The general conditions of an area which are usually there or the weather conditions for a longer period in a particular area are referred to as the climate of that region.

The climate varies according to the locations. It is changing now over the years due to some human activities and also naturally. In some places, it may lead to the extinction of certain species.

The average weather of a place for many years is called climate. Climate takes millions of years to change whereas weather can change in a couple of hours. Our planet has seen multiple climatic variations since its birth.

Change in Climate

• The climate of our surroundings in which we live has been present for almost the last 10,000 years with minor fluctuations.
• Glacial and Interglacial periods are there. High altitudes and high latitudes show features and advances of glaciers.
• The occurrence of warm and cold periods can also be seen from the examples of sediment deposits in glacial lakes.
• The rings found in the trees also reveal clues about wet and dry periods.
• All this evidence suggests that change has occurred for many years and it is a natural and continuous process.
• India has also a history of alternate dry and wet periods. Some archeological findings show that the desert of Rajasthan has a wet and cool climate around 8,000 B.C. This region was also a center of Harappan civilization from 2,000 to 1700 B.C.

• From the viewpoint of the geological past, it has been seen that through the Cambrian, Ordovician and Silurian periods, the earth was warm about 500-300 million years ago.
• Glacial and interglacial periods occurred during the Pleistocene epoch. The last and major glacial period was about 18000 years ago.
• The interglacial period at present started about 10,000 years ago.

Some Effects of Climate Change

• The rise in global temperature
• The rise in sea level
• Shrinking of ice sheets
• Warming of oceans
• Declining of ice at Arctic Sea
• The retreat of the glaciers
• Decreasing snow cover
• Acidification of Ocean
• Extreme and disastrous natural events

The Climate in the Recent Past

• Variability is like a feature of the climate which occurs all the time.
• Extreme weather events were witnessed by the nineties decade of the last century.
• During the 1990s, the world recorded the warmest temperature of the century and some of the worst floods.
• An example of such variability is from 1967-1977, when the worst devastating drought occurred in the Sahel region, the south of the Sahara desert.
• A severe drought has also been seen in the southwestern Great Plains of the United States during the 1930s. It is described as a dust bowl.

• Records of crop yield or crop failures, floods, and migration of people also tell about the changes occurring in the climate and its effect in the past years.
• Europe has witnessed significant episodes of warm, wet, cold, and dry periods during the tenth and eleventh periods when the Vikings settled in Greenland.
• From 1550 to about 1850, there was a “Little Ice Age” in Europe.
• But during 1885-1940, an upward trend was shown in the world temperature.
• The rate of increase in temperature slowed down after 1940.

Causes of Climate Change: Astronomical Causes

There are many causes of climate change. It can be divided into multiple heads-

• Astronomical causes can be referred to as changes in solar output which is associated with sunspot activities.
• Sunspots are dark patches on the sun that can increase and decrease cyclically.
• Due to the increase in the number of sunspots, the weather is cooler and wetter and there occurs great storminess. If there is a decrease in the number of sunspots, it is associated with the warm and drier conditions on Earth. But these statements are only according to the meteorologists, it is not statically significant yet.
• Milankovitch oscillations is also an astronomical theory, which describes the characteristics of the cycles of variations occurring in the earth’s orbital around the sun. The wobbling of the earth and changes in the earth’s axial tilt is also described in it.
• All these effects of Milankovitch oscillations theory alter the insolation from the sun received by the earth, which results in the change of the climate.

Causes of Climate Change: Volcanism

• Climate change can also be done by Volcanism. A lot of aerosols are thrown out in the atmosphere during the volcanic eruptions.
• These aerosols remain in the atmosphere for a considerable time which then reduces the sun’s radiation reaching the Earth’s surface.
• An example of this type of climate change is Pinatoba and El Cion volcanic eruptions, due to which the average temperature of Earth fell to some extent for some years.

