Global Warming and Greenhouse Gases (GHGs) are among the most important topics in the People, Development and Environment (PDE) unit of UGC NET Paper 1. According to the session, questions from this topic have appeared in previous UGC NET examinations, making it an important area for aspirants preparing for upcoming attempts. The discussion explains the concepts using simple examples, memory tricks, and exam-oriented explanations to help candidates understand the topic more effectively.

In this article, we will understand the concepts discussed in the session, including atmospheric layers, ozone, ultraviolet (UV) rays, ozone formation, greenhouse gases, and the basics of global warming.

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Why Is Global Warming an Important Topic for UGC NET Paper 1?

According to the discussion, Global Warming is one of the recurring topics from the People, Development and Environment (PDE) unit.

The speaker recommends that aspirants preparing for UGC NET December 2026 should not skip this topic because it has been asked repeatedly in previous examinations and forms an important part of the Paper 1 syllabus.

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Understanding Earth’s Atmospheric Layers

The session begins by explaining the different layers of the Earth’s atmosphere.

According to the discussion, the atmosphere consists of the following layers:

• Troposphere

• Stratosphere

• Mesosphere

• Thermosphere

• Exosphere

The speaker introduces these layers before explaining the concepts of ozone, greenhouse gases, and global warming because understanding their location in the atmosphere helps students connect the overall concept.

Atmospheric Layer	Mentioned in Discussion
Troposphere	Contains “Bad Ozone” according to the session.
Stratosphere	Contains “Good Ozone.”
Mesosphere	Upper atmospheric layer discussed in sequence.
Thermosphere	Atmospheric layer above the mesosphere.
Exosphere	Outermost atmospheric layer.

Good Ozone vs Bad Ozone

One of the first concepts explained in the session is the difference between Good Ozone and Bad Ozone.

What is Good Ozone?

According to the discussion, Good Ozone is present in the Stratosphere.

The speaker explains that this ozone layer protects the Earth by preventing harmful ultraviolet (UV) rays from reaching the Earth’s surface.

Therefore, ozone present in the stratosphere is considered beneficial.

What is Bad Ozone?

According to the session, Bad Ozone is present in the Troposphere.

The discussion associates this layer with a higher concentration of greenhouse gases and pollution. For this reason, ozone present in the troposphere is referred to as “Bad Ozone” during the explanation.

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Difference Between Good Ozone and Bad Ozone

Feature	Good Ozone	Bad Ozone
Atmospheric Layer	Stratosphere	Troposphere
Role in Discussion	Protects Earth from harmful UV rays	Associated with pollution and greenhouse gases
Importance	Beneficial	Harmful according to the session

Understanding Ultraviolet (UV) Rays

The discussion explains that sunlight contains three types of ultraviolet (UV) rays.

These are:

• Ultraviolet A (UV-A)

• Ultraviolet B (UV-B)

• Ultraviolet C (UV-C)

The speaker also discusses their effects on human health.

UV-A Rays

According to the session, exposure to UV-A rays may affect the eyes and is associated with cataract-related problems.

UV-B Rays

The discussion states that prolonged exposure to UV-B rays may lead to skin-related problems, including skin cancer.

UV-C Rays

According to the explanation, UV-C rays are described as the most dangerous among the three. However, the session explains that these rays normally do not reach the Earth’s surface because they are blocked by the ozone layer present in the stratosphere.

Types of UV Rays

UV Ray	Mentioned Effect in Discussion
UV-A	Associated with cataract-related eye problems
UV-B	Associated with skin cancer
UV-C	Described as the most dangerous but normally blocked by the ozone layer

How Does the Ozone Layer Protect the Earth?

According to the discussion, the ozone layer present in the Stratosphere acts as a protective shield.

The speaker explains that this layer prevents harmful ultraviolet radiation from directly reaching the Earth’s surface, thereby protecting living organisms from excessive UV exposure.

This is why the ozone present in the stratosphere is described as “Good Ozone.”

How is Ozone Formed?

The discussion briefly explains the formation of ozone.

According to the session:

• Oxygen undergoes photolysis in the presence of sunlight.

• This process produces oxygen atoms.

• These oxygen atoms combine with oxygen molecules to form ozone.

The speaker introduces this explanation to help students understand the natural formation of the ozone layer before moving toward greenhouse gases and global warming.

