An ocean current is a continuous movement flowing in the ocean. It is caused by many forces such as solar heating, winds, gravity, earth’s rotation, and many more, which explain the fragility of its constitution.
It takes the form of a river inside the ocean, and is hot or cold depending on their starting point. It basically redistributes the heat received near the equator and the cold from the polar region. This has an important impact on the climate of nearby continents. Today, climate change is modifying the interaction between the elements that create the currents. For instance, as glaciers melt the ocean gets fresher, also, the polar region is heating up faster then any other region.
The outcome is that the temperature difference between the poles and the equator is shrinking. Since ocean currents depend on the clash of temperature, they will slow down. Without any doubt, some continents will experience changes in term of temperature and precipitations. In fact, it has been shown in the past that areas like Iceland and Greenland have plunged into an ice age when their heat currents shut down.
Nothing is proven for sure that an ice age could occur on a larger scale, although fears of the disappearance of the Gulf Stream have led to movies like The Day After Tomorrow. One thing is for sure, is that our climate is very sensitive to changes and this adds another domino effect to ecological change.