Explanation:

1 and 2 only

Statement 1 is correct, because: Cold ocean currents are large masses of cold water that move towards the equator, from a level of high altitude to lower levels.  They absorb the heat they receive in the tropics, thereby cooling the air above them. The cold currents often form when the air on the subtropical high blows over a cold mass of water, then the cold air is dragged to the equator. eg: Peruvian Current, California Current, Canariess Current, Benguela Current etc all are in western margins of the continents. 
Cold ocean currents contribute to the formation of coastal deserts. Air blowing toward shore, chilled by contact with cold water, produces a layer of fog. This heavy fog drifts onto land. Although humidity is high, the atmospheric changes that normally cause rainfall are not present. A coastal desert may be almost totally rainless, yet damp with fog. The Atacama Desert, on the Pacific shores of Chile, is a coastal desert. 

Statement 3 is incorrect because: When the warm and the cold currents meet, dense fog is created. This is because air above the warm currents is warm which contains water vapour. When this warm current meet the cold current, the air above the cold current, causes the water vapour of the warm current to condense into tiny particles which form fog.