El Niño and La Niña are climate patterns characterized by fluctuations in sea surface temperatures in the equatorial Pacific Ocean. During El Niño, warm water shifts eastward, suppressing coastal upwelling and reducing nutrients. La Niña has the opposite effect, with stronger trade winds pushing warm water westward and enhancing coastal upwelling and nutrients. These changes impact global weather patterns and ocean productivity.
7. Surface winds
blow westward
EQUATOR
AUSTRALIA Warm waters SOUTH
pushed westward AMERICA
Warm water
Cold water
Normal Conditions
8. Causes
cold
tongue to
extend
west
Deep, cold &
nutrient rich
waters NORMAL CONDITIONS
SUPPORT COASTAL
UPWELLING.
9. SUNLIGHT
ONLY UPWELLING CAN
RETURN THE FERTILIZING
NUTRIENTS TO THE PHOTIC
ZONE
NORMAL CONDITIONS
SUPPORT COASTAL
UPWELLING.
10. El nino conditions
Normally, temperatures of surface waters in the western Pacific are
6 to 8 degrees Celsius (10 to 15 degrees Fahrenheit) warmer than in
the east. But during an El Niño, the temperature differential
reverses.
The nutrient-poor warm water forces the fish that normally thrive
off the west coast of South America to go elsewhere to find food.
Birds that would feed on the fish die off, and the local fishing
economy suffers.
El Niño causes far-reaching weather events as well, including
drought and heatwaves across Australia, torrential rainfall in
Central and South America, and heavy winter snows and floods in
the southern United States -- all of which affect water resources and
food supply.
17. HOT
POOL
SHIFTS
EAST
NO
COLD
TONGUE
NO
UPWELLING
EL NINO CONDITIONS
18. El Niño Conditions
• Weakening of Walker
• Decreased pressure gradient
• Weaken Trade winds
• Stronger Eq Counter Current
• Migration of warm pool
• Reduced upwelling (east)
• Shallower thermocline (west)
• Shift in rainfall to the east
19. Winds weaken,
causing updrafts
and storms
Drought in
Australia and
Southeast Asia
EQUATOR
Warm water
AUSTRALIA flow stopped SOUTH
or reversed AMERICA
Warm water deepens off
Warm water South America
Cold water
El Niño Conditions
20. EL NINO SUPRESSES COASTAL
UPWELLING, REDUCES NUTRIENTS
& CAUSES SURFACE POPULATIONS
TO DISAPPEAR.
22. El Niño plays havoc with world weather
Fires in the Amazon
Worsening drought in Sahel
• Weakens Indian Monsoon.
• Causes drought in central North America.
23. 1983 El Niño caused
severe drought, heat waves and
Bushfires in Australia.
Flames devour farmland in Victoria,
Australia.
El Niño triggered prolonged drought
of 1983 made fire a constant hazard.
In 1983, winds whipped fires from
Adelaide to Melbourne, destroying
seven towns and several thousand
homes.
24.
25. EN
EN
Approximately 25% of the
23,000 pups born in June 1997
at San Miguel Island died.
26.
27.
28. El Niño
• During an El Niño year
– normally strong trade winds weaken, and sometimes even
reverse direction
– warm water of the western Pacific Ocean moves eastward,
keeping deep cold water from rising to the surface off
the west coast of South America.
– Jet stream brings warm, moist air to the US
– causes
• Storms in California
• Heavier than normal precipitation in much of the US
• Droughts in Africa and Australia
• Monsoon rains in Indonesia
31. La Niña
• During a La Niña year
– Trade winds increase in strength and blow even
stronger than normal from east to west
• water in the western Pacific Ocean becomes
warmer
• water in the Eastern Pacific near the coast of South
America becomes colder
• Warm ocean waters, clouds and moisture are
pushed away from North America
– Causes:
• Hot, dry weather with droughts in the southern US
• Cool weather and excess rainfall in the
northeastern US
32. El Niño / La Niña
• El Niño and La Niña change worldwide weather
patterns in complex ways.
• Scientists do not yet understand what triggers these
events.
• An El Niño or La Niña event lasts 1 to 2 years, and
occurs every 3 to 6 years, but some events are mild
while others are severe.
• The most severe recent El Niño events occurred in
1982-83 and 1998.
• An El Niño generally causes more disruption in global
weather patterns than La Niña, but severe drought
occurs in the southern U.S. during a La Niña.
35. HOT
POOL
LA NINA CONDITIONS
SHIFTS EXTENDED
WEST COLD
TONGUE
HUGE
UPWELLING
36. El Niño La Niña impacts ocean productivity
Normal Conditions and La Nina = more productive
Nutrients
El Nino Conditions = less productive
Editor's Notes
During an El Niño event, the southeast trade winds weaken and so does the amount upwelling in the eastern Pacific. The deeper thermocline means that any upwelling that does occur is unable to tap into the rich nutrients found in deeper waters. Consequently, warm nutrient-poor water predominates the region and a decrease in the fish population is observed. During non-El Niño years, the southeast trade winds, drag surface water westward away from shore. As surface water moves away, upwelling brings up colder waters from depths of 40-80 meters or more. This deep sea water is rich in nutrients which can sustain large fish populations.