Why Understanding Ozone is Important Before Studying Global Warming

According to the session, students should first understand:

• Atmospheric layers.

• Good Ozone.

• Bad Ozone.

• UV Rays.

• Ozone formation.

Only after understanding these concepts does the discussion move toward greenhouse gases and global warming, as all these topics are interconnected.

Key Takeaways from Part 1

Topic	Key Learning
Atmospheric Layers	Troposphere, Stratosphere, Mesosphere, Thermosphere, Exosphere
Good Ozone	Present in the Stratosphere and protects Earth from harmful UV rays
Bad Ozone	Present in the Troposphere and associated with pollution
UV Rays	UV-A, UV-B, and UV-C discussed in the session
Ozone Formation	Explained through oxygen photolysis in sunlight
Exam Importance	Global Warming is highlighted as an important UGC NET Paper 1 topic

What are Greenhouse Gases (GHGs)?

After explaining the ozone layer and atmospheric structure, the discussion introduces the concept of Greenhouse Gases (GHGs).

According to the session, greenhouse gases are naturally present in the Earth’s atmosphere and play an important role in maintaining a suitable temperature for life. The speaker explains that during the early stages of the Earth’s existence, nights were extremely cold. Greenhouse gases helped retain warmth, making the planet more suitable for living organisms.

However, the discussion highlights that excessive human activities have significantly increased the concentration of these gases, leading to global warming.

Why Do Greenhouse Gases Increase?

According to the session, human activities have accelerated the emission of greenhouse gases through:

• Increasing air pollution.

• Excessive use of automobiles.

• Widespread use of air conditioners and refrigerators.

• Burning of fuels and other materials.

• Industrial activities.

The discussion explains that as greenhouse gas emissions continue to rise, the Earth’s average temperature also increases.

How Does Global Warming Occur?

According to the discussion, the primary function of greenhouse gases is to trap heat.

When the concentration of greenhouse gases increases beyond natural levels:

• More heat gets trapped in the atmosphere.

• Less heat escapes back into space.

• The Earth’s average temperature gradually rises.

According to the speaker, this increase in the Earth’s temperature is referred to as Global Warming.

Greenhouse Effect Explained

The discussion explains the Greenhouse Effect using a simple example.

Imagine a greenhouse made of glass where plants are grown.

• Sunlight enters through the glass.

• Heat gets trapped inside.

• The trapped heat cannot easily escape.

• As a result, the temperature inside the greenhouse becomes higher.

According to the session, this trapping of heat is known as the Greenhouse Effect.

The same principle is used to explain how greenhouse gases retain heat within the Earth’s atmosphere.

Car Example Used in the Session

The speaker also uses a common real-life example to explain the greenhouse effect.

Imagine a car parked in direct sunlight for several hours.

When someone opens the door during the afternoon:

• The inside of the car feels much hotter than the outside air.

• Heat has accumulated inside the vehicle.

• The glass allows sunlight to enter but restricts heat from escaping quickly.

According to the discussion, this example helps students understand how trapped heat raises temperature, similar to the greenhouse effect occurring in the Earth’s atmosphere.

Difference Between Greenhouse Effect and Global Warming

Although the terms are closely related, the discussion treats them as separate concepts.

Greenhouse Effect	Global Warming
Heat gets trapped within the atmosphere.	Increase in Earth’s average temperature due to excessive greenhouse gases.
A natural process necessary for life.	Occurs when greenhouse gas concentrations increase significantly.
Maintains warmth.	Leads to excessive heating of the planet.

According to the session, greenhouse gases naturally help keep the Earth warm, but excessive emissions disturb this balance.

Major Greenhouse Gases Mentioned in the Session

The discussion identifies the following greenhouse gases:

• Carbon Dioxide (CO₂)

• Methane (CH₄)

• Chlorofluorocarbons (CFCs)

• Ozone (O₃)

• Nitrous Oxide (N₂O)

• Water Vapour

The speaker advises students to remember these gases because questions related to greenhouse gases are commonly asked in UGC NET Paper 1.

List of Greenhouse Gases

Greenhouse Gas	Mentioned in Discussion
Carbon Dioxide (CO₂)	Yes
Methane (CH₄)	Yes
Chlorofluorocarbons (CFCs)	Yes
Ozone (O₃)	Yes
Nitrous Oxide (N₂O)	Yes
Water Vapour	Yes

Why Are Greenhouse Gases Called Heat-Trapping Gases?

