World Geography

Model Answer

Introduction

El Niño and La Niña are two opposing phases of the El Niño-Southern Oscillation (ENSO), a natural climate cycle occurring in the Pacific Ocean. These phases influence global weather patterns by altering sea surface temperatures, ocean currents, and atmospheric conditions.

El Niño and La Niña: Key Differences

• El Niño is characterized by warmer-than-average sea surface temperatures in the central and eastern Pacific. This phase weakens the trade winds and reduces upwelling along the American coast, leading to significant weather disruptions, such as droughts, heatwaves, and wildfires in some regions, and increased rainfall and flooding in others.
• La Niña, on the other hand, is marked by cooler-than-average sea surface temperatures and stronger-than-average trade winds. It enhances upwelling along the American coast and brings about contrasting weather patterns, such as floods, heavy rainfall, and landslides in some areas, while causing drier conditions elsewhere.

Global Weather Impact

Both El Niño and La Niña disrupt weather patterns worldwide:

• South America experiences extreme weather under both phases. El Niño causes heavy rainfall and flooding along the Pacific coast, while La Niña brings drier conditions and cooler temperatures inland.
• Australia and Southeast Asia suffer from reduced rainfall and wildfires during El Niño, while La Niña increases rainfall and causes flooding.
• North America sees warmer temperatures and drought in the west during El Niño, with cooler temperatures and drier conditions in the south during La Niña.
• Africa faces drought in the east and increased rainfall in the south during El Niño, whereas La Niña reverses this, causing more rainfall in the east and drought in the south.
• India experiences reduced monsoon rainfall, droughts, and heatwaves during El Niño, but increased rainfall and flooding during La Niña.

Conclusion

El Niño and La Niña are crucial to understanding global weather patterns, with their far-reaching impacts on regions worldwide. These phases illustrate how interconnected and dynamic the Earth’s climate systems are, requiring proactive risk management and disaster preparedness.

Model Answer

Significance of Coral Reefs in Maintaining Marine Ecosystems

Coral reefs are often referred to as the “rainforests of the sea” due to their immense biodiversity and ecological importance. They are home to around 25% of all marine species, including fish, mollusks, crustaceans, and other marine life. The Great Barrier Reef, for example, hosts over 1,500 species of fish and more than 400 species of coral. In addition to supporting marine biodiversity, coral reefs offer a variety of ecosystem services, including coastal protection, water filtration, and carbon sequestration.

Impacts of Global Warming on Coral Reefs

However, coral reefs are highly vulnerable to the effects of global warming, with rising sea temperatures being one of the primary threats. When sea temperatures increase, corals undergo a process called “bleaching,” where they expel the algae living inside them, which provide them with nutrients. This weakens the corals, making them more susceptible to disease and death. The destruction of coral reefs has several far-reaching consequences for marine ecosystems:

1. Loss of Biodiversity: Coral reefs support a vast array of marine life, and their destruction could lead to the extinction of many species. For instance, the decline of coral reefs could significantly affect fish populations, including those that are important for commercial fishing.
2. Increased Coastal Erosion: Coral reefs act as natural barriers, protecting coastlines from the destructive forces of waves and storms. Without them, coastal areas are more vulnerable to erosion, leading to loss of property and infrastructure. For example, the coral reefs off Belize reduce wave energy by up to 97%.
3. Reduction in Carbon Storage: Coral reefs play a key role in the global carbon cycle by absorbing carbon dioxide. The destruction of these reefs could reduce their capacity to sequester carbon, thus exacerbating climate change.
4. Water Quality Decline: Coral reefs help maintain water quality by filtering pollutants and excess nutrients. Their loss could lead to a decline in water quality, negatively impacting both marine life and human health.
5. Economic and Societal Impacts: Coral reefs provide economic benefits through fisheries, tourism, and coastal protection. The destruction of these reefs could disrupt local economies, especially in regions where communities rely on them for livelihoods. Additionally, many cultures have deep cultural ties to coral reefs, and their loss could impact these communities’ heritage.

Conclusion

The destruction of coral reefs due to global warming poses a grave threat to marine ecosystems and human societies. Immediate action to mitigate climate change, protect coral reefs, and reduce pollution is critical to preserving these vital ecosystems for future generations.