Final answer:
Ocean currents are primarily affected by varying salt content, unequal heating, wind direction, and the Coriolis effect. These factors combined create currents that can transport heat across great distances and influence global climate patterns.
Step-by-step explanation:
Ocean currents are influenced by a variety of factors, and the correct answer to what varies in the water to contribute to these currents is varying salt content of the water. These currents are shaped by unequal heating of the Earth's surface, which not only impacts air movements but also the flow of oceans. The Coriolis effect, a phenomenon resulting from the rotation of the Earth, also significantly affects the direction and flow of ocean currents. Furthermore, other factors like wind direction and the physical properties of the water itself, including its density which is affected by salt content, play crucial roles in the dynamics of ocean circulation.
Ocean currents have considerable power and significantly affect global climate patterns. While water moves slower than air, the density of water compensates for this, allowing ocean currents to transport heat efficiently across great distances. This creates more stable climates, particularly in maritime regions, and contributes to phenomena such as El Niño, which impacts weather globally.