According to the session, greenhouse gases trap heat in the atmosphere in a manner similar to the glass panels of a greenhouse.

The discussion explains that:

• Solar radiation reaches the Earth.

• Heat is absorbed by the Earth’s surface.

• Greenhouse gases prevent a portion of this heat from escaping.

• As greenhouse gas concentrations increase, more heat remains trapped.

This continuous trapping of heat contributes to rising global temperatures.

Exam-Oriented Concepts from the Discussion

The speaker highlights several concepts that aspirants should remember for UGC NET examinations.

Concept	Exam Relevance
Greenhouse Effect	Frequently discussed in environmental science topics.
Global Warming	Important conceptual question.
Greenhouse Gases	Direct factual questions may be asked.
Good Ozone	Present in the Stratosphere.
Bad Ozone	Present in the Troposphere.

According to the session, understanding these basic concepts helps students answer both conceptual and objective questions.

Quick Revision

Before moving to advanced concepts, the discussion summarizes the following points:

• Greenhouse gases naturally help maintain Earth’s temperature.

• Human activities have increased greenhouse gas emissions.

• More greenhouse gases trap more heat.

• Trapped heat raises the Earth’s average temperature.

• This increase in temperature is called Global Warming.

• Carbon dioxide, methane, CFCs, ozone, nitrous oxide, and water vapour are discussed as greenhouse gases.

Key Takeaways from Part 2

Topic	Key Learning
Greenhouse Gases	Naturally present gases that help retain heat.
Human Activities	Increase greenhouse gas emissions.
Greenhouse Effect	Heat gets trapped within the atmosphere.
Global Warming	Rise in Earth’s average temperature due to excessive greenhouse gases.
Greenhouse Example	Glass greenhouse traps heat.
Car Example	Parked car demonstrates heat trapping.
Important GHGs	CO₂, CH₄, CFCs, O₃, N₂O and Water Vapour.

 

What is the Ozone Hole?

After explaining greenhouse gases and global warming, the discussion moves to the concept of the Ozone Hole.

According to the session, some greenhouse gases—particularly Carbon Dioxide (CO₂) and Chlorofluorocarbons (CFCs)—remain in the atmosphere for a long time. The speaker describes them as persistent pollutants, meaning they stay in the environment for an extended period.

The discussion explains that these persistent pollutants eventually reach the stratospheric ozone layer, where they weaken it over time.

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How Does the Ozone Hole Form?

According to the session, continuous pollution and increased greenhouse gas emissions weaken the ozone layer present in the stratosphere.

The discussion explains the process as follows:

• Greenhouse gases remain in the atmosphere for long periods.

• Some gases gradually reach the stratosphere.

• They weaken the protective ozone layer.

• As a result, an Ozone Hole develops.

The speaker mentions that the ozone hole was identified over the Antarctic region, making it an important fact for examination purposes.

Why is the Ozone Hole Harmful?

According to the discussion, the ozone layer acts as a protective shield against harmful ultraviolet radiation.

When the ozone layer becomes thinner or develops a hole:

• More ultraviolet rays can pass through.

• Greater UV exposure reaches the Earth’s surface.

• The risk of health-related problems increases.

The speaker connects this concept with the harmful effects of UV-A and UV-B rays discussed earlier in the session.

Health Effects Mentioned in the Discussion

According to the session, increased ultraviolet exposure due to ozone depletion may lead to:

• Cataract-related eye problems.

• Skin cancer (Melanoma).

The discussion explains that weakening of the ozone layer allows more harmful radiation to reach living organisms.

What Happens if Ozone Depletion Continues?

The speaker explains that if greenhouse gas emissions continue increasing without control:

• The ozone hole may expand.

• The protective ozone layer may become weaker.

• More ultraviolet radiation may reach the Earth’s surface.

According to the discussion, this highlights the importance of reducing pollution and greenhouse gas emissions.

Effects of Global Warming

The session also discusses the major impacts of increasing global temperatures.

According to the speaker, global warming can result in:

• Melting glaciers.

• Extreme weather conditions.

• Loss of biodiversity.

• Negative effects on agriculture.

• Increased environmental imbalance.

These impacts are presented as important conceptual points for UGC NET Paper 1 preparation.

