Explain how the different greenhouse gases contribute to the raising global temperature. Add a note on the adverse effects of global warming and how to mitigate.

Contribution of Different Greenhouse Gases

Different greenhouse gases have varying abilities to trap heat and remain in the atmosphere. Their impact is often measured by their Global Warming Potential (GWP), which compares the amount of heat trapped by a unit mass of a gas to that of carbon dioxide (CO2) over a specific time horizon (usually 100 years).

Carbon Dioxide (CO2)

CO2 is the most significant anthropogenic greenhouse gas, accounting for approximately 76% of global GHG emissions. It’s primarily released through the burning of fossil fuels (coal, oil, and natural gas) for energy production, deforestation, and industrial processes. CO2 has a GWP of 1. It remains in the atmosphere for hundreds of years.

Methane (CH4)

Methane is a potent GHG with a GWP of 25 over 100 years, meaning it traps 25 times more heat per unit mass than CO2. Major sources include livestock farming, natural gas and petroleum systems, agricultural practices (rice cultivation), and decaying organic matter in wetlands. Although its atmospheric lifetime is shorter than CO2 (around 12 years), its immediate warming impact is substantial.

Nitrous Oxide (N2O)

Nitrous oxide has a very high GWP of 298. It’s emitted from agricultural soil management, industrial activities, fossil fuel combustion, and wastewater treatment. N2O remains in the atmosphere for over 114 years.

Fluorinated Gases (F-gases)

These are synthetic gases used in various industrial applications, including refrigeration, aerosols, and fire suppression. They have extremely high GWPs – for example, hydrofluorocarbons (HFCs) can have GWPs ranging from 124 to 14,800. Although emitted in smaller quantities, their potent warming effect makes them significant contributors to climate change. The Kigali Amendment to the Montreal Protocol aims to phase down HFCs.

Water Vapor (H2O)

While water vapor is the most abundant greenhouse gas, its concentration is largely determined by temperature. Increased temperatures lead to more evaporation, creating a positive feedback loop. It’s not directly controlled by human emissions, but warming caused by other GHGs increases water vapor in the atmosphere, amplifying the warming effect.

Greenhouse Gas	Chemical Formula	GWP (100-year horizon)	Major Sources	Atmospheric Lifetime
Carbon Dioxide	CO2	1	Fossil fuel combustion, deforestation	Hundreds of years
Methane	CH4	25	Livestock, natural gas leaks, rice paddies	12 years
Nitrous Oxide	N2O	298	Agriculture, industrial processes	114 years
HFCs	Various	124-14,800	Refrigeration, aerosols	1-270 years

Adverse Effects of Global Warming

Global warming is already manifesting in numerous adverse effects across the globe:

• Rising Sea Levels: Thermal expansion of water and melting glaciers/ice sheets contribute to rising sea levels, threatening coastal communities and ecosystems.
• Extreme Weather Events: Increased frequency and intensity of heatwaves, droughts, floods, and storms.
• Disruption of Ecosystems: Changes in temperature and precipitation patterns disrupt ecosystems, leading to species extinction and biodiversity loss. Coral bleaching is a prime example.
• Impacts on Agriculture: Altered growing seasons, water scarcity, and increased pest outbreaks threaten food security.
• Human Health Impacts: Increased heat-related illnesses, spread of vector-borne diseases, and respiratory problems due to air pollution.
• Economic Losses: Damage to infrastructure, reduced agricultural yields, and increased healthcare costs.

Mitigation Strategies

Mitigation involves reducing GHG emissions. Key strategies include:

• Transition to Renewable Energy: Shifting from fossil fuels to solar, wind, hydro, and geothermal energy.
• Energy Efficiency: Improving energy efficiency in buildings, transportation, and industry.
• Sustainable Transportation: Promoting public transport, cycling, and electric vehicles.
• Afforestation and Reforestation: Increasing forest cover to absorb CO2 from the atmosphere.
• Carbon Capture and Storage (CCS): Capturing CO2 emissions from industrial sources and storing them underground.
• Reducing Methane Emissions: Implementing measures to reduce methane leaks from natural gas infrastructure and livestock farming.
• International Cooperation: Strengthening international agreements like the Paris Agreement and providing financial and technological support to developing countries.

India’s Nationally Determined Contributions (NDCs) under the Paris Agreement include goals to reduce the emissions intensity of GDP and increase the share of non-fossil fuel energy sources.