Sea Level Rise Due to Melting Glaciers

GS Paper III Environment & Ecology

A new study published in Nature found that melting glaciers have contributed nearly 2 cm to global sea level rise this century.

About Glaciers

Glaciers rank as the second-largest contributor to global sea level rise, following ocean warming.
They are also natural indicators of climate change and play a vital role in many communities, providing vital water resources, especially during dry seasons.

About Sea Level Rise: Sea level rise is an increase in the level of the world’s oceans due to the effects of global warming.
Causes of Sea Level Rise
- Glacier and Ice Sheet Melting: Global warming has led to the rapid melting of glaciers and ice sheets.
  - Since 2000, glaciers have lost between 2% and 39% of their ice regionally and 5% globally—18% more than the ice lost from Greenland and Antarctica combined.
- Thermal Expansion of Seawater: Thermal expansion occurs when water expands as it heats up due to rising global temperatures.
  - As oceans absorb more heat, their volume increases, contributing to sea level rise.
  - Warmer oceans cause seawater to expand, contributing one-third to half of global sea level rise (NASA).

Loss of Ice: Over the past 25 years, glaciers have been losing 273 billion tonnes of ice annually.
- Between 2000 and 2023, the world’s glaciers lost 6.542 trillion tonnes of ice, contributing an 18mm rise in sea levels.
Rate of Sea Level Rise: Since 1880, global sea levels have risen by 21 cm.
- The rate has accelerated from 0.18 cm/year (1993) to 0.42 cm/year (2024).
- Over 10 cm of sea level rise has been recorded between 1993 and 2024.
Regional Variations: The southwestern Indian Ocean experiences a higher-than-average rise at 2.5 mm per year (World Meteorological Organization, 2022).
- Local factors like ocean heat content and salinity changes cause uneven sea level rise.
Impact on India
- Mumbai: Witnessed a 4.44 cm rise (1987–2021), making it the worst-affected Indian city.
- Other affected Cities are : Haldia, West Bengal, Visakhapatnam, Andhra Pradesh as well as Kochi, Kerala.

Coastal Flooding and Land Erosion: Increased flooding and coastal erosion can displace communities.
- The West Bengal coast lost 99 sq km of land between 1990 and 2016 (NCCR Report, 2018).
Impact on Coastal Populations: 29% of the world’s population lived within 50 km of the shore in 2018.
- 15% lived just 10 km from water (Scientific Reports, 2024).
Stronger Storm Surges: Rising sea levels increase the intensity of tropical storms, worsening flooding and damage.
Threat to Coastal Ecosystems: Mangroves, coral reefs, and salt marshes face degradation.
- Rising seas contaminate freshwater sources, impacting agriculture and drinking water.
Future Projections: If emissions are not curbed, sea levels could rise by 20 cm by 2050—doubling the increase of the past century (NASA Statement, 2024).
- This would result in more frequent and intense floods worldwide.

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