First off, certain famous ocean currents have well-known effects on climate. Consider the Gulf Stream. The climate in Northwestern Europe (the UK especially) is much more mild than it is directly across the Atlantic in Canada and the Northeastern US. There can be up to a 30-40 degree (Fahrenheit) air temperature difference in January between these two areas. The Atlantic Ocean near Canada is locked in ice in winter but the Atlantic Ocean near England is not. It is thought that the huge temperature difference is due to the Gulf Stream, one of the strongest currents in the ocean, and one of the best studied. (Ben Franklin was one of the first people to map this current. You can check out information on Gulf stream History.)
The Gulf Stream brings warm water from the Carribean and Florida north, along the coast of the US, and then east across the Atlantic to Europe. Because it takes a right-hand turn somewhere around North Carolina, the warming effect of its waters misses the Northeast US and Canada, but does reach England and Ireland. Take a look at some maps of the The Gulf stream and maps.
Wheither or not you think that the relatively mild climate in England, Scotland, Wales, Ireland and Northern Ireland is due to the direct effect of the warm water in the Gulf Stream, or to the indirect effect of The Great Ocean Conveyor Belt ("thermohaline circulation"), of which the Gulf Stream is a part, either way the warming is partly caused by ocean currents. If the Gulf stream was to slow down considerably (as it has in the past), then winters in Europe would become very cold. The last time this happened, from 1450-1900, it was called The Little Ice Age.
There is some concern that current global warming caused by rising carbon dioxide concentrations will cause the polar ice cap to melt and slow down the Great Ocean Conveyor Belt, thus slowing down the Gulf Stream and sparking a cooling event in Western Europe. This is the (tiny bit of) science behind the movie...
Please join StudyMode to read the full document