Climate Change

World likely to breach 1.5°C limit in next five years: WMO

Context: A recent report by the World Meteorological Organisation (WMO) has sounded an alarm on climate change, warning that there is a 70% chance of global temperatures exceeding the 1.5°Celsius threshold above pre-industrial levels between 2025 and 2029.

Relevance of the Topic: Prelims: Key trends related to climate change; Paris Climate deal; India’s climate commitments. 

Major Highlights of forecasts by WMO

  • Global mean near-surface temperature for each year between 2025 and 2029 will be between 1.2°C and 1.9°C above the pre-industrial average. There is a 70% chance that average warming will exceed 1.5°C, if the current warming trend continues.
    • In 2024, WMO estimated that the average global temperature was between 1.34°C and 1.41°C higher than pre-industrial levels (1850-1900).
    • WMO now projects the 20-year average warming for 2015-2034 to reach around 1.44°C above pre-industrial levels.
  • Average Arctic temperature over the next five winters (2025-2029) is expected to be 2.4°C warmer than the 1991-2020 average. Sea ice is expected to keep shrinking, particularly in the Barents, Bering, and Okhotsk Sea. This will contribute to rising sea levels and disrupted weather patterns worldwide.

About Paris Climate Agreement

  • Adopted in 2015 by 196 Parties during the 21st Conference of Parties (COP21) to the UN Framework Convention on Climate Change (UNFCCC) at Paris, France.
  • Aim: To limit global warming to well below 2°C, preferably 1.5°C, above pre-industrial levels.
  • Key Features of the Climate deal: 
    • Nationally Determined Contributions (NDCs): Each country sets its own emission reduction targets, with updates every five years to enhance ambition.
    • Global Stocktake: A periodic review of the progress on climate action at global level (not the national level) and identify overall gaps, conducted every five years.
    • Climate Finance: Developed countries pledged to mobilise $100 billion annually by 2020 to support climate action in developing nations, with plans for scaling this amount post-2025.
    • Adaptation and Resilience: Focuses on helping countries adapt to climate impacts and build resilience against future challenges.
  • Significance: First universal, legally binding, global climate deal. It emphasises global cooperation, fairness, and a commitment to sustainable development while recognising the individual capacities of nations.
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India’s Panchamrit (nectar elements) of climate action: 

The Government of India at the COP26 to the UNFCCC held in Glasgow, United Kingdom 2021 made the following commitments. The five elements of India’s climate action:

i. Reach 500 GW Non-fossil energy capacity by 2030.

ii. Meet 50% of the total energy requirement from renewable energy by 2030.

iii. Reduction of total projected carbon emissions by one billion tons from now to 2030.

iv. Reduction of the carbon intensity of the economy by 45% by 2030, compared to 2005 levels.

v. Achieve the target of net zero emissions by 2070.

Concerns: 180 of the 195 United Nations Framework Convention on Climate Change (UNFCCC) countries are yet to submit their next round of nationally determined contributions (NDCs) or climate plans for 2031-35 before the 30th Conference of the Parties (COP30). Climate plans are crucial to limit global temperature rise to 1.5°C.

A growing number of climate scientists now hold the 1.5-degree target to be impossible to achieve due to the increasing levels of CO2 emissions.

Atypical Summers in 2025: Role of Western Disturbances

Context: A cooler-than-usual summer over large geographical areas of the country has contributed to keeping all-India average temperatures within the normal range in May 2025. The primary reason is the frequent passage of streams of western disturbances in the lower latitudes.

Relevance of the Topic: Prelims: Key facts about Western Disturbances. 

Unusual weather conditions

As per the India Meteorological Department (IMD): 

  • All-India weekly average maximum temperature was 3-5 degrees Celsius below normal over West, Central, and North India. Normal temperatures prevailed over remaining parts of the country.
  • Core Heatwave Zone (CHZ)- spanning Central, North, and Peninsular India between Gujarat and West Bengal, which is prone to heatwave conditions every year from March to June, has not as yet experienced significant heatwaves.
  • May has been exceptionally wet over the South and Central Indian regions. Southern Peninsular India has benefited from intermittent spells of rain throughout the ongoing pre-monsoon season. 

