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Type: Prelims Only

  • Kokrajhar-Gelephu and Banarhat-Samtse Railway Lines to Bhutan

    Why in the News?

    India and Bhutan have launched their first-ever rail links, connecting Kokrajhar–Gelephu (69 km, Assam–Bhutan) and Banarhat–Samtse (20 km, West Bengal–Bhutan).

    Kokrajhar-Gelephu and Banarhat-Samtse Railway Lines to Bhutan

    About India–Bhutan Railway Connectivity:

    • Overview: Agreements were signed during PM Modi’s visit to Bhutan (March 2024) and formalised in 2025.
    • Projects:
      1. Kokrajhar–Gelephu line: 6 stations, multiple bridges, viaducts, designed for Vande Bharat trains; expected completion in 4 years.
      2. Banarhat–Samtse line: 2 stations, major & minor bridges, flyovers, underpasses; expected completion in 3 years.
    • Both lines will be fully electrified, giving Bhutan direct access to India’s 1,50,000 km railway network, boosting passenger and goods transport.

    Significance of the Project for India:

    • Bilateral Relations: Strengthens ties with Bhutan, India’s closest neighbour and largest recipient of Indian development assistance.
    • Strategic Security: Enhances regional security and serves as a counterbalance to China’s influence in South Asia.
    • Economic Integration: Supports Bhutan’s trade (80% with India), boosts hydropower exports, and aids industrial development.
    • Tourism & Culture: Improves people-to-people exchanges, especially linking Gelephu’s Mindfulness City and Samtse’s industrial hub.
    • Act East Policy: Advances India’s policy through cross-border infrastructure in the eastern and northeastern region.
    • Rail Diplomacy: Positions Indian Railways as a strategic enabler of diplomacy and connectivity in the neighbourhood.
    [UPSC 2023] With reference to India’s projects on connectivity, consider the following statements:

    1. East-West Corridor under Golden Quadrilateral Project connects Dibrugarh and Surat.

    2. Trilateral Highway connects Moreh in Manipur and Chiang Mai in Thailand via Myanmar.

    3. Bangladesh-China-India-Myanmar Economic Corridor connects Varanasi in Uttar Pradesh with Kunming in China.

    How many of the above statements are correct?

    Options: (a) Only one (b) Only two (c) All three (d) None*

     

  • Bihar adds 2 more Wetlands to Ramsar List

    Why in the News?

    India has added two new wetlands in Bihar, Gokul Jalashay (Buxar district) and Udaipur Jheel (West Champaran district), to the global Ramsar list of Wetlands of International Importance.

    Important Facts:

    • With this, India’s Ramsar sites rise to 93, consolidating its top rank in Asia and third in the world, after the UK (176) and Mexico (144).
      • Bolivia has the largest Ramsar wetland area (Llanos de Moxos wetlands – 6.9 million ha).
    • India’s Ramsar sites have expanded from 26 in 2012 to 93 in 2025, covering 13.6 lakh hectares, with 51 sites added since 2020.
    • Globally, there are 2,544 Ramsar sites.

    Facts about the two Wetlands:

    1. Gokul Jalashay (Buxar District):

      • Oxbow lake spread over 448 hectares on the southern edge of the Ganga River.
      • Acts as a flood buffer during high water events.
      • Supports 50+ bird species and provides livelihoods through fishing, farming, and irrigation.

    2. Udaipur Jheel (West Champaran District):

      • Oxbow lake covering 319 hectares, part of the Udaipur Wildlife Sanctuary ecosystem, formed by the Gandaki River.
      • Enhances ecological connectivity and supports the Central Asian Flyway for migratory birds.

    About the Ramsar Convention:

    • Establishment: Signed on 2 February 1971 in Ramsar, Iran.
    • Objective: Provide a framework for conservation and wise use of wetlands and their resources.
    • Functions:
      • Identify and designate wetlands of international importance.
      • Promote effective management of wetlands.
      • Foster international cooperation for conservation.
    • Members: 173 countries (as of 2025).
    • India and Ramsar:
      • India joined in 1982.
      • First Ramsar site: Chilika Lake, Odisha (1981).
      • Current total: 93 sites (Sept 2025), covering 13,60,718 hectares.
      • Growth: From 26 sites in 2012 to 93 in 2025 (51 added since 2020).
      • State-wise: Tamil Nadu has the highest (20), followed by Uttar Pradesh (10).
      • About 10% of India’s total wetland area is under Ramsar listing.
    • Montreux Record: List of Ramsar sites under threat of ecological change.
      • 48 sites globally (2025).
      • 2 Indian sites included: Keoladeo National Park (Rajasthan) and Loktak Lake (Manipur).
    • World Wetlands Day: Celebrated on February 2nd every year.
      • 2025 Theme: “Protecting Wetlands for Our Common Future”.

