Climate Change and Its Impacts

Learning Outcomes:

1. Understand the causes of climate change, both natural and human-induced.
2. Comprehend the role and impact of greenhouse gases (GHGs).
3. Analyze the effects of climate change on ecosystems, agriculture, and human health.
4. Evaluate the global and regional efforts to mitigate climate change, including international protocols.
5. Learn about specific climate events, their causes, and implications.

Climate change refers to long-term changes in temperature, precipitation, and other atmospheric patterns. It can be evidenced in geological records, changes in landforms, and vegetation shifts. Minor variations in climate have been observed since the 1850s, including a rise in CO₂ levels and a 1°C warming trend.

Causes of Climate Change

Climate change is driven by both natural phenomena and human activities, with current changes accelerated by human impact.

Natural Causes

1. Volcanic Eruptions: Emit gases and particulates that affect the Earth’s climate.
2. Ocean Currents: Influence global weather patterns by redistributing heat.
3. Orbital Changes: Variations in the Earth’s orbit affect solar radiation received.
4. Solar Variations: Changes in the Sun’s intensity directly impact climate.

Anthropogenic Causes

1. Greenhouse Gases (GHGs): Increased emissions of CO₂, methane (CH₄), and nitrous oxide (N₂O), along with purely man-made GHGs like HFCs, PFCs, and SF₆, contribute to the greenhouse effect.
2. Cryogenic Processes: Permafrost melting, glaciation, and defrosting contribute to climate change by releasing stored gases such as methane.
3. Black Carbon: Produced from the incomplete combustion of materials, it accounts for more than 30% of Arctic warming.
4. Deforestation: Reduces the Earth’s carbon sinks, increasing CO₂ in the atmosphere.

Important Note: Methane is 20 times more potent than CO₂ in trapping heat, significantly impacting global warming.

Greenhouse Effect

The greenhouse effect involves solar energy warming the Earth’s surface, which then radiates back into space. GHGs in the atmosphere trap some of this energy, leading to a temperature rise. The main GHGs include water vapor, CO₂, CH₄, N₂O, and industrial gases like HFCs.

Global Warming

An increase in average global temperatures due to natural events and human activities, primarily from rising GHG levels. Strategies like cirrus cloud thinning and aerosol injection aim to mitigate its effects.

Effects of Climate Change

1. Ecosystems: Species may migrate or die out due to changing habitats. Aquatic and terrestrial ecosystems face severe disruptions.
2. Agriculture: Altered planting seasons and increased pests affect crop yields. Changes in forestry include higher incidences of fires.
3. Sea Level Rise: Currently rising at 2mm per year, thermal expansion could amplify this rate, potentially submerging low-lying areas.
4. Health: Higher temperatures facilitate the spread of infections, weaken human immunity, and increase exposure to UV radiation.
5. Weather Patterns: Increased frequency and intensity of storms, floods, and droughts.

Continent-Wise Effects

1. Australia: Loss of biodiversity in Great Barrier Reef; reduced agricultural production by 2030.
2. Small Islands: Inundation, erosion, and infrastructure damage due to rising sea levels.
3. Africa: Water stress affecting 75-250 million people by 2020; reduction in rain-fed agriculture by up to 50%.
4. Asia: Reduced freshwater by the 2050s; increased flooding, morbidity, and mortality.
5. Europe: Glacier retreat, water scarcity, and wildfires due to drought.
6. North America: Reduced snowpack, more winter floods, and changes in agricultural yields.
7. Latin America: Replacement of tropical forests by savanna; reduced water availability due to glacial loss.

Important Note: A 1m sea level rise in the 21st century could displace millions, submerging entire island nations.

Global Initiatives

United Nations Framework Convention on Climate Change (UNFCCC)

Established to assess global warming and climate change. Signed by over 150 countries at the Rio Earth Summit in 1992, it provides a framework for negotiating treaties like the Kyoto Protocol.

1. Kyoto Protocol: Legally binds developed countries to reduce emissions based on the principle of “Common But Differentiated Responsibilities” (CBDRs).
2. Paris Agreement: Aims to keep global temperature rise below 2°C with efforts to limit it to 1.5°C. Obligates developed countries to provide $100 billion annually to developing nations starting from 2020.

Key Principle: Developed nations bear a greater responsibility for historical GHG emissions and must take a leading role in mitigation efforts.

Notable Extreme Climate Events (Selected Examples)

Mitigation Strategies

Flexibility Mechanisms (Kyoto Protocol)

1. International Emissions Trading (IET): Allows countries to sell excess emissions permits.
2. Clean Development Mechanism (CDM): Developed nations invest in emission reduction projects in developing countries, earning Certified Emission Reduction (CER) credits.
3. Joint Implementation (JI): Countries earn Emission Reduction Units (ERUs) by investing in emission reduction projects in other Annex B parties.

Reducing Emissions from Deforestation and Forest Degradation (REDD+)

Involves creating financial incentives for developing nations to reduce emissions from deforestation and invest in sustainable development.

Important Concept: REDD+ extends beyond deforestation to include conservation, sustainable forest management, and enhancement of carbon stocks.

National Action Plans (India’s NAPCC)

Other Climate-Related Issues

Ozone Depletion

Ozone in the stratosphere acts as a protective layer against UV radiation. CFCs and other halogenated compounds are the main culprits behind ozone depletion, leading to increased UV exposure and climate effects.

Ocean Acidification

Increasing CO₂ absorption by oceans leads to acidity, disrupting marine ecosystems by affecting organisms’ ability to form calcium carbonate shells.

Blockquote Example

Concept: Global Dimming – Caused by pollution, it leads to more reflective clouds, reducing solar energy reaching Earth’s surface.

Recent Climate Summits

1. COP 22 (Marrakech, 2016): Adopted the Marrakech Partnership to mobilize swift climate actions.
2. COP 23 (Bonn, 2017): Emphasized urgency in implementing the Paris Agreement.
3. COP 24 (Katowice, 2018): Established Accounting Guidance Rules for comparing and aggregating INDCs.

Concept: Carbon Footprint – Total greenhouse gas emissions caused by an organization, event, product, or individual. Example: USA’s per capita footprint is 20 tonnes, whereas India’s is 1.2 tonnes.

Blockquote: One MCQ

Question: What is the main goal of the Paris Agreement?
Options:

1. Limit global warming to below 3°C.
2. Establish legally binding emission reduction targets for all countries.
3. Keep global temperature rise below 2°C with an effort to limit it to 1.5°C.
4. Provide financial aid exclusively to developed countries.
   **Correct Answer

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