Sea Level Rise | Geology Optional Notes for UPSC PDF Download

Sea Level Rise

• Sea-level change is a natural process that has been occurring on Earth for billions of years, influencing coastal processes and land formations.
• There are three main mechanisms of sea-level change:
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  • Eustatic sea-level changes are global changes linked to variations in the volume of glacial ice on land or shifts in the shape of the sea floor due to plate tectonic activities.
  • Isostatic sea-level changes are local alterations resulting from the subsidence or uplift of the Earth's crust, often associated with changes in ice mass on land or geological processes like mountain formation or erosion.
  • Tectonic sea-level changes are localized shifts influenced by tectonic movements.
• Human-induced activities, such as global warming, significantly impact sea level through the release of greenhouse gases from activities like burning fossil fuels, agriculture, and deforestation.
• Global warming contributes to sea-level rise in two primary ways:
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  • Firstly, rising global temperatures and polar warming lead to the melting of glaciers and ice sheets on land, resulting in increased water volume in oceans and subsequent sea-level rise.
  • Secondly, the warming atmosphere causes water in the oceans to expand as it absorbs heat, occupying more space and causing sea level to rise; this process is known as thermal expansion.

Sea-Level Rise and Coastal Characteristics

• Estuaries and fiords commonly characterize coastlines in areas with net sea-level rise in the recent geological past.
• Uplifted wave-cut platforms are typical features of coastlines in areas with net sea-level drop in the recent geological past.
• Uplifted beach lines, resulting from relative sea-level drop, may be challenging to identify in densely vegetated areas.

Impacts of Sea-Level Changes

• Displacement of Human and Animal Populations: Sea-level changes can lead to flooding and erosion, forcing human populations and species to move to safer areas.
• Groundwater Salinity Increase: Coastal flooding can raise groundwater salinity, impacting freshwater quality and availability, and reducing soil quality. This, in turn, affects agricultural yields and livestock.
• Coastal Habitat Distribution: Marshes and swamps play a crucial role in protecting coastlines by reducing erosion and promoting sedimentation. As sea level rises, the ability for these habitats to migrate inland helps decrease coastal vulnerability to sea-level rise and storm surges.
• Species Range Shifts: Sea-level rise influences the habitats of organisms, their movement patterns, and interactions with other species.