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Understanding the Context

Sea level rise refers to the gradual increase in the global average height of the world’s oceans. This phenomenon is driven primarily by two climate-related factors: thermal expansion (ocean water expands as it warms) and the melting of land-based ice from glaciers and ice sheets in Greenland and Antarctica.

Current Observations: How Much Has Sea Levels Already Risen?

Since the late 19th century, global sea levels have risen by approximately 20 centimeters (8 inches). According to data from NASA and the National Oceanic and Atmospheric Administration (NOAA), the rate of rise has accelerated significantly over the past few decades:

• 1900–1990: ~1.7 mm per year
  
• 1993–2018: ~3.4 mm per year
  
• As of 2024, sea levels are rising at about 4.5 mm (0.18 inches) per year—nearly double the rate of the 20th century.

Key Insights

These observations confirm that sea level rise is not a distant threat—it’s already happening and accelerating.

Future Projections: How Much Higher Will Seas Rise?

According to the latest assessments by the Intergovernmental Panel on Climate Change (IPCC Sixth Assessment Report (AR6, 2021) and updated studies from 2023–2024, sea levels are projected to rise significantly over the coming decades, depending on future greenhouse gas emissions.

IPCC High-Emission Scenario (SSP5-8.5):

Under continued high emissions, sea levels could rise by 0.61 to 1.10 meters (2 to 3.6 feet) by 2100—and possibly more with potential instability in Antarctic ice sheets.

Intermediate Emissions Scenario (SSP2-4.5):

With moderate emissions reductions, sea levels could rise 0.28 to 0.55 meters (11 to 22 inches) by 2100.

Final Thoughts

Low-Emission Scenario (SSP1-2.6):

If global warming is limited to 1.5°C through rapid emissions cuts, sea level rise by 2100 could be constrained to around 0.26 to 0.55 meters (10 to 22 inches), with lower long-term risks.

These projections emphasize the critical importance of climate action: the higher the greenhouse gas emissions, the greater the sea level rise—and the greater the risks.

Which Areas Are Most at Risk?

Coastal regions worldwide face increased flooding, erosion, saltwater intrusion, and infrastructure damage. Marginalized and low-lying communities—especially in South and Southeast Asia, the Pacific Islands, and parts of Africa—are among the most vulnerable.

Key impacts include:

• More frequent and severe coastal flooding during high tides and storms
  
• Loss of habitable land and displacement of populations
  
• Threats to freshwater resources from saltwater intrusion
  
• Damage to ecosystems like mangroves, wetlands, and coral reefs
  
• Economic losses estimated in trillions of dollars globally by 2100 if no adaptation occurs

Adapting to Rising Seas: Solutions and Actions