Making Sense of Coldwater Ocean Currents The basic understanding of ocean currents is that warm currents carry moisture whereas cold currents carry nutrients.  This is why some scientists believe in the connection between the Arctic ice caps and the warm Gulf Stream and the frigid Humboldt and Benguela currents turning the tropical lands of Chile and Namibia bone-dry.

With that, there are some confusions with the workings of coldwater ocean currents.  Antarctica is surrounded by the Antarctic Circumpolar Current, a coldwater current, yet it is covered in mile after mile of frozen water.  The Pacific coast of North America is nurtured by coldwater currents, yet we see temperate rainforests.

So what's going on?  Why are there habitats that require a lot of moisture near coldwater ocean currents that can't carry that much?
The currents run counterclockwise. That's why the Humboldt Current cools the Pacific coast of South America, because the water is coming from the "six o'clock" position in the Antarctica. But in the Northern Hemisphere, the "six o'clock" position is warm water near the equator, which warms Oregon and Washington.

In the northern hemisphere, the cold Labrador current cools land to its west. That's because the water is coming from the "12 o'clock position near the Arctic. On the other hand, the west coast benefits from warm water currents running in a counterclockwise direction. That's because the "6 'oclock" position in the northern hemisphere is near the tropics, which brings warm water to Washington and Oregon at the "2-3 o'clock" position.

All other things being equal, colder air carries less moisture than warm air, and land near cold water currents is dryer than land near warm water currents.