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Subject: Climate Change

1. Global Warming and Issues
2. All about Pollution

  • India is focusing on PM10 but PM 2.5 is the real threat

    Introduction

    Air pollution in India is no longer episodic or seasonal; it is a structural public health emergency. While global best practices increasingly rely on health-based air quality standards, India’s regulatory architecture continues to emphasise coarser particulate matter (PM10) due to administrative convenience and visible enforcement outcomes. This regulatory bias weakens India’s ability to reduce disease burden, undermines scientific policymaking, and distorts progress assessment under the National Clean Air Programme (NCAP).

    Why in the News?

    A new comparative study by the Sustainable Futures Collaborative (SFC) highlights that India’s air pollution control framework remains disproportionately focused on PM10, while PM2.5, responsible for deeper health damage. remains inadequately addressed. The report is significant because it systematically contrasts India’s regulatory pathway with countries such as China, Mexico, Brazil, Poland, South Korea, and Germany, revealing a structural mismatch between India’s monitoring priorities and the actual toxicity of pollutants. 

    The Scientific Hierarchy of Harm in Particulate Matter

    1. PM2.5 Toxicity: Penetrates deep into the lungs and bloodstream, causing cardiovascular and respiratory diseases.
    2. PM10 Characteristics: Larger particles with lower systemic penetration and comparatively lesser health impact.
    3. Policy Mismatch: Regulatory attention remains fixed on PM10 despite PM2.5 being the primary health risk.
    4. Outcome: Misalignment between pollution control metrics and actual disease burden.

    Regulatory Bias Towards PM10 in India

    1. Monitoring Focus: NCAP progress is measured primarily through PM10 reductions.
    2. Administrative Ease: PM10 reductions are easier to demonstrate through visible actions like road sweeping and construction controls.
    3. Institutional Incentives: City authorities prefer pollutants that show quicker compliance outcomes.
    4. Policy Consequence: PM2.5 mitigation receives limited planning, funding, and enforcement priority.

    Geography and Urban Form as Pollution Amplifiers

    1. Delhi’s Topography: Located on a plateau surrounded by mountains, restricting pollutant dispersion.
    2. Atmospheric Stagnation: Winter inversion traps pollutants close to the ground.
    3. Regional Inflows: Pollutants from surrounding regions add to local emissions.
    4. Result: Structural accumulation of PM2.5 beyond city-level control measures.

    International Regulatory Pathways Compared

    1. China: Transitioned from PM10 to PM2.5 standards after public health pressure; implemented national emission standards and fuel quality upgrades.
    2. Mexico: Introduced health-based air quality standards following judicial and civil society intervention.
    3. Poland: Adopted EU emission norms after civil resistance and local political change.
    4. Common Feature: Strong national regulation, judicial pressure, and health-based standards.
    5. Indian Contrast: Fragmented authority, weak enforcement, and delayed regulatory evolution.

    Institutional Capacity Constraints in India

    1. State Pollution Control Boards (SPCBs): Resource-poor and understaffed.
    2. Monitoring Load: Engineers responsible for air, water, and waste compliance simultaneously.
    3. Outsourcing Dependence: Compliance monitoring outsourced to private agencies, creating conflicts of interest.
    4. Regulatory Gap: Limited accountability and weak on-ground enforcement.

    Monitoring Deficit and Data Blindness

    1. Ground Monitoring: Insufficient real-time PM2.5 monitoring infrastructure.
    2. Compliance Illusion: Cities meet PM10 reduction targets while PM2.5 levels remain hazardous.
    3. NCAP Limitation: PM2.5 reduction not central to non-attainment city evaluation.
    4. Outcome: Policy success measured through incomplete indicators.

    Policy Instruments and Their Limitations

    1. Smog Guns: Symbolic interventions with minimal impact on PM2.5.
    2. Construction Controls: Effective for PM10, marginal for PM2.5.
    3. Road Dust Management: Visibility-driven policy with limited health outcomes.
    4. Structural Failure: Absence of emission source targeting for fine particulates.

    Conclusion

    India’s air pollution strategy suffers not from lack of intent, but from misaligned priorities and weak institutional design. By privileging PM10 over PM2.5, policymakers risk managing visibility rather than mortality. Without a decisive shift towards health-based air quality standards, strengthened monitoring capacity, and PM2.5-centric regulation, India’s pollution control efforts will continue to underperform despite visible compliance gains.

    PYQ Relevance

    [UPSC 2021] Describe the key point of the revised Global Air Quality Guidelines [AQGs] recently released by the World Health Organisation [WHO].How are these different from its last update in 2005? What changes in India’s National Clean Air Programme are required to achieve these revised standards ?

