to explain recent global warming. Human activities are highly likely to be responsible for the majority of the recent warming observed.

A century and a half ago, Glacier National Park boasted 147 glaciers. However, the current scenario reveals a stark decline, with only 37 glaciers remaining, and scientists project their potential disappearance by 2030. This pattern of retreat and vanishing glaciers extends to the Himalayas and Alps, where a similar trend is observed annually. In Polar Regions and high mountain environments, nearly 160,000 glaciers exist. Consequently, researchers are turning to satellite remote sensors as a more efficient means to regularly survey the world's glaciers, enabling comprehensive monitoring within a fraction of the time. 

Glacial Recession