Account for variations in oceanic salinity and discuss its multidimensional effects.

Theme

T33 Oceans & marine environment: currents, salinity, dead zones, oil pollution, marine resources

What UPSC asks in this theme

UPSC asks about forces behind ocean currents and their role in climate, fishing and navigation; salinity variations; dead zones; oil pollution; and ocean resources for the resource crisis.

What to cover

• Currents: wind, Coriolis, temperature, salinity; warm vs cold currents
• Fishing grounds where warm and cold currents meet
• Salinity distribution and effects
• Dead zones: eutrophication, hypoxia
• Oil spills: impacts on marine life and coasts
• Ocean resources: minerals, energy, food, deep sea mission

Writing the answer

• Map-based examples (Grand Banks, Peru) add marks

These notes are for the whole theme, built from all 6 of its PYQs. UPSC does not publish model answers.