Page 325 - Earth's Climate Past and Future
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CHAPTER 16 • Climate Changes During the Last 1000 Years 301
BOX 16–2 CLIMATE INTERACTIONS AND FEEDBACKS
CONTINUED
of latent heat and moisture for local rains. When the flow northern Australia and Indonesia. Eventually El Niño con-
reaches the Americas, it deflects northward and south- ditions subside and the tropical ocean reverts to its nor-
ward along the coast, bringing warmer and wetter condi- mal state. On occasion it overshoots its normal state and
tions north to California and south to Peru, along with produces abnormally cool sea-surface temperatures in the
reduced upwelling. In the western Pacific, slightly cooler eastern Pacific. This overshoot is called La Niña, or “the
conditions during El Niño years result in the drying in girl child.”
North
America
L Equator Strong trade winds
H
Tahiti H
Australia
South
America
A Non El Nino year
~
North
America
Equator Weak
H L
trade winds
Tahiti H
Australia
Circulation in El Niño and non–El
South
America Niño years El Niño events change
atmospheric and ocean circulation
across the entire Pacific Ocean,
from Australia and Indonesia to the
~
B El Nino year west coast of South America.