    Criteria for Declaration (9 Criteria):

    A wetland can be declared a Ramsar site if it meets at least one of these:

    1. Has unique, rare, or representative wetland types.
    2. Supports vulnerable, endangered, or endemic species.
    3. Provides critical habitat for waterfowl, especially during migration.
    4. Contains significant ecological, botanical, zoological, limnological, or hydrological features.
    5. Supports biodiversity conservation and scientific research.
    6. Provides ecosystem services like flood control, groundwater recharge, and water purification.
    7. Has cultural, spiritual, or recreational importance.
    8. Ensures sustainable livelihoods for local communities.
    9. Faces threats requiring international cooperation for conservation.
    [UPSC 2022] Consider the following pairs:

    Wetland/Lake Location

    1. Hokera Wetland — Punjab 2. Renuka Wetland — Himachal Pradesh

    3. Rudrasagar Lake — Tripura 4. Sasthamkotta Lake — Tamil Nadu

    How many pairs given above are correctly matched?

    Options: (a) Only one pair (b) Only two pairs* (c) Only three pairs (d) All four pairs

     

  • World’s highest bridge opens to traffic in China 

    Why in the News?

    The Huajiang Grand Canyon Bridge in Guizhou province, China, is now the world’s tallest bridge, standing 625 m above the Beipan River.

    World's highest bridge opens to traffic in China 

    About Huajiang Grand Canyon Bridge:

    • Height: Rises 625 m above the Beipan River, surpassing the previous record-holder, the Beipanjiang Bridge (565 m).
    • Connectivity: Links the Liuzhi Special District and Anlong Special District, reducing travel time from 2 hours to just 2 minutes.
    • Transport Network: Part of the Guizhou S57 Expressway and the 190 km Shantian–Puxi Expressway, boosting transport, economy, and tourism.
    • Engineering Hub: Guizhou, called the “bridge museum of the world”, now has nearly half of the world’s 100 tallest bridges, showcasing China’s leadership in high-altitude civil engineering.

    Key Features of the Bridge:

    • Height Record: Deck-to-water clearance of 625 m, taller than most skyscrapers.
    • Span & Length: Total length 2,890 m, with a 1,420 m suspension span, the longest in any mountainous region globally.
    • Construction: Began January 2022, completed in just over three years; final truss installed January 2025; load-tested with 96 trucks.

  • Cold Desert named India’s 13th UNESCO Biosphere Reserve

    Why in the News?

    UNESCO added India’s Cold Desert Biosphere Reserve (CDBR) to the World Network of Biosphere Reserves (WNBR) under the Man and the Biosphere (MAB) programme.

    With this, India now has 13 UNESCO-recognized biosphere reserves out of 18 designated nationally.

    What are UNESCO Biosphere Reserves?

    • Overview: Sites integrating biodiversity conservation + cultural heritage + sustainable development.
    • Programme: MAB (1971).
    • Designation Criteria:
      • Must include a protected core zone.
      • Must represent a unique biogeographical unit.
      • Involve local communities in conservation.
      • Potential to preserve traditional lifestyles.
    • Functions: Conservation, Development, Logistic Support.
    • Global Network (WNBR): 785 sites, 142 countries (2025); 7.4 million sq. km (~5% Earth’s surface); home to 275 million people.

    About Cold Desert Biosphere Reserve (CDBR):

    • Location: Lahaul–Spiti (Himachal Pradesh), part of Trans-Himalayan biogeographic province.
    • Constituents: Includes Pin Valley National Park, Kibber Wildlife Sanctuary, Chandratal Wetland, Sarchu Plains.
    • Biodiversity:
      • Flora:  732 vascular plants, incl. 30 endemic, 47 medicinal plants (Amchi / Sowa Rigpa).
      • Fauna: Snow leopard (flagship), Tibetan wolf, Himalayan ibex, blue sheep (800+ in Spiti), Himalayan snowcock, golden eagle, bearded vulture.
    • Communities: ~12,000 people; practice yak & goat herding, barley/pea farming, Tibetan herbal medicine, Buddhist monastic councils.
    • Significance: Boosts eco-tourism, climate research, community-led conservation, sustainable livelihoods. Supports climate-resilient development in fragile ecosystems.

