Causes and effects of climate change

1. Introduction

Climate change refers to the long-term alteration in the Earth’s average temperature, rainfall, wind patterns, and other climatic conditions over decades or centuries. While climate has changed naturally throughout Earth’s history due to factors such as volcanic eruptions, changes in solar radiation, and variations in Earth’s orbit, the current phase of climate change is primarily driven by human activities. The large-scale burning of fossil fuels, deforestation, industrialization, and unsustainable land-use practices have significantly increased the concentration of greenhouse gases (GHGs) in the atmosphere, leading to rapid global warming.

It is important to distinguish weather from climate. Weather refers to short-term atmospheric conditions such as temperature, rainfall, or humidity at a particular place and time, whereas climate is the long-term average of weather patterns over a period of at least 30 years. Thus, a heatwave or heavy rainfall is a weather event, while an increasing frequency of such events over several decades indicates climate change.

The Intergovernmental Panel on Climate Change (IPCC) has concluded that human influence has unequivocally warmed the atmosphere, oceans, and land. According to the World Meteorological Organization (WMO), the global average temperature is already around 1.5°C above the 1850–1900 baseline during recent years, resulting in more frequent heatwaves, floods, droughts, cyclones, and sea-level rise.

Climate change is no longer merely an environmental issue; it has become a major challenge for human health, food security, water availability, livelihoods, economic growth, and sustainable development. Developing countries such as India are particularly vulnerable because a large section of the population depends on climate-sensitive sectors like agriculture, fisheries, and forestry.

2. Causes of Climate Change (Human-Induced)

Human activities since the Industrial Revolution (around 1750) have significantly increased the concentration of greenhouse gases (GHGs) in the atmosphere. These gases trap outgoing heat, resulting in the enhanced greenhouse effect and global warming. According to the IPCC Sixth Assessment Report (AR6), human influence is the dominant cause of the observed warming since the mid-20th century.

(i) Greenhouse Gas (GHG) Emissions

Greenhouse gases absorb and retain heat in the Earth’s atmosphere, leading to a gradual rise in global temperatures.

Major Greenhouse Gases

• Carbon Dioxide (CO₂): Accounts for nearly three-fourths of global greenhouse gas emissions. Mainly released through burning coal, oil, and natural gas, cement production, and deforestation. It can remain in the atmosphere for hundreds of years, making it the largest contributor to long-term warming.
• Methane (CH₄): Has over 80 times greater warming potential than CO₂ over a 20-year period. Major sources include livestock, rice cultivation, landfills, and fossil fuel extraction. Though it remains in the atmosphere for a shorter duration, it contributes significantly to near-term warming.
• Nitrous Oxide (N₂O): Released mainly from excessive use of nitrogen-based fertilizers, livestock manure, and industrial activities. Has a global warming potential nearly 270 times greater than CO₂ over a 100-year period.
• Fluorinated Gases (F-gases): Used in refrigeration, air conditioning, and semiconductor manufacturing. Though emitted in smaller quantities, they possess an extremely high global warming potential, often thousands of times greater than CO₂.

(ii) Burning of Fossil Fuels

The combustion of coal, petroleum, and natural gas is the largest source of greenhouse gas emissions worldwide. It is one of the major Causes of Climate Change.

Major contributing sectors include:

• Power Generation: Coal-fired thermal power plants remain a major source of CO₂ emissions.
• Transport: Road transport, aviation, and shipping depend heavily on petroleum fuels.
• Industries: Cement, steel, chemicals, and manufacturing industries consume large amounts of fossil fuels.

According to the International Energy Agency (IEA), the energy sector contributes around three-fourths of global greenhouse gas emissions. Fossil fuels still account for about 80% of global primary energy consumption, making energy transition a major climate challenge.

(iii) Deforestation and Land Use Change

Forests act as natural carbon sinks, absorbing atmospheric carbon dioxide through photosynthesis. Deforestation not only reduces this carbon absorption capacity but also releases stored carbon into the atmosphere. It is therefore one of the important Causes of Climate Change.

Major causes include:

• Expansion of agriculture
• Urbanisation
• Mining
• Infrastructure projects
• Illegal logging

According to the Food and Agriculture Organization (FAO), nearly 10 million hectares of forests are lost every year globally. Land-use change and deforestation contribute around 10–12% of global greenhouse gas emissions.

(iv) Agriculture and Livestock

Agriculture is both highly vulnerable to climate change and a significant contributor to greenhouse gas emissions.

Major sources include:

• Methane emissions from cattle and buffaloes (enteric fermentation).
• Methane released from flooded paddy fields.
• Nitrous oxide emissions from chemical fertilizers.
• Crop residue burning and manure management.