Reasons for cooler temperature in Summers: 

  • Western Disturbances: The primary reason for a wetter- and cooler-than-usual summer is the frequent passage of streams of western disturbances in the lower latitudes. Western disturbances are eastward-bound winds that originate in the Mediterranean Sea and cause rain or snow along their way.
  • Continuous incursion of Moisture: There has also been a continuous incursion of moisture from the Bay of Bengal and Arabian Sea into the Indian mainland, with the subsequent wind interactions causing rainfall and thundershowers.
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What are Western Disturbances?

  • Western disturbances are extra-tropical cyclones that originate in the Mediterranean region and move eastwards towards the Indian subcontinent, affecting Northern India, northern Bangladesh, and south-eastern Nepal.
  • The sub-tropical westerly jet streams help western disturbances to enter the Indian sub-continent and affect its weather. The winds while moving take up the moisture from the Mediterranean Sea, Black Sea and Caspian Sea.
  • These moisture laden winds eventually reach the northwestern Himalayas and get blocked, as a result the moisture gets trapped, and precipitation is shared. This ultimately leads to:
    • Snowfall in western Himalayas (J&K, Himachal Pradesh, Uttarakhand)
    • Non-monsoonal rainfall over Indo-Gangetic plains (Punjab, Haryana, Delhi, Uttar Pradesh). These disturbances provide moisture to Rabi season crops
  • On an average 4-6 disturbances (temperate cyclones) per month pass over northern India between November to April. 

India warns of Retaliation if UK imposes Carbon Tax Under CBAM

Context: India has strongly opposed the UK’s proposed Carbon Border Adjustment Mechanism (CBAM), citing that it reserves the right to retaliate if the UK proceeds without granting fair exemptions to Indian exporters.

Relevance of the Topic Prelims : key facts related to carbon Border Adjustment Mechanism (CBAM) Mains : Impact of CBAM on Indian exports.

Carbon Border Adjustment Mechanism (CBAM)

  • CBAM is a policy tool introduced by the European Union to ensure that imported goods are subject to the same carbon costs as products produced within the EU.
  • It aims to prevent "carbon leakage," where companies shift production to countries with lower carbon standards to avoid carbon costs.
  • The United Kingdom, though no longer part of the EU, is now planning its own version of CBAM, which has sparked fresh trade tensions with India. It is expected to start from January 1, 2027. 

Also Read: Carbon Border Adjustment Mechanism 

Impact of CBAM on Indian Exports: 

  • Reduce price competitiveness: Carbon tax on carbon intensive goods (steel, aluminium, cement, and fertilisers etc.) imported from India will make Indian goods more expensive than local or other compliant imports reducing price Competitiveness
  • Undermines FTA benefits: While the FTA might reduce or eliminate tariffs, Indian exports could still face hefty carbon taxes, potentially far exceeding the UK’s current average tariff rate of under 2%.
  • Burden on MSMEs: MSMEs often lack the resources to measure and report carbon emissions, making CBAM compliance costly and potentially forcing them out of export markets.

India’s Response

  • India has labelled the CBAM as an unfair measure and a violation of the "common but differentiated responsibilities" (CBDR) principle.
    • CBDR principle is a multilateral climate negotiations which says developed and developing countries should not be treated the same when it comes to climate responsibilities. Developed nations, having polluted more historically, must bear a greater responsibility.
  • India had requested the UK for Special treatment for Indian MSMEs under CBAM and a ‘rebalancing mechanism’ – a clause in the trade deal that would compensate Indian exporters if they suffer losses due to this tax. However the UK remains unwilling to grant any concession under CBAM.
  • India inserted a clause related to rebalancing inside the “General Exceptions” chapter of the trade agreement draft. In global trade rules (like WTO’s GATT agreement), this chapter says a country can take actions that normally break trade rules, if it is doing so to protect the environment or public health.
  • So, this protects India from legal trouble at the WTO, if it takes action against the UK’s carbon tax.

Also Read: India and UK conclude Free Trade Agreement 

India must negotiate with UK firmly to ensure that market access gained through tariff elimination is not undermined by other barriers.  

Climate Change is disrupting the Human Gut

Context: As per the latest research, climate-driven food shortage and undernourishment could affect the composition of the human gut microbiota, exacerbating the effects of climate change on human health.

Relevance of the Topic: Prelims: Key facts related to gut bacteria; Impacts of Climate Change. 

