Geography

Model Answer

Introduction

The Circum-Pacific Zone stands out globally due to its unique geophysical features, primarily driven by the tectonic processes at its boundaries. This region, known as the Ring of Fire, is home to extensive seismic and volcanic activity, which significantly differs from other tectonic regions in several ways.

Subduction Zones

The Circum-Pacific Zone is primarily composed of subduction zones, where one tectonic plate is forced beneath another, creating deep ocean trenches. Some of the largest and deepest trenches in the world are located here, such as the Mariana Trench. In contrast, other tectonic regions feature a more diverse array of plate boundaries, including divergent and transform boundaries. For example, the Mid-Atlantic Ridge is a divergent boundary, and the San Andreas Fault is a transform boundary, leading to different geological outcomes.

Seismic Activity

The seismic activity in the Circum-Pacific Zone is among the highest on Earth, due to the constant interaction and movement of tectonic plates. This results in frequent and intense earthquakes. In other tectonic regions, while seismic activity is present, it is often less frequent or intense. For instance, regions like the Himalayas experience seismic events, but not on the same scale as the Circum-Pacific Zone.

Volcanism

The Circum-Pacific Zone is the site of extensive volcanic activity, hosting over 75% of the world’s active and dormant volcanoes. Some of the most famous and destructive volcanoes, such as Mount St. Helens and Mount Fuji, are located here. Comparatively, other regions, such as the Mediterranean or East Africa, have smaller active volcanoes, but the frequency and scale of eruptions are less than in the Circum-Pacific.

Conclusion

In summary, the Circum-Pacific Zone’s geophysical characteristics—dominated by subduction zones, high seismic and volcanic activity, and large tectonic plates—set it apart from other tectonic regions, which may exhibit different types of plate boundaries and less intense geological activity.

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

Introduction

Sea Surface Temperature rise (SST) refers to the significant increase in the temperature of ocean surface waters, primarily driven by anthropogenic climate change. Over the last four decades, the average SST has increased by about 0.6°C, and approximately 0.9°C since the pre-industrial era, which has profound implications for cyclone formation and intensity.

The Phenomenon of Sea Surface Temperature Rise

1. Greenhouse Gas Emissions: Increased greenhouse gas concentrations trap heat in the atmosphere, causing oceans to absorb more heat, which contributes to rising SST and alters marine ecosystems.
2. Carbon Dioxide Absorption: Oceans absorb about 30% of human-emitted CO₂, leading to changes in ocean chemistry and contributing to the warming of surface waters.
3. Albedo Effect: The melting of polar ice reduces the Earth’s reflective surface, allowing more sunlight to be absorbed by ocean waters, which accelerates SST rise and disrupts polar ecosystems.
4. Global Temperature Rise: Global SST has risen in parallel with atmospheric temperatures, increasing by approximately 1°C since 1880 .
5. Altered Ocean Currents: Changes in ocean currents disrupt heat distribution, leading to localized warming.
6. Increased Solar Radiation: Enhanced greenhouse gas concentrations trap more heat, causing oceans to absorb more solar energy.

Impact of SST Rise on Tropical Cyclone Formation

1. Increased Intensity: Higher SST provides more energy to developing tropical cyclones, intensifying their strength. For example, Cyclone Amphan (2020) was fueled by warm Bay of Bengal waters, reaching super-cyclone status.
2. More Frequent and Severe Storms: Rising SSTs lead to an increase in the number of severe tropical cyclones. The 2020 Atlantic hurricane season saw 30 named storms, driven in part by higher-than-average SSTs.
3. Amplified Rainfall: Warmer ocean surfaces increase atmospheric moisture, leading to heavier rainfall during cyclones, which can cause devastating floods.
4. Extended Duration: Cyclones fueled by higher SSTs tend to last longer and travel further inland. Cyclone Idai (2019) maintained its intensity well after landfall in Mozambique due to warm waters.
5. Shifts in Cyclone Tracks: SST rise can alter cyclone tracks, pushing them toward regions that historically experienced fewer storms. For instance, Hurricane Ophelia (2017) reached Ireland, a rare occurrence attributed to anomalous SSTs.
6. Impact on Vulnerable Regions: Countries with warmer waters, such as those bordering the Indian and Pacific Oceans, face increased risks of intensified tropical cyclones.

The rise in sea surface temperatures significantly challenges us by increasing the intensity and frequency of tropical cyclones. However, global climate action, including reducing greenhouse gas emissions and adopting sustainable practices, can help mitigate this rise.