Model Answer
0 min readIntroduction
The Earth’s atmosphere is undergoing significant alterations due to anthropogenic activities, impacting global climate patterns. These changes, ranging from increased greenhouse gas concentrations to aerosol pollution, are fundamentally altering the planet’s energy balance. Understanding these modifications, particularly the greenhouse effect, is crucial for comprehending the current climate crisis and formulating effective mitigation strategies. The Intergovernmental Panel on Climate Change (IPCC) reports consistently highlight the dominant role of human activities in driving these atmospheric changes.
Human-Induced Changes in the Atmosphere
Human activities have significantly altered the composition of the atmosphere. Key changes include:
- Greenhouse Gas Emissions: Burning of fossil fuels (coal, oil, and natural gas), deforestation, and industrial processes release carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and fluorinated gases.
- Aerosol Pollution: Industrial activities, biomass burning, and volcanic eruptions release particulate matter (aerosols) like sulfates, nitrates, black carbon, and dust.
- Ozone Depletion: Emission of chlorofluorocarbons (CFCs) and other ozone-depleting substances (ODS) led to thinning of the ozone layer, particularly over Antarctica. (Montreal Protocol, 1987 addressed this).
- Land Use Changes: Deforestation and agricultural practices alter surface reflectivity (albedo) and evapotranspiration rates, impacting regional climate.
- Acid Rain: Emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) from industrial sources contribute to acid rain, affecting ecosystems.
The Greenhouse Effect
The greenhouse effect is a natural process that warms the Earth’s surface. Shortwave radiation from the sun penetrates the atmosphere and warms the Earth. The Earth then emits longwave radiation (infrared radiation). Greenhouse gases in the atmosphere absorb some of this infrared radiation and re-emit it in all directions, including back towards the Earth’s surface, thus trapping heat. This process is analogous to the glass roof of a greenhouse.
However, increased concentrations of greenhouse gases due to human activities enhance this effect, leading to a warming trend. The primary greenhouse gases and their Global Warming Potential (GWP) are:
| Greenhouse Gas | Chemical Formula | GWP (100-year horizon) |
|---|---|---|
| Carbon Dioxide | CO2 | 1 |
| Methane | CH4 | 25 |
| Nitrous Oxide | N2O | 298 |
| Hydrofluorocarbons (HFCs) | Various | 1430 (average) |
Impact of the Greenhouse Effect
The enhanced greenhouse effect has numerous impacts:
- Global Warming: Average global temperatures are rising, leading to heatwaves and altered weather patterns.
- Sea Level Rise: Thermal expansion of water and melting of glaciers and ice sheets contribute to rising sea levels, threatening coastal communities.
- Extreme Weather Events: Increased frequency and intensity of extreme weather events like hurricanes, droughts, floods, and wildfires.
- Ocean Acidification: Absorption of excess CO2 by oceans leads to acidification, harming marine ecosystems.
- Biodiversity Loss: Changes in climate and habitat loss threaten species survival.
- Impact on Agriculture: Altered rainfall patterns and increased temperatures affect crop yields and food security.
Conclusion
Human-induced changes to the atmosphere, particularly the intensification of the greenhouse effect, pose a significant threat to the planet. Addressing this challenge requires a concerted global effort to reduce greenhouse gas emissions through transitioning to renewable energy sources, improving energy efficiency, and promoting sustainable land management practices. International cooperation, as exemplified by the Paris Agreement (2015), is essential for mitigating the impacts of climate change and ensuring a sustainable future.
Answer Length
This is a comprehensive model answer for learning purposes and may exceed the word limit. In the exam, always adhere to the prescribed word count.