Microbiota in Human Gut

  • The human gut is home to around 100 trillion microbes like bacteria, fungi, and viruses- mostly bacteria. The collective genetic material of these microbes (known as gut microbiome) contains over 100 times more genes than the human genome. 
  • These microbes produce thousands of chemicals (metabolites) that support- digestion and nutrient absorption, immune system regulation, blood sugar and metabolic balance and protection against harmful pathogens.
  • A healthy gut depends on a balanced relationship between beneficial and harmful bacteria.
    • Good bacteria help break down food, produce vitamins, and protect against harmful invaders. 
    • Bad bacteria, when overgrown, can cause inflammation, infections, or disease. A healthy gut depends on a balanced relationship between these beneficial and harmful bacteria. 

However, climate change is now threatening this balance with long-term implications for public health.

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Impacts of Climate Change on Gut Microbiota and Population:

1. Nutritional Disruptions and Microbial Imbalance: 

  • Climate change is adversely affecting the yield and nutritional quality of crops and animal-based food sources. High atmospheric carbon dioxide levels can diminish the quantity of plant micronutrients like phosphorus, potassium, zinc, and iron, along with protein concentrations in vital crops such as wheat, maize, and rice.
  • This reduction compromises the nutritional intake necessary for maintaining microbial diversity in the gut, potentially leading to gut dysbiosis or microbiota dysbiosis - the imbalance in gut microbial population.

Microbiota Dysbiosis can lead to dysregulation of bodily functions and diseases such as: 

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2. Rising Heat and Disease Burden: 

  • Foodborne and waterborne infectious diseases and malnutrition increase with heat. These diseases further disturb gut microbiota and worsen the burden of malnutrition and gastrointestinal illnesses, especially in vulnerable populations like children and the elderly.

3. Vulnerability of LMICs and Indigenous Communities: 

  • Low- and middle-income countries (LMICs), are particularly  vulnerable, as these regions face the brunt of climate stressors, including higher temperature and atmospheric carbon dioxide, which affect their agricultural output and make nutrient deficiencies more common.
  • Indigenous peoples often rely on local and traditional food sources and exhibit high gut microbial diversity. Climate-induced changes in ecosystems threaten these food systems, potentially reducing microbial diversity and thus impacting their health disproportionately.

The Challenge: Limited understanding of Gut Microbiome

However our understanding of the gut microbiota’s role in human health is still evolving.

  • While the gut microbiome is critical to health, its connection to climate change is still poorly understood. Many gut health studies do not yet account for environmental factors like pollution, rising heat, or changing crop patterns.
  • Moreover, individual gut microbiomes are unique, making it difficult to predict how each person will respond to climate-induced changes in diet or disease exposure.

Way Forward

  • Need for Multidisciplinary and Global Research: Scientists are calling for more collaboration across fields- nutrition, climate science, public health, and microbiology to study how environmental changes affect the gut.
  • Advances in computational biology and metagenomics (the study of microbial genes) are helping scientists better understand gut microbes. Tools like GutBugBD, an open-access database from India, allow researchers to track how gut microbes interact with food and drugs. These developments could lead to personalised treatments using probiotics and nutraceuticals to restore gut balance. 

Rising Temperatures and Mango Productivity

Context: Despite rising temperatures and erratic weather affecting mango quality and flowering, India’s mango productivity has grown largely due to the fruit’s genetic diversity, which enhances its resilience to climate change.

Relevance of the Topic: Mains: Impact of rising temperatures on production of crops. 

Rising Temperatures:  

  • According to the India Meteorological Department’s (IMD) Annual Climate Survey of 2024, the year 2024 was the warmest year on record since 1901. 
  • The country’s annual mean land surface air temperature during the year 2024 was +0.65°C above the 1991-2020 average. IMD data also shows that the last 12 years have been warmer than earlier years.

Impacts of rising temperatures on Mango Production

1. Anticipated Impact: 

  • Higher temperatures lead to early maturity, fruit drop, and disorders such as spongy tissue in varieties like Alphonso. 
  • Anecdotal information suggests that mango productivity has been affected due to rising temperatures.

2. Observed Impact: 

  • Empirical evidence and statistical data of the Horticulture Department in India suggest otherwise contradicting the perception of decline. 
  • Data from the Horticulture Department and Agricultural Market Intelligence Centre show that mango productivity and cultivated area in India have both increased.
    • Mango productivity in India has increased from 5.5 metric tonnes per hectare (MT/Ha) in FY2009 to 9.7 MT/Ha in FY2018.
    • India’s productivity in 2024–25 is expected to surpass that of major producers like China and Thailand. 
Impacts of rising temperatures on Mango Production

Reasons behind increased production despite rising temperatures: 

  • Experts explain this resilience is due to the genetic diversity of mangoes. Genetic diversity allows the fruit to adapt to changing conditions, such as high temperatures and irregular rainfall.
  • Indian researchers and horticulture experts suggest that while extreme weather can disrupt flowering and fruiting stages, the physiological mechanisms and genetic variation in mango species help them withstand environmental stress.