Causes of Climate Change: Greenhouse Effect

• The most important anthropogenic effect on climate change is the increasing concentration of greenhouse gas in the atmosphere which is likely to cause global warming.
• Due to the presence of greenhouse gases like carbon dioxide, Chlorofluorocarbons, etc the atmosphere behaves like a greenhouse, that’s why they are called greenhouse gases.
• Some of the solar radiation that reaches the earth is trapped due to the greenhouse gases present on the earth, thus the heating due to this reason is called the Greenhouse Effect.
• A greenhouse is a place used in cold areas for preserving heat. It is made up of glass, and it allows the radiation coming from the sun and prevents the longwave radiation of the incoming sun rays, which causes the temperature inside the glasshouse to be warmer than outside.
• Another example of the greenhouse effect is that we feel warmer inside a bus or a car where windows and doors are closed.
• The gases which absorb the longwave radiation of the sun are known as greenhouse gases.

The Concentration of Greenhouse Gases (GHGs)

• Some of the primary concerns of Greenhouse gases are Carbon Dioxides (CO2), Chlorofluorocarbons (CFCs), Methane (CH4), Nitrous Oxide (N2O), and Ozone (O3).
• Other gases like Nitric Oxide (NO) and carbon monoxide (CO) easily react with greenhouse gases and affect their concentration in the atmosphere.
• Carbon Dioxide is the gas present in abundance in the atmosphere.

Effects of Greenhouse Gases

The factors that describe the effectiveness of a greenhouse gas molecule are –

(i) Magnitude of the increase in its concentration,

(ii) Lifetime of its presence in the atmosphere,

(iii) Wavelength of radiation that a gas absorbs.

• The highly effective gas of the GHGs present in the atmosphere is Chlorofluorocarbons (CFCs).
• Ozone which when present in the stratosphere absorbs violet radiation is very effective in absorbing the terrestrial radiation when present in the lower troposphere.
• Another point worth noting is that the more time the greenhouse gas molecule remains in the atmosphere, the longer it will take for the earth’s atmosphere to recover from the climatic changes.

• Carbon Dioxide is the greenhouse gas that is present in the largest concentration in the atmosphere. It comes mainly from the combustion of fossil fuels (oil, gas, and coal). Forests and oceans act like sinks of carbon dioxide. Forests absorb carbon dioxide and use it for their growth.
• So, deforestation due to changes in land use can cause greater harm and increase the concentration of CO2 in the atmosphere.
• The time required to consume the carbon dioxide by the sinks is about 20-50 years. But it is rising at about 0.5 per cent annually.
• Chlorofluorocarbons (CFCs) are nothing but the results of human activities.

Ozone that occurs in the stratosphere is formed by ultraviolet rays. Ultraviolet rays convert oxygen into ozone. The CFCs drifted into the stratosphere thus destroying the atmosphere. Large depletion has been seen in Antarctica over the years. The ‘ozone hole’ is a term given to the depletion of ozone concentration.

Global Warming

• The Greenhouse effect is a collective term said to the processes that warm the atmosphere and lead to Global Warming.
• Global Warming is caused by GHGs which entraps the heat on the earth.
• Due to Global Warming, the earth is turning into a Greenhouse.

Steps Taken to Reduce Greenhouse Emissions

Important initiatives are taken to control the Greenhouse Emissions into the atmosphere.In 1997, the Kyoto Protocol was an important one considering greenhouse emissions. This protocol came into effect in 2005. It bounds different countries to reduce their emissions of greenhouse gases in the atmosphere.

Different organizations working in this field suggest some ways to reduce emissions - (i) Installation of the solar photovoltaic systems, (ii) Policies for reduction of air travel, (iii) Insulation and lighting systems in Buildings should be upgraded and (iv) Efficient Cooling systems should be installed.

FAQs

Question. What are the main causes of climate change?

Question. What are the primary greenhouse gases responsible for climate change?

Question. How do human activities influence climate change?

Question. What are the effects of climate change?

Question. How can climate change be mitigated?

