Chart of ocean currents. The direction of the currents is marked by arrows.There are 17 major surface ocean currents. They circulate water around the world affecting the movement of energy and moisture between the oceans and the atmosphere thus affecting the world's weather. For example the Gulf Stream which originates in the Gulf of Mexico is a warm current making Western Europe warmer than other areas at the same latitiude. The Humboldt current is a cold low-salinity current flowing north-westwards from the southern tip of Chile to northern Peru. It has a cooling influence on Chile, Peru and Ecuador and is a major cause of the desert conditions in northern Chile and is the most productive marine ecosystem in the world providing about a fifth of the world's fish supply. Changes in temperature of the Earth's surface affect ocean currents and their impact.