Why in News

• Over 2,000 people from the Bodo, Garo, Khasi and Rabha communities rallied at Ukiam against a 55-MW hydropower-cum-irrigation project planned jointly by Assam and Meghalaya on the Kulsi river.

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• Three traditional chiefs, of Nongkhlaw, Nongmynsaw and Rambrai, said they will not issue the no-objection certificates that are required for projects on Meghalaya land.
• The dam site lies near Borduar and Langpih, two of the six disputed border sectors.

About Kulsi River

• The Kulsi is formed by the confluence of the Dron, Shree and Dilma rivers, which rise in the Meghalaya hills.
• It is a left-bank (south-bank) tributary of the Brahmaputra and flows through Assam’s Kamrup district.
• It is a natural habitat of the endangered Gangetic river dolphin.

About Gangetic River Dolphin

• Its scientific name is Platanista gangetica, and it has been India’s National Aquatic Animal since 2009.
• It is listed as Endangered by the IUCN and placed in Schedule I of the Wildlife (Protection) Act, 1972.
• The dolphin is nearly blind and navigates by echolocation.
• Project Dolphin was announced in 2020 for its conservation.

About Assam–Meghalaya Boundary Dispute

• Meghalaya was carved out of Assam in 1972, which left 12 areas of difference along the border.
• A March 2022 MoU settled six of these areas. The remaining six, including Langpih and Borduar, are still pending.

Mains Angle

• The project shows the tension between hydropower development and the protection of river ecosystems that host endangered species.
• The chiefs’ refusal highlights the importance of free, prior and informed consent in tribal areas.
• Communities long divided by the border dispute are now united by a shared ecological concern.

Why in News

• 32 merchant ships with Indian crew have been attacked in the Black Sea this year amid the Russia–Ukraine conflict.

About Black Sea

• The Black Sea is an inland sea between Eastern Europe and Western Asia. It is bordered by Ukraine, Russia, Georgia, Turkey, Bulgaria and Romania.
• It connects to the Mediterranean through the Bosphorus, the Sea of Marmara and the Dardanelles, which are together called the Turkish Straits.
• The Kerch Strait links it to the Sea of Azov, which lies between Crimea and mainland Russia.
• Major rivers draining into it include the Danube, Dnieper, Dniester and Southern Bug. The Don and Kuban flow into the Sea of Azov.
• Its waters have low salinity because of heavy river inflow. Below about 150–200 m, the water is anoxic and rich in hydrogen sulphide, which makes the Black Sea the world’s largest body of anoxic water.
• The Crimean Peninsula juts into its northern part. Its port of Sevastopol is the base of Russia’s Black Sea Fleet.
• Key ports include Odesa and Izmail (Ukraine), Novorossiysk and Sochi (Russia), Constanța (Romania), Varna (Bulgaria), Batumi (Georgia) and Samsun (Turkey).
• Snake Island, a small Ukrainian island near the Danube delta, has been a flashpoint in the Russia–Ukraine conflict.

Why in News

• Agencies are tracking a possible “super” El Niño, with eastern Pacific waters about 2°C warmer than average. Unlike the rest of India, Tamil Nadu may see heavier northeast monsoon rain.

More on the News

• The IMD forecasts normal to above-normal rain over southern Tamil Nadu, with a neutral IOD. The southern Bay of Bengal is about 1°C warmer than usual.
• In 2015, an El Niño year, Chennai recorded 1,522 mm of rain in just four days in December.

About El Niño Southern Oscillation (ENSO)

• ENSO is a Pacific climate cycle that recurs every two to seven years, with El Niño (warm), La Niña (cool) and neutral phases.
• In normal years, trade winds push warm water west towards Indonesia, and cold water upwells off Peru through the Humboldt Current.
• During El Niño, the trade winds weaken, warm water shifts east, and upwelling off Peru is suppressed.
• The Southern Oscillation is a pressure see-saw between Tahiti and Darwin, measured by the SOI, which turns negative during El Niño.
• El Niño weakens the Walker Circulation, which brings dry, sinking air and usually deficient rain over India.
• An El Niño is declared when the Niño 3.4 anomaly stays at or above +0.5°C. An anomaly of about +2°C marks a “super” El Niño.
• In El Niño Modoki, warming peaks in the central Pacific.

About Indian Ocean Dipole (IOD)

• The IOD is a sea temperature difference between the western and eastern equatorial Indian Ocean. It is also called the “Indian Niño”, and it was identified in 1999.
• In a positive IOD, the western part near Africa is warmer than the eastern part near Indonesia. A negative IOD is the reverse.
• A positive IOD generally strengthens the Indian monsoon and can offset El Niño, as it did in 1997. A negative IOD generally weakens the monsoon.
• The IOD usually peaks in September–November.

About Tamil Nadu’s Exception

• In strong El Niño years, a pressure difference between the Bay of Bengal and the Arabian Sea creates a “wind tunnel” effect that drives moist air into coastal Tamil Nadu.
• Warmer Bay waters increase evaporation, and cyclonic circulations in November–December release this heat as intense rain.
• Tamil Nadu receives nearly half of its annual rainfall from the northeast monsoon, between October and December.

Mains Angle

• Global climate drivers affect Indian regions differently, so a single national forecast can mislead regional planning.
• A warming Bay of Bengal raises the risk of extreme rain and cyclones on the Tamil Nadu coast.
• Sustained ocean observation, such as the new OceanEye initiative, is vital for early warning.

Why in News

• The 2026 science Nobels went to Henri Kagan and Kenso Soai (Chemistry), Karl Deisseroth, Peter Hegemann and Georg Nagel (Medicine) and Francis Halzen (Physics).

About Chirality (Chemistry Nobel)

• Chirality means a molecule cannot be superimposed on its mirror image. The two mirror forms are called enantiomers.
• Life uses only one form: amino acids are left-handed (L) and the sugars in DNA are right-handed (D).
• Kagan and Soai showed that a small excess of one form can be amplified to make very pure products, which is useful for safer drugs.

About Optogenetics (Medicine Nobel)

• Optogenetics uses light to switch specific nerve cells on or off.
• It relies on channelrhodopsin, a light-sensitive protein from algae that responds to blue light.
• It helps scientists study brain disorders such as Alzheimer’s, addiction and depression.

About IceCube and Neutrinos (Physics Nobel)

• Neutrinos are tiny particles with no charge and almost no mass, and they rarely interact with matter.
• IceCube, in Antarctica, uses 5,160 sensors buried deep in about a cubic kilometre of ice to detect them.
• The sensors catch Cherenkov radiation, a faint blue glow produced when a neutrino strikes an atom in the ice.