Effects of Global Warming

Impact	Mentioned in Discussion
Melting Glaciers	Yes
Extreme Weather Events	Yes
Biodiversity Loss	Yes
Agricultural Impact	Yes
Rising Temperature	Yes

Global Warming vs Global Cooling

An important comparison discussed in the session is between Global Warming and Global Cooling.

According to the speaker:

Global Warming

Global warming refers to the increase in the Earth’s average temperature due to excessive greenhouse gas emissions.

Global Cooling

Global cooling is described as the opposite process, where the Earth’s average temperature decreases over a prolonged period.

The discussion introduces this comparison to help students distinguish between the two concepts in objective-type questions.

Difference Between Global Warming and Global Cooling

Global Warming	Global Cooling
Earth’s temperature increases.	Earth’s temperature decreases.
Associated with increasing greenhouse gases.	Associated with factors that reduce temperature according to the discussion.
Leads to melting glaciers.	Associated with colder climatic conditions.

Understanding the Albedo Effect

The discussion introduces another important examination concept—the Albedo Effect.

According to the speaker, snow-covered regions reflect a significant portion of incoming solar radiation.

The session associates this reflective property with Global Cooling, explaining that surfaces covered with snow reflect more sunlight and absorb less heat.

Students are advised to remember the relationship between Albedo and Global Cooling for examination purposes.

Aerosols and Global Cooling

According to the discussion, aerosols also play a role in global cooling.

The speaker specifically mentions that:

• Aerosol particles contribute to cooling.

• Black Carbon is discussed separately from other aerosols in the session.

This distinction is presented as an exam-oriented point that students should remember.

Persistent Greenhouse Gases

Another concept introduced during the discussion is persistent pollutants.

According to the speaker, certain greenhouse gases remain in the atmosphere for a very long time, making them more environmentally significant.

The discussion particularly highlights:

• Carbon Dioxide (CO₂)

• Chlorofluorocarbons (CFCs)

These gases are described as persistent because they continue affecting the atmosphere over extended periods.

Important Exam Concepts Covered

The speaker highlights several concepts that students should remember for UGC NET Paper 1.

Concept	Key Point
Ozone Hole	Identified over Antarctica according to the discussion.
Persistent Pollutants	CO₂ and CFCs remain in the atmosphere for long periods.
Albedo	Associated with global cooling.
Aerosols	Discussed as contributors to cooling (except Black Carbon as explained in the session).
Global Warming	Rise in Earth’s average temperature.
Global Cooling	Decrease in Earth’s average temperature.

Quick Revision

According to the discussion:

• Persistent greenhouse gases weaken the ozone layer.

• The ozone hole has been identified over Antarctica.

• Ozone depletion allows more harmful UV radiation to reach Earth.

• Global warming causes melting glaciers and biodiversity loss.

• Global cooling is discussed as the opposite of global warming.

• Albedo and aerosols are associated with cooling in the session.

Key Takeaways from Part 3

Topic	Key Learning
Ozone Hole	Develops as the ozone layer weakens.
Antarctica	Mentioned as the region where the ozone hole was identified.
Persistent Pollutants	CO₂ and CFCs remain in the atmosphere for long periods.
Global Warming	Causes rising temperatures and environmental impacts.
Global Cooling	Opposite of global warming according to the discussion.
Albedo Effect	Reflection of sunlight contributes to cooling.
Aerosols	Discussed in relation to global cooling.

Electromagnetic Radiation: Important Sequence for UGC NET

Towards the end of the session, the discussion introduces the electromagnetic spectrum, which is another important topic from the People, Development and Environment (PDE) unit.

According to the session, aspirants should remember the following sequence of electromagnetic radiations:

• Gamma Rays

• X-Rays

• Ultraviolet Rays

• Visible Light

• Infrared Rays

• Microwaves

• Radio Waves

The speaker emphasizes remembering this order because questions based on the sequence, wavelength, and frequency have appeared in competitive examinations.

Memory Trick for Electromagnetic Spectrum

To simplify memorization, the session provides the following trick:

GXUVIMR

Where:

• G – Gamma Rays

• X – X-Rays

• UV – Ultraviolet Rays

• V – Visible Light

• I – Infrared Rays

• M – Microwaves

• R – Radio Waves

According to the discussion, this mnemonic helps students quickly recall the correct sequence during the examination.