Despite climatic stressors like heat waves and erratic rainfall, India’s mango production remains robust, largely due to genetic adaptability. This offers hope for future agricultural resilience in the face of climate change.

India’s Urban Future is at Crossroads

Context: India's urban governance needs urgent reform to effectively implement SDG-11, i.e., to make cities and human settlements inclusive, safe, resilient and sustainable. 

Relevance of the Topic: Mains: Limitations in current urban governance and planning frameworks.

Urbanisation: Double-edged sword

  • India is undergoing an unprecedented urban transformation, with more than 30% of its population residing in cities. 
  • However, Urbanisation is a double-edged sword. While it brings economic opportunities and development, it also exacerbates environmental degradation, congestion, pollution, and social inequalities.
  • E.g., the recent crisis in cities like Bengaluru and Hyderabad indicate, water shortages, power deficits, and extreme heat are no longer seasonal anomalies but signs of systemic fragility.
  • The 2023 Annual Survey of Indian City Systems by Janaagraha revealed that only 16 cities had a city sustainability plan, and just 17 had a resilience strategy. This highlights the foundational work still required to align urban governance with SDG-11. 

The 2025 report by the Sustainable Futures Collective titled- ‘Is India Ready for a Warming World?’ notes serious gaps in long-term urban climate planning. 

Limitations in Existing Indices

  • Inadequate SDG-11 Tracking: NITI Aayog’s SDG Urban Index ranks 56 cities on 77 indicators. But its SDG-11 component is limited to four indicators: Swachh Survekshan, road deaths, PMAY-U housing, and waste treatment. It excludes critical aspects like climate resilience, social inclusivity, and urban safety.
  • Fragmented Assessment Tools: Ease of Living Index covers 111 cities but lacks a dedicated SDG-11 framework. International indices (e.g., Mercer, Economist) often fail to capture localised Indian realities.
  • Policy-Research Gap: The absence of city-specific data and disaggregated indicators inhibits targeted policymaking and the identification of urban stress zones.

The absence of a focused SDG-11 index hinders policymakers from identifying genuinely safe, sustainable, and inclusive cities, creating a policy-research gap. To bridge this gap, a new research initiative was undertaken.

The New Research Initiative

  • The research initiative constructed four separate indices aligned with the pillars of SDG-11: safety, inclusivity, sustainability, and resilience.
  • Ten major Indian cities: Hyderabad, Delhi, Bengaluru, Chennai, Mumbai, Pune, Kolkata, Jaipur, Ahmedabad, and Surat were ranked across selected indicators. 
  • These included 9 indicators for safety, 19 for inclusivity, and 15 for sustainability and resilience each.
  • Data sources included Census 2011, the Road Transport Yearbook, Indian Forest Survey, NCRB, PLFS, NFHS-5, RBI statistics, IMD Climatological Tables, and Ola Mobility Institute's 2022 Ease of Moving Index. 
  • A multi-criteria decision-making model, the Shannon Entropy Weighting Technique, was used to ensure objectivity in assigning weights to the indicators.

Key Findings from the Study

  • Many cities regarded as front-runners by NITI Aayog performed poorly in this assessment, exposing the shortcomings of existing indices. For instance, disparities in the inclusivity index underscored uneven access to economic and social opportunities.
  • Safety rankings highlighted differences in law enforcement efficacy and crime prevention.
  • Sustainability scores revealed gaps in pollution control and waste management, while resilience rankings exposed weaknesses in disaster preparedness and recovery planning.

Way Forward

  • Cities must establish better mechanisms for tracking SDG-11 at the urban local body (ULB) level. While some States and Union Territories have adopted district-level monitoring frameworks, urban local bodies must follow suit. 
  • Integrated Command and Control Centres, developed under the Smart Cities Mission, should be leveraged to collect real-time data and enhance urban planning and development processes.
  • As almost one-third of urban residents are poor, addressing their needs is critical. India still relies on Census 2011 data, leading to severe underestimation of urban poverty. A periodic Urban Poor Quality of Living Survey at the State level is necessary to bridge this gap.
  • Each city (small and large) faces unique challenges, requiring localised governance, better planning, and city-specific strategies. 