    Linkage: This PYQ directly aligns with the article’s core argument that India’s NCAP remains PM10-centric, whereas WHO AQGs prioritise PM2.5 due to higher health risks. The article provides analytical grounding to argue why India’s air quality framework requires a shift to health-based PM2.5 standards rather than visibility-based PM10 compliance.

  • Gallbladder Cancer in the Gangetic Belt 

    Why in the News

    • New analysis calls gallbladder cancer (GBC) an “invisible epidemic” in India’s Gangetic belt, especially among women.
    • Despite high prevalence, GBC is not a national health priority, poorly monitored, and driven by environmental pollution.

    Key Highlights

    1. High-Burden Geography

    • India accounts for ~10% of global GBC cases.
    • Highest incidence in Uttar Pradesh, Bihar, West Bengal, Assam.

    2. Environmental Drivers

    • Arsenic, cadmium, lead contamination in groundwater.
    • Industrial effluent discharge into rivers.
    • Pesticide residues, adulterated oils, contaminated fish.
    • Chronic exposure through water, food, soil.

    3. Gendered Impact

    • ~70% of GBC patients are women.
    • Factors contributing:
      • Reuse of cooking oil
      • Consumption of unrefrigerated food
      • High exposure to contaminated water during domestic chores
    • 80%+ diagnosed at Stage III/IV, when surgery is not viable.

    4. Socio-Economic Burden

    • Treatment costs ₹8–12 lakh → debt, treatment abandonment.
    • Hotspots overlap with districts having high poverty and poor sanitation.

    5. Governance Failures

    • Cancer registries cover only 10% of the population → clusters remain invisible.
    • Weak enforcement of pollution laws.
    • No mandatory cancer reporting.
    Which of the following can be found as pollutants in the drinking water in some parts of India? (2013)

    (1). Arsenic 

    (2). Sorbitol 

    (3). Fluoride 

    (4). Formaldehyde 

    (5). Uranium 

    Select the correct answer using the codes given below. 

    (a) 1 and 3 only (b) 2, 4 and 5 only (c) 1, 3 and 5 only (d) 1, 2, 3, 4 and 5

  • UNEA-7: Rift Over UNEP’s Medium-Term Strategy and Funding Crunch

    Why in the news?

    The seventh UN Environment Assembly (UNEA-7) begins in Nairobi amid deep divisions over the UN Environment Programme’s (UNEP) Medium-Term Strategy (MTS) 2026–2030 and a significant decline in core funding. The MTS acts as UNEP’s operational mandate guiding global work on climate, biodiversity, pollution and land restoration.

    UPSC Prelims Pointers

    About UNEP

    • Headquarters: Nairobi, Kenya
    • Established: 1972 (Stockholm Conference outcome)
    • Governing body: UN Environment Assembly (UNEA)
    • Works on: climate, biodiversity, pollution, land, chemicals, resource efficiency, environmental governance.

    About UNEA

    • Meets biennially.
    • World’s highest-level decision-making body on environment.
    • Each member state of the UN has one vote.

    UNEP’s Environment Fund (EF)

    • Voluntary, but based on an indicative scale of contributions.
    • Provides core, unearmarked funding.
    • Decline in EF impacts UNEP’s operational independence.

    Medium-Term Strategy (MTS)

    • 5-year framework guiding programmatic priorities.
    • Needed for budget approval.
    • Current debate concerns the 2026–2030 MTS text.

    Triple Planetary Crisis

    • Climate change
    • Biodiversity loss
    • Pollution and waste

    Plastics Treaty Process

    • Negotiated under the Intergovernmental Negotiating Committee (INC).
    • UNEP serves as secretariat, but mandate expansion is contested.
    Which one of the following is associated with the issue of control and phasing out of the use of ozone-depleting substances? (2015)

    (a) Bretton Woods Conference 

    (b) Montreal Protocol 

    (c) Kyoto Protocol 

    (d) Nagoya Protocol

  • Why pollution affects north Indian cities more than south and west

    Introduction

    Over 2015-2025, no northern Indian city recorded “safe” air quality even once, with Delhi emerging as the most polluted city. In contrast, cities in the south and west maintained comparatively better AQI levels. This consistent divergence reflects entrenched geographical, meteorological, and structural constraints that trap pollutants in the Indo-Gangetic Plain while aiding dispersion along the coasts.

    Why in the news

    A new assessment titled Air Quality Assessment of Major Indian Cities (2015-2025) reported that Delhi continues to be the most polluted city, with AQI stagnating at unhealthy levels. The study shows sharp regional contrasts, revealing that only southern and western cities showed sustained air quality improvements, making this a significant environmental governance concern.