Electromagnetic Spectrum Sequence

Memory Trick	Radiation
G	Gamma Rays
X	X-Rays
UV	Ultraviolet Rays
V	Visible Light
I	Infrared Rays
M	Microwaves
R	Radio Waves

Wavelength vs Frequency Trick

The session also explains the relationship between wavelength and frequency.

According to the discussion:

• As frequency increases, wavelength decreases.

• As wavelength increases, frequency decreases.

The speaker advises students to remember that these two properties are inversely related, making it easier to solve sequence-based questions in UGC NET Paper 1.

Increasing Order of Wavelength

Based on the sequence discussed in the session, the increasing order of wavelength is:

Gamma Rays → X-Rays → Ultraviolet Rays → Visible Light → Infrared Rays → Microwaves → Radio Waves

According to the discussion, Gamma Rays have the shortest wavelength, while Radio Waves have the longest.

Increasing Order of Frequency

The session explains that because wavelength and frequency are inversely proportional, the increasing order of frequency is the reverse of wavelength.

Thus, according to the discussion:

Radio Waves → Microwaves → Infrared Rays → Visible Light → Ultraviolet Rays → X-Rays → Gamma Rays

Students are encouraged to use the GXUVIMR trick to answer such questions quickly.

PYQ-Based Concept Discussed in the Session

The speaker demonstrates how sequence-based questions can be solved using the mnemonic.

An example discussed in the session asks candidates to identify the correct increasing order of wavelength.

Using the GXUVIMR sequence, aspirants can arrange the radiations correctly without memorizing numerical values.

According to the speaker, understanding the sequence is more important than remembering exact wavelength values for objective-type questions.

Important Exam Tricks

The discussion summarizes several quick revision points for UGC NET aspirants.

Trick 1: Atmospheric Layers

Remember the order:

• Troposphere

• Stratosphere

• Mesosphere

• Thermosphere

• Exosphere

Trick 2: Good vs Bad Ozone

• Good Ozone → Stratosphere

• Bad Ozone → Troposphere

Trick 3: UV Rays

Remember the three ultraviolet rays:

• UV-A

• UV-B

• UV-C

According to the discussion, the stratospheric ozone layer protects the Earth from harmful ultraviolet radiation.

Trick 4: Greenhouse Gases

The greenhouse gases discussed in the session are:

• Carbon Dioxide (CO₂)

• Methane (CH₄)

• Chlorofluorocarbons (CFCs)

• Ozone (O₃)

• Nitrous Oxide (N₂O)

• Water Vapour

Trick 5: Global Warming vs Global Cooling

According to the discussion:

Global Warming	Global Cooling
Increase in Earth’s temperature	Decrease in Earth’s temperature
Associated with greenhouse gases	Associated with Albedo and aerosols discussed in the session

Trick 6: Electromagnetic Spectrum

Remember:

GXUVIMR

This single mnemonic helps solve several sequence-based questions.

Last-Minute Revision Table

Topic	Quick Revision
Atmospheric Layers	Troposphere → Stratosphere → Mesosphere → Thermosphere → Exosphere
Good Ozone	Present in Stratosphere
Bad Ozone	Present in Troposphere
UV Rays	UV-A, UV-B, UV-C
Greenhouse Gases	CO₂, CH₄, CFCs, O₃, N₂O, Water Vapour
Ozone Hole	Mentioned over Antarctica
Global Warming	Increase in Earth’s temperature
Global Cooling	Opposite of global warming according to the discussion
Albedo	Associated with cooling
Electromagnetic Spectrum	GXUVIMR

Conclusion

The session provides a comprehensive explanation of Global Warming, Greenhouse Gases (GHGs), Good and Bad Ozone, UV Rays, Ozone Hole, Global Cooling, Albedo, and the Electromagnetic Spectrum from an examination perspective. Rather than relying only on definitions, the discussion uses simple examples, memory tricks, and concept-based explanations to make the topics easier to understand.

For UGC NET Paper 1 aspirants, mastering these concepts can help answer both factual and conceptual questions from the People, Development and Environment (PDE) unit. Regular revision of the tricks, tables, and sequences discussed in the session can strengthen preparation for future examinations.

 

UGC NET Paper 1 PDE Global Warming and Greenhouse Gases FAQs