World’s Physical Geography

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.

Model Answer

Impact of Ocean Currents and Waves on Marine Ecosystems

Ocean currents and waves significantly influence marine ecosystems in multiple ways, including nutrient distribution, migration patterns, and climate regulation:

1. Larvae Dispersal: Ocean currents act as highways for marine organisms, aiding in the movement and colonization of species. For instance, the North Equatorial Current helps transport coral larvae across vast distances, promoting coral reef diversity.
2. Migration Patterns: Currents serve as pathways for marine species such as whales, fish, and sea turtles during their migrations. The East Australian Current, for example, assists in the migration of humpback whales and sea turtles along Australia’s coast.
3. Temperature and Climate Regulation: Some currents, like the Gulf Stream, transport warm waters, impacting regional climates. The Gulf Stream affects eastern North America’s climate and supports marine biodiversity in the region.
4. Nutrient Transport: Upwelling, driven by ocean currents, brings nutrient-rich waters to the surface, supporting phytoplankton growth, which is the base of the marine food chain. This sustains entire ecosystems.
5. Oxygen Distribution: Ocean currents also ensure oxygen distribution in marine environments, moving oxygen-rich surface waters to deeper areas, essential for marine life’s survival.

Impact on Coastal Communities

Ocean currents and waves also have direct implications for coastal communities, influencing climate, economy, and even disaster risks:

1. Climate and Weather: Warm ocean currents, such as the North Atlantic Drift, bring milder temperatures to coastal regions, supporting agriculture and tourism. In contrast, cold currents like the Canary Current bring cooler temperatures and fog, affecting local climate.
2. Fishing and Economy: Upwelling zones created by ocean currents concentrate nutrients, attracting fish and supporting fishing industries. The Peruvian coast benefits from this high productivity, supporting its economy.
3. Navigation and Shipping: Ocean currents assist ships in reducing travel time and fuel consumption, benefiting shipping industries.
4. Marine Pollution: Ocean currents can transport pollutants and marine debris to coastal regions, harming ecosystems and human health.
5. Disaster Risks: Ocean currents, such as the Gulf Stream, influence storm trajectories and intensity, increasing the vulnerability of coastal communities to hurricanes and storm surges.

In conclusion, ocean currents and waves play a vital role in both marine ecosystems and coastal economies, influencing everything from biodiversity to climate and shipping industries. Understanding these factors is crucial for sustainable coastal 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.