GHG UPSC Notes: Sources, Effects, & Measures to reduce GHGs

Greenhouse gases are gases that trap heat in the atmosphere. They allow sunlight to pass through the atmosphere, but they prevent heat from leaving the atmosphere. The major Greenhouse Gases present in the atmosphere are Carbon dioxide, methane, nitrous oxide, hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs) and ozone. Atmospheric gases such as carbon dioxide, methane, nitrous oxide (N2O), water vapour, and chlorofluorocarbons can trap incoming infrared radiation from the earth’s surface, resulting in the greenhouse effect. As a result, these gases are referred to as greenhouse gases, and the heating effect is referred to as the greenhouse effect.

This topic of Greenhouse Gases is important from the perspective of UPSC IAS Examinations which falls under the General Studies 1 ( Preliminary) and General Studies Paper 3 ( Mains) and particularly in the Indian Ecology and Environment Section. For further information and an explanation of the topic visit UPSC CSE Coaching here!

In this article we shall discuss the Greenhouse Gases. We shall have an insight into its major sources of emissions. We will also discuss how greenhouse gases lead to global warming and Climate Change.

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What is GHG Greenhouse Gas?

Greenhouse gases, which both absorb and emit infrared light, contribute to the greenhouse effect. These gases absorb a considerable amount of infrared radiation emitted by the Earth's surface. By doing so, they prevent a portion of this long-wave energy from escaping the Earth's system. Greenhouse gases then re-radiate the absorbed infrared energy back to the Earth's surface. The trapping of heat by these gases contributes to the warming of the planet. The re-emission of energy in all directions leads to a warming of the Earth's surface and lower atmosphere. Greenhouse gases are essential for maintaining the Earth's average surface temperature at 14 °C. Without the natural greenhouse effect, the average surface temperature would be about -18°C. These gases significantly impact the Earth's heat budget. The concentration of greenhouse gases plays a crucial role in influencing the global climate, underscoring their importance.

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Why the name GHGs?

Greenhouse gases are termed so after the ‘Greenhouses’, structures that trap the heat from the sun and which are used to grow fruits, vegetables and flowers. Trapping of heat does not allow the heat to escape thus causing a rise in temperature. Greenhouse gases act in a similar manner in the atmosphere by trapping the incoming infrared rays from escaping the atmosphere, thus resulting in rise in temperature on the surface of the earth.

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List of GHGs

The Greenhouse Gases ( GHGs) are given below in a tabular form for better understanding.

Particulars	Description
Water vapour	Water vapour is a variable gas in the atmosphere, and its concentration decreases with altitude. It is the most abundant greenhouse gas (GHG) in the earth’s atmosphere, but it only stays in the atmosphere for a short time. It is regarded as the most significant GHG. The amount of water vapour varies greatly depending on time, region, and altitude. Water vapour decreases as one moves from the equator to the poles. It may account for 4% of the air volume in the warm and wet tropics, while it may account for less than 1% of the air in the dry and cold desert and polar regions. This greenhouse gas is unique in that it absorbs both incoming and outgoing solar radiation.
Carbon dioxide (CO2)	Carbon dioxide is a very important meteorological gas because it is transparent to incoming solar radiation but opaque to outgoing terrestrial radiation. It is the most significant GHG and is produced both naturally and as a result of human activity. Since it is denser than air, its concentration is higher near the earth’s surface. It absorbs some terrestrial radiation and reflects some of it back to the earth’s surface. It is primarily to blame for the greenhouse effect. CO2 is naturally released into the atmosphere via volcanic eruptions and animal respiration. It is also emitted as a result of human activities such as deforestation and the use of fossil fuels for energy. Deforestation contributes to global warming by reducing the number of plants available to absorb carbon dioxide from the atmosphere CO2 remains in the atmosphere for a long time, increasing its impact. Humans have increased atmospheric CO2 concentration by 30% since the industrial revolution.
Methane ( CH4 )	After carbon dioxide, methane is the most significant greenhouse gas. By producing gobar gas or Bio gas from animal waste and biological matter, this gas emission can be minimized (methane). The main sources of methane are the decomposition of organic matter, such as in landfills and agriculture, as well as ruminant digestion (cows, goats etc). Because it can absorb more heat than CO2, it is a more potent GHG. However, the atmosphere contains much less of it. It is emitted from: Growing paddy, excreta of cattle and other livestock, termites, burning of fossil fuel, wood, landfills, wetlands, fertilizer factories.
Ozone ( O3)	Ozone is a crucial greenhouse gas. On the surface, though, it is very small. The majority of it is contained in the stratosphere, where it absorbs dangerous UV rays. Ozone is created at ground level when pollutants like NO2 react with volatile organic compounds in the presence of sunlight (tropospheric ozone).
Nitrous Oxide (N2O)	Nitrous oxide, also known as N2O, is a greenhouse gas. Nitric oxide and nitrogen dioxide emissions, also known as NO and NO2, are responsible for global cooling because they produce (OH) radicals, which break down methane molecules and thus offset the effects of GHGs. It is thought to be a very potent greenhouse gas that is produced in large quantities in the agricultural industry, particularly during the creation and application of organic fertilizers. Burning fossil fuels also results in its production.
Chlorofluorocarbons (CFCs)	These artificial substances were created for industrial applications, primarily in refrigerants and air conditioners. They are now governed by the Montreal Protocol because of their harmful impact on the ozone layer. The Montreal Protocol was aimed towards phasing out CFCs because of their contribution to ozone depletion. Additionally a greenhouse gas, this man-made substance has a much greater capacity to intensify the greenhouse effect than CO2.
Carbon Monoxide	Carbon monoxide is a transient greenhouse gas (it is less dense than air). It has an indirect radiative forcing effect by increasing the concentrations of methane and tropospheric ozone through chemical reactions with other atmospheric components, such as the hydroxyl radical, OH, that would otherwise destroy them. It eventually oxidizes to carbon dioxide through atmospheric natural processes.
Brown Carbon	Interest in brown carbon (organic carbon that absorbs light) as a potential contributor to climate change has grown. This type of organic carbon, distinguished by its light brownish hue, absorbs strongly in ultraviolet wavelengths but less so in visible ones. The breakdown products from burning biomass, a combination of organic compounds released from the soil, and volatile organic compounds released by vegetation are all examples of brown carbon. Black carbon is typically used to describe particles produced by impure combustion, such as soot and dust, while brown carbon is typically used to describe greenhouse gases.