Indian Context

• Agriculture contributes significantly to India’s methane emissions due to its large livestock population and extensive rice cultivation.
• Sustainable agricultural practices such as natural farming, precision irrigation, and balanced fertilizer use can reduce emissions while maintaining productivity.

(v) Urbanisation and Unsustainable Consumption

Rapid urbanisation, industrial expansion, and changing lifestyles have substantially increased energy consumption and greenhouse gas emissions.

Major contributing factors

• Growing demand for electricity and air conditioning.
• High dependence on private vehicles.
• Energy-intensive construction using cement and steel.
• Increasing generation of municipal solid waste.
• Rising consumption of resource-intensive goods.

According to the United Nations, cities consume about 75–80% of the world’s energy and account for more than 70% of global CO₂ emissions. By 2050, nearly 68% of the global population is expected to live in urban areas, making sustainable urban planning essential for climate mitigation.

Major Causes and Associated Greenhouse Gases

Although climate change can occur naturally due to volcanic eruptions or variations in solar radiation, the IPCC has unequivocally concluded that the rapid warming observed since the mid-20th century is overwhelmingly caused by human activities, particularly greenhouse gas emissions from fossil fuels and land-use changes.

3. Scientific Evidence of Climate Change

Scientific observations collected over the past century provide unequivocal evidence that the Earth’s climate is warming at an unprecedented rate. Reports of the Intergovernmental Panel on Climate Change (IPCC), World Meteorological Organization (WMO), NASA, and the Copernicus Climate Change Service confirm that the recent changes in temperature, glaciers, oceans, and extreme weather events are primarily the result of human-induced greenhouse gas emissions.

Rise in Global Temperature

The most direct evidence of climate change is the continuous rise in the Earth’s average surface temperature.

• According to the WMO, 2024 was the warmest year on record, with the global average temperature about 1.55°C above the 1850–1900 (pre-industrial) average.
• The last ten years (2015–2024) have been the ten warmest years ever recorded.
• The IPCC AR6 concludes that human activities have caused approximately 1.1°C of global warming during the industrial era, with warming continuing thereafter.
• Higher temperatures increase the frequency and intensity of heatwaves, wildfires, droughts, and crop failures.

Increasing Atmospheric Greenhouse Gas Concentration

The concentration of greenhouse gases has reached its highest level in at least the last 800,000 years.

• According to the WMO Greenhouse Gas Bulletin, atmospheric carbon dioxide (CO₂) concentration exceeded 420 parts per million (ppm) in recent years, compared to about 280 ppm before the Industrial Revolution.
• Methane (CH₄) and Nitrous Oxide (N₂O) concentrations have also reached record highs.
• Rising GHG concentrations strengthen the greenhouse effect, trapping more heat in the atmosphere.
• The increase in greenhouse gases is the principal driver of global warming and long-term climate change.

Melting Glaciers and Polar Ice

Rapid melting of glaciers and polar ice sheets is a visible indicator of rising global temperatures.

• The Arctic is warming nearly four times faster than the global average.
• Greenland and Antarctica continue to lose ice mass every year, contributing to rising sea levels.
• According to the International Centre for Integrated Mountain Development (ICIMOD), the Hindu Kush Himalayan glaciers could lose up to 80% of their ice by 2100 under high-emission scenarios.
• Retreating Himalayan glaciers threaten the long-term water security of rivers such as the Ganga, Brahmaputra, and Indus, affecting millions of people.

Rising Sea Level and Ocean Warming

Oceans absorb nearly 90% of the excess heat generated by greenhouse gas emissions.

• Global mean sea level has risen by over 20 cm since 1900, with the rate of increase accelerating in recent decades.
• Thermal expansion of seawater and melting glaciers are the primary causes.
• Oceans also absorb around one-fourth of human-generated CO₂ emissions, leading to ocean acidification.
• Rising sea levels increase the risk of coastal flooding, erosion, saltwater intrusion, and displacement of coastal populations.

Increase in Extreme Weather Events

Climate change has increased the frequency, intensity, and duration of extreme weather events.

Observed Trends

• More frequent and intense heatwaves.
• Increased occurrence of heavy rainfall and flash floods.
• Longer and more severe droughts.
• Stronger tropical cyclones over warm oceans.
• Increased incidence of forest fires.

Indian Examples

• Frequent heatwaves across northern and central India.
• Increased intensity of cyclones such as Amphan (2020), Tauktae (2021), Biparjoy (2023), and Remal (2024).
• Recurrent floods in Assam, Bihar, Himachal Pradesh, and Kerala.

