UPSC Mains Daily Answer Writing (18-11-2022) - GS 1

Questions

Q1. Warmer waters of Bay of Bengal are typically more prone to cyclones than the cooler and calmer Arabian Sea, but the trend seems to be changing. Examine. (250 words) 15 marks

Q2. Highlight the conditions suitable for formation and development of coral reefs. Also, discuss various natural and anthropogenic factors responsible for their destruction. (250 words)   15 marks

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Model Solutions

Q1. Warmer waters of Bay of Bengal are typically more prone to cyclones than the cooler and calmer Arabian Sea, but the trend seems to be changing. Examine. (250 words) 15 marks

Model Structure
Introduction:

• Tropical cyclones are intense circular destructive storms with a low-pressure center forming over tropical ocean waters.
• When both are compared, the BOB sees approximately 5 times more cyclones than Arabian sea. Also, cyclones in BOB are stronger and deadlier.

Main Body:

• Bay of Bengal (BoB) is more prone to cyclones than Arabian Sea because:
  • Sluggish winds: Slow moving air around BoB keeps temperatures relatively high.
    • This aids the formation of cyclones due to higher vaporization from sea.
    • The Arabian Sea, on the other hand experiences stronger winds which dissipate the heat and prevent cyclone formation.
  • Freshwater inflow: BoB receives high inflow of warm water from Ganga and Brahmaputra, and of all the rainfall in their catchment areas.
    • The large influx keeps surface temperatures high.
    • Lack of constant fresh water supply in the Arabian sea results in better mixing of warm and cold layers, preventing formation of strong depressions.
  • Coastline: The trough-like shape of Bay of Bengal’s coastline intensifies cyclonic winds.
    • Shallow depth due to the emerging coast helps push the water up to create storm systems. Such features are absent in the Arabian sea.
  • Pacific cyclones: Cyclones from the Pacific Ocean, move towards BOB.
    • Lack of large landmass between Pacific and Bay aids easy movement of cyclonic winds.
• In recent times, the frequency of cyclones in Arabian sea is increasing because of climate change. Causal relationship between climate change and cyclones in Arabian sea can be understood as:
  • Rising temperature: A 2014 study found that Indian Ocean temperature rose by 0.7℃, but the Arabian sea experienced 1.2℃ rise during summer.
    • Ocean has warmed up to greater depth. Churning of ocean water by wind no longer cools down the Sea Surface temperature.
  • El-Nino: Climate change is altering the cycles of El Nino (EN) and El Nino Modoki (ENM).
    • A study by the National Institute of Oceanography, suggests that ENM and EN which usually intensify cyclone formation over BOB have been creating larger areas for wind convergence over Arabian sea, intensifying cyclonic activities.
  • Wind intensity: Climate change is altering the global atmospheric circulations.
    • It has led to intensification of easterly winds, which is pushing cyclones from BOB towards Arabian sea.
    • For example, cyclone Ockhi generated in BOB and drifted towards Arabian Sea due to intense easterly winds.

Conclusion:

• With increased cyclone frequency in Arabian Sea, India should prepare itself to prevent any large loss of lives.
• Early warning system should consider the changing climate scenario. Local communities need to be trained to deal with changing situations.

Q2. Highlight the conditions suitable for formation and development of coral reefs. Also, discuss various natural and anthropogenic factors responsible for their destruction. (250 words) 15 marks
Model Structure
Introduction:

• A coral is a marine organism which exists in symbiotic relationship with zooxanthellae (algae) in tropical waters to form coral reefs. There are three main types of coral reefs: fringing, barrier and atoll.
• Coral reefs, also known as rainforests of the oceans, are one of the most diverse and important marine ecosystems. Coral reefs have great economic significance as they are rich fishing grounds as well as tourist attractions.

Main Body:

• Following conditions are suitable for formation and development of coral reefs:
  • Shallow Depth: Corals depend on zooxanthellae which need sunlight to survive. Thus, Coral reefs grow at shallow depths, where sunlight filters through to support the symbiotic algae.
  • Warm Water: Most corals survive in a narrow temperature range of 23-29 ℃ with some species surviving at as low as 20 ℃ and few others at as high as 32 ℃.
  • Clean saltwater: Corals are sensitive to pollution and sediments. So, corals require clean water for growth. In addition, corals require balanced salinity to survive and grow.
  • Oxygen and Plankton: Adequate oxygen and microscopic marine food, called phytoplankton, is essential for coral growth. Often, these are found near sea surface.
• Coral bleaching is the process where corals turn white because coral polyps expel the algae zooxanthellae that live inside their tissue. Coral bleaching/ coral destruction occur as a result various natural and anthropogenic factors discussed below:
  • Natural factors:
    • Weather-related damage: Corals frequently sustain weather-related damage. Eg. powerful waves from hurricanes and cyclones can break apart or flatten large coral heads.
    • Tidal Changes: Long periods of exceptionally low tides leave coral heads exposed, and damage the reef. The amount of damage depends on the time of day and the weather conditions.
    • El Nino: Increased sea-surface temperatures and salinity can occur due to El Nino, which can kill corals. Eg. During the 1997-1998 El Nino, extensive coral reef bleaching in the Indo-Pacific and Caribbean destroyed 90% of the corals.
  • Anthropogenic factors:
    • Global warming: Increased GHGs from deforestation, burning of fossil fuels etc.. With effects on ocean temperatures, storm patterns, and sea level has altered habitat conditions of corals.
    • Pollution: Pollution in form of oil spillage, flow of urban and industrial waste, and agrochemicals into seas are poisoning reefs.
    • Destructive fishing practices: These include cyanide fishing, blast or dynamite fishing, bottom trawling, and muro-ami (banging on reefs with sticks).
    • Careless tourism: Careless tourism including boating, diving, snorkeling, with people touching reefs, collecting coral, etc. Resorts being built on reefs are destroying corals around the world.
    • Construction and mining: Erosion due to illegal construction, mining, including effects of higher riverine and coastal sediments kill corals by depriving them of sunlight.

Conclusion:

• Anthropogenic activities, which have led to global warming, have created existential threats for the coral ecosystem.
• There is a need to conserve the highly biodiverse coral reefs through regulation of human activities in coral regions, while increasing the scientific understanding of coral ecosystems to find solutions for their regeneration.

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