One globally important consequence of the horizontal ocean circulation and one globally important consequence of vertical circulation in the oceans?

Answer 1

For an example of the first effect, read "The Impact of the Gulf Stream Current" at
http://geography.about.com/od/physicalgeography/a/gulfstream.htm
The current helps keep the climate of Ireland and Great Britain much milder than it would be otherwise.

For an important example of vertical circulation, read about the importance of nutrient distribution, phytoplankton and krill off the coast of Antarctica. Learn more about it at
http://en.wikipedia.org/wiki/Antarctic_krill