THE CONTEXT: Global sea levels are rising at an unprecedented rate, posing significant threats to low-lying islands and coastal communities worldwide. This phenomenon is primarily driven by global warming, which causes ice sheets to melt and ocean waters to expand.
CURRENT SEA LEVEL RISE
- Global sea levels have risen more than 20 cm (over 8 inches) since records began in 1880.
- The rise in sea level is accelerating with each decade.
- In 2023, global mean sea levels hit a record high, according to the World Meteorological Organization.
- In some areas of the southwestern Pacific, sea levels have risen close to twice the global rate since 1993.
RATE OF INCREASE
- Sea levels are rising faster now than at any point in the last 3,000 years.
- Global sea levels have risen by over 10 cm between 1993 and 2024, according to NASA.
- The current rate of increase is about 3.9 mm (0.15 inches) per year.
CAUSES OF SEA LEVEL RISE
Sea level rise is a significant consequence of climate change, primarily driven by human-induced global warming.
- Thermal Expansion: As the ocean absorbs heat from the atmosphere, water expands, leading to rising sea levels. This process, known as thermal expansion, directly results from global warming.
- Melting Ice Sheets and Glaciers: The melting of ice sheets in Greenland and Antarctica and mountain glaciers worldwide contributes significantly to sea level rise. Approximately 150 billion tons of ice mass are lost annually from Antarctica and 270 billion tons from Greenland.
- Changes in Land Water Storage: Human activities such as groundwater extraction can alter land water storage, increasing ocean water volume. This, along with natural processes, contributes to sea level rise.
- Greenhouse Gas Emissions: Fossil fuel burning releases carbon dioxide (CO2) and methane (CH4), which are potent greenhouse gases contributing to global warming. Methane is particularly effective at trapping heat, being over 80 times more potent than CO2 over 20 years.
- Climate Tipping Points: Rising temperatures could trigger climate tipping points, such as the irreversible collapse of ice sheets in Greenland and West Antarctica, drastically accelerating sea level rise.
REGIONAL VARIATIONS IN SEA LEVEL RISE
- Southwestern Pacific: Since 1993, this region has experienced sea level rise at nearly twice the global average. This is due to natural variability in ocean currents and winds, which affect heat distribution in the ocean.
- Tropical Regions in Asia: Countries like Bangladesh, India, and China are particularly vulnerable due to their geographical location and high population density in low-elevation zones. River deltas in these regions are especially at risk.
- Low-lying Islands: Islands such as Fiji, the Maldives, and Tuvalu face existential threats from even moderate sea level rises. Their geographical features make them particularly susceptible to flooding and erosion.
- Coastal Cities: Due to their coastal locations, major cities like Cairo, Lagos, Los Angeles, Mumbai, Buenos Aires, and London are expected to experience significant impacts. These areas are already dealing with issues like coastal erosion and saltwater intrusion.
- North America: In the United States, projections suggest that sea levels could rise significantly by 2100 depending on greenhouse gas emission pathways. Coastal areas will face challenges related to infrastructure and population displacement.
- Polar Regions: The melting of ice sheets in Greenland and Antarctica contributes significantly to the rise of the global sea level. Due to rising temperatures, these regions are losing ice mass at an accelerating rate.
FUTURE PROJECTIONS OF SEA LEVEL RISE
- IPCC Projections: The Intergovernmental Panel on Climate Change (IPCC) projects a global sea level rise of 0.6 to 1.1 meters by 2100 if greenhouse gas emissions remain high (RCP8.5 scenario) . If emissions are significantly reduced (RCP2.6 scenario), the rise will be between 0.3 to 0.6 meters.
- High-End Estimates: Recent assessments suggest that the global mean sea level could rise by up to 1.3-1.6 meters by 2100 under robust warming scenarios. In the worst-case scenario involving rapid ice sheet collapse, sea levels could rise as much as 2 meters by the end of the century.
- Long-Term Projections: Under worst-case scenarios, sea levels could rise to 5 meters by 2300 if emissions remain unchecked. In contrast, fulfilling the Paris Agreement targets could limit the rise to approximately 2.2-2.5 meters by 2300.
GLOBAL IMPLICATIONS
- Nearly 40% of the world’s population lives near coastlines, making a significant portion of humanity vulnerable to rising seas.
- Sea level rise threatens critical infrastructure, agriculture, freshwater supplies, and human settlements worldwide.
- Adaptation measures are essential but require substantial financial support from wealthier nations to be effective in developing regions.
ADAPTATION AND MITIGATION STRATEGIES FOR SEA LEVEL RISE
ADAPTATION STRATEGIES
- Sea Walls and Storm Surge Barriers: Coastal cities are constructing sea walls to protect against rising sea levels and storm surges. For example, the Netherlands has implemented extensive dike systems to manage water levels.
- Flood-Resistant Buildings: In areas prone to flooding, buildings are being designed or retrofitted to withstand water ingress, such as elevating structures on stilts or using water-resistant materials.
- Mangrove Restoration: Countries like Cameroon are regenerating mangrove forests, which act as natural barriers against coastal erosion and storm surges.
- Beach Nourishment: Some regions add sand to eroding beaches to maintain their width and protect inland areas from rising seas.
- Village Relocation: In Fiji, entire villages are being moved to higher ground to escape the threat of rising seas.
- Floating Cities: The Maldives is exploring floating cities as a long-term adaptation strategy.
- Local Engagement: Communities plan and implement adaptation measures, ensuring that strategies are culturally appropriate and locally supported.
MITIGATION STRATEGIES
- Transition to Renewable Energy: Shifting from fossil fuels to renewable energy sources like solar and wind is crucial to reducing emissions that contribute to global warming.
- Energy Efficiency Improvements: Enhancing energy efficiency in the industrial, residential, and transportation sectors can significantly reduce emissions.
- Afforestation and Reforestation: Planting trees can help absorb carbon dioxide from the atmosphere, mitigating the effects of climate change.
- Soil Carbon Management: Practices such as no-till farming can increase carbon storage in soils, reducing atmospheric CO2 levels.
- Paris Agreement Compliance: Achieving the targets set by international agreements like the Paris Agreement can limit global temperature and slow sea level rise.
- National Policies: Countries are developing policies to reduce emissions and promote sustainable practices across various sectors.
- Carbon Capture and Storage (CCS): Technologies that capture and store CO2 emissions from industrial processes underground are being developed to reduce atmospheric carbon levels.
- Geoengineering Research: Investigating methods like solar radiation management to reflect sunlight away from Earth could potentially mitigate warming effects.
THE CONCLUSION:
Reducing greenhouse gas emissions and implementing adaptive measures are crucial to mitigating the impacts of rising sea levels. Despite these efforts, some level of sea rise is inevitable, necessitating global cooperation and financial support for vulnerable regions.
UPSC PAST YEAR QUESTIONS:
Q.1 Explain the causes and effects of coastal erosion in India. What are the available coastal management techniques for combating the hazard? 2022
Q.2 How do the melting of the Arctic ice and glaciers of the Antarctic differently affect the weather patterns and human activities on the Earth? Explain. 2021
Q.3 How will the melting of Himalayan glaciers have a far-reaching impact on India’s water resources? 2020
MAINS PRACTICE QUESTION:
Q.1 Discuss the global causes and consequences of rising sea levels. What measures can be implemented to mitigate the impacts on vulnerable regions?
SOURCE:
https://indianexpress.com/article/explained/explained-climate/sea-levels-rising-9591199/lite/
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