What role do currents play in transporting heat? how does water temperature affect land nearby?

When warm currents move over cool land surface, they dissipate heat due to the temperature gradient . They hence warm up the land they blow over. If a cold current blows over warm land, the land loses heat to the current. This is how currents distribute heat across the earth.

When the current blow from water to land, the current will be warm or cold depending on the water temperatures. Therefore, they will warm up or cool the adjacent land mass.