Oceans and Climate Changes. Ocean Currents Movement of water from one place to another.

Oceans and Climate Changes

Ocean Currents

•Movement of water from one place to another

Surface Currents•Powered by wind

•Move upper few 100 meters of seawater

•Wind forms when air in an area of high pressure moves to an area of lower pressure

•Equator’s warm air is pushed up by denser, colder air

•The Pole’s cold air, sinks below less dense air

•Due to the movement of the earth, wind and currents DO NOT move in straight lines

•The Coriolis Effect – rotation of the Earth causes moving air and water to change direction–To the right north of the equator

–To the left south of the equator

Gulf Stream Current - Warm• Atlantic Ocean• Brings warm water

from the equator up North

• Keeps N. American East Coast Waters warm

• Keeps Iceland mild and ice-free all year

California Current - Cold

•Pacific Ocean•Brings waters

from North pole down South

•Keeps North American West Coast Cool

Density Currents

• More dense water sinks and pushes up less dense water

• This moves water around globe

What makes Water Dense?

• Cold Temperature

• High Salinity (amount of salt in water)

Cold, Salty Water

• When water freezes, salts are dissolved and left in unfrozen water – This makes unfrozen water VERY DENSE

• When frozen water melts, it is less dense• This causes a change in density and

movement of water…DENSITY CURRENTS

WHY IS THIS IMPORTANT?

It is important because…• If the ice caps where to melt, then

we would have a large amount of less dense water

• If salinity is reduced, then density currents would WEAKEN or STOP

•This would cause major CLIMATE SHIFTS–Change in climate–Change in weather

El Nino

•An occasional climatic event in which strong Pacific winds WEAKEN or REVERSE

Effects of El Nino

•Ocean temperatures near Peru HEAT UP.

•The position and strength of one of the jet streams may be altered, changing wind and precipitation patterns around the world.

•Africa and Australia may experience drought

La Nina

•The winds blowing across the Pacific are stronger than normal