Addressing these differences through data-backed, city-specific policies is crucial for a more equitable urban future.

Greenhouse Gases Emissions Intensity Target Rules 2025

Context: The Ministry of Environment, Forest and Climate Change (MoEFCC) notified draft Greenhouse Gases Emissions Intensity (GEI) Target Rules 2025. The rules introduce targets for the reduction of greenhouse gas (GHG) emissions by “obligated entities” in energy-intensive sectors and industries.

Relevance of the Topic: Prelims & Mains: Greenhouse Gases Emissions Intensity (GEI) Target Rules, 2025. 

  • The draft rules mark a critical development in India’s climate policy and its ongoing commitment to the Paris Agreement. 
  • They lay the foundation for operationalising the Carbon Credit Trading Scheme (CCTS), 2023, by setting specific emission intensity reduction targets for high-emission industries.

What is Greenhouse Gas Emissions Intensity (GEI)?

  • Greenhouse Gas Emissions Intensity refers to the amount of GHG emissions per unit of product output.
  • It is measured in tCO₂e (tonnes of carbon dioxide equivalent) per equivalent unit of output, taking into account all major greenhouse gases, such as: Carbon dioxide (CO₂), Methane (CH₄), Nitrous oxide (N₂O), Ozone (O₃), Fluorinated gases like CFCs and HCFCs.
  • The aim is to assess and reduce emissions without necessarily lowering total production, thus enabling sustainable economic growth.

Key Features of the Draft GEI Target Rules, 2025: 

1. Coverage and Scope:

  • GHG intensity reduction targets and benchmarks have been set for the highly energy-intensive aluminium, chlor-alkali, pulp and paper, and cement industries.
  • Applicable to over 280 industrial units across four energy-intensive sectors : Aluminium plants, Cement plants, Pulp and Paper plants, Chlor-alkali plants.
  • Among the large corporations that have been assigned targets under the rules are:  Vedanta, Hindalco, Bharat Aluminium, JSW Cement, Ultratech, Nalco, JK Cement, Dalmia Cement, Shree Cement, Grasim Industries, and JK Paper.

2. Baseline and Targets: 

  • The Rules set forth baseline emissions for 2023-24 and define gradual reduction targets for the years 2025-26 and 2026-27 as part of the mechanism to make India’s Carbon Credits Trading Scheme, 2023, operational.
  • The Rules also lay down the compliance mechanism for industries to comply with these targets, and specify penalties for their failure to do so.

3. Integration with Carbon Credit Trading Scheme (CCTS):

  • GEI targets define the emissions reduction goal for each industry. If an industry reduces its emissions intensity below the target, it earns carbon credits. These credits can be traded on the Indian Carbon Market, offering a financial incentive for industries to adopt clean technology.
  • Industries that fail to meet their targets must either buy carbon credits to offset the shortfall or face penalties imposed by the Central Pollution Control Board.
  • The Bureau of Energy Efficiency (BEE) oversees this trading process under the Ministry of Power. This system is based on international models like the Kyoto Protocol’s carbon market (Article 17) and similar schemes running in Europe and China.

The draft Rules make carbon trading operational by setting the standards that industries must meet to earn, sell, or buy carbon credits, thus turning climate responsibility into an economic opportunity. Targets have been set for the reduction of GHG emissions intensity for the first time.

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Why are these rules important?

  • Meet India’s climate goals: To push industries towards a low-carbon growth trajectory through reduction, removal or avoidance of GHG emissions. E.g., use of biomass in cement kilns.
  • Meet India’s commitment under the Paris Agreement: To reduce the emissions intensity of its gross domestic product (the amount of energy used per unit of GDP) by 45% by 2030 compared to 2005 levels.

The draft GEI Target Rules, 2025, are a significant move towards operationalising India’s carbon market and achieving its climate goals.  

Changes in Monsoon affect Marine Productivity

Context: A recent study has found that both strong and weak monsoons can influence (disrupt) marine productivity in the Bay of Bengal. This can pose serious ecological and livelihood challenges. 

Relevance of the Topic: Prelims: Impacts of Climate Change. 

