MAINS Current Affairs includes First-ever UN Declaration on Sea Level Rise, and India’s Coastal Vulnerability & Southwest Monsoon Ends with 12% Deficit

Environment

1. First-ever UN Declaration on Sea Level Rise, and India’s Coastal Vulnerability

Context: The United Nations General Assembly adopted the first-ever UN Declaration on Sea Level Rise, which recognises rising sea levels as an existential threat.

Status of Global Sea-Level Rise

• Sea-level rise refers to an increase in the average height of the ocean surface relative to a reference point on land or the Earth’s geocentric reference system.
• Low-lying island nations are particularly vulnerable because much of their land lies only a few metres above sea level, exposing them to coastal erosion, flooding, saltwater intrusion and the loss of habitable land.
  • In 2015, the low-lying Republic of Kiribati said that climate change effects were threatening its existence as a nation.
• Global mean sea level is rising at an accelerating rate. The WMO estimates that the rate increased from 2.1 mm per year during 1993–2002 to 4.7 mm per year during 2015–2024.

Global Mean Sea Level

• The global mean sea level is the average height of the sea surface.
• It is measured by satellites using radar altimeters, which measure the height of the sea surface.
• Tide gauges along global coastlines have also been used to measure the global mean sea level since the late 19th century.

Leading Causes of Sea Level Rise

• The global warming-driven melting of glaciers (accumulation of ice and snow that slowly flows over land) and ice sheets (glaciers which cover more than 50,000 square km of land).
• The thermal expansion of seawater, a process by which water expands as it warms up.
  • With global temperatures rising, oceans are becoming warmer, and as a result, the volume of water is increasing as well.
  • Thermal expansion of seawater is responsible for one-third to half of global sea level rise, according to the National Aeronautics and Space Administration (NASA).
• Fluctuations in land water storage: Global sea level is also affected by reservoir storage and groundwater removal.

Impacts 

• Rising sea levels. Waves and storm surges can reach further inland, accelerating the erosion of shorelines and damaging residences, roads, ports, and other infrastructure.
• Saltwater intrusion : The incursion of seawater into coastal aquifers and farmland, thus decreasing the supply of fresh water and perhaps affecting the agricultural output.
• Coastal ecosystems under jeopardy: Rising sea levels, warmer waters, and changing salinity are rapidly threatening reefs of coral, mangrove forests, tidal marshes and estuaries.
• Displacement and Migration: Groups may be compelled to migrate due to shortage of useable land creating concerns of livelihoods, land rights, citizenship and human rights.

UN Declaration on Sea-Level Rise

• The UN Declaration on Sea-Level Rise, adopted by the UN General Assembly by consensus in 2026, is the first UN-wide political framework specifically addressing the legal, humanitarian and developmental consequences of rising sea levels.
• Background: The process for the UN Declaration on Sea-Level Rise began with UN General Assembly Decision 78/558 in 2024, which called for a high-level meeting on the issue and an action-oriented declaration negotiated by consensus.
  • The 2026 high-level meeting subsequently led to the adoption of the Declaration.
• Nearly 900 million people currently live in low-lying coastal zones, while more than one billion people could face coastal hazards by 2050, highlighting the scale of the challenge.

Can a Country Retain Statehood Despite Losing Its Territory?

• Under the 1933 Montevideo Convention, a state is defined using four main criteria: a permanent population, a defined territory, a government, and the capacity to enter into relations with other states.
  • However, these criteria do not fully address the continuity of an existing state whose territory becomes uninhabitable or submerged due to sea-level rise.
• The International Law Commission (ILC), in its 2025 report, recognised the legal basis for preserving statehood, drawing on territorial integrity, self-determination, sovereign equality and legal stability.
• The 2026 UN Declaration on Sea Level Rise affirms a presumption of continued statehood, indicating that the loss of territory due to sea-level rise does not automatically result in the loss of statehood.

Implications for India

• India welcomed the UN Declaration on Sea Level and supported stable marine zones and continuity of statehood, while maintaining the notion of Common but Differentiated Responsibilities and Respective Capabilities (CBDR-RC).
  • In the face of rising sea levels, fixing maritime boundaries preserves India’s territorial seas and those of fragile island states.
  • It also strengthens India’s historic involvement with the Pacific island countries through the FIPIC (2014) and the Infrastructure for Resilient Island States (IRIS) program (2021).
• Large and Vulnerable Coastline: India has a coastline of approximately 11,098 km, along with numerous offshore islands.
  • Its coastal geography includes highly populated urban and industrial centres, deltas, estuaries, mangroves, beaches and low-lying islands.
• Importance of Island Territories: Lakshadweep in the Arabian Sea and the Andaman and Nicobar Islands in the Bay of Bengal extend India’s maritime presence and influence.
  • Stability of maritime boundaries therefore has implications for India’s EEZ, marine resources and strategic interests.
• Human Displacement: The Sundarbans illustrates the interaction between sea-level rise, coastal erosion, cyclones, salinity and human displacement.
  • Islands such as Ghoramara have experienced substantial land loss, while the disappearance of Lohachara demonstrates how erosion and inundation can permanently alter inhabited landscapes.