    Persistent Regional Air Quality Divide

    Why northern cities remain severely polluted

    1. Consistent high pollution: Northern cities experienced prolonged severe pollution episodes across the decade.
    2. Limited “healthy days”: None recorded AQI within safe thresholds in 2025.
    3. Stagnant improvement: Even when AQI dipped (e.g., 2019), levels remained far above healthy limits.

    How southern and western cities compare

    1. Cleaner AQI bands: Chennai, Chandigarh, Visakhapatnam, and Mumbai maintained AQI between 80-140.
    2. Steady progress: These cities displayed clear improvements between 2015-2025.
    3. Best performer: Bengaluru recorded the best AQI among all 11 cities.

    Why Delhi Emerges as the Worst Performer

    Data trends

    1. Peak AQI: Delhi saw its worst AQI in 2016 (over 250).
    2. Temporary dips: AQI improved in 2019 but did not meet healthy standards.
    3. Current status: AQI stagnated at 180.5 in 2025, indicating persistent failure to achieve safe limits.

    Structural challenges

    1. Urban surface roughness: Dense built-up surfaces inhibit wind flows and pollutant dispersion.
    2. Trapping effect: Reduced ventilation leads to prolonged retention of pollutants.

    Why Secondary Northern Cities Remain Highly Polluted

    Cities in focus: Lucknow, Varanasi, Ahmedabad, and Pune showed:

    1. Prolonged elevated AQI: Frequent high pollution days with slow improvement.
    2. Mixed progress: Improvements after 2019, but still above healthy limits.
    3. Heavy pollutant load: Emissions + weak dispersion exacerbate poor quality.

    Why Southern & Western Cities Perform Better

    1. Favourable winds: Sea breezes in coastal cities aid pollutant dispersal.
    2. Better atmospheric ventilation: Stronger monsoon winds and less winter stagnation.
    3. Urban characteristics: Less surface roughness compared to Delhi’s dense built-up terrain.

    Outcome

    1. Improved AQI stability
    2. Lower incidence of sharp pollution spikes

    Geography and Winter Inversion: The Deciding Factors

    Geographical lock-in

    1. Indo-Gangetic Basin: Landlocked region bounded by the Himalayas prevents outflow of pollutants.
    2. Pollutant entrapment: Cold northern boundary and flat terrain acts like a “pollution bowl”.

    Winter inversion

    1. Temperature inversion effect: Warm air traps cold, dense air near the surface and this leads to pollutants settling close to ground level.
    2. Seasonal peak: December-February shows intensified pollution due to reduced boundary layer height.

    Built environment factor

    1. Surface roughness: Urban canyons in Delhi slow wind speed, increasing stagnation.

    Seasonal Wind Patterns and Air Dispersion

    Why southern/western cities improve during monsoon

    1. Strong monsoon flows disperse pollutants effectively.
    2. Regular ventilation cycles prevent accumulation.

    Why northern cities worsen in winter

    1. Weak westerly winds
    2. Lower atmospheric mixing height
    3. Persistent fog, cold air trapping, and stagnation

    Conclusion

    The decade-long air quality analysis underscores a structural, region-specific pollution challenge rooted in geography, climate, and urban form. Northern cities, especially those in the Indo-Gangetic Basin, remain trapped in severe winter pollution cycles, while southern and western cities benefit from favourable winds and dispersion conditions. Any meaningful pollution mitigation strategy must therefore be region-sensitive and climatologically informed.

    PYQ Relevance

    [UPSC 2021] Describe the key points of the revised Global Air Quality Guidelines (AQGs) released by the World Health Organisation (WHO). How are these different from its last update in 2005? What changes in India’s National Clean Air Programme are required to achieve these revised standards?

    Linkage: This topic is important for UPSC as it highlights India’s deep regional air-quality disparities and the structural limits of current pollution-control policies. It links directly to GS-3 themes of air pollution, WHO AQGs, NCAP reforms, and the recurring winter inversion-driven smog episodes in north Indian cities.

  • SC ruling on post-facto clearances sets environmental law back by decades

    Introduction

    The Environmental Impact Assessment (EIA) is a preventive system requiring environmental clearance before a project begins. In 2025, the Supreme Court’s Vanashakti judgment banned all post-facto clearances as unconstitutional. In a new 2:1 ruling, the Court has now recalled that decision, warning that continuing the ban would cause “devastating” consequences and jeopardise major public investments. This marks a clear shift away from earlier strictures on environmental approvals.

    Why in the news?

    The Supreme Court’s recent endorsement of post-facto environmental clearances marks a sharp break from earlier rulings where such permissions were held illegal. For the first time, industries operating without prior approval may regularise their violations by paying penalties. This undermines the preventive purpose of Environmental Impact Assessments (EIAs), weakens compliance in a country already facing severe pollution challenges. The ruling enables violators to bypass mandatory safeguards like public hearings and ecological assessments, allowing large-scale industries to operate first and seek approval later.

