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Climate change refers to long-term shifts or alterations in the average weather patterns on Earth. Unlike weather, which describes short-term atmospheric conditions such as rain, sunshine, or temperature on a given day, climate is the average of these conditions over decades or centuries. Understanding climate change is crucial because it affects ecosystems, human health, agriculture, water resources, and the overall stability of the environment.
In Earth Sciences and Environmental Science, studying climate change helps us evaluate how natural processes and human activities influence the planet's climate system. This knowledge guides us in developing strategies to reduce harmful impacts and adapt to changes.
Global warming is the observed increase in Earth's average surface temperature over the past century. This rise is primarily due to the accumulation of certain gases in the atmosphere that trap heat. To understand this, we first need to explore how energy from the sun interacts with the Earth.
Solar radiation reaches Earth, warming its surface. The Earth then emits energy back as infrared radiation. However, some gases in the atmosphere absorb and re-emit this infrared radiation, effectively trapping heat and warming the planet. This natural process is called the greenhouse effect.
Human activities have increased the concentration of these heat-trapping gases, enhancing the greenhouse effect and causing global warming.
Greenhouse gases (GHGs) are atmospheric gases that absorb infrared radiation and trap heat. The major greenhouse gases include:
Each gas differs in how long it stays in the atmosphere and how strongly it traps heat. This is measured by the Global Warming Potential (GWP), which compares the warming effect of a gas relative to CO2 over a 100-year period.
| Gas | Sources | Atmospheric Lifetime | Global Warming Potential (GWP) |
|---|---|---|---|
| Carbon dioxide (CO2) | Fossil fuel combustion, deforestation | ~100 years | 1 (reference) |
| Methane (CH4) | Agriculture, landfills, wetlands | 12 years | 28-36 |
| Nitrous oxide (N2O) | Fertilizers, industry, biomass burning | 114 years | 265-298 |
| Fluorinated gases | Refrigerants, industrial processes | Up to thousands of years | Thousands to tens of thousands |
Climate mitigation involves actions to reduce or prevent the emission of greenhouse gases, aiming to limit global warming and its harmful effects. Effective mitigation strategies include:
graph TD A[Climate Mitigation] --> B[Energy] A --> C[Land Use] A --> D[Policy & Agreements] B --> E[Renewable Energy] B --> F[Energy Efficiency] C --> G[Afforestation] C --> H[Soil Carbon Storage] D --> I[Paris Agreement] D --> J[National Policies]
Scientists monitor climate change through several key indicators:
To fully understand climate change, it is important to distinguish between:
Step 1: Calculate CO₂ emissions from coal-based electricity:
\( CF = E \times EF = 1000 \, \text{kWh} \times 0.9 \, \text{kg CO}_2/\text{kWh} = 900 \, \text{kg CO}_2 \)
Step 2: Calculate CO₂ emissions from solar power (zero emissions):
\( CF = 1000 \times 0 = 0 \, \text{kg CO}_2 \)
Step 3: Calculate emission reduction:
\( 900 - 0 = 900 \, \text{kg CO}_2 \)
Answer: Replacing 1000 kWh of coal electricity with solar saves 900 kg of CO₂ emissions annually.
Step 1: Calculate radiative forcing \(\Delta F\):
\[ \Delta F = 5.35 \times \ln\left(\frac{410}{280}\right) = 5.35 \times \ln(1.464) = 5.35 \times 0.381 = 2.04 \, \text{W/m}^2 \]
Step 2: Calculate temperature change \(\Delta T\):
\[ \Delta T = \lambda \times \Delta F = 0.8 \times 2.04 = 1.63^\circ C \]
Answer: The estimated temperature increase is approximately 1.63°C.
Step 1: Observe the graph trend: temperature anomalies increase over time, indicating warming.
Step 2: Note fluctuations due to natural variability (e.g., volcanic eruptions, El Niño events).
Step 3: Link the upward trend to increased greenhouse gas emissions from human activities.
Answer: The graph shows a clear warming trend consistent with enhanced greenhouse effect caused by anthropogenic emissions.
Step 1: Multiply fuel consumption by emission factor:
\( CF = 1200 \, \text{liters} \times 2.31 \, \text{kg CO}_2/\text{liter} = 2772 \, \text{kg CO}_2 \)
Answer: The vehicle emits approximately 2772 kg (2.77 tonnes) of CO₂ annually.
Step 1: Multiply area by sequestration rate and time:
\( \text{Total CO}_2 = 1 \, \text{ha} \times 5 \, \text{t CO}_2/\text{ha/year} \times 10 \, \text{years} = 50 \, \text{tonnes CO}_2 \)
Answer: One hectare of forest can sequester approximately 50 tonnes of CO₂ over 10 years.
When to use: Quick recall of greenhouse gases during exams.
When to use: Calculating temperature changes from CO₂ concentration changes.
When to use: Answering conceptual questions on climate change impacts.
When to use: Data interpretation and analysis questions in CUET PG.
When to use: Numerical problems involving energy and emissions.
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