IPCC Future Projections

Climate models project that without rapid emission reductions, global warming and its impacts will intensify during the 21st century.

• According to the IPCC, limiting warming to 1.5°C requires rapid, deep, and sustained reductions in greenhouse gas emissions.
• Under current global policies, warming could reach around 3°C or more by the end of the century.
• Every additional fraction of a degree of warming significantly increases the risks to human health, ecosystems, food production, and economies.

The consistency of observations from multiple independent scientific institutions leaves little doubt that climate change is occurring and is predominantly driven by human activities. These changes directly threaten human health, livelihoods, food security, and sustainable development.

4. Effects of Climate Change on Human

Climate change is not merely an environmental challenge but a human development crisis. Rising temperatures, extreme weather events, and changing rainfall patterns directly affect human health, livelihoods, food production, water resources, and socio-economic stability. The adverse impacts are disproportionately borne by vulnerable groups such as farmers, women, children, the elderly, and economically weaker sections.

Impact on Human Health

Climate change poses one of the greatest threats to public health in the 21st century. Rising temperatures have increased the frequency and intensity of heatwaves, leading to heat exhaustion, heatstroke, dehydration, and higher mortality, particularly among the elderly and outdoor workers. Changes in temperature and rainfall have also expanded the spread of vector-borne diseases such as malaria, dengue, chikungunya, and Japanese encephalitis. In addition, air pollution resulting from fossil fuel combustion aggravates respiratory and cardiovascular diseases. Extreme weather events often damage healthcare infrastructure and disrupt the delivery of essential medical services, while prolonged exposure to climate-related disasters also contributes to mental health problems such as anxiety, depression, and post-traumatic stress disorder (PTSD).

Impact on Food and Nutritional Security

Climate change threatens agricultural productivity by altering rainfall patterns, increasing temperatures, and intensifying droughts, floods, and pest attacks. Reduced crop yields directly affect food availability and increase food prices, making nutritious food less affordable for poor households. Heat stress also reduces livestock productivity and fisheries, affecting the availability of milk, meat, and fish. In countries like India, where agriculture supports a large population, climate-induced crop failures can increase malnutrition, especially among children and pregnant women, thereby undermining food and nutritional security.

Impact on Water Security

Climate change has significantly altered the global water cycle, resulting in irregular rainfall, prolonged droughts, and more frequent floods. Melting glaciers initially increase river flows but eventually threaten the long-term availability of freshwater. Groundwater recharge is also affected due to changing precipitation patterns. Consequently, many regions experience severe drinking water shortages, reduced irrigation potential, and growing competition for water among households, agriculture, and industries. Water scarcity also increases the risk of water-borne diseases due to inadequate sanitation and poor water quality.

Impact on Livelihood and Economy

Climate-sensitive sectors such as agriculture, fisheries, forestry, tourism, and construction are highly vulnerable to climate change. Extreme weather events damage crops, infrastructure, industries, and transport networks, resulting in significant economic losses. Heat stress lowers labour productivity, particularly for workers engaged in outdoor occupations such as farming, mining, and construction. Repeated climate disasters also increase public expenditure on disaster relief, rehabilitation, and reconstruction, thereby placing additional pressure on national and state economies. Overall, climate change slows economic growth and widens income inequalities.

Impact on Human Settlements and Migration

Sea-level rise, coastal erosion, floods, cyclones, and prolonged droughts have made many regions increasingly unsuitable for habitation. Climate-related disasters destroy homes, roads, schools, and public infrastructure, forcing people to migrate in search of safer living conditions and employment opportunities. Such displacement often leads to overcrowding in urban areas, pressure on civic amenities, unemployment, and social conflicts. According to international estimates, millions of people are displaced every year due to weather-related disasters, making climate-induced migration an emerging humanitarian challenge.

Impact on Vulnerable Sections of Society

Although climate change affects everyone, its consequences are most severe for vulnerable populations. Small and marginal farmers suffer income losses due to crop failures, while poor households often lack the financial capacity to recover from disasters. Women and children face increased risks due to food insecurity, water scarcity, and health challenges, particularly in rural areas where they are primarily responsible for collecting water and fuel. Elderly people are more susceptible to heat-related illnesses, while coastal communities, tribal populations, and informal workers face greater livelihood insecurity because of their dependence on climate-sensitive natural resources. Thus, climate change deepens existing social and economic inequalities.

5. Impact of Climate Change in India

India is among the countries most vulnerable to climate change due to its long coastline, dependence on the monsoon, large agrarian population, Himalayan ecosystem, and high population density. Rising temperatures, erratic rainfall, glacier retreat, and frequent extreme weather events are increasingly affecting the country’s economy, environment, and human well-being.