    Understanding Ex Post Facto Environmental Clearances

    Meaning and Basic Idea

    • Retrospective approvals: Permissions granted after a project has already started construction, expansion, or operation without the mandatory prior Environmental Clearance (EC).
    • Departure from preventive logic: Converts a forward-looking safeguard into a mechanism to regularise completed violations.

    Intended Purpose: Rare exceptions: Initially justified only for unusual situations where procedural lapses occurred without deliberate violation.

    Actual Use: Regularisation tool: Gradually used to “legalise” ongoing or completed activities that had bypassed due environmental scrutiny.

    Legal Context

    1. EPA, 1986 as foundation: The Environment (Protection) Act establishes prior approval as the norm for activities affecting the environment.
    2. EIA 1994 & 2006 notifications: Both frameworks emphasise that major projects, industrial, mining, construction, must undergo assessment before commencement.

    Supreme Court’s Stand in the Vanashakti Judgment (2025)

    Key Findings

    1. Invalidation of government provisions: Struck down specific notifications and office memoranda that enabled retrospective clearances.
    2. Violation of environmental principles: Held that such clearances contradict the precautionary principle, which seeks to prevent harm at the outset.

    Judicial Observations

    1. Labelled as serious illegality: The Court stated that post-facto approvals erode environmental rule of law.
    2. Restriction on future permissions: Directed that no further mechanisms be created to enable or replicate retrospective ECs. 

    How Does the Ruling Change India’s Environmental Safeguards?

    1. Shift from Prevention to Regularisation: India’s environmental law is built on prior approval, but the ruling legitimises post-violation approvals. This weakens deterrence and changes the core architecture of environmental governance.
    2. Dilution of Public Hearings: Many industrial activities will now bypass public consultations, one of the most important safeguards under the EIA process.
    3. Weakening of the No-Fault Liability Principle: Earlier, industries operating without clearance faced closure; now they may continue operating after paying monetary penalties.
    4. Increased Environmental Risk: Projects threatening forests, rivers, and air quality gain legal pathways to operate retrospectively, exacerbating existing ecological crises.

    How Has Policy Drift in Recent Years Enabled Post-Facto Approvals?

    1. Draft EIA Notification 2020: Attempted to institutionalise post-facto approvals and reduce public participation, an approach the ruling now indirectly validates.
    2. Forest Conservation Act Amendments (2023): Redefined “forests” to exclude large tracts of land, enabling diversion without scrutiny and bypassing earlier safeguards.
    3. Coastal Regulation Zone (CRZ) Dilution (2018): Relaxed no-development zones and allowed extensive construction in vulnerable coastal areas.
    4. Expansion of Exemptions: Over 45 industrial categories have been exempted from prior clearances in the past decade.
    5. Legalisation of Violations: Historical decisions like TN Godavaraman protected forests strictly, but recent changes enable easier diversion and commercial use.

    Why Is the Ruling Especially Concerning for India’s Current Environmental Crisis?

    1. Extreme Pollution Levels: With 83 of the world’s 100 most polluted cities in India, any weakening of safeguards directly harms public health.
    2. Children’s Health Impact: Delhi’s children lose up to 10 years of lung function, highlighting the urgency of strict compliance.
    3. Carcinogenic Exposure: Farmers in Punjab and Haryana inhale toxic particulates every winter, worsening respiratory health.
    4. Hospital Overload: Urban hospitals deal with chronic respiratory disease surges every winter.
    5. Climate-Driven Disasters: Cyclones, erosion, and floods already strain ecosystems; weaker laws increase vulnerability.

    How Does the Ruling Affect Democratic Accountability?

    1. Reduced Public Participation: By enabling post-facto approvals, the ruling sidelines communities, especially those in pollution-affected regions.
    2. Bypassing Transparency: Industries may avoid public hearings and statutory scrutiny.
    3. Weakening of Citizen Rights: The apex court’s earlier stance held the environment as part of Article 21’s right to life; this shift undermines that framework.
    4. Centralisation of Power: State-level mechanisms become redundant if industries secure clearances retrospectively.

    What Long-Term Risks Does the Judgment Create?

    1. Systematic Legal Erosion: A decade-long pattern of exempting industries and diluting norms is now legitimised judicially.
    2. Encouragement of Violations: Industries may prefer paying a penalty over compliance, cheaper and faster.
    3. Increased Ecological Degradation: Forests, rivers, coasts, and air quality may deteriorate further due to weakened oversight.
    4. Regulatory Capture: Industries gain disproportionate influence over environmental decision-making.
    5. Undermining Global Climate Commitments: India’s commitments under the Paris Agreement require stronger, not weaker, compliance frameworks.