MCQs

1. Which of the following is the main human-made cause of climate change?

A) Volcanic eruptions

B) Solar radiation changes

C) Deforestation and burning fossil fuels

D) Changes in Earth’s orbit

2. Which of the following is a greenhouse gas?

A) Oxygen

B) Methane

C) Nitrogen

D) Argon

3. What is the primary effect of melting glaciers and ice caps due to climate change?

A) Sea level rise

B) Increased agricultural productivity

C) Decrease in ocean salinity

D) Decrease in global temperature

4. Which of the following is an impact of climate change on weather patterns?

A) More frequent and intense storms

B) Cooling of ocean temperatures

C) Decrease in extreme weather events

D) Increase in rainfall in deserts

5. Which international agreement aims to mitigate climate change by limiting global temperature rise?

A) Kyoto Protocol

B) Paris Agreement

C) Montreal Protocol

D) Earth Summit

GS Mains Questions and Model Answers

Q1: Analyze the role of human activities in driving climate change and the subsequent effects on ecosystems.

Answer: Human activities, particularly burning fossil fuels, deforestation, and industrial emissions, have led to a dramatic increase in the concentration of greenhouse gases in the atmosphere, primarily carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). These gases trap heat in the atmosphere, leading to the greenhouse effect and a rise in global temperatures. As a result, climate patterns are undergoing significant changes, including more frequent heatwaves, intense storms, and flooding. The melting of glaciers and polar ice caps is contributing to rising sea levels, which threaten coastal ecosystems and infrastructure. Ecosystems are disrupted, with species facing habitat loss and extinction due to changing temperature and precipitation patterns. Agricultural productivity is also affected, with changes in rainfall leading to droughts and flooding, impacting food security and rural economies. The interconnectedness of human activities and climate change highlights the need for sustainable development practices, including the transition to renewable energy, afforestation, and more efficient use of resources.

Q2: What are the socio-economic impacts of climate change, particularly in developing countries?

Answer: Climate change disproportionately affects developing countries, which are more vulnerable due to their limited resources to adapt and mitigate its effects. Rising sea levels threaten coastal populations, particularly in countries like Bangladesh and India, where millions live in low-lying areas. Agriculture in these regions is highly sensitive to climate change, with droughts and floods leading to crop failures, food shortages, and loss of livelihoods. Water scarcity is becoming a critical issue in many parts of the world, affecting both human consumption and agricultural productivity. The health impacts of climate change are also severe, with the spread of diseases like malaria and dengue fever in warmer climates. Moreover, extreme weather events, such as cyclones and storms, cause widespread damage to infrastructure, leading to loss of homes, livelihoods, and economic assets. These impacts exacerbate poverty, increase migration pressures, and create barriers to achieving sustainable development. Addressing these challenges requires international cooperation and adaptation strategies, including the transfer of green technologies, capacity building, and financial support for vulnerable regions.

Q3: What are the challenges in implementing global climate change agreements and how can they be overcome?

Answer: Implementing global climate change agreements, such as the Paris Agreement, faces several challenges. These include:

• Differing national interests: Countries have varying levels of development, economic priorities, and capacities to tackle climate change, which creates barriers to reaching a consensus. Developed countries have historically contributed more to emissions, while developing countries argue for financial and technical support to address climate change.
• Funding issues: The cost of mitigation and adaptation efforts is enormous, and mobilizing climate finance for developing nations remains a key challenge. The $100 billion per year target for climate finance set by developed nations has not been met consistently.
• Lack of enforcement mechanisms: While climate agreements set ambitious targets, they lack robust enforcement mechanisms, making compliance challenging. Countries are encouraged to voluntarily submit their Nationally Determined Contributions (NDCs), but there is no global penalty for non-compliance.
• Political will: Domestic political considerations often take precedence over long-term environmental goals, especially in countries heavily reliant on fossil fuel industries.

To overcome these challenges, it is essential to enhance global cooperation, increase climate finance, and implement transparent reporting systems to hold countries accountable. Capacity building and technology transfer to developing nations can also support their efforts to transition to low-carbon economies.

Previous Year Questions on Causes of Climate Change and Its Effects

1. UPSC 2020

Question: "Discuss the causes and effects of climate change and its impact on human health."

Answer: This question required candidates to analyze the causes of climate change, particularly human activities, and the effects on ecosystems and human health, including the spread of diseases.

2. UPSC 2019

Question: "Examine the impact of climate change on agriculture in developing countries."

Answer: The question focused on understanding how climate change impacts agriculture in developing countries, affecting food security, livelihoods, and economic stability.