Major Highlights of the Study

The researchers reconstructed the past 22,000 years of monsoon history by comparing ancient patterns (chemical signatures and fossil records) with modern ocean data and climate model projections.

  • Extreme monsoon conditions (abnormally strong or weak monsoons) cause major disruptions in ocean mixing. They interfere with the vertical movement of nutrient-rich waters from the deep ocean to the surface. 
  • Consequences: This can lead to a 50% reduction in food for marine life (like planktons) in the surface waters. This will directly result in decline in the growth of plankton, and thus, impact the entire aquatic food chain. 
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Significance and Impacts on the Bay of Bengal: 

  • Significance: Despite covering less than 1% of the world’s ocean area, the Bay of Bengal accounts for 8% of global fishery production. Its nutrient-rich coastal waters are vital to the densely populated communities along its shores, many of whom rely heavily on fisheries for food and income. 
  • Impacts: If ocean productivity declines, it will powerfully affect the ecosystem, ultimately reducing fish stocks. This in turn will threaten food security for coastal communities and risk their livelihoods. 

The study is significant given that several climate models warn of significant disruption to the monsoon, under the impact of human-caused global warming. 

Arctic Biome rejects more Carbon

Context: The 2024 Arctic Report Card issued by the US National Oceanic and Atmospheric Administration (NOAA) stated that frequent wildfires are turning the Arctic Boreal Zone from a carbon sink to a carbon source. 

Relevance of the topic:

Prelims: Key facts about Arctic Boreal Zone.

Mains: Climate change: Key trends.

Arctic Boreal Zone

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  • It is a vast transitional zone, also known as ‘boreal forests’, stretching between Arctic tundra and the temperate forests of the Northern Hemisphere. 
  • It represents 1/3rds of the Earth's forested area- the largest terrestrial biome. Found across: Canada, Alaska (US), Russia, Mongolia and Scandinavian nations (Norway, Finland, Sweden). 
  • It is a significant global carbon sink dominated by coniferous forests, and also comprises tundra, wetlands and permafrost zones.
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Why is the Arctic Boreal Zone releasing more carbon dioxide?

  • Frequent and intense wildfires: A study published in Nature Climate Change reports that more than 30% of the ABZ has shifted from being a carbon sink to a carbon source, largely due to intense and frequent wildfires. Wildfires burn through natural carbon reservoirs like forests and peatlands. This transforms these ecosystems into sources of carbon emissions. 
  • Thawing of tundra permafrost: Permafrost (permanently frozen grounds beneath the tundra) hold 2.5 times the carbon that is currently in the atmosphere. Due to Arctic warming, the permafrost has begun to thaw. This leads to release of carbon dioxide and methane, and thus, has undermined the carbon storage capacity of ABZ.  
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Increasing intensity and frequency of wildfires: 

  • Multiple regions around the globe including the U.S., Japan, and India — have witnessed a surge in wildfires, dust storms, and extreme weather events.
    • According to the Copernicus Air Monitoring Service (CAMS) of the European Union, wildfires in January 2025 alone have released approximately 800,000 tonnes of carbon, nearly four times the emissions from a decade earlier.
  • India’s wildfires are estimated to emit 69 million tonnes of CO₂ annually. Heat waves are now arriving earlier, lasting longer, and moving slower, creating conditions ripe for forest fires. It has long-term implications for climate change.

Also Read: Forest Fire Incidents in India 

Aerosol Paradox: Why removing Aerosols can Heat up India

Context: Rapidly reducing aerosol emissions, without concurrently reducing greenhouse gas emissions, could expose a large fraction of vulnerable people in highly polluted regions of India to a sudden acceleration of warming and extreme heat.

Relevance of the Topic: Prelims: Aerosols: Role and Removal; Aerosols vs GHGs.  

What are Aerosols?

  • Aerosols are tiny solid or liquid particles suspended in the atmosphere. E.g., black soot, sulphur aerosols, sea salt, dust etc. 
  • Origin: 
    • Natural sources (such as volcanic eruptions, forest fires, and sea spray)
    • Human activities (such as industrial emissions, vehicular pollution, and burning of fossil fuels).
  • Role of Aerosols:
    • Aerosols scatter solar radiation, thus, reducing the amount of heat reaching the Earth's surface.
    • They act as cloud-condensation nuclei and contribute to cloud formation and influence the water cycle.
Aerosolos and climate

What are Greenhouse Gases?

