The greenhouse effect is the rise in the earth's global average temperature. The greenhouse effect occurs when gases in the Earth's atmosphere capture the sun's heat. This process warms the Earth significantly more than it would be without an atmosphere. The greenhouse effect is one of the factors that contribute to Earth being a desirable place to live. In this article, we will discuss the Greenhouse Effect which will be helpful for UPSC exam preparation.

What is a Greenhouse?

• A greenhouse is a structure with a transparent roof and walls, such as glass, that is used to grow plants that require regulated climatic conditions.
• The incident solar radiation passes through the glass roof and walls of a greenhouse and is absorbed by the floor and contents, which warm up and re-emit the energy as longer-wavelength infrared radiation (heat radiation).
• Because glass and other greenhouse wall materials do not transmit infrared radiation, it cannot escape by radiative transfer.
• Heat cannot escape through convection since the structure is not open to the atmosphere, hence the temperature inside the greenhouse rises. This is referred to as the 'greenhouse effect.'

What is a Greenhouse Effect?

• The greenhouse effect is a naturally occurring phenomenon that blankets and warms the earth's lower atmosphere, keeping it at a temperature suitable for living things to survive.
• Water vapour and greenhouse gases warm the Earth in the same way that greenhouses keep the air warm inside their chambers.
• Greenhouse gases play an important role in the Earth's cooling and warming cycles.
• The greenhouse effect is a process (similar to the green house effect) caused by greenhouse gases that naturally occur in the atmosphere. This process is critical in warming the Earth's surface and making it habitable.
• Human-caused greenhouse gas emissions, on the other hand, disrupt the natural balance and lead to increased warmth.

Incoming Energy

• The Sun emits energy, which is carried to Earth. Because the Sun is extremely hot, its energy is emitted in high-energy short wavelengths that pass through the Earth's atmosphere.

Absorption

• The Earth's atmosphere, clouds, and surface reflect approximately 30% of the Sun's energy directly back into space.
• The remaining energy from the Sun is absorbed by the Earth's system.

Emission

• The Earth returns energy to the atmosphere.
• Because the Earth is cooler than the Sun, the energy is emitted as infrared radiation with longer wavelengths than the incoming solar energy.

Role of Greenhouse Gases

• Greenhouse gases in the atmosphere absorb a significant portion of the long-wave energy (infrared radiation) emitted by the Earth's surface, preventing it from escaping the Earth's system.
• The energy is then re-emitted by greenhouse gases in all directions, warming the Earth's surface and lower atmosphere.

Human Role

• The concentration of greenhouse gases in the atmosphere has risen significantly over the last two centuries, owing primarily to human-caused carbon dioxide emissions from the combustion of fossil fuels and deforestation.
• This increase has exacerbated the natural greenhouse effect by trapping more of the Earth's energy.
• The Earth's surface temperature rises as a result of this change.

Causes of Greenhouse Effect

• The burning of Fossil fuels for domestic and industrial purposes releases carbon dioxide into the atmosphere which contributes to an increase in earth temperature.
• Plants and trees absorb carbon dioxide and emit oxygen. The cutting and burning of trees causes a significant increase in greenhouse gases, which raises the earth's temperature.
• Fertilizers: Nitrous oxide, a component of fertilisers, contributes to the greenhouse effect in the atmosphere.
• Industries: Industries and factories produce hazardous gases that are released into the atmosphere.
• Landfills: Landfills also emit carbon dioxide and methane, which contribute to greenhouse gas emissions.

Runaway Greenhouse Effect

• A runaway greenhouse effect occurs when the atmosphere of a planet contains enough greenhouse gas to block thermal radiation from leaving the planet, preventing it from cooling and having liquid water on its surface.
• A runaway greenhouse effect is defined as a limit on a planet's outgoing longwave radiation that is reached asymptotically due to higher surface temperatures evaporating a condensable species (often water vapour) into the atmosphere, increasing its optical depth.