    Conclusion

    The Supreme Court’s endorsement of post-facto clearances marks a turning point in India’s environmental jurisprudence. While the ruling attempts to balance economic development and compliance, it risks normalising illegality and weakening safeguards that exist to protect public health, ecological integrity, and constitutional rights. At a time of worsening pollution and climate vulnerability, India needs stronger, not diluted, environmental governance.

    PYQ Relevance

    [UPSC 2014] What role do environmental NGOs and activists play in influencing Environmental Impact Assessment (EIA) outcomes for major projects in India? Cite four examples with all important details.

    Linkage: With post-facto clearances weakening formal EIA safeguards, NGOs become vital watchdogs ensuring accountability. This topic links directly to environmental governance, EIA dilution, and current judicial-policy debates.

  • How Delhi’s air quality monitors work and why their readings can falter

    INTRODUCTION

    Delhi operates a dense network of 40 Continuous Ambient Air Quality Monitoring Stations (CAAQMS) that serve as automated laboratories tracking eight key pollutants. These stations guide the daily AQI, enable pollution-control measures and emergency responses, and form the backbone of environmental governance. However, recent judicial scrutiny and scientific studies highlight significant gaps in equipment suitability, calibration, meteorological sensitivity, and data reliability, creating a critical governance challenge.

    WHY IN THE NEWS 

    The Supreme Court recently demanded clarity on whether Delhi’s air-quality monitoring equipment is suited to city-specific pollution and meteorological conditions. This scrutiny is significant because Delhi heavily depends on AQI data for health advisories and regulatory actions, yet multiple stations fail to generate adequate, validated data on many days. A CAG report and recent scientific studies show systematic errors, including 30-40% overestimation of PM2.5 under high humidity, raising concerns about the credibility of pollution data itself.

    How Delhi’s Air Quality Monitoring System Functions

    1. CAAQMS Network: Operates 40 automated, temperature-controlled stations functioning as compact laboratories across different city zones.
    2. Regulatory Basis: Functions under CPCB’s 2012 guidelines, which define calibration steps, quality-control procedures, and uniform monitoring standards.
    3. Pollutant Coverage: Tracks eight pollutants, PM2.5, PM10, NO₂, SO₂, CO, O₃, NH₃, Pb, ensuring representative citywide measurement.
    4. Instrumentation Setup: Stations contain racks of analysers, pumps, and data loggers, with sampling inlets mounted on masts above the roof to capture ambient air.

    How Pollutants Are Measured Inside the Stations

    1. Beta Attenuation Monitors (BAM): Use beta ray attenuation to measure particulate concentration by assessing signal weakening through collected particulate mass.
    2. Gaseous Pollutant Monitors: Use optical and chemiluminescent methods, depending on pollutant type, to detect gas behaviour under specific wavelengths.
    3. National Standards: Measurements follow NAAQS procedures, including “gravimetric, wet-chemical and automatic instrument-based techniques” ensuring comparable data across India.

    Factors That Distort or Corrupt Monitoring Readings

    1. Equipment Performance: AQI depends on validated data; CPCB requires 16 hours of reliable data per day for at least three pollutants, including PM2.5 or PM10.
    2. System Failures: Calibration lapses, power outages, and extreme weather cause routine station downtime.
    3. CAG Findings: A report tabled in Parliament revealed several stations failed to generate adequate, valid, real-time data, especially for pollutants like lead, Ammonia, etc.
    4. Location-Based Distortions: Stations placed near buildings, trees, or exhaust vents risk skewed results due to poor dispersion.
    5. Meteorological Disruptions: Severe weather disrupts data transmission, reducing continuity in real-time updates.

    What Scientific Studies Reveal About Measurement Accuracy

    1. Variability with Humidity: CSIR–NPL’s 2021 analysis showed PM2.5 measurements vary with RH, particle mass loading, boundary layer height, and ventilation effects.
    2. Overestimation Threshold: When RH > 60%, BAM monitors exhibited 30-40% overestimation of PM2.5 because water absorption artificially increases mass signal attenuation.
    3. High-Pollution Episodes: Dust-heavy conditions can cause a factor up to 5 underestimation, as heavy loading disturbs air beam pathways.
    4. USEPA Insights: Notes that “high filter loading can lead to flow perturbations,” and “excessive particulate accumulation” disrupts instrument stability.
    5. Recommended Corrections: Scientists recommend site-specific correction factors, which were shown to reduce overestimation errors from 46% to under 2%.

    Why This Issue Matters for Governance and Public Health

    1. Policy Dependence on Data: Emergency actions (GRAP stages, school closures, construction bans) rely on AQI accuracy.
    2. Public Health Impact: Misreporting distorts exposure assessments, health risk communication, and hospital preparedness.
    3. Environmental Justice: Vulnerable groups (elderly, children, labourers) depend on reliable alerts for safe mobility.
    4. Accountability: Data reliability determines CPCB, DPCC and state-level regulatory performance.