  • GHGs are gases that trap heat in the Earth's atmosphere, leading to global warming.
  • Key GHGs: Carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and fluorinated gases.

Greenhouse Gases vs. Aerosols

  • GHGs trap heat and contribute to global warming, whereas aerosols can counteract this effect by reflecting sunlight.
  • GHGs have a long atmospheric lifespan- persisting for decades to centuries; their effects are global and long-term. Aerosols have a shorter lifespan compared to GHGs, meaning their effects are more immediate and localised.

Aerosols as Pollutants: 

While aerosols provide a temporary cooling effect, they also contribute to air pollution which has significant health and environmental repercussions. 

  • Coal-based thermal power plants in India contribute significantly to GHG, aerosol emissions and particulate matter pollution. 
  • Sulphur dioxide (SO2) emitted from coal combustion forms sulphate aerosols, which reflect sunlight and cool the atmosphere.

Impacts of Aerosol Removal from Environment

The removal of aerosols at its source to reduce pollution could inadvertently contribute to warming.

1. Aerosols affecting Temperature rise in India: 

  • Studies indicate that aerosols have masked a portion of the warming caused by GHG emissions.
    • Between 1906 and 2005, India warmed by 0.54°C, but the actual warming due to GHGs was around 2°C, with aerosols offsetting approximately 1.5°C.
    • If aerosols were not present, India would have experienced much greater warming.
  • The Ministry of Earth Sciences reported that India's average temperature rose by 0.7°C from 1901 to 2018, with GHG-induced warming being partially countered by aerosols.

2. Impact on Monsoon and Rainfall Patterns: 

  • Aerosols have played a role in decreasing Indian monsoon rainfall due to their cooling effect, especially in the Northern Hemisphere. Aerosols have a cooling effect by scattering sunlight. This results in reduced land-sea temperature contrast, which in turn results in a weaker South-West monsoon. 
  • The removal of aerosols may increase rainfall, but the resulting warming can cause erratic weather patterns, climate volatility and extreme events.

3. Global and Regional Implications of Aerosol Reduction: 

  • The impact of aerosols is not confined to national borders; changes in emissions in one region can affect distant locations. E.g., China's reduction in aerosol emissions intensified heatwaves along the west coast of North America.
  • Similarly, any significant increase in aerosols over India could negatively impact the hydrological cycle. The remote effects of aerosols must be considered when formulating climate policies.

Net-Zero Targets and Future Challenges: 

  • While reducing aerosols improves air quality and public health, it may also lead to a sudden increase in heat stress. Achieving net-zero emissions requires simultaneous reductions in both GHGs and aerosols. 
  • A gradual approach to aerosol reduction, coupled with aggressive GHG mitigation, is crucial for maintaining climate balance.

Need for Long-Term Adaptation Policies

  • Policymakers must prepare for the consequences of aerosol reduction by implementing robust heat action plans and comprehensive long-term strategies.
  • Future policies should consider the trade-offs between improved air quality, increased temperatures, and altered rainfall patterns.
  • Investment in urban planning, climate adaptation measures, and early warning systems will be essential.

A well-planned transition strategy is crucial to ensuring climate resilience while addressing pollution control measures effectively. Policymakers must balance short-term and long-term climate goals to protect vulnerable populations while mitigating global warming. 

Water levels in key reservoirs down below 40%

Context: As per the recent data from the Central Water Commission, India’s 161 major reservoirs dropped below 40% of the capacity at the end of March 2025, with the levels in 65 of them below 50%. 

Relevance of the Topic : Mains: Declining water levels in reservoirs - reasons and impact. 

Major Highlights

  • Water storage, in the 161 major reservoirs, had dropped to 72.91 billion cubic metres (BCM) of the 182.375 BCM capacity. It was still higher than last year and normal (last 10 years) levels. 
  • Barring the Central region, the level in the rest of the country was below 40% of the capacity. 
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Reason for Declining water levels

  • The decline in water level of reservoirs is attributed to deficient post-monsoon and winter rainfall affecting a large portion of the country. 
  • The India Meteorological Department (IMD) reports that 83% of India experienced deficient rainfall from January 1 to January 24. This period has seen over 60% of the country receiving scanty or no rainfall.