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Sources and Emission of GHGs

The sources and emission of Greenhouse Gases are given as follows:

• Production of Electricity and Heat – The largest single source of emissions is the burning of coal, oil, and natural gas, which accounts for one-fourth of all emissions caused by human activity worldwide. It is the second-largest source of emissions behind transportation, accounting for about 27.5% of emissions worldwide.
• Buildings – This industry’s greenhouse gas emissions are caused by the production of energy on-site and the burning of fuels for cooking or heating.
• Industry – The industrial sector, which includes the production of goods and raw materials (such as cement and steel), food processing, and construction, is responsible for about one-fifth of all human-caused emissions worldwide. This sector also includes emissions from waste management activities as well as emissions from non-energy-related chemical, metallurgical, and mineral transformation processes.
• Agriculture, forestry, and other land uses – These are the main sources of greenhouse gas emissions. This is in spite of the fact that this sector excludes the carbon dioxide (CO2) that ecosystems remove from the atmosphere by storing it in biomass, decomposing organic matter, and soils.
• Deforestation – Deforestation is another major source of CO2. The carbon that trees normally store for photosynthesis is released when they are cut down for fuel or to make goods. According to the World Resources Institute, this process contributes to the annual release of up to 4.8 billion metric tons of carbon into the atmosphere.

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Fig: Sources of Greenhouse Gases

Greenhouse Gases ( GHGs) Calculator An effective, user-friendly tool for calculating and comparing GHG emissions across various modes is the GHG Calculator. It makes it possible to compare transportation costs overall, including environmental costs, between moving by road and rail on the basis of commodities. The tool’s goal is to assist everyone in making the right modal choice.

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Greenhouse Effect

• The greenhouse effect is a phenomenon associated with warming of the earth’s atmosphere. It results from the trapping of the long wave infrared radiations within the atmosphere of the earth.
• This warming of the earth’s surface keeps the Earth’s climate comfortable.

Working of Greenhouse Effect

• A greenhouse resembles a building that has glass walls accompanied with a glass roof.
• These greenhouses are used to grow fruits and vegetables.
• During the daytime, the infrared rays of the sun heats up the air inside the greenhouse and helps in the growth of plants.
• The greenhouse effect on the surface of the earth works in a similar manner. The greenhouse gases and water vapour trap the outgoing solar radiation similar to a glass roof of the greenhouse. These greenhouse gases, thus, raise the temperature of the earth.