    CONCLUSION

    Delhi’s air pollution management depends critically on trustworthy, scientifically robust, and well-maintained monitoring infrastructure. While the city has one of India’s largest automatic monitoring networks, recent judicial scrutiny and scientific findings reveal persistent calibration errors, equipment inconsistencies, and meteorological vulnerabilities. Ensuring accuracy requires standardised maintenance, site-specific correction factors, stronger institutional oversight, and resilient instrumentation capable of performing reliably under Delhi’s complex pollution environment.

    PYQ Relevance

    [UPSC 2021] Describe the key points of the revised Global Air Quality Guidelines (AQGs) released by WHO (2021). How are these different from the 2005 update? What changes in India’s National Clean Air Programme are required to achieve these standards?

    Linkage: The question links directly to GS-III themes of environmental pollution, health-based standards, and regulatory capacity. It is highly relevant as India’s NCAP, NAAQS and AQI-based governance must realign with WHO’s stricter 2021 guidelines to ensure credible monitoring, policy effectiveness, and public health protection.

  • Ningaloo Reef Mass Coral Mortality 

    Why in the News?

    A new survey in 2025 shows that nearly 70% of corals in Australia’s UNESCO World Heritage–listed Ningaloo Reef have died due to the most intense and prolonged marine heatwave on record.

    About Ningaloo Reef  

    • Located in Western Australia.
    • A UNESCO World Heritage Site.
    • One of the largest fringing reefs in the world (~260 km long).
    • Important for marine biodiversity, supporting whale sharks, turtles, reef sharks, and diverse coral species.

    Extent of Coral Mortality

    • ~70% mortality recorded in latest survey.
    • In eight northern lagoon sites (Osprey → Tantabiddi Sanctuary Zones), mortality >60%.
    • Of 1,600+ corals assessed in March, only ~600 survived by October.

    Species Impact

    • Highly Affected (Dominant Species Lost)

        • Staghorn corals: Acropora tenuis, Acropora millepora and Acropora spicifera
        • Thin birdsnest coral (Seriatopora hystrix).

    • Relatively Resilient

      • Veron’s tube coral (Echinopora ashmorensis)
      • Lesser knob coral (Cyphastrea microphthalma)
    • Structural decline:
      • Dead corals now overgrown by sponges, turf algae, reducing reef stability & biodiversity.

    Broader Ecological Significance

    • Coral reefs support ~1/3 of global marine species.
    • Mass mortality compromises: Fish breeding grounds, Shelter for marine organisms, Coastal protection and Tourism & local economies.

    Widespread Global Coral Stress

    According to the United States National Oceanic and Atmospheric Administration (NOAA):

    • 84.4% of the world’s reef areas experienced bleaching-level heat stress (Jan 2023–Sept 2025).
    • Mass bleaching in 83+ countries.
    • Marine heatwaves in 2023 lasted 4× longer than the long-term average and affected 96% of the world’s oceans.
    The scientific view is that the increase in global temperature should not exceed 2 ∘ C above pre-industrial level. If the global temperature increases beyond 3 ∘ C above the pre-industrial level, what can be its possible impact/impacts on the world? 

    1. Terrestrial biosphere tends toward a net carbon source. 

    2. Widespread coral mortality will occur. 

    3. All the global wetlands will permanently disappear. 

    4. Cultivation of cereals will not be possible anywhere in the world. 

    Select the correct answer using the code given below: 

    (a) 1 only (b) 1 and 2 only (c) 2, 3 and 4 only (d) 1, 2, 3 and 4 only

  • Thermal Power Plants Near Delhi Operating Without FGD

    Why in the news?

    Delhi’s air quality deteriorated sharply in November 2025. A major contributing factor identified is the continued operation of several thermal power plant units within a 300-km radius of Delhi without Flue Gas Desulphurisation (FGD) systems.

    What is FGD?

    Flue Gas Desulphurisation (FGD) is a pollution-control technology used in thermal power plants and industrial units to remove sulphur dioxide (SO₂) from exhaust flue gases before they are released into the atmosphere.

    Status of FGD Installation 

    Thermal Power Plants within 300 km of Delhi

    • Total plants: 11
    • Total units: 35
    • Units with FGD (as of Apr 2025): 13
    • Units without FGD: 22
    • Units currently operating without FGD (Nov 2025): 15
    • Units shut/reserve shutdown: 6

    States & Operators

    • Haryana (HPGCL): Panipat TPS, Yamuna Nagar TPS.
    • Punjab (PSPCL): Guru Hargobind TPS and Ropar TPS.
    • Private: Talwandi Sabo (Vedanta).

