Paleo Slide Set: Coral Paleoclimatology:Natural Record of Climate change for High School Student
South Pacific cross-section during normal years.

ENSO (El Niņo-Southern Oscillation) refers to changes of the entire Pacific climate system. This slide displays 
the Pacific Ocean during a normal period. The trade winds continually push the water and air from the east to the west. 
The sea level on the west side of the Pacific Ocean (Australia), is about a half of a meter higher than on the 
South American side during this time! The cold water rises (upwells) from the deep ocean replacing the warm water 
in the eastern Pacific, and carrying to the surface the nutrients from decomposing animals at the bottom. 
This process of cold water bringing nutrients to the surface is called upwelling.

Water warms as it is transported through the tropics to the west via the trade winds. The warm water causes 
the moist maritime air to rise. As the air rises it cools, causing water to condense into droplets 
(just like humid air that cools on the outside of a glass of ice water). This process brings abundant rainfall 
to Indonesia and other parts of the western Pacific region. 

Photo Credits:
Sarah H. Dawson 
NOAA Paleoclimatology Program