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6.25: How Ocean Currents Moderate Climate

Difficulty Level: Basic Created by: CK-12
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How do ocean currents create giant redwoods?

The California Current brings cool water south along the western U.S. Cool water contacting warmer water creates fog. This creates a favorable habitat for the giant redwoods of the northern California coast.

Surface Currents and Climate

Large ocean currents can have a big impact on climate, especially of nearby coasts. The equator and the poles have very different climates today. But these regions woud be much more different without ocean surface currents. These currents move heat around the globe. The best known of these is the Gulf Stream, which warms parts of Europe. But other currents also alter near-shore climates. Like the Gulf Stream, the Kushiro Current warms Japan. Cooler currents that move from the polar regions to the equator also alter climate.

The Gulf Stream

The Gulf Stream carries warm water from near the equator up the eastern coast of North America. Look at the map in Figure below. It shows how the Gulf Stream warms both the water and land along the coast.

In this satellite photo, different colors indicate the temperatures of water and land. The warm Gulf Stream can be seen snaking up eastern North America.

The warm water then flows across the Atlantic Ocean to Europe. The Gulf Stream's warm waters raise temperatures in the North Sea. The warmer ocean temperatures raise the air temperatures over land. The difference is between 3 to 6oC (5 to 11oF). London, U.K., for example, is about six degrees further south than Quebec, Canada. However, London’s average January temperature is nearly 16oC (28oF) warmer. London also gets a lot of rain (see Figure below). Air traveling over the warm Gulf Stream water picks up moisture. Quebec is much drier, but much snowier (see Figure below).

London, England in winter.

Quebec City, Quebec in winter.


  • Water in the Gulf Stream warms as it travels along the equator. The Gulf Stream brings warm water north along the United States. It then travels across the northern Atlantic to the British Isles.
  • The Gulf Stream creates a relatively warm wet climate for the British Isles. This compares with the frigid Quebec at about the same latitude.
  • Ocean currents transfer heat from the equator toward the poles. This moderates Earth's temperature.


Use this resource to answer the questions that follow.

Global Weather Extremes and the Gulf Stream at http://www.youtube.com/watch?v=Lb854zXy2IQ (6:03)

  1. What occurred in the Atacoma desert in July 2011?
  2. What was the weather like in Australia in August and September 2011?
  3. What happened in the summer of 2011 in the United States?
  4. How many temperature records were broken in 2011?
  5. Why are scientists monitoring the Arctic ice?
  6. What are the effects of the ice melt?
  7. How is the Gulf Stream affected by the melting of the Arctic ice?


  1. Why is England relatively mild and rainy in winter? Why is central Canada, at the same latitude and during the same season, relatively dry and frigid?
  2. Where else do you think ocean currents might moderate global climate?
  3. What would Earth be like if ocean water did not move?

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Gulf Stream

A large, swift ocean current that transports warm equatorial waters northward and moderates climate.

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Difficulty Level:
6 , 7
Date Created:
Jan 04, 2013
Last Modified:
Aug 12, 2016
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