Rising Heatwaves and Temperature Extremes

India has witnessed a significant increase in the frequency, intensity, and duration of heatwaves over the past decade. States such as Rajasthan, Gujarat, Bihar, Uttar Pradesh, Delhi, and Odisha frequently experience temperatures exceeding 45°C during summer. Heatwaves reduce labour productivity, increase electricity demand for cooling, strain healthcare systems, and lead to heat-related illnesses and deaths. Urban areas are particularly vulnerable due to the Urban Heat Island Effect, where concrete structures and reduced green cover trap more heat than surrounding rural areas.

Changes in Monsoon Pattern and Water Resources

Climate change has altered the Indian monsoon by making rainfall more erratic and unevenly distributed. While some regions experience intense cloudbursts and floods, others face prolonged dry spells and droughts. Such unpredictable rainfall affects agricultural planning, groundwater recharge, and drinking water availability. In addition, the retreat of Himalayan glaciers threatens the long-term water supply of major river systems such as the Ganga, Brahmaputra, and Indus, which support millions of people across northern India.

Threat to Agriculture and Food Security

Agriculture remains one of the most climate-sensitive sectors in India, employing nearly half of the country’s workforce. Rising temperatures, irregular rainfall, floods, droughts, and pest infestations have reduced the productivity of major crops such as rice, wheat, pulses, and maize. Livestock and fisheries are also adversely affected by heat stress and changing climatic conditions. These impacts reduce farmers’ incomes, increase rural distress, and pose serious challenges to national food security and nutritional well-being.

Increasing Frequency of Extreme Weather Events

India has experienced a noticeable rise in extreme weather events, including floods, cyclones, droughts, landslides, and cloudbursts. States such as Assam and Bihar frequently face severe floods, while the eastern and western coasts have witnessed high-intensity cyclones like Amphan (2020), Tauktae (2021), Biparjoy (2023), and Remal (2024). Similarly, the Himalayan states have experienced devastating landslides and flash floods. These disasters result in loss of lives, displacement of people, destruction of infrastructure, and significant economic losses.

Coastal Vulnerability and Sea-Level Rise

India’s coastline of over 7,500 km is increasingly threatened by rising sea levels, coastal erosion, storm surges, and saline intrusion into freshwater resources. Coastal cities such as Mumbai, Chennai, Kolkata, Kochi, and Visakhapatnam face growing risks of flooding and infrastructure damage. Coastal agriculture, fisheries, tourism, and livelihoods are also under pressure, while small island territories like Lakshadweep and the Andaman & Nicobar Islands remain highly vulnerable to long-term sea-level rise.

Impact on Public Health and Human Development

Climate change has intensified public health challenges by increasing heat-related illnesses, respiratory diseases, and vector-borne diseases such as dengue and malaria. Water scarcity and floods contribute to the spread of water-borne diseases, while food insecurity and declining agricultural productivity aggravate malnutrition. Climate-induced displacement and loss of livelihoods also increase poverty, migration, and social vulnerability, thereby affecting India’s progress towards the Sustainable Development Goals (SDGs).

Bihar Perspective

Bihar is particularly vulnerable to climate change due to its dependence on agriculture and its location in the flood-prone Gangetic plains. The state frequently experiences floods in north Bihar due to Himalayan rivers such as the Kosi, Gandak, Bagmati, and Kamla, while south Bihar often faces drought-like conditions because of erratic monsoon rainfall. Rising temperatures and changing rainfall patterns have adversely affected crop productivity, water availability, and rural livelihoods, making climate-resilient agriculture and disaster preparedness crucial for the state.

6. Government Initiatives to Address Climate Change

India has adopted a comprehensive strategy to combat climate change through mitigation (reducing greenhouse gas emissions) and adaptation (enhancing resilience to climate impacts). These initiatives align with the objectives of the Paris Agreement and India’s commitment to achieving Net Zero emissions by 2070.

National Action Plan on Climate Change (NAPCC), 2008

• Launched in 2008 to integrate climate concerns into national development planning.
• Provides the overall policy framework for climate change mitigation and adaptation.
• Comprises eight National Missions, including:
• National Solar Mission
  • National Mission for Enhanced Energy Efficiency
  • National Water Mission
  • National Mission for Sustainable Agriculture
  • National Mission for Green India
  • National Mission on Sustainable Habitat
  • National Mission for Sustaining the Himalayan Ecosystem
  • National Mission on Strategic Knowledge for Climate Change.