Effects of Increased Greenhouse Gases

• Global Warming: This is the gradual rise in the average temperature of the Earth's atmosphere.
  • The main cause of this environmental problem is the increased production of greenhouse gases such as carbon dioxide and methane from the combustion of fossil fuels, as well as emissions from vehicles, industries, and other human activities.
• Ozone Layer Depletion: The ozone layer protects the earth from the sun's harmful ultraviolet rays. It can be found in the stratosphere's upper reaches.
  • The depletion of the ozone layer allows harmful UV rays to enter the earth's surface, which can cause skin cancer and drastically alter the climate.
  • The accumulation of natural greenhouse gases such as chlorofluorocarbons, carbon dioxide, methane, and others is the primary cause of this phenomenon.
• Smog and Air Pollution: Smog is created when smoke and fog combine. It can be caused by both natural and man-made factors.
  • Smog is caused by the accumulation of more greenhouse gases, such as nitrogen and sulphur oxides.
  • Automobile and industrial emissions, agricultural fires, natural forest fires, and chemical reactions are the major contributors to smog formation.
• Acidification of Water Bodies: As the total amount of greenhouse gases in the atmosphere has increased, most of the world's water bodies have become acidic.
  • The greenhouse gases combine with rainwater to form acid rain. This causes water bodies to become acidic.
  • Furthermore, rainwater carries contaminants with it and deposits them in rivers, streams, and lakes, causing acidification.

Greenhouse Effect Prevention

• Afforestation - Large-scale afforestation will aid in the absorption of carbon dioxide from the atmosphere. Green plants absorb carbon dioxide and release oxygen into the atmosphere, except at night.
• Conservation of Energy - Energy conservation can significantly reduce greenhouse gas emissions. It is because the majority of industrial processes and electricity production rely on the use of fossil fuels.
  • Energy conservation will be aided by increased use of alternative or renewable energy.
  • Switching to renewable energy sources such as solar, wind, and hydropower will minimize the consumption of fossil fuels.
  • This eventually reduces carbon dioxide emissions into the atmosphere.
• Policy Intervention - There is a greater need for government policy intervention, both in terms of developing appropriate regulations and enforcing them. International cooperation is critical to the success of such policies.
• Public Transportation - Various modes of transportation emit nearly 30% of greenhouse gases.
  • A well-developed public transportation system helps to reduce the number of automobiles on the road on a regular basis, thereby reducing harmful gas emissions.

Global Initiatives to Reduce Greenhouse Gas Emissions

• Intergovernmental Panel on Climate Change (IPCC): The World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) established IPCC in 1988 to provide policymakers with periodical assessments of the scientific basis of climate change, its impacts and future risks, as well as alternatives for adaptation and mitigation.
• United Nations Framework Convention on Climate Change: It was signed in 1992 and entered into force in 1994 to achieve "stabilisation of atmospheric greenhouse gas concentrations at a level that would prevent dangerous anthropogenic intervention with the climate system."
• The Kyoto Protocol (KP): It is an international agreement that was adopted at the 3rd COP in 1997. Its primary goal was to cut global greenhouse gas emissions by at least 5% compared to 1990 levels by 2012.
• CO2, CH4, N2O, Hydrofluorocarbons (HFCs), Perfluorocarbons (PFCs), and Sulfur Hexafluoride (SF6) were among the greenhouse gases to be reduced.

Greenhouse Gas Protocol

• The Greenhouse Gas Protocol (GHGP), established in 1990 is a collaborative effort of the World Resources Institute and the World Business Council for Sustainable Development (WBCSD).
• The GHG Protocol creates global standardised frameworks for measuring and managing greenhouse gas (GHG) emissions from private and public sector operations, value chains, and mitigation actions.
• It is an international accounting tool for government and business leaders to understand, quantify and manage greenhouse gas emissions
• GHG Protocol is developing guidelines, techniques, and online training to assist countries, cities, and organizations in tracking their progress toward their climate commitments.

