GED Science TestEarth and Space ScienceMedium
A climatologist is studying the factors that influence global ocean currents. Which of the following plays the most significant role in driving the deep-ocean currents, also known as the thermohaline circulation?
- ADifferences in water temperature and salinity.
- BPrevailing surface winds pushing water horizontally.
- CHeat transfer from the Earth's core to the ocean floor.
- DGravitational pull of the Moon and Sun.
Show answer & explanationAnswer & explanation
Correct answer: A. Differences in water temperature and salinity.
Thermohaline circulation, which drives deep-ocean currents, is primarily driven by differences in water density. These density differences are caused by variations in temperature (thermo) and salinity (haline) of the ocean water.
Why the other options are wrong
- B. Prevailing surface winds primarily drive surface ocean currents, not the deep-ocean thermohaline circulation.
- C. Heat transfer from the Earth's core is minimal at the ocean floor and does not significantly drive large-scale ocean currents.
- D. The gravitational pull of the Moon and Sun causes tides, which are distinct from large-scale ocean currents.
Thermohaline Circulation
A global-scale system of ocean currents driven by differences in water density, which is controlled by temperature (thermo) and salinity (haline).
- Also known as the 'great ocean conveyor belt'.
- Transports heat, salt, and nutrients around the globe.
- Plays a crucial role in regulating Earth's climate.
Memory trick: Thermohaline: Temperature and Salinity's Tug-of-War.