India’s Updated Nationally Determined Contributions (NDCs)

• Updated in 2022 under the Paris Agreement.
• Key commitments include:
• Reduce the emissions intensity of GDP by 45% by 2030 (from 2005 levels).
• Achieve about 50% of installed electric power capacity from non-fossil fuel sources by 2030.
• Create an additional carbon sink of 2.5–3.0 billion tonnes of CO₂ equivalent through forests and tree cover.
• India has also pledged to achieve Net Zero emissions by 2070.

National Green Hydrogen Mission

• Launched in 2023 with an outlay of ₹19,744 crore.
• Aims to make India a global hub for the production, utilisation, and export of Green Hydrogen.
• Targets production of 5 million metric tonnes (MMT) of Green Hydrogen annually by 2030.
• Expected to reduce dependence on imported fossil fuels and lower carbon emissions from hard-to-abate sectors.

PM-KUSUM Scheme

• Promotes the use of solar energy in agriculture.
• Supports installation of: Solar-powered irrigation pumps. Grid-connected solar power plants. Solarisation of existing agricultural pumps.
• Benefits include: Reduced diesel consumption. Lower greenhouse gas emissions. Additional income for farmers through surplus electricity generation.

National Mission for Green India (Green India Mission)

• One of the eight missions under the NAPCC.
• Focuses on: Increasing Forest and tree cover. Restoring degraded ecosystems. Enhancing carbon sequestration. Conserving biodiversity.
• Supports India’s target of creating an additional carbon sink under the Paris Agreement.

Mission LiFE (Lifestyle for Environment)

• Launched by Prime Minister Narendra Modi at COP26 and globally introduced with the United Nations in 2022.
• Promotes sustainable lifestyles through behavioural changes.
• Encourages citizens to: Conserve energy and water. Reduce waste generation. Adopt sustainable consumption practices. Minimise single-use plastics.
• Emphasises that climate action is a people’s movement, not merely a government responsibility.

Renewable Energy Expansion

• India is among the world’s fastest-growing renewable energy producers.
• Major initiatives include: National Solar Mission. Rooftop Solar Programme. PM Surya Ghar: Muft Bijli Yojana. Development of solar parks and wind energy projects.
• Renewable energy expansion helps reduce dependence on coal and supports India’s clean energy transition.

International Climate Leadership

• Founding member of the International Solar Alliance (ISA).
• Co-founder of the Coalition for Disaster Resilient Infrastructure (CDRI).
• Active participant in: Paris Agreement. UN Framework Convention on Climate Change (UNFCCC). Conference of Parties (COP) negotiations.
• Advocates the principle of Climate Justice and Common But Differentiated Responsibilities and Respective Capabilities (CBDR-RC), emphasizing equitable climate action while safeguarding the developmental needs of developing countries.

7. Conclusion

Climate change has emerged as one of the greatest challenges to human survival and sustainable development in the 21st century. Rising temperatures, extreme weather events, water scarcity, food insecurity, health risks, and climate-induced displacement demonstrate that its impacts extend far beyond the environment, directly affecting human lives and livelihoods. Scientific evidence clearly establishes that human activities are the primary driver of the current climate crisis, making urgent action indispensable.

For a developing country like India, the challenge lies in achieving rapid economic growth while ensuring environmental sustainability. India’s initiatives such as the National Action Plan on Climate Change (NAPCC), Mission LiFE, Green Hydrogen Mission, renewable energy expansion, and the Net Zero target of 2070 reflect its commitment to balancing development with climate responsibility. However, achieving long-term climate resilience will require global cooperation, technological innovation, sustainable lifestyles, climate-resilient infrastructure, and active public participation.

Ultimately, addressing climate change is not merely an environmental obligation but a collective responsibility towards present and future generations. As emphasized in Sustainable Development Goal (SDG) 13 – Climate Action, timely and coordinated efforts today will determine the quality of life and ecological security of humanity tomorrow.

BPSC Mains Practice Questions

1. “Climate change is no longer merely an environmental issue but a major challenge to human health, food security, water availability and economic development.” Discuss the major causes and effects of climate change with special reference to India.
2. Examine the vulnerability of India to climate change. Discuss its major impacts on agriculture, water resources, public health and livelihoods, with special reference to Bihar.
3. “Climate change mitigation and adaptation must go hand in hand for sustainable development.” Discuss the major initiatives taken by the Government of India to address climate change and assess their significance in achieving India’s climate goals.

Learn More About Climate Change

For official information on climate change, India’s climate policies, mitigation measures, and national climate action, visit the Ministry of Environment, Forest and Climate Change (MoEFCC), Government of India official website: Ministry of Environment, Forest and Climate Change – Climate Change