Ocean currents are major heat distribution mechanisms for the planet and thus have a large impact on regional climate. Of the following events, which would be most likely to disrupt the density-driven thermohaline cycling of ocean currents (in particular. the Gulf Stream), causing much of Europe to experience much colder temperatures?

Coral bleaching releasing carbonate into the water

Increased whale harvests removing radiant loss from mammals

Melting of Greenland ice sheets

Addition of salt run-off from salinized Middle Eastern soil

Reduced continental run-off of freshwater stimulated by enhanced drought conditions in WESTERN North America