Policy Framework in India

• Coastal Regulation Zone Notification, 2019: It regulates development activities along India’s coastal stretches.
  • It seeks to balance coastal conservation, livelihood requirements and regulated development.
• Coastal states and Union Territories prepare Coastal Zone Management Plans (CZMPs) to regulate development according to coastal vulnerability and environmental conditions.
• The Survey of India has prepared a coastal hazard line incorporating factors such as shoreline changes and sea-level rise.
• International Engagement: India launched the Infrastructure for Resilient Island States (IRIS) initiative at COP26 in Glasgow in 2021. 
  • It seeks to support small island developing states in developing climate-resilient infrastructure.

Way Ahead

• Sea-level rise is no longer merely an environmental challenge; it is increasingly a question of human security, territorial integrity, international law and economic resilience.
• For India, the priority should be to translate this international commitment into risk-sensitive coastal planning, resilient infrastructure, ecosystem restoration, protection of vulnerable communities and a credible framework for climate-induced displacement.

Climatology

2. Southwest Monsoon Ends with 12% Deficit

Context: As per the India Meteorological Department (IMD) India’s 2026 southwest monsoon ended with 759.4 mm of rain, 12.6% below the 868.6 mm normal.

About

• This is the lowest rainfall recorded during the monsoon season since 2015.
• The east and northeast region, which recorded 1,017.1 mm of rainfall, had its driest monsoon since 1901.

Monsoon

• The monsoon is a seasonal reversal of winds because of differential heating and the resulting pressure differences between land and sea.
• Onset and Retreat: The monsoon season in India generally starts in early June and lasts until September.
  • The onset of the monsoon is marked by the arrival of the southwest monsoon winds, which bring moisture-laden air from the Indian Ocean.
  • The withdrawal or retreat of the monsoon typically begins in October.
  • The northeast monsoon, occurring from October to December, brings rainfall to parts of southern India.
    • The northeast monsoon is key for Tamil Nadu, Kerala, Puducherry, Karaikal, coastal Andhra Pradesh, Rayalaseema, and Yanam in southern India.
    • The Northeast monsoon is also known as the winter monsoon, retreating monsoon, or reverse monsoon.

Factors Affecting Indian Monsoon

• El Niño: El Niño means “Little Boy” in Spanish. It is a climate phenomenon characterized by the periodic warming of sea surface temperatures in the central and eastern equatorial Pacific Ocean.
  • During El Niño, trade winds weaken, and warm water is pushed back east, toward the west coast of the Americas, and as a result, cold water is pushed towards Asia.
• Impact of El Niño on weather patterns: It leads to a rise in global temperature, weakens the monsoon, increases the risk of wildfires, and triggers extreme weather events such as hurricanes and cyclones, particularly in the Pacific Ocean and Atlantic.
• Madden-Julian Oscillation (MJO): The MJO is a moving system of winds, clouds, and pressure that brings rain as it circles around the equator. It was discovered in 1971 by Roland Madden and Paul Julian.
  • The system travels eastward at 4–8 m/s and circles the globe typically every 30–60 days, though it can take up to 90 days.
  • As it moves, strong MJO activity often splits the planet into two parts — one in which the MJO is in active phase and brings rainfall, and the other in which it suppresses rainfall.
• During an active MJO phase, regions within its influence experience above-average rainfall, often due to increased cloud formation, convection, and cyclonic activity.
• Western Disturbance: A Western Disturbance (WD) is an extra-tropical weather system that originates outside India and moves from west to east, bringing rain, snowfall, and storms to northern parts of the Indian subcontinent.
  • Origin and Formation: Western disturbances originate over the Mediterranean region, Black Sea, or the Caspian Sea.
  • They form when cold polar air interacts with warmer, moist air, creating low-pressure systems.
  • These systems are carried eastward by westerly winds in the upper atmosphere, particularly the subtropical westerly jet stream.
• Indian Ocean Dipole: In 1999, N. H. Saji of Japan discovered an ENSO-like phenomenon in the Indian Ocean, which they named the Indian Ocean Dipole (IOD).
  • Like ENSO, IOD also has three phases—positive, negative, and neutral. During the positive phase of IOD, sea surface temperatures are warmer in the western Indian Ocean, which gives a boost to monsoon winds.
  • The reverse happens during IOD negative, and no gradient is observed during the IOD neutral period.
• Somali Jet: It is a fast-moving interhemispheric, cross-equatorial flow of air which originates near Mauritius and the northern part of Madagascar in the Southern Hemisphere. 
  • The winds cross the Equator and move along the eastern coast of Africa through Kenya, Ethiopia, and Somalia.
  • During May, the jet moves into the Arabian Sea, and by June it reaches the west coast of India.
  • As it travels, it carries a large amount of moisture (water vapour) from the ocean.
  • When the Somali Jet becomes stronger, it brings heavier and more reliable monsoon rainfall to Peninsular India.

Monsoons & the Economic Life in India

• Multiplier effect: Agricultural prosperity in India depends very much on timely and adequately distributed rainfall.
  • The success or failure of the monsoon directly shapes livelihoods at a national scale.
• Crop Diversity Advantage: Different rainfall zones allow India to cultivate a diversity of crops that few countries can match — a direct product of the monsoon’s geographic spread.

Conclusion

• The Indian monsoon isn’t just an important geographical phenomenon; it holds great economic value as well. 
  • About 64% of people in India depend on agriculture for their livelihoods, and agriculture itself is dependent on the southwest monsoon.
• A good monsoon raises agricultural production, aids GDP growth, and drives up rural earnings and consumption. Thus, it has been called the lifeline of the Indian economy.

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