Associated Concerns: 

This situation raises concerns about water availability for various sectors: 

  • Security of agriculture and food supply chain: Lower irrigation supply could affect the upcoming Kharif season, impacting food security.
  • Groundwater depletion: 80% of India’s irrigation depends on groundwater. With reservoirs (surface water) drying up, farmers are forced to pump more groundwater, leading to aquifer depletion.
  • Drinking water shortage: Many cities rely on reservoirs for drinking water. Declining levels can force water restrictions and impact daily life.
  • Reduced water levels can worsen the effects of droughts. 

Way Forward

  • Restoring the hydrological cycle and rejuvenating water bodies such as rivers, streams, lakes, storm drains and reservoirs. 
  • Encourage rainwater water percolation through soil layers and facilitate groundwater recharge. 
  • Use treated wastewater, modernisation of water courses, groundwater conservation and recycling of water. 
  • Improving efficiency of water use by adopting water use efficiency (WUE) measures and treating grey water in industries. Resorting to micro-irrigation, crop diversification, direct seeding of crops in agriculture.
  • Adopting the concept of water as an economic good. Water is considered as free, non-economic good such as air. The UN Dublin Principle 1992 emphasised on the importance of economic value of water in general and irrigation water in particular. 

Central Water Commission (CWC)

  • CWC is a premier Technical Organisation of India in the field of Water Resources.
  • Mission: To promote integrated and sustainable development and management of India's Water Resources by using state-of-art technology and competency and coordinating all stakeholders.
  • Functions: In consultation with the concerned State Governments, CWC initiates, coordinates and investigates implementation of the schemes for:
    • Control, conservation and utilisation of water resources throughout India.
    • Flood Control, Irrigation, Navigation, Drinking Water Supply and Water Power Development.

Also Read: List of Water Conservation Campaigns & Schemes 

United Nations World Water Development Report 2025

Context: The ‘United Nations World Water Development Report 2025 – Mountains and glaciers: Water towers’ was released to mark the first-ever World Day for Glaciers on March 21. 

Relevance of the Topic: Mains: Impact of global warming on mountain ecosystems and its consequences. 

United Nations World Water Development Report (WWDR)

  • WWDR is a global report that provides a comprehensive assessment of the world’s freshwater resources. 
  • It is produced annually by the UNESCO World Water Assessment Programme, and published by UNESCO.

Major Highlights of the UNESCO’s Report

1. Glacial Melting:

  • Glaciers are disappearing faster than ever. Since 1975, glaciers (which do not include the Greenland and Antarctica ice sheets) have lost >9,000 billion tonnes of mass. 450 gigatons of mass was lost in 2024 alone.
  • Reasons for accelerating glacier melting:
    • Warmer temperatures
    • More frequent and intense wildfires
    • Dust storms lead to more deposition of black carbon and other particulate matter on glacier surfaces, leading to greater absorption of solar radiation (decreased Albedo).  
image 23

2. Accelerating Permafrost Thaw: In high-altitude regions, permafrost is any ground that stays frozen — 0 degrees Celsius or lower — for at least two years straight. Rising temperatures are melting permafrost in these regions rapidly. 

3. Decline in Snow Cover: Reduction in snow cover in nearly all mountain regions, especially in spring and summer. Snow cover is the total of all the snow and ice on the ground. It includes new snow and previous snow and ice that have not melted. Earlier, a 2024 study found a 7.79% decline in global snow cover between 1979-2022.

4. Erratic Snowfall Patterns: Due to atmospheric warming, the rain-snow transition zone is shifting upwards, i.e., mountain ranges are receiving a greater fraction of precipitation falling as rain rather than snow. Snow duration has reduced, snow-melt is taking place earlier than usual. 

Implications of the Changing Climatic Patterns: 

  • Consequences of permafrost thawing:  
    • Release of organic carbon into the atmosphere, exacerbating climate change. Permafrost contains a vast amount of organic carbon (4.5% of the global soil organic carbon) and other nutrients.
    • Mountain slopes become more vulnerable to erosion, increasing the risk of landslides and other hazards.
  • Consequences of increased glacial melting:
    • Increased glacial lake formation and higher risk of glacial lake outburst floods (GLOFs). 
    • Rise in the sea level: Melted glacier ice contributes 25-30% of global sea-level rise. Between 2006 and 2016, the global mass loss of glacier ice amounted to 335 billion tonnes of lost ice per year, which corresponded to an increase in sea levels of almost 1 mm per year. 
  • Shorter snow duration: affects ecosystems, water supply, and agriculture. Earlier snowmelt means water is available too early in the season, causing shortages later. 

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