Fig: Greenhouse Effect

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Global Warming and Climate Change

• The rise of greenhouse gases in our atmosphere is what causes the phenomenon of global warming and climate change. By increasing the heat in the atmosphere, greenhouse gases are responsible for the greenhouse effect, which ultimately leads to global warming.
  • A greenhouse gas’s potential to contribute to global warming depends on three factors: its GWP, a measure of how much of it is in the atmosphere at any given time.
• In recent years, the concentration of greenhouse gases in the atmosphere has soared to dangerous heights.
  • Prior to the Industrial Revolution, atmospheric CO2 varied over a 20,000-year period between 180 parts per million (ppm) during ice ages and 280 ppm during mild interglacial intervals. However, the amount of CO2 has increased by over 50% since the start of the Industrial Revolution in the 1750s. Emissions of non-CO2 greenhouse gases have also increased significantly since 1900.
• These greenhouse gases are opaque to the outgoing terrestrial radiation which traps this heat in the atmosphere and is directed back to the surface of the earth resulting in reabsorption. This discrepancy between the amount of heat entering and exiting the earth has been a major cause of global warming.

Fig: Greenhouse Gases and Global Warming

GHG and its Emission in India

• The country’s net greenhouse gas emissions for 2016 were 2.5 billion tonnes, according to India’s third Biennial Update Report, which was submitted to the United Nations Framework Convention on Climate Change (UNFCCC) in February 2021.
• Despite being a home to around one-sixth of the world’s population, India’s emissions from 1850 to 2019 were just about 4% of the total global emissions.
• However, the emissions of GHGs have risen by 335% since 1990. India is currently the world’s third largest emitter of greenhouse gases after China and the US.
• The major sources of greenhouse emissions in India are thermal power plants, paddy fields and livestock.
• The Center for Study of Science, Technology & Policy notes that although coal has remained a major source of electricity due to policies promoting economic development, rising demand, and aspirations for development, emissions from coal-based power generation are anticipated to gradually decline as a result of more efficient newly developed technologies, such as super-critical boilers for thermal power generation.
• Between 1990 and 2014, emissions from agriculture grew by 25%, mostly due to emissions from synthetic fertilisers (47%) and enteric fermentation from cattle (30%).
• India’s GDP expanded 357% between 1990 and 2014, but GHG emissions rose 180%, according to figures from the World Resources Institute.
• In 2014, India produced more greenhouse gases (GHGs) per unit of GDP than the rest of the world combined.
• India, on the other hand, has made great strides in launching a low-carbon economy across a number of sectors and promised in its Intended Nationally Determined Contribution (INDC) to cut GDP emissions intensity by 33–55% by 2030 from 2005 levels.
• India is on course to significantly outperform its 2030 goals despite having an aggressive 40% non-fossil fuel capacity share goal.

Fig: Concentration of GHGs

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Measures to reduce GHG emissions

There are some ways given below to reduce Greenhouse Gases emissions.

• The greenhouse gases that needed to be reduced included CO2, CH4, N2, hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulphur hexafluoride (SF6).
• Climate Change Framework Agreement of the United Nations: To achieve “stabilisation of atmospheric greenhouse gas concentrations at a level that would prevent dangerous anthropogenic intervention with the climate system,” it was signed in 1992 and came into effect in 1994.
• A large number of states will take part in the Transportation and Climate Initiative (TCI), which is dedicated to creating a cap-and-invest program aimed at reducing emissions from the transportation sector.
• Growing onshore wind and solar energy, as well as offshore wind power.
• lowering livestock methane emissions by enhancing manure processing.
• through pilot programs for climate-friendly land use, soil and vegetation can store carbon.
• incentives for reducing food waste and consuming foods that are good for the environment.
• The Kyoto Protocol (KP) is a global accord that was ratified in 1997 at the third COP. Its main objective was to reduce greenhouse gas emissions globally by at least 5% by 2012 compared to 1990 levels.
• Intergovernmental Panel on Climate Change (IPCC): The IPCC was established in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) to offer policymakers periodic assessments of the science behind climate change, its effects, and potential risks. It also offers alternatives for adaptation and mitigation.
• Fewer cars are on the road and less greenhouse gas is released into the atmosphere when people use public transportation, carpool, bike, and walk more frequently.
• electric grids should be cleaned. Using sources of energy like solar, wind, and hydro will gradually replace the use of coal, oil, and natural gas to produce electricity.
• Limiting global warming to well below 2 degrees Celsius, ideally to 1.5 degrees Celsius, in comparison to pre-industrial levels, is the objective set forth in the Paris Agreement.

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Conclusion

The atmosphere naturally traps some of the sun’s energy in the greenhouse effect, warming the planet just enough to support life. Despite being a natural cycle, humans have significantly increased the concentrations of greenhouse gases, which has increased the greenhouse effect’s overall impact. The human-caused enhancement of the greenhouse effect involves a number of gases. These gases include ozone, CFCs, nitrous oxide, methane, and carbon dioxide (CO2) (03). In order to warm the Earth’s surface and make it habitable, this process is essential. On the other hand, greenhouse gas emissions brought on by human activity upset the natural order and result in increased warmth.

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UPSC Previous Year Questions on GHG

1.Assess the impact of global warming on coral life systems with examples. [2019]

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