Why do oceans moderate climate?

Answer: High water heat capacity

Ocean currents distribute cold — Wrong. Currents do transport heat, but basic reason is water's high heat capacity—absorbs/releases enormous heat without big temperature change.

High water heat capacity ✓ — Correct! Thermal mass effect! Oceans moderate climate because: (1) Water: very high specific heat capacity (4x higher than land). (2) Absorbs huge heat with small temperature rise. (3) Releases heat slowly in winter. (4) Coastal areas: cooler summers, warmer winters. (5) Continental interiors: extreme temperature swings. Ocean: 70% of Earth surface—massive heat reservoir. Example: San Francisco vs Kansas City (same latitude)—SF moderate year-round, KC extreme seasons. Also: currents transport heat globally (Gulf Stream warms Europe). Evaporation adds humidity (moderates temperature further)!

Salt water stores more heat — Wrong. Salinity has minimal effect on heat capacity. Fresh or salt water both have high heat capacity—much greater than land/rock.