    Why SO₂ Emissions Matter?  

    • SO₂ converts into secondary PM2.5, the most harmful pollutant for human health.
    • Causes: Respiratory diseases, Acid rain and Visibility reduction (smog)
    • Travels long distances, affecting entire regions beyond plant boundaries.
    According to the Environmental Protection Agency (EPA), which one of the following is the largest source of sulphur dioxide emissions? (2024)

    (a) Locomotives using fossil fuels 

    (b) Ships using fossil fuels 

    (c) Extraction of metals from ores 

    (d) Power plants using fossil fuels

  • SC allows CAQM to take ‘proactive’ measures to curb Delhi air pollution

    Why In The News?

    The Supreme Court allowed CAQM full freedom to take proactive anti-pollution measures in Delhi-NCR, including applying GRAP-IV options like work-from-home and 50% office attendance during the ongoing GRAP-III stage.

    About the Judgement:

    • Supreme Court’s Direction: SC empowered CAQM to take proactive pollution-control measures in Delhi-NCR.
    • Bench Observation: CJI Gavai urged stakeholder consultation.
    • Key Proposals: Early use of GRAP-IV measures, vehicle exemptions, staggered timings, and congestion control.
    • Additional Proposals: CAQM proposed advancing GRAP measures, enforcing congestion control, notifying vehicle aggregator policies, reviewing school sports during pollution months, and adopting long-term steps like EV policy review and higher charges on luxury diesel SUVs

    2) What is CAQM (Commission for Air Quality Management)?

    • About: A statutory body managing air quality in Delhi-NCR and adjoining areas, created under the CAQM Act, 2021, replacing the earlier EPCA (1998) and initially introduced via a 2020 ordinance.
    • Structure: Chairperson is a senior government official (Secretary/Chief Secretary); includes 5 ex-officio members from Delhi, Punjab, Haryana, Rajasthan, Uttar Pradesh; 3 full-time technical members; 3 NGO members; supported technically by CPCB, ISRO, and NITI Aayog.
    • Functions: Responsible for monitoring, coordinating, and implementing air quality policies, researching pollution sources, proposing mitigation strategies, and raising public awareness.
    • Powers: Holds jurisdiction over Delhi, Punjab, Haryana, Uttar Pradesh, Rajasthan; can issue binding directions, restrict polluting activities, enforce environmental rules, act against non-compliance, and initiate complaints under the CAQM Act, 2021.

    3) What is GRAP (Graded Response Action Plan)?

    • About: A pre-emptive and emergency framework to control Delhi-NCR air pollution; created under Supreme Court directions in C. Mehta vs Union of India (2016); notified in 2017 and implemented by CAQM, MoEFCC, and State authorities; operates through four graded stages linked to AQI levels.
    • Stages of GRAP:
      Stage I – Poor (AQI 201–300): Road dust control and enforcement of PUC norms.
      Stage II – Very Poor (AQI 301–400): Limits on diesel generators and actions in pollution hotspots.
      Stage III – Severe (AQI 401–450): Vehicle restrictions, construction curbs, and remote schooling
      Stage IV – Severe+ (AQI > 450): Ban on heavy vehicles, school closures, and shutdown of non-essential industries.
    • Purpose: To ensure a graded, coordinated, time-bound response that prevents air quality from escalating to hazardous levels.

    4)Air Quality Monitoring Measures:

    1) AQI (Air Quality Index)

    • Launched in 2014 with the concept “One Number – One Color – One Description” for easy public understanding.
    • Developed by the Central Pollution Control Board (CPCB).
    • Based on 8 pollutants: PM10, PM2.5, NO2, SO2, CO, O3, NH3, Pb.
    • Contains six air quality categories ranging from Good to Severe.

    2) SAFAR (System of Air Quality and Weather Forecasting and Research)

    • Provides location-specific, real-time air quality information for major Indian metropolitan cities.
    • Introduced by the Ministry of Earth Sciences, developed by IITM Pune.
    • Measures pollutants: PM2.5, PM10, O3, CO, NOx, SO2, Benzene, Toluene, Xylene, Mercury.
    • Uses Continuous Ambient Air Quality Monitoring Systems (CAAQMS); an example includes the one commissioned by the Indian Army in Kolkata.

    3) NAAQS (National Ambient Air Quality Standards)

    • Set by CPCB in 2009 under the Air (Prevention & Control of Pollution) Act, 1981.
    • Covers 12 pollutants, including SO2, NO2, PM10, PM2.5, O3, Pb, CO, NH3, Benzene, Benzopyrene, As, Ni.
    • Specifies annual and 24-hour standards for industrial, residential, rural, and ecologically sensitive areas.