    cold desert biosphere reserve

    Biosphere Reserves in India:

    • Total: 18 designated, of which 13 in UNESCO-WNBR (as of 2025).
    • First: Nilgiri BR (1986); Largest: Gulf of Kachchh (Gujarat); Smallest: Dibru-Saikhowa (Assam).
    • Scheme: Launched 1986; implemented by MoEFCC under MAB Programme.
    • Three zones: Each biosphere reserve is organised into-
      1. Core zone (strictly protected),
      2. Buffer zone (limited human activity such as research, grazing, and tourism permitted), and
      3. Transition zone (sustainable human settlements and economic activities allowed).
    • Funding: 90:10 (NE & Himalayan states); 60:40 (others).
    [UPSC 2019] Which of the following are in Agasthyamala Biosphere Reserve?

    Options: (a) Neyyar, Peppara and Shendurney Wildlife Sanctuaries; and Kalakad Mundanthurai Tiger Reserve*

    (b) Mudumalai, Sathyamangalam and Wayanad Wildlife Sanctuaries; and Silent Valley National Park

    (c) Kaundinya, Gundla Brahmeswaram and Papikonda Wildlife Sanctuaries; and Mukurthi National Park

    (d) Kawal and Sri Venkateswara Wildlife Sanctuaries; and Nagarjunasagar-Srisailam Tiger Reserve

     

  • National Security Act of 1980

    Why in the News?

    Climate activist Sonam Wangchuk, leading the demand for statehood and Sixth Schedule protections for Ladakh, was detained under the National Security Act (NSA) in Leh.

    About the National Security Act, 1980:

    • Enactment: Passed on 23 September 1980; applicable across India (earlier not in Jammu & Kashmir).
    • Constitutional Basis: Rooted in Article 22(3)(b) (preventive detention permitted) and Article 22(4) (limit of 3 months unless Board approves).
    • Objective: Provides for preventive detention to safeguard defence, national security, public order, foreign relations, and essential supplies/services.
    • Grounds for Detention: Acts prejudicial to India’s defence or security, harming foreign relations, disturbing public order, endangering essential supplies, or regulating foreigners’ presence/expulsion.
    • Authorities Empowered: Centre, States, District Magistrates, and Police Commissioners (if authorised).
    • Duration: Detention up to 12 months; must communicate grounds within 5 days (extendable to 15). A person can be held 10 days without disclosure of charges.
    • Advisory Board: Composed of three persons qualified to be High Court judges. Orders reviewed within 3 weeks; if no sufficient cause exists, release is mandatory.
    • Background: Builds on colonial-era Bengal Regulation III (1818), Rowlatt Acts (1919), post-independence Preventive Detention Act (1950), and MISA (1971, repealed 1977). Reintroduced by Indira Gandhi in 1980.

    Legal Options after Arrest under NSA:

    • Representation to Government: Detainee can file a written representation challenging detention.
    • Advisory Board Review: Must be reviewed within 3 weeks; release ordered if detention unjustified.
    • Judicial Remedies: Writ petition in High Court (Art. 226) or Supreme Court (Art. 32).
    • Revocation: Centre or State may revoke detention anytime.
    • Limitations: No right to lawyer before Advisory Board; grounds may be withheld in “public interest.”
    [UPSC 2023] Consider the following statements:

    1. According to the Constitution of India, the Central Government has a duty to protect States from internal disturbances.

    2. The Constitution of India exempts the States from providing legal counsel to a person being held for preventive detention.

    3. According to the Prevention of Terrorism Act, 2002, the confession of the accused before the police cannot be used as evidence.

    How many of the above statements are correct?

    (a) Only one* (b) Only two (c) All three (d) None

     

  • India’s first space observatory AstroSat completes 10 years

    Why in the News?

    AstroSat, India’s first multi-wavelength space observatory has completed 10 years on September 28, 2025, boosting India’s role in multi-messenger astronomy.

    What is Multi-Messenger Astronomy?

    • Overview:  A modern approach that uses different cosmic messengers to study the universe, not just light.
    • Messengers:
      • Light (photons): Radio, visible, UV, X-ray, gamma rays.
      • Gravitational waves: From black hole/neutron star mergers.
      • Neutrinos: From nuclear reactions in stars.
      • Cosmic rays: Charged particles from space.
    • Insights: Light shows stellar surfaces; Gravitational waves show collisions; Neutrinos probe stellar interiors.
    • Example: 2017 neutron star collision observed with both light and gravitational waves, proving origin of heavy elements like gold.
    • AstroSat’s Role: Enabled simultaneous UV, optical, and X-ray observations, tracking flares, black holes, and neutron stars.

