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Context:

• A new study published in the journal Science warns that within a century, a quarter of China's coastal land could sink below sea level due to land subsidence and climate change. This puts hundreds of millions of people at risk of flooding.

Details of the study on trends of sea level rise:

• Sea Level Rise Since 1880: Since 1880, the global sea level has risen by approximately 8–9 inches or 21–24 centimeters, as reported by the National Oceanic and Atmospheric Administration (NOAA).
• Accelerating Rate of Increase: Since 1993, the rate of sea level rise has accelerated significantly, more than doubling from 0.07 inches or 0.18 centimeters per year in 1993 to the current rate of 0.17 inches or 0.42 centimeters per year.
• Recent Trends: From 2022 to 2023, the global average sea level rose by about 0.3 inches or 0.76 centimeters. This increase was attributed largely to the development of El Niño, a weather pattern associated with warmer oceans, in June 2023.
• Expected Slowdown: With the weakening of El Niño, experts anticipate a slowdown in the rate of sea level rise.
• Future Projections:
  • According to the study, current acceleration rates suggest that another 20 centimeters of global mean sea level could be added by 2050.
  • This projection indicates a doubling of the sea level rise compared to the previous 100 years, leading to increased frequency and impacts of floods worldwide.

How climate change is leading to sea level rise?

• Global Warming: Rising sea levels are primarily driven by global warming, which leads to increased temperatures worldwide. As temperatures rise, glaciers and ice sheets melt, adding water to the ocean.
• Thermal Expansion: Global warming also warms the ocean, causing thermal expansion, where warmer water expands in volume. This thermal expansion phenomenon contributes significantly to sea level rise.
• Ice Melting and Heat Expansion: From the 1970s until the last decade, both melting ice and thermal expansion were roughly equal contributors to observed sea level rise. However, the melting of mountain glaciers and ice sheets has accelerated in recent years.
• Accelerated Melting: Studies have shown accelerated melting rates, such as glaciers in Greenland melting five times faster than in the previous 20 years.
• Shift in Contributions: The NOAA report highlights a shift in contributions to sea level rise, with the amount due to melting nearly doubling between 2005 and 2012 compared to thermal expansion.

Impact of Sea Level Rise:

• Flooding of Coastal Areas: Sea level rise poses a significant threat to coastal areas worldwide, leading to the flooding of low-lying regions. As reported by MSI, a global risk management firm, Critical properties and road networks in coastal cities like Mumbai, Kochi, Mangalore, Chennai, Visakhapatnam, and Thiruvananthapuram are projected to be submerged by 2050.
• Impact on Island Nations: Island nations like Indonesia face even greater risks, with Indonesia announcing plans to relocate its capital from Jakarta to East Kalimantan on the island of Borneo due to flooding concerns.
• Intensification of Storm Surges: Sea level rise exacerbates the intensity of storm surges, leading to more severe flooding and damage to coastal areas during hurricanes and storms. Higher sea levels allow more water to penetrate inland during storm surges, increasing the risk to coastal communities.
• Saltwater Intrusion: Rising sea levels also result in saltwater intrusion into freshwater aquifers, compromising their quality. Freshwater aquifers are essential for agricultural and drinking purposes, and contamination by saltwater poses significant challenges to communities reliant on these resources.

Source:

https://indianexpress.com/article/explained/explained-climate/sea-level-rise-9284789/

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