Greenhouse Gas [GHG]

Greenhouse Gases [GHG] are atmospheric gases that trap infrared radiation, leading to the greenhouse effect.

According to the WMO's Greenhouse Gas Bulletin, the amount of GHGs in the atmosphere hit a new high last year (2020).

The yearly rate of increase was higher than the average for the period 2011-2020. This is true notwithstanding a 5.6 per cent reduction in fossil fuel emissions owing to pandemic-related restrictions in 2020.

List of Greenhouse Gases [GHG]

Carbon Dioxide

The most significant Greenhouse Gas [GHG] produced by anthropogenic activities is carbon dioxide (CO2). In 2020, it reached more than 149 per cent of pre-industrial levels.

• It is present in the atmosphere as part of the Earth's carbon cycle.
• Human activities impact the carbon cycle by discharging additional CO2 into the atmosphere and affecting the ability of natural sinks such as woodlands and soils to absorb carbon dioxide through carbon sequestration.
• While many natural sources emit carbon dioxide, anthropogenic emissions account for their increase in the environment.
• The use of fossil fuels like coal, natural gas, and oil for energy generation and transportation is the largest source of CO2 emissions by humans.
• Some industrial processes and land-use changes, on the other hand, produce CO2.

Methane

Currently, methane (CH4) levels are 262 per cent higher than the pre-industrial levels. Human activity is responsible for 50-65 per cent of global CH4 emissions.

• Anthropogenic methane emissions include natural gas infrastructure leaks and livestock production.
• Wetlands produce methane.
• Natural soil processes and chemical interactions in the atmosphere contribute to the removal of CH4 from the environment.
• CH4 has a 25-fold greater impact than CO2 over 100 years.

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Nitrous Oxide

N2O levels in the atmosphere are now 123 per cent higher than in 1750. Also, Human activities are responsible for around 40% of global N2O emissions.

• Combustion of fossil fuels, agriculture, managing wastewater, and industrial processes all contribute to the increasing levels of nitrous oxide in the atmosphere.
• Nitrous oxide is a naturally occurring gas in the atmosphere.
• Nitrous oxide molecules will be present in the atmosphere for an average of 114 years.
• One pound of N2O has 300 times the warming effect of one pound of CO2.

Fluorinated Gases

There are four forms of fluorinated gases. They are:

• Hydrofluorocarbons
• Perfluorocarbons
• Sulfur hexafluoride
• Nitrogen trifluoride

Unlike many other Greenhouse Gases [GHG], these gases have no natural sources. They are entirely the result of human activity.

• They are emitted through ozone-depleting substitutes like refrigerants and in a range of industrial processes such as aluminium and semiconductor manufacturing.
• Some fluorinated gases have disproportionately high global warming potentials compared to other GHGs. Therefore, even small amounts can have disproportionately large effects on global temperatures.
• They exist in the atmosphere for years. For instance, perfluorocarbons can stay in the atmosphere for up to 50.000 years.
• Fluorinated gases, like other long-living greenhouse gases, mix and spread throughout the atmosphere.
• They are the most potent and long-lasting GHGs created by human activity.

Since the beginning of the Industrial Revolution, human activities have increased atmospheric carbon dioxide levels by more than half, from 280 parts per million in 1750 to 419 parts per million in 2021.

Being the causative agents of unprecedented increases in global temperature and the concomitant changes in climate, it is imperative to take productive measures toward reducing anthropogenic Greenhouse Gas [GHG] emissions.

FAQs on Greenhouse Gas [GHG]

Q.1. Why Amazon Rainforests are failing to effectively trap a Greenhouse Gas [GHG] like carbon dioxide?

Parts of the Amazon rainforest have switched from being a carbon sink to a CO2 producer due to deforestation and decreased humidity in the region. For this reason, they are unable to trap carbon dioxide and similar Greenhouse Gases [GHG].

Q.2. What is the Kigali amendment? What Greenhouse Gas [GHG] was it legislated to prevent?

In Kigali in 2016, Montreal Protocol was amended to phase out Hydro Fluoro Carbon, a Greenhouse Gas [GHG] frequently used in the air-conditioning and refrigeration industries.

Q.3. What is the importance of Greenhouse Gas [GHG]?

The greenhouse effect is essential to the survival of life on Earth. Without Greenhouse Gas [GHG], the average temperature of the Earth would be -18°C, rather than 15°C as it is currently.

Q.4. What is Global Warming Potential? How is it linked to Greenhouse Gas [GHG]?

The heat absorbed by any Greenhouse Gas [GHG] in the atmosphere represented as a multiple of the heat absorbed by the same mass of carbon dioxide is referred to as the global warming potential. Sulfur Hexafluoride has the highest GPW, absorbing 22,800 times the heat absorbed by carbon dioxide.