    What is AstroSat?

    • Overview: India’s first dedicated multi-wavelength space observatory, launched on September 28, 2015 by PSLV-C30 from Sriharikota.
    • Objective: To study celestial sources simultaneously in X-ray, ultraviolet (UV), and optical bands, unlike most single-band missions.
    • Management: Controlled by the Mission Operations Complex (MOX), ISTRAC, Bengaluru.
    • Mission Life: Designed for 5 years but operational even after 10 years.
    • Payloads:
      • UVIT (Ultra Violet Imaging Telescope).
      • LAXPC (Large Area X-ray Proportional Counter).
      • CZTI (Cadmium-Zinc-Telluride Imager).
      • SXT (Soft X-ray Telescope).
      • SSM (Scanning Sky Monitor).

    Its Accomplishments:

    • Extended Life: Surpassed design life; still generating data.
    • Black Hole Studies: Captured 500+ black hole births, advancing high-energy astrophysics.
    • Galaxy Detection: Tracked extreme UV light from a galaxy 9.3 billion light-years away, aiding early universe studies.
    • Gamma-Ray Bursts: 500+ bursts studied by CZTI.
    • Discoveries: Identified rare UV-bright Milky Way stars, thousands of times brighter than the Sun.
    [UPSC 2016] With reference to ‘Astrosat’,’ the astronomical observatory launched by India, which of the following statements is/are correct?

    1. Other than USA and Russia, India is the only country to have launched a similar observatory into space.

    2. Astrosat is a 2000 kg satellite placed in an orbit at 1650 km above the surface of the Earth.

    Select the correct answer using the code given below.

    (a) 1 only (b) 2 only (c) Both 1 and 2 (d) Neither 1 nor 2*

     

  • [pib] Who was Rani Rashmoni (1793-1861)?

    Why in the News?

    The Prime Minister has paid tribute to Rani Rashmoni on her birth anniversary on 28th September.

    Rani Rashmoni (1793-1861)

    Who was Rani Rashmoni (1793–1861)?

    • Overview: A prominent zamindar, businesswoman, philanthropist, and social reformer from 19th-century Bengal.
    • Birth: Born on 28 September 1793 in Halisahar, Bengal.
    • Marriage: Married at the age of 11 to Raja Raj Chandra Das, wealthy zamindar of Janbazar, Kolkata.
    • Leadership: Took charge of the estate and business after her husband’s death in 1836, unusual for women of her time.
    • Reputation: Revered as “Lokmata” (Mother of the People) for her courage, administration, and social commitment.

    Her Contributions:

    • Patronage: Built the Dakshineswar Kali Temple (1847–1855); appointed Sri Ramakrishna Paramahamsa as chief priest despite caste opposition.
    • Social Reforms: Opposed polygamy and child marriage; supported widow remarriage; submitted a draft bill against polygamy to the British.
    • Public Welfare & Infrastructure: Constructed major ghats on the Ganga including Babughat, Ahiritola Ghat, Nimtala Ghat. Funded roads, reservoirs, and pilgrim facilities, such as the road from Subarnarekha River to Puri.
    • Resistance to British Rule: Fought against fishing taxes on Hooghly fishermen by blocking river traffic, compelling British to abolish the tax. Defied British restrictions on Durga Puja processions, preserving traditions.
    • Support for Education & Culture: Donated to the Imperial Library (now National Library of India) and Hindu College (now Presidency University). Established schools for women and marginalized groups.
    [UPSC 2024] Consider the following statements about Raja Ram Mohan Roy:

    I. He possessed great love and respect for the traditional philosophical systems of the East.

    II. He desired his countrymen to accept the rational and scientific approach and the principle of human dignity and social equality of all men and women.

    Which of the statements given above is/are correct?

    (a) I only (b) II only (c) Both I and II* (d) Neither I nor II

     

  • Ganga River is drying faster than in 1,300 years: Report

    Why in the News?

    A recent study by researchers from IIT Gandhinagar and the University of Arizona warns that the Ganga River is drying at a rate unseen in more than a millennium.