Conclusion

The greenhouse effect is a process caused by greenhouse gases that naturally occur in the atmosphere. This process is critical in warming the Earth's surface and making it habitable. Human-caused greenhouse gas emissions, on the other hand, disrupt the natural balance and lead to increased warmth.

FAQs

Q1: What is the greenhouse effect?

Q2: Which gases are considered greenhouse gases?

Q3: How does human activity contribute to the greenhouse effect?

Q4: What is the impact of the enhanced greenhouse effect?

Q5: How can we mitigate the greenhouse effect?

MCQs

1. Which of the following is not a greenhouse gas?

a) Carbon dioxide

b) Methane

c) Oxygen

d) Nitrous oxide

2. What role do greenhouse gases play in the Earth’s climate?

a) They absorb ultraviolet radiation.

b) They trap heat and keep the Earth warm.

c) They reflect solar energy.

d) They cool the Earth's atmosphere.

3. Which sector is the largest contributor to greenhouse gas emissions?

a) Agriculture

b) Industry

c) Transport

d) Energy generation

4. What is the primary greenhouse gas responsible for global warming?

a) Methane

b) Nitrous oxide

c) Carbon dioxide

d) Water vapor

5. Which international agreement aims to limit greenhouse gas emissions?

a) Kyoto Protocol

b) Montreal Protocol

c) Paris Agreement

d) Geneva Convention

GS Mains Questions and Model Answers

Q1: Explain the role of the greenhouse effect in climate regulation.

Answer: The greenhouse effect plays a vital role in maintaining Earth’s temperature by trapping heat through gases like carbon dioxide, methane, and water vapor. Without it, the planet would be too cold for life. However, human activities have enhanced this natural effect, causing global warming. This leads to climate change, affecting ecosystems, agriculture, and weather patterns. Managing greenhouse gas emissions is critical for climate stability.

Q2: Discuss the impact of global warming on ecosystems and biodiversity.

Answer: Global warming has disrupted ecosystems by altering habitats, migration patterns, and food availability. Polar ice melt, coral bleaching, and forest degradation threaten biodiversity. Species unable to adapt to changing conditions face extinction. Ecosystem shifts also affect human livelihoods, especially in agriculture and fisheries. Conservation efforts and emission control are essential to mitigate these impacts.

Q3: What steps can governments take to address greenhouse gas emissions?

Answer: Governments can implement policies promoting renewable energy, enforce carbon taxes, and encourage energy efficiency. International cooperation through agreements like the Paris Accord is vital. National initiatives, such as afforestation and green infrastructure, can reduce emissions. Raising public awareness and supporting technological innovation are also essential for sustainable progress.

Previous Year Questions on  Greenhouse Effect

1. UPSC CSE 2020

Question: "Discuss the impact of the Paris Agreement on global efforts to tackle climate change." 

Answer: The Paris Agreement, adopted in 2015, aims to limit global temperature rise to below 2°C above pre-industrial levels. It encourages countries to set Nationally Determined Contributions (NDCs) and regularly update their goals. While the agreement promotes accountability, the lack of binding enforcement mechanisms is a concern. The shift toward renewable energy and green technologies reflects its influence, but challenges remain, such as disparities in emission reductions among nations. Effective implementation will depend on collective global action and long-term political commitment.

2. UPSC CSE 2019

Question: "What are the causes and consequences of global warming? Suggest measures to mitigate it." 

Answer: Causes: Global warming is primarily driven by human activities like fossil fuel burning, deforestation, and industrial emissions, increasing greenhouse gas concentrations.
Consequences: It results in rising temperatures, sea-level rise, extreme weather events, and loss of biodiversity. Ecosystem degradation and threats to food security further compound the issue.
Mitigation Measures: To combat global warming, efforts must focus on reducing emissions through renewable energy, improving energy efficiency, afforestation, and international cooperation. Public awareness and sustainable practices are crucial for long-term solutions.