MEVE 011: Unit 04 - Climate Change

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 UNIT 4: CLIMATE CHANGE

4.1 Introduction

Climate change is one of the most serious global challenges today, caused largely by human activities. This unit focuses on how various factors such as urbanization, deforestation, desertification, agriculture, livestock management, and aerosols contribute to climate change. It also explores the environmental impacts and the steps being taken to mitigate these effects.

4.2 Objectives

The objectives of this unit are:

  • To understand how urbanization and deforestation contribute to climate change
  • To study the role of desertification, agriculture, and livestock in increasing greenhouse gases
  • To explore how aerosols affect the climate system
  • To learn about sustainable practices that can reduce environmental damage

4.3 Urbanization

Urbanization refers to the rapid growth of cities, which increases demand for energy, transportation, housing, and infrastructure. This often leads to increased emissions of greenhouse gases (GHGs) and environmental degradation.

4.3.1 Burning of Fossil Fuels

Urban areas depend heavily on coal, oil, and gas for energy, transportation, and industrial use. Burning these fuels releases large amounts of CO₂, CH₄, and NO₂, which trap heat in the atmosphere and contribute to global warming.

4.3.2 Waste Decomposition

Improper waste management in urban areas leads to methane (CH₄) emissions from landfills, a potent greenhouse gas. Wastewater also releases nitrous oxide and carbon dioxide.

4.3.3 Impact of Urbanization

  • 4.3.3.1 Loss of Green Cover: Urban expansion often leads to the cutting down of trees and vegetation, reducing the Earth’s capacity to absorb CO₂.
  • 4.3.3.2 Urban Heat Island (UHI) Effect: Urban areas are warmer than rural areas due to concrete structures, vehicles, and reduced greenery. This intensifies heat stress and energy consumption.
  • 4.3.3.3 Greenhouse Gas Emissions: Cities contribute significantly to GHGs due to industrial activity, transport, and construction.

4.3.4 Sustainable Cities

Steps like promoting public transport, green buildings, urban forests, solar energy, and waste recycling are essential to make cities more sustainable and climate-resilient.

4.4 Deforestation

Deforestation is the large-scale removal of forests for agriculture, construction, and development. Trees act as carbon sinks by absorbing CO₂. Their removal results in more CO₂ in the atmosphere, contributing to global warming. Deforestation also leads to biodiversity loss and disrupts rainfall patterns.

4.5 Desertification

Desertification is the degradation of land in arid and semi-arid regions, making it less productive. It is driven by both natural processes and human actions.

4.5.1 Processes and Drivers

  • 4.5.1.1 Soil Erosion: Removal of topsoil due to wind and water reduces soil fertility.
  • 4.5.1.2 Soil Acidification, Salinization, and Moisture Loss: Overuse of chemicals and irrigation leads to soil becoming unfit for crops.
  • 4.5.1.3 Increased CO₂ Levels: High CO₂ can reduce plant growth in already dry areas.
  • 4.5.1.4 Forest Fires: Fires caused by climate or human activity destroy large areas of vegetation, speeding up desertification.

4.6 Agriculture

4.6.1 Emissions

Agriculture contributes to GHG emissions through:

  • Use of fertilizers releasing N₂O
  • Paddy fields releasing methane
  • Land use changes like clearing forests for farming

4.6.2 Mitigation Practices

Climate-smart agriculture includes:

  • Efficient irrigation
  • Organic farming
  • Crop rotation
  • Agroforestry
    These practices help reduce emissions while maintaining food security.

4.7 Livestock Management

Animals like cows and sheep produce methane during digestion (enteric fermentation). Manure management also releases methane and nitrous oxide. Better feed, breeding, and waste management can reduce these emissions.

4.8 Aerosols

Aerosols are tiny particles or droplets suspended in the atmosphere. They affect climate by interacting with sunlight and clouds.

4.8.1 Pathways and Radiative Forcing

Aerosols can reflect sunlight (cooling) or absorb heat (warming). Their overall impact on radiative forcing depends on their type and amount.

4.8.2 Lifetime

Aerosols have short atmospheric lifespans—from a few days to a few weeks, unlike GHGs, which can persist for decades.

4.8.3 Sources of Aerosols

  • 4.8.3.1 Industrial Dust: From factories and construction
  • 4.8.3.2 Carbonaceous Aerosols: Like black carbon from burning wood, coal, or diesel
  • 4.8.3.3 Nitrate Aerosols: From agricultural and vehicular NOx emissions, contribute to cooling
  • 4.8.3.4 Other Primary Aerosols: Such as sea salt, pollen, and desert dust
  • 4.8.3.5 Secondary Organic Aerosols (SOA): Formed by chemical reactions in the atmosphere

4.8.3.6 Effects of Aerosols

Aerosols:

  • Reduce sunlight (global dimming)
  • Affect monsoon patterns
  • Cause respiratory and cardiovascular health issues
  • Influence cloud formation and rainfall

4.9 Let Us Sum Up

This unit explained how several human and natural activities are linked to climate change. Urbanization, deforestation, desertification, agriculture, livestock, and aerosols all contribute in different ways to the rise in global temperatures and environmental damage. The unit also highlighted the importance of sustainable practices like green urban planning, clean agriculture, and better waste management in mitigating these effects. Understanding these factors helps in building a more climate-resilient future.

 

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