    About Drying of the Ganga River: New Study Findings

    • Overview: Reconstructed streamflow since 700 AD using tree-ring records (Monsoon Asia Drought Atlas) and hydrological models. Validated against historic droughts and famines such as the Bengal famine.

    • Findings:

      • Between 1991 and 2020, multiple droughts lasted 4–7 years, the rarest in the past 1,300 years.
      • The 2004–2010 drought was the most severe in 1,300 years.
      • Post-1990s drying was 76% more intense than the worst 16th-century drought.

    • Causes:

      • Weaker monsoons from Indian Ocean warming and aerosol pollution.
      • Groundwater over-extraction reducing river baseflow.
      • Land-use change disrupting natural recharge.
    • Climate Models: Most fail to reproduce the drying trend, raising doubts about optimistic rainfall projections.
    • Implications: Severe threats to agriculture, 600 million livelihoods, Bay of Bengal ecosystems, and the 40% GDP share of the basin. Calls for adaptive water management.

    ganga

    About the Ganga River:

    • Length: ~2,525 km, the longest river in India.
    • Origin: Gangotri Glacier in Uttarakhand at 3,892 m elevation as Bhagirathi.
    • Formation: Named Ganga at Devprayag after meeting Bhagirathi and Alaknanda.
    • Course: Flows through Uttarakhand, Uttar Pradesh, Bihar, Jharkhand, West Bengal before entering Bangladesh as Padma and emptying into the Bay of Bengal through the Sundarbans Delta.
    • Basin: Covers about 8.61 lakh sq. km, which is 26.4% of India’s area.

    • Tributaries:

      • Left bank: Ramganga, Gomti, Ghaghara, Gandak, Burhi Gandak, Koshi, Mahananda.
      • Right bank: Yamuna, Tons, Karamnasa, Sone, Punpun, Falgu, Kiul, Chandan, Ajoy, Damodar, Rupnarayan.
    • Population: Supports over 600 million people, making it the world’s most densely populated river basin.
    • Cultural Importance: Sacred in Indian culture; declared National River in 2008.
    • Economic Role: Central to agriculture, fisheries, and trade, contributing about 40% of India’s GDP.
    • Ecological Significance: Home to snow leopard, elephants, and Ganga dolphin; includes Corbett, Dudhwa, and Sundarbans reserves.
    • Conservation Efforts: Ganga Action Plan (1985) and Namami Gange Programme (2014); persistent issues of pollution, over-extraction, and climate change.
    [UPSC 2024] With reference to the Himalayan rivers joining the Ganga downstream of Prayagraj from West to East, which one of the following sequences is correct?

    Options: (a) Ghaghara – Gomati – Gandak – Kosi

    (b) Gomati – Ghaghara – Gandak – Kosi*

    (c) Ghaghara – Gomati – Kosi – Gandak

    (d) Gomati – Ghaghara – Kosi – Gandak

     

  • Who was Ishwar Chandra Vidyasagar (1820–1891)?

    Why in the News?

    On his birth anniversary (26 September), the Union Home Minister paid tribute to the Bengali social reformer, Ishwar Chandra Vidyasagar.

    Ishwar Chandra Vidyasagar

    About Ishwar Chandra Vidyasagar:

    • Birth & Death: Born on 26 September 1820 in Birsingha, Paschim Medinipur, West Bengal; died on 29 July 1891 in Kolkata.
    • Early Life: Born into a poor priest family to Thakurdas Bandyopadhyay and Bhagavati Devi.
    • Title “Vidyasagar”: Meaning “Ocean of Knowledge,” conferred by Sanskrit College for his mastery of Sanskrit and philosophy.
    • Education: Excelled in Sanskrit grammar, Vedanta, literature, astronomy, logic; graduated with honours in 1841 from Sanskrit College, Calcutta.
    • Career: Served as Head Pandit at Fort William College, later Principal of Sanskrit College, Kolkata, and also Inspector of Schools.

    His Contributions:

    • Educational Reforms:

      • Simplified and modernised the Bengali alphabet and prose.
      • Authored “Borno Porichoy”, a primer still used to teach Bengali script.
      • Opened teacher training institutions and promoted non-Brahmin access to Sanskrit College.
      • Advocated blending traditional Indian learning with Western education.

    • Women’s Rights and Social Reform:

      • Leading advocate of Hindu widow remarriage; efforts led to the Hindu Widows’ Remarriage Act, 1856.
      • Strongly opposed child marriage and polygamy.
      • Championed raising the age of consent, influencing the Age of Consent Act, 1891.
      • Promoted women’s education, serving as secretary of the Hindu Female School (later Bethune School).

