Where do warm ocean currents start?

Warm ocean currents start in tropical regions, near the equator. In comparison, cold ocean currents start near polar regions. Atmospheric winds and Earth's rotation cause the warm ocean water (from near the equator) to flow towards the polar regions in the form of western boundary currents. Some examples of these western boundary currents are the Gulf Stream, Somali Current and Kuroshio. The Gulf Stream, which originates from the Gulf of New Mexico, is one of the fastest warm currents and moves towards Europe. It is this warm ocean current that keeps a significant area of northern Europe relatively warm, as compared to other places on similar latitudes. Similarly, the Somali Current brings warm water to the Indian Ocean (at least for some part of the year, as it reverses direction twice a year).

This continuous motion of ocean currents (both warm and cold) maintains the global weather patterns and provides nutrients to the organisms of the ocean.

Hope this helps.