Sea Level Rise Is Certain

Context: The rising of sea level needs to be controlled by controlling in rising emissions.

Climate change a reality: Gloomy predictions

• Recently published IPCC Assessment Report from Working Group I — ‘Climate Change 2021: The Physical Science Basis’, is a clarion call for climate action.
  • The report discusses five different shared socio-economic pathways for the future with varying levels of greenhouse gas (GHG) emissions.
  • The average global temperature is already 1.09°C higher than pre-industrial levels and CO2 concentration in the atmosphere is currently 410 ppm compared to 285 ppm in 1850.
  • Even in intermediate scenario, it is extremely likely that average warming will exceed 2°C near mid-century.
• According to the UN Environment Programme Emissions Gap Report, the world is heading for a temperature rise above 3°C this century, which is double the Paris Agreement aspiration.

About sea level rise

• Factors driving sea level rise: Mainly due to expansion of warm ocean waters, melting of glaciers on land, and melting of ice sheets in Greenland and Antarctica.
  • Shifting contributions: While sea level rise in the last century was mainly due to thermal expansion, glacier and ice sheet melt are now big contributors.
• An intensifying trend: Global mean sea level (GMSL) rose by 0.2m between 1901 and 2018. The average rate of sea level rise was 1.3 mm/year (1901-1971) and rose to 3.7 mm/year (2006-2018).
  • Dangerous predictions: In low emissions scenario, GMSL is expected to be 0.19m in 2050 and 0.44m by 2100. In very high emissions scenario, it can be about 0.23m in 2050 and 0.77m in 2100.

High vulnerabilities due to sea level rise

• High uncertainties in predictions: As studies and predictions does not include many aspects such as
  • Marine ice sheet instability or MISI: Rapid destabilisation of ice sheets as water gets warm.
  • Marine ice cliff instability, MICI: As ice cliffs can collapse swiftly in a related process.
• Sea level to continue even after emissions stagnate: As oceans respond slowly to warming.
  • Centennial-scale irreversibility of sea level rise has implications for future even under low emissions scenarios.
• Huge population at stake: Close to 700 million people worldwide live along the coast and there continue to be plans to expand coastal cities.
• Vulnerabilities to India: Communities along coast in India are vulnerable to sea level rise and storms, which will become more intense and frequent. They will be accompanied by storm surges, heavy rain and flooding.
  • Even the 0.1m to 0.2m rise expected along India in the next few decades can cause frequent coastal flooding.

Way forward: Adaptation to sea level rise must include a range of measures including

• Stricter coastal regulation measures.
• Coastal communities should be alerted in advance and protected during severe weather events.
• Natural and other barriers should be considered in a limited manner to protect certain vulnerable areas,
• Retreat should be part of adaptation strategies for some very low-lying areas.