    • Philanthropy and Grassroots Work:

      • Founded schools for girls and adults in Santhal Parganas (Jharkhand).
      • Set up a free homeopathy clinic for tribals and the poor.

    • Language and Literature:

      • Regarded as the Father of Modern Bengali Prose.
      • Made Bengali prose clear, concise, and accessible to common people.
    [UPSC 2021] Who among the following was associated as Secretary with Hindu Female School which later came to be known as Bethune Female School?

    Options: (a) Annie Besant (b) Debendranath Tagore  (c) Ishwar Chandra Vidyasagar* (d) Sarojini Naidu

     

  • What are ‘Planetary Boundaries’?

    Why in the News?

    The Planetary Health Check (PHC) 2025 has warned that 7 of 9 planetary boundaries have now been breached.

    About Planetary Health Check (PHC):

    • The PHC is a global scientific assessment of Earth system health, tracking ecological thresholds that keep the planet habitable.
    • The 2025 report warns that 7 of 9 planetary boundaries have now been breached, with ocean acidification crossing the safe zone for the first time.
    • It highlights how human activities — fossil fuel combustion, deforestation, unsustainable agriculture, and industrial waste — are driving Earth beyond its safe operating space for the first time in 11,000 years.

    What are ‘Planetary Boundaries’?

    What are Planetary Boundaries?

    • Proposition: Coined in 2009 by scientists led by Johan Rockstrom.
    • What are they: Defines safe operating space for humanity by setting ecological thresholds that regulate Earth system stability and resilience.
    • Basis: Based on Holocene conditions (last ~11,000 years) that enabled human civilisation to thrive.
    • Significance: Crossing boundaries risks irreversible environmental collapse.

    • Nine Planetary Boundaries (PBs):

      1. Climate Change (CO₂ Concentration & Radiative Forcing): Safe atmospheric Carbon Dioxide (CO₂) level: 350 parts per million (ppm). Current: 423 ppm (2025); radiative forcing at +2.97 Watts per square meter (W/m²) (safe: +1.5 W/m²).
      2. Biosphere Integrity (Biodiversity Loss / Extinction Rate): Extinction rate at 100 extinctions per million species years (E/MSY) vs safe 10 E/MSY; severe biodiversity decline continues.
      3. Land System Change (Deforestation / Ecosystem Conversion): Global forest cover reduced to 59% (safe: 75%). All major terrestrial biomes breached.
      4. Freshwater Change (Streamflow & Soil Moisture Deviations): Over 20% of global land shows significant streamflow (22.6%) and soil moisture (22%) deviations beyond thresholds. Indo-Gangetic Plain & North China basins most at risk.
      5. Biogeochemical Flows (Nitrogen & Phosphorus Cycles): Excessive use of Nitrogen (N) and Phosphorus (P) in agriculture, worsening dead zones and eutrophication in water bodies.
      6. Novel Entities (Synthetic Pollutants & Plastics): Release of plastics, synthetic chemicals, and untested compounds exceeds the safe zero-threshold for environmental introduction.
      7. Ocean Acidification (Aragonite Saturation State): Surface ocean acidity has increased by 30–40% since the industrial era. Aragonite saturation state (Aragonite) at 2.84 (safe: 2.86). Threatens corals, molluscs, and plankton.
      8. Atmospheric Aerosol Loading (Aerosol Optical Depth – AOD) [Currently Safe]: Interhemispheric Aerosol Optical Depth (AOD) difference: 0.063, below safe threshold 0.10. Still harmful for health despite planetary stability.
      9. Stratospheric Ozone Depletion (Ozone Concentration in Dobson Units – DU) [Currently Safe]: Global ozone concentration stable at 285–286 Dobson Units (DU) (safe: 277 DU). Ozone hole recovery continues, though new threats flagged from rocket launches and satellite debris.
    [UPSC 2018] The term “sixth mass extinction/sixth extinction” is often mentioned in the news in the context of the discussion of:

    (a) Widespread monoculture practices in agriculture and large-scale commercial farming with indiscriminate use of chemicals.

    (b) Fears of a possible collision of a meteorite with the Earth.

    (c) Large scale cultivation of genetically modified crops.

    (d) Mankind’s over-exploitation/misuse of natural resources, fragmentation/loss of natural habitats, destruction of ecosystems, pollution and global climate change.