    4) NAMP (National Air Quality Monitoring Programme)

    • Executed by CPCB to monitor ambient air quality across India.
    • Network includes 800+ stations in 344 cities/towns, covering 28 states and 6 UTs.
    • Objectives: track air quality trends, assess compliance with NAAQS, identify non-attainment cities.
    • Monitors SO2, NO2, PM10, and PM2.5 along with meteorological factors like wind speed, humidity, and temperature.

    5) WHO Ambient Air Quality Database

    • A global database compiling annual mean concentrations of PM2.5, PM10, and NO2.
    • First released in 2011; updated periodically—2023 is the sixth update.
    • Linked to WHO’s 2021 Global Air Quality Guidelines (AQGs), which tightened acceptable pollution limits.
    [UPSC 2022] In the context of WHO Air Quality Guidelines, consider the following statements:

    1. The 24-hour mean of PM 2.5 should not exceed 15 μg/m³ and annual mean of PM 2.5 should not exceed 5 μg/m³.

    2. In a year, the highest levels of ozone pollution occur during the periods of inclement weather.

    3. PM 10 can penetrate the lung barrier and enter the bloodstream.

    4. Excessive ozone in the air can trigger asthma.

    Which of the statements given above are correct?

    Options: (a) 1, 3 and 4 (b) 1 and 4 only* (c) 2, 3 and 4 (d) 1 and 2 only

  • India’s CO₂ Emission Trends as per Global Carbon Budget, 2025

    ​Why in the News?

    The Global Carbon Budget 2025 shows India’s fossil fuel emissions barely rising (3.19 to 3.22 billion tonnes) with growth slowing to 1.4 per cent, hinting at early stabilisation.

    India’s CO₂ Emission Trends:

    • Annual Growth: Fossil fuel CO₂ emissions rose from 3.19 billion tonnes (2024) to 3.22 billion tonnes (2025) a 1.4% increase, significantly slower than the 4% rise seen in 2024.
    • Decadal Trend: Average annual growth fell to 3.6% (2015–2024) from 6.4% (2005–2014), indicating efficiency gains and rapid renewable energy deployment.
    • Sectoral Profile: Roughly 90% of emissions originate from power generation, transport, industry, and buildings; 10% from land-use factors like deforestation.
    • Drivers of 2025 Slowdown: An early monsoon in 2024 reduced electricity demand for cooling; renewable energy growth reduced reliance on coal.
    • Electricity Sector Shift: CREA reported that India’s power-sector CO₂ emissions declined in early 2025 for the first time, due to strong solar and wind generation.
    • Global Context: India is the third-largest CO₂ emitter, yet its per capita emissions (~2.3 tonnes) remain far below the global average and major emitters like the U.S. (14.4 t) and China (8.7 t).
    • Outlook: Global fossil CO₂ emissions expected to rise 1.1% to 38.1 Gt, with total emissions (including land use) stabilising near 42 Gt.

    India’s CO₂ Emission Trends as per Global Carbon Budget, 2025

    What is the Global Carbon Budget?

    • Overview: It is an annual scientific assessment by Global Carbon Project (GCP) that quantifies global CO₂ sources and sinks across fossil fuels, land use, and oceans, forming the most authoritative dataset on global carbon trends.
    • GCP Origins: Established in 2001 under Future Earth and the World Climate Research Programme as a global consortium of climate scientists.
    • Mandate: To measure, monitor, and explain the global carbon cycle and its influence on the climate system.
    • Purpose of the Global Carbon Budget:
      • Quantifies CO₂ sources and sinks globally.
      • Tracks emission trends, carbon sequestration, and atmospheric CO₂ levels.
      • Provides authoritative data for COP negotiations and national climate assessments.
    • Scope and Methodology
      • Covers CO₂, methane (CH₄), and nitrous oxide (N₂O) using global datasets.
      • Combines national inventories, satellite data, and earth system models.
      • Uses the Global Carbon Atlas to visualise national and sector-wise emissions.
    • Significance:
      • Produces transparent, peer-reviewed carbon accounting.
      • Helps evaluate national performance under Paris Agreement targets.
      • Supports policy design on energy transition, carbon removal, and land use.
    • Key Collaborations: Works with major climate bodies including: IPCC, UNFCCC, WMO.
    [UPSC 2024] Consider the following statements:

    I. Carbon dioxide (CO₂) emissions in India are less than 0.5 t CO2/capita.

    II. In terms of CO2 emissions from fuel combustion, India ranks second in Asia-Pacific region.

    III. Electricity and heat producers are the largest sources of CO2 emissions in India.

    Which of the statements given above is/are correct?

    (a) I and III only (b) II